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Sample records for abundant fossil record

  1. Two Years of Plankton Tows in a Seasonal Upwelling Region: Foraminiferal Abundances and Implications for the Fossil Record

    NASA Astrophysics Data System (ADS)

    Davis, C. V.; Hill, T. M.; Jahncke, J.

    2014-12-01

    Planktic foraminifera have a long history of use as paleoceaographic proxies due to their environmental sensitivity, cosmopolitan distribution and extensive fossil record. The seasonal, spatial and water mass affinities of foraminifera species have implications for the interpretation of fossil assemblages and the interpretation of shell geochemistry. Two years (2012-2014) of shallow (<200 m) plankton tows, taken along the continental shelf inside the California Current system, offer new insights into the spatial and seasonal dynamics of planktic foraminifera in an upwelling regime. Tows along with intensive hydrologic monitoring by CTD casts and discrete bottle sampling (temperature, salinity, oxygen, thermocline depth, carbonate saturation state) have spanned two complete seasonal upwelling-relaxation cycles. We present the results from these tows as well as preliminary models linking environmental drivers and foraminifera assemblages in this highly dynamic environment. Species abundances appear to be highly seasonal, in keeping with water column structure, with a seasonal upwelling to relaxation trade off between the non-spinose foraminifers Neogloboquadrina pachyderma and Neogloboquadrina incompta. We focus on the implications of species seasonality and hydrologic affinities to the interpretation of the fossil record in upwelling regions.

  2. Ants and the fossil record.

    PubMed

    LaPolla, John S; Dlussky, Gennady M; Perrichot, Vincent

    2013-01-01

    The dominance of ants in the terrestrial biosphere has few equals among animals today, but this was not always the case. The oldest ants appear in the fossil record 100 million years ago, but given the scarcity of their fossils, it is presumed they were relatively minor components of Mesozoic insect life. The ant fossil record consists of two primary types of fossils, each with inherent biases: as imprints in rock and as inclusions in fossilized resins (amber). New imaging technology allows ancient ant fossils to be examined in ways never before possible. This is particularly helpful because it can be difficult to distinguish true ants from non-ants in Mesozoic fossils. Fossil discoveries continue to inform our understanding of ancient ant morphological diversity, as well as provide insights into their paleobiology.

  3. The early eukaryotic fossil record.

    PubMed

    Javaux, Emmanuelle J

    2007-01-01

    The Precambrian era records the evolution of the domain Eucarya. Although the taxonomy of fossils is often impossible to resolve beyond the level of domain, their morphology and chemistry indicate the evolution of major biological innovations. The late Archean record for eukaryotes is limited to trace amounts of biomarkers. Morphological evidence appears in late Paleoproterozoic and early Mesoproterozoic (1800-1300 Ma) rocks. The moderate diversity of preservable eukaryotic organisms includes cell walls without surface ornament (but with complex ultrastructure), with regularly distributed surface ornamentation, and with irregularly or regularly arranged processes. Collectively, these fossils suggest that eukaryotes with flexible membranes and cytoskeletons existed in mid-Proterozoic oceans. The late Mesoproterozoic-early Neoproterozoic (1300-750 Ma) is a time of diversification and evolution when direct evidence for important biological innovations occurs in the fossil record such as multicellularity, sex, photosynthesis, biomineralization, predation, and heterotrophy. Members of extant clades can be recognized and include bangiophyte red algae, xanthophyte algae, cladophorale green algae, euglyphid, lobose, and filose amoebae and possible fungi. In the late Neoproterozoic, besides more diversification of ornamented fossils, florideophyte red algae and brown algae diversify, and animals take the stage. The record of biological innovations documented by the fossils shows that eukaryotes had evolved most cytological and molecular complexities very early in the Proterozoic but environmental conditions delayed their diversification within clades until oxygen level and predation pressure increased significantly.

  4. Extinction and the fossil record

    NASA Technical Reports Server (NTRS)

    Sepkoski, J. J. Jr; Sepkoski JJ, ,. J. r. (Principal Investigator)

    1994-01-01

    The author examines evidence of mass extinctions in the fossil record and searches for reasons for such large extinctions. Five major mass extinctions eliminated at least 40 percent of animal genera in the oceans and from 65 to 95 percent of ocean species. Questions include the occurrence of gradual or catastrophic extinctions, causes, environment, the capacity of a perturbation to cause extinctions each time it happens, and the possibility and identification of complex events leading to a mass extinction.

  5. Aestivation in the fossil record: evidence from ichnology.

    PubMed

    Hembree, Daniel I

    2010-01-01

    Aestivation is a physiological and behavioral response to high temperature or low moisture conditions. Therefore, it is typically not considered to be capable of being preserved in the fossil record. However, most aestivating organisms produce a burrow to protect themselves from the harmful environmental conditions that trigger aestivation. These structures can be preserved in the rock record as trace fossils. While trace fossils are abundant in the continental fossil record, few are definitively associated with aestivation. Interpreting aestivation behavior from fossil burrows requires a detailed examination and interpretation of the surrounding sedimentary rocks and comparisons with taxonomically and ecologically similar extant organisms. Currently, only four types of aestivation structures are recognized in the fossil record: Pleistocene earthworm chambers, Devonian to Cretaceous lungfish burrows, Permian lysorophid burrows, and Permian to Triassic dicynodont burrows. The trace fossil evidence suggests that aestivation evolved independently among continental organisms in several clades during the middle to late Paleozoic.

  6. Organic molecules as chemical fossils - The molecular fossil record

    NASA Technical Reports Server (NTRS)

    Eglinton, G.

    1983-01-01

    The study of biochemical clues to the early earth and the origin of life is discussed. The methods used in such investigation are described, including the extraction, fractionation, and analysis of geolipids and the analysis of kerogen. The occurrence of molecular fossils in the geological record is examined, discussing proposed precursor-product relationships and the molecular assessment of deep sea sediments, ancient sediments, and crude petroleums. Alterations in the molecular record due to diagenesis and catagenesis are considered, and the use of microbial lipids as molecular fossils is discussed. The results of searches for molecular fossils in Precambrian sediments are assessed.

  7. Cladistics and the hominid fossil record.

    PubMed

    Trinkaus, E

    1990-09-01

    Cladistic methodology has become common in phylogenetic analyses of the hominid fossil record. Even though it has correctly placed emphasis on morphology for the primary determination of affinities between groups and on explicit statements regarding traits and methods employed in making phylogenetic assessments, cladistics nonetheless has limitations when applied to the hominid fossil record. These include 1) the uncritical assumption of parsimony, 2) uncertainties in the identification of homoplasies, 3) difficulties in the appropriate delimitation of samples for analysis, 4) failure to account for normal patterns of variation, 5) methodological problems with the appropriate identification of morphological traits involving issues of biological relevance, intercorrelation, primary versus secondary characters, and the use of continuous variables, 6) issues of polarity identification, and 7) problems in hypothesis testing. While cladistics has focused attention on alternative phylogenetic reconstructions in hominid paleontology and on explicit statements regarding their morphological and methodological underpinnings, its biological limitations are too abundant for it to be more than a heuristic device for the preliminary ordering of complex human paleontological and neonatological data.

  8. The fossil record of the sixth extinction.

    PubMed

    Plotnick, Roy E; Smith, Felisa A; Lyons, S Kathleen

    2016-05-01

    Comparing the magnitude of the current biodiversity crisis with those in the fossil record is difficult without an understanding of differential preservation. Integrating data from palaeontological databases with information on IUCN status, ecology and life history characteristics of contemporary mammals, we demonstrate that only a small and biased fraction of threatened species (< 9%) have a fossil record, compared with 20% of non-threatened species. We find strong taphonomic biases related to body size and geographic range. Modern species with a fossil record tend to be large and widespread and were described in the 19(th) century. The expected magnitude of the current extinction based only on species with a fossil record is about half of that of one based on all modern species; values for genera are similar. The record of ancient extinctions may be similarly biased, with many species having originated and gone extinct without leaving a tangible record.

  9. Insect diversity in the fossil record

    NASA Technical Reports Server (NTRS)

    Labandeira, C. C.; Sepkoski, J. J. Jr; Sepkoski JJ, J. r. (Principal Investigator)

    1993-01-01

    Insects possess a surprisingly extensive fossil record. Compilation of the geochronologic ranges of insect families demonstrates that their diversity exceeds that of preserved vertebrate tetrapods through 91 percent of their evolutionary history. The great diversity of insects was achieved not by high origination rates but rather by low extinction rates comparable to the low rates of slowly evolving marine invertebrate groups. The great radiation of modern insects began 245 million years ago and was not accelerated by the expansion of angiosperms during the Cretaceous period. The basic trophic machinery of insects was in place nearly 100 million years before angiosperms appeared in the fossil record.

  10. Adaptation, plant evolution, and the fossil record

    NASA Technical Reports Server (NTRS)

    Knoll, A. H.; Niklas, K. J.

    1987-01-01

    The importance of adaptation in determining patterns of evolution has become an important focus of debate in evolutionary biology. As it pertains to paleobotany, the issue is whether or not adaptive evolution mediated by natural selection is sufficient to explain the stratigraphic distributions of taxa and character states observed in the plant fossil record. One means of addressing this question is the functional evaluation of stratigraphic series of plant organs set in the context of paleoenvironmental change and temporal patterns of floral composition within environments. For certain organ systems, quantitative estimates of biophysical performance can be made on the basis of structures preserved in the fossil record. Performance estimates for plants separated in time or space can be compared directly. Implicit in different hypotheses of the forces that shape the evolutionary record (e.g. adaptation, mass extinction, rapid environmental change, chance) are predictions about stratigraphic and paleoenvironmental trends in the efficacy of functional performance. Existing data suggest that following the evolution of a significant structural innovation, adaptation for improved functional performance can be a major determinant of evolutionary changes in plants; however, there are structural and development limits to functional improvement, and once these are reached, the structure in question may no longer figure strongly in selection until and unless a new innovation evolves. The Silurian-Devonian paleobotanical record is consistent with the hypothesis that the succession of lowland floodplain dominants preserved in the fossil record of this interval was determined principally by the repeated evolution of new taxa that rose to ecological importance because of competitive advantages conferred by improved biophysical performance. This does not seem to be equally true for Carboniferous-Jurassic dominants of swamp and lowland floodplain environments. In these cases

  11. Adaptation, plant evolution, and the fossil record.

    PubMed

    Knoll, A H; Niklas, K J

    1987-01-01

    The importance of adaptation in determining patterns of evolution has become an important focus of debate in evolutionary biology. As it pertains to paleobotany, the issue is whether or not adaptive evolution mediated by natural selection is sufficient to explain the stratigraphic distributions of taxa and character states observed in the plant fossil record. One means of addressing this question is the functional evaluation of stratigraphic series of plant organs set in the context of paleoenvironmental change and temporal patterns of floral composition within environments. For certain organ systems, quantitative estimates of biophysical performance can be made on the basis of structures preserved in the fossil record. Performance estimates for plants separated in time or space can be compared directly. Implicit in different hypotheses of the forces that shape the evolutionary record (e.g. adaptation, mass extinction, rapid environmental change, chance) are predictions about stratigraphic and paleoenvironmental trends in the efficacy of functional performance. Existing data suggest that following the evolution of a significant structural innovation, adaptation for improved functional performance can be a major determinant of evolutionary changes in plants; however, there are structural and development limits to functional improvement, and once these are reached, the structure in question may no longer figure strongly in selection until and unless a new innovation evolves. The Silurian-Devonian paleobotanical record is consistent with the hypothesis that the succession of lowland floodplain dominants preserved in the fossil record of this interval was determined principally by the repeated evolution of new taxa that rose to ecological importance because of competitive advantages conferred by improved biophysical performance. This does not seem to be equally true for Carboniferous-Jurassic dominants of swamp and lowland floodplain environments. In these cases

  12. An overview of the dinosaur fossil record from Chile

    NASA Astrophysics Data System (ADS)

    Rubilar-Rogers, David; Otero, Rodrigo A.; Yury-Yáñez, Roberto E.; Vargas, Alexander O.; Gutstein, Carolina S.

    2012-08-01

    In Chile, the record of dinosaurs in Jurassic and Cretaceous sediments is often restricted to footprints, with few skeletal remains. Tetanuran theropods are known in the Upper Jurassic, and bones of titanosaur sauropods in the Late Cretaceous, including partial skeletons (e.g. Atacamatitan chilensis Kellner et al.). Also from the late Cretaceous, an ornithopod vertebra, a pair of theropod teeth and one tarsometatarsus of a gaviiform bird (Neogaeornis wetzeli Lambrecht) have been reported. The Cenozoic fossil record comprises abundant and well-preserved marine birds from Eocene and Miocene units, with a specially abundant record of Sphenisciformes and less frequently, Procellariiformes. There is an excellent Miocene-Pliocene record of other birds such as Odontopterygiformes, including the most complete skeleton ever found of a pelagornithid, Pelagornis chilensis Mayr and Rubilar-Rogers. Fossil birds are also known from Pliocene and Pleistocene strata. A remarkable collection of birds was discovered in lacustrine sediments of late Pleistocene age associated to human activity. The perspectives in the study of dinosaurs in Chile are promising because plenty of material stored in institutional collections is not described yet. The record of Chilean dinosaurs is relevant for understanding the dynamics and evolution of this group of terrestrial animals in the western edge of Gondwana, while Cenozoic birds from the Region may contribute to the understanding of current biogeography for instance, the effect of the emergence and establishment of the Humboldt Current.

  13. Fossil Signatures Using Elemental Abundance Distributions and Bayesian Probabilistic Classification

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.; Storrie-Lombardi, Michael C.

    2004-01-01

    Elemental abundances (C6, N7, O8, Na11, Mg12, Al3, P15, S16, Cl17, K19, Ca20, Ti22, Mn25, Fe26, and Ni28) were obtained for a set of terrestrial fossils and the rock matrix surrounding them. Principal Component Analysis extracted five factors accounting for the 92.5% of the data variance, i.e. information content, of the elemental abundance data. Hierarchical Cluster Analysis provided unsupervised sample classification distinguishing fossil from matrix samples on the basis of either raw abundances or PCA input that agreed strongly with visual classification. A stochastic, non-linear Artificial Neural Network produced a Bayesian probability of correct sample classification. The results provide a quantitative probabilistic methodology for discriminating terrestrial fossils from the surrounding rock matrix using chemical information. To demonstrate the applicability of these techniques to the assessment of meteoritic samples or in situ extraterrestrial exploration, we present preliminary data on samples of the Orgueil meteorite. In both systems an elemental signature produces target classification decisions remarkably consistent with morphological classification by a human expert using only structural (visual) information. We discuss the possibility of implementing a complexity analysis metric capable of automating certain image analysis and pattern recognition abilities of the human eye using low magnification optical microscopy images and discuss the extension of this technique across multiple scales.

  14. Exopaleontology and the search for a fossil record on Mars

    NASA Technical Reports Server (NTRS)

    Farmer, Jack D.; Desmarais, D. J.

    1994-01-01

    Although present Martian surface conditions appear unfavorable for life as we know it, there is compelling geological evidence that the climate of early Mars was much more Earth-like, with a denser atmosphere and abundant surface water. The fact that life developed on the Earth within the first billion years of its history makes it quite plausible that life may have also developed on Mars. If life did develop on Mars, it is likely to have left behind a fossil record. This has led to the development of a new subdiscipline of paleontology, herein termed 'exopaleontology', which deals with the exploration for fossils on other planets. The most important factor enhancing microbial fossilization is the rapid entombment of microorganisms by fine-grained, stable mineral phases, such as silica, phosphate, or carbonate. The oldest body fossils on Earth are preserved in this way, occurring as permineralized cells in fine-grained siliceous sediments (cherts) associated with ancient volcanic terranes in Australia and South Africa. Modern terrestrial environments where minerals may precipitate in the presence of microorganisms include subaerial thermal springs and shallow hydrothermal systems, sub-lacustrine springs and evaporitic alkaline lakes, zones of mineralization within soils where 'hardpans' (e.g. calcretes, silcretes) form, and high latitude frozen soils or ground ice.

  15. Rates of speciation in the fossil record.

    PubMed Central

    Sepkoski, J J

    1998-01-01

    Data from palaeontology and biodiversity suggest that the global biota should produce an average of three new species per year. However, the fossil record shows large variation around this mean. Rates of origination have declined through the Phanerozoic. This appears to have been largely a function of sorting among higher taxa (especially classes), which exhibit characteristic rates of speciation (and extinction) that differ among them by nearly an order of magnitude. Secular decline of origination rates is hardly constant, however; many positive deviations reflect accelerated speciation during rebounds from mass extinctions. There has also been general decline in rates of speciation within major taxa through their histories, although rates have tended to remain higher among members in tropical regions. Finally, pulses of speciation appear sometimes to be associated with climate change, although moderate oscillations of climate do not necessarily promote speciation despite forcing changes in species' geographical ranges. PMID:11541734

  16. Rates of speciation in the fossil record

    NASA Technical Reports Server (NTRS)

    Sepkoski, J. J. Jr; Sepkoski JJ, J. r. (Principal Investigator)

    1998-01-01

    Data from palaeontology and biodiversity suggest that the global biota should produce an average of three new species per year. However, the fossil record shows large variation around this mean. Rates of origination have declined through the Phanerozoic. This appears to have been largely a function of sorting among higher taxa (especially classes), which exhibit characteristic rates of speciation (and extinction) that differ among them by nearly an order of magnitude. Secular decline of origination rates is hardly constant, however; many positive deviations reflect accelerated speciation during rebounds from mass extinctions. There has also been general decline in rates of speciation within major taxa through their histories, although rates have tended to remain higher among members in tropical regions. Finally, pulses of speciation appear sometimes to be associated with climate change, although moderate oscillations of climate do not necessarily promote speciation despite forcing changes in species' geographical ranges.

  17. The fossil record and macroevolutionary history of the beetles

    PubMed Central

    Smith, Dena M.; Marcot, Jonathan D.

    2015-01-01

    Coleoptera (beetles) is the most species-rich metazoan order, with approximately 380 000 species. To understand how they came to be such a diverse group, we compile a database of global fossil beetle occurrences to study their macroevolutionary history. Our database includes 5553 beetle occurrences from 221 fossil localities. Amber and lacustrine deposits preserve most of the beetle diversity and abundance. All four extant suborders are found in the fossil record, with 69% of all beetle families and 63% of extant beetle families preserved. Considerable focus has been placed on beetle diversification overall, however, for much of their evolutionary history it is the clade Polyphaga that is most responsible for their taxonomic richness. Polyphaga had an increase in diversification rate in the Early Cretaceous, but instead of being due to the radiation of the angiosperms, this was probably due to the first occurrences of beetle-bearing amber deposits in the record. Perhaps, most significant is that polyphagan beetles had a family-level extinction rate of zero for most of their evolutionary history, including across the Cretaceous–Palaeogene boundary. Therefore, focusing on the factors that have inhibited beetle extinction, as opposed to solely studying mechanisms that may promote speciation, should be examined as important determinants of their great diversity today. PMID:25788597

  18. The fossil record and macroevolutionary history of the beetles.

    PubMed

    Smith, Dena M; Marcot, Jonathan D

    2015-04-22

    Coleoptera (beetles) is the most species-rich metazoan order, with approximately 380 000 species. To understand how they came to be such a diverse group, we compile a database of global fossil beetle occurrences to study their macroevolutionary history. Our database includes 5553 beetle occurrences from 221 fossil localities. Amber and lacustrine deposits preserve most of the beetle diversity and abundance. All four extant suborders are found in the fossil record, with 69% of all beetle families and 63% of extant beetle families preserved. Considerable focus has been placed on beetle diversification overall, however, for much of their evolutionary history it is the clade Polyphaga that is most responsible for their taxonomic richness. Polyphaga had an increase in diversification rate in the Early Cretaceous, but instead of being due to the radiation of the angiosperms, this was probably due to the first occurrences of beetle-bearing amber deposits in the record. Perhaps, most significant is that polyphagan beetles had a family-level extinction rate of zero for most of their evolutionary history, including across the Cretaceous-Palaeogene boundary. Therefore, focusing on the factors that have inhibited beetle extinction, as opposed to solely studying mechanisms that may promote speciation, should be examined as important determinants of their great diversity today.

  19. The Quaternary fossil-pollen record and global change

    SciTech Connect

    Grimm, E.C. . Research and Collections Center)

    1993-03-01

    Fossil pollen provide one of the most valuable records of vegetation and climate change during the recent geological past. Advantages of the fossil-pollen record are that deposits containing fossil pollen are widespread, especially in areas having natural lakes, that fossil pollen occurs in continuous stratigraphic sequences spanning millennia, and that fossil pollen occurs in quantitative assemblages permitting a multivariate approach for reconstructing past vegetation and climates. Because of stratigraphic continuity, fossil pollen records climate cycles on a wide range of scales, from annual to the 100 ka Milankovitch cycles. Receiving particular emphasis recently are decadal to century scale changes, possible from the sediments of varved lakes, and late Pleistocene events on a 5--10 ka scale possibly correlating with the Heinrich events in the North Atlantic marine record or the Dansgaard-Oeschger events in the Greenland ice-core record. Researchers have long reconstructed vegetation and climate by qualitative interpretation of the fossil-pollen record. Recently quantitative interpretation has developed with the aid of large fossil-pollen databases and sophisticated numerical models. In addition, fossil pollen are important climate proxy data for validating General Circulation Models, which are used for predicting the possible magnitude future climate change. Fossil-pollen data also contribute to an understanding of ecological issues associated with global climate change, including questions of how and how rapidly ecosystems might respond to abrupt climate change.

  20. Special Creation and the Fossil Record: The Central Fallacy.

    ERIC Educational Resources Information Center

    Miller, Kenneth R.

    1982-01-01

    Fossil records are used to point out two major flaws in the scientific creationist theory: (1) factual evidence does not support the theory, and (2) the creationists' own characterization of the fossil record contradicts their theory. Claims that creationists avoid discussing specifics about their model because of weaknesses. (DC)

  1. Aragonite and the fossil record: are we overlooking something?

    NASA Astrophysics Data System (ADS)

    Balthasar, Uwe

    2016-04-01

    Aragonite and calcite are the two most common minerals from which marine organisms secrete their skeletons, yet their potential to preserve in the fossil record is very different. While calcite is generally very stable, aragonite dissolves relatively easily either during diagenesis or even pre-burial. While the complete loss of aragonitic shells is generally acknowledged, the original contribution of aragonite to commonly preserved calcareous fossils is generally overlooked, particularly in groups with no recent representatives. Palaeozoic brachiopods and stromatoporoid sponges, for example, are traditionally considered to have been made of calcite. However, EBSD work on stromatoporoids shows a complex early diagenesis during which the skeletal walls recrystallised first and served as the nucleation surface for the cements infilling the open galleries between the walls. This suggests that the original mineral composition of the skeletal walls had a high diagenetic potential which makes a stable low-magnesium calcite composition unlikely. Equally, the biggest subphylum of brachiopods, Rhynchonelliformea, is traditionally considered to have shells that are exclusively made of low-magnesium calcite. However, a survey of the shell thickness of 176 Ordovician-Silurian brachiopod valves reveals that the calcitic remains of some of the larger shells (particularly of pentamerids) are far too thin with several specimens exhibiting the irregular internal margins typical of dissolution, thus suggesting a bimineralic composition with an outer calcite and an inner aragonite layer. These examples indicate that existing estimates of Phanerozoic aragonite and calcite skeletal mineralogy are not only biased by the complete dissolution of shells, but we probably overestimate the abundance of original calcite composition in the fossil record.

  2. The earliest fossil record of the animals and its significance.

    PubMed

    Budd, Graham E

    2008-04-27

    The fossil record of the earliest animals has been enlivened in recent years by a series of spectacular discoveries, including embryos, from the Ediacaran to the Cambrian, but many issues, not least of dating and interpretation, remain controversial. In particular, aspects of taphonomy of the earliest fossils require careful consideration before pronouncements about their affinities. Nevertheless, a reasonable case can now be made for the extension of the fossil record of at least basal animals (sponges and perhaps cnidarians) to a period of time significantly before the beginning of the Cambrian. The Cambrian explosion itself still seems to represent the arrival of the bilaterians, and many new fossils in recent years have added significant data on the origin of the three major bilaterian clades. Why animals appear so late in the fossil record is still unclear, but the recent trend to embrace rising oxygen levels as being the proximate cause remains unproven and may even involve a degree of circularity.

  3. On the fossil record of the Gekkota.

    PubMed

    Daza, Juan D; Bauer, Aaron M; Snively, Eric D

    2014-03-01

    Gekkota is often interpreted as sister to all remaining squamates, exclusive of dibamids, or as sister to Autarchoglossa. It is the only diverse lineage of primarily nocturnal lizards and includes some of the smallest amniotes. The skeleton of geckos has often been interpreted as paedomorphic and/or "primitive" but these lizards also display a wide range of structural specializations of the postcranium, including modifications associated with both scansorial locomotion and limb reduction. Although the concept of "Gekkota" has been variously applied by different authors, we here apply a rigorous apomorphy based definition, recent advances in gekkotan morphology and phylogenetics, and diverse comparative material to provide a comprehensive assessment of 28 known pre-Quaternary geckos, updating the last such review, published three decades ago. Fossils evaluated include both sedimentary fossils and amber-embedded specimens. Known Cretaceous geckos are exclusively Asian and exhibit character combinations not seen in any living forms. Cenozoic gekkotans derive from sites around the world, although Europe is especially well represented. Paleogene geckos are largely known from disarticulated remains and show similarities to Sphaerodactylidae and Diplodactylidae, although resemblances may be plesiomorphic in some cases. Many Neogene gekkotans are referable to living families or even genera, but their geographic occurrences are often extralimital to those of modern groups, as is consistent with paleoclimatic conditions. The phylogenetic placement of fossil gekkotans has important repercusions for timetree calibration, but at present only a small number of fossils can be confidently assigned to even family level groupings, limiting their utility in this regard.

  4. Fossils of parasites: what can the fossil record tell us about the evolution of parasitism?

    PubMed

    Leung, Tommy L F

    2017-02-01

    Parasites are common in many ecosystems, yet because of their nature, they do not fossilise readily and are very rare in the geological record. This makes it challenging to study the evolutionary transition that led to the evolution of parasitism in different taxa. Most studies on the evolution of parasites are based on phylogenies of extant species that were constructed based on morphological and molecular data, but they give us an incomplete picture and offer little information on many important details of parasite-host interactions. The lack of fossil parasites also means we know very little about the roles that parasites played in ecosystems of the past even though it is known that parasites have significant influences on many ecosystems. The goal of this review is to bring attention to known fossils of parasites and parasitism, and provide a conceptual framework for how research on fossil parasites can develop in the future. Despite their rarity, there are some fossil parasites which have been described from different geological eras. These fossils include the free-living stage of parasites, parasites which became fossilised with their hosts, parasite eggs and propagules in coprolites, and traces of pathology inflicted by parasites on the host's body. Judging from the fossil record, while there were some parasite-host relationships which no longer exist in the present day, many parasite taxa which are known from the fossil record seem to have remained relatively unchanged in their general morphology and their patterns of host association over tens or even hundreds of millions of years. It also appears that major evolutionary and ecological transitions throughout the history of life on Earth coincided with the appearance of certain parasite taxa, as the appearance of new host groups also provided new niches for potential parasites. As such, fossil parasites can provide additional data regarding the ecology of their extinct hosts, since many parasites have

  5. Estimating times of extinction in the fossil record

    PubMed Central

    Marshall, Charles R.

    2016-01-01

    Because the fossil record is incomplete, the last fossil of a taxon is a biased estimate of its true time of extinction. Numerous methods have been developed in the palaeontology literature for estimating the true time of extinction using ages of fossil specimens. These methods, which typically give a confidence interval for estimating the true time of extinction, differ in the assumptions they make and the nature and amount of data they require. We review the literature on such methods and make some recommendations for future directions. PMID:27122005

  6. The shape of pterosaur evolution: evidence from the fossil record.

    PubMed

    Dyke, G J; McGowan, A J; Nudds, R L; Smith, D

    2009-04-01

    Although pterosaurs are a well-known lineage of Mesozoic flying reptiles, their fossil record and evolutionary dynamics have never been adequately quantified. On the basis of a comprehensive data set of fossil occurrences correlated with taxon-specific limb measurements, we show that the geological ages of pterosaur specimens closely approximate hypothesized patterns of phylogenetic divergence. Although the fossil record has expanded greatly in recent years, collectorship still approximates a sigmoid curve over time as many more specimens (and thus taxa) still remain undiscovered, yet our data suggest that the pterosaur fossil record is unbiased by sites of exceptional preservation (lagerstätte). This is because as new species are discovered the number of known formations and sites yielding pterosaur fossils has also increased - this would not be expected if the bulk of the record came from just a few exceptional faunas. Pterosaur morphological diversification is, however, strongly age biased: rarefaction analysis shows that peaks of diversity occur in the Late Jurassic and Early Cretaceous correlated with periods of increased limb disparity. In this respect, pterosaurs appear unique amongst flying vertebrates in that their disparity seems to have peaked relatively late in clade history. Comparative analyses also show that there is little evidence that the evolutionary diversification of pterosaurs was in any way constrained by the appearance and radiation of birds.

  7. How Good is the Fossil Record?

    ERIC Educational Resources Information Center

    Boucot, A. J.

    1983-01-01

    Suggests that earth scientists become active in the creationist debate by making sure that the religious concept creationism is not taught in schools and that well-based, informative material about organic evolution, earth's age, and nature of stratigraphic record are employed by science teachers. (Author/JN)

  8. NGST: Exploring the Fossil Record of Galaxy Formation

    NASA Technical Reports Server (NTRS)

    Rich, R. Michael

    1998-01-01

    During this grant period the investigator has accomplished the following: developed and researched the science case for high resolution optical imaging with NGST (Next Generation Space Telescope); presented to the ASWG (Ad-Hoc Science Working Group) on the use of NGST to image and measure the proper motions of white dwarf stars that could account for the MACHO events toward the LMC (Large Magellanic Cloud); wrote proposals for the Design Reference Mission. Three proposals have been written on the following topics: Measuring the faint end of the white dwarf luminosity function to get an independent measure of the age of the oldest stars, measurement of the stellar luminosity function over the full range of age, abundance, and population type, and deep imaging of Local Group halos to measure the relative ages of the oldest stars in the Milky Way and other galaxies; he has introduced simulations of crowded field stellar photometry on a hypothetical population in the M31 halo. Using a physically correct luminosity function and a surface brightness of 24.5 mag/sq. arcsec, NGST imaging in 10 hours easily measures the turnoff and reaches 3 mags down the main sequence in the halo of M31; and has delivered talks at the NGST workshop in Liege, and at the meeting in Paris entitled "Connecting the Distant Universe with the Local Fossil Record".

  9. Absolute measures of the completeness of the fossil record

    NASA Technical Reports Server (NTRS)

    Foote, M.; Sepkoski, J. J. Jr; Sepkoski JJ, J. r. (Principal Investigator)

    1999-01-01

    Measuring the completeness of the fossil record is essential to understanding evolution over long timescales, particularly when comparing evolutionary patterns among biological groups with different preservational properties. Completeness measures have been presented for various groups based on gaps in the stratigraphic ranges of fossil taxa and on hypothetical lineages implied by estimated evolutionary trees. Here we present and compare quantitative, widely applicable absolute measures of completeness at two taxonomic levels for a broader sample of higher taxa of marine animals than has previously been available. We provide an estimate of the probability of genus preservation per stratigraphic interval, and determine the proportion of living families with some fossil record. The two completeness measures use very different data and calculations. The probability of genus preservation depends almost entirely on the Palaeozoic and Mesozoic records, whereas the proportion of living families with a fossil record is influenced largely by Cenozoic data. These measurements are nonetheless highly correlated, with outliers quite explicable, and we find that completeness is rather high for many animal groups.

  10. Evidence for Evolution from the Vertebrate Fossil Record.

    ERIC Educational Resources Information Center

    Gingerich, Philip D.

    1983-01-01

    Discusses three examples of evolutionary transition in the vertebrate fossil record, considering evolutionary transitions at the species level. Uses archaic squirrel-like Paleocine primates, the earliest primates of modern aspect, as examples. Also reviews new evidence on the origin of whales and their transition from land to sea. (JN)

  11. Giving the early fossil record of sponges a squeeze.

    PubMed

    Antcliffe, Jonathan B; Callow, Richard H T; Brasier, Martin D

    2014-11-01

    Twenty candidate fossils with claim to be the oldest representative of the Phylum Porifera have been re-analysed. Three criteria are used to assess each candidate: (i) the diagnostic criteria needed to categorize sponges in the fossil record; (ii) the presence, or absence, of such diagnostic features in the putative poriferan fossils; and (iii) the age constraints for the candidate fossils. All three criteria are critical to the correct interpretation of any fossil and its placement within an evolutionary context. Our analysis shows that no Precambrian fossil candidate yet satisfies all three of these criteria to be a reliable sponge fossil. The oldest widely accepted candidate, Mongolian silica hexacts from c. 545 million years ago (Ma), are here shown to be cruciform arsenopyrite crystals. The oldest reliable sponge remains are siliceous spicules from the basal Cambrian (Protohertzina anabarica Zone) Soltanieh Formation, Iran, which are described and analysed here in detail for the first time. Extensive archaeocyathan sponge reefs emerge and radiate as late as the middle of the Fortunian Stage of the Cambrian and demonstrate a gradual assembly of their skeletal structure through this time coincident with the evolution of other metazoan groups. Since the Porifera are basal in the Metazoa, their presence within the late Proterozoic has been widely anticipated. Molecular clock calibration for the earliest Porifera and Metazoa should now be based on the Iranian hexactinellid material dated to c. 535 Ma. The earliest convincing fossil sponge remains appeared at around the time of the Precambrian-Cambrian boundary, associated with the great radiation events of that interval.

  12. The quality of the fossil record of Mesozoic birds.

    PubMed

    Fountaine, Toby M R; Benton, Michael J; Dyke, Gareth J; Nudds, Robert L

    2005-02-07

    The Mesozoic fossil record has proved critical for understanding the early evolution and subsequent radiation of birds. Little is known, however, about its relative completeness: just how 'good' is the fossil record of birds from the Mesozoic? This question has come to prominence recently in the debate over differences in estimated dates of origin of major clades of birds from molecular and palaeontological data. Using a dataset comprising all known fossil taxa, we present analyses that go some way towards answering this question. Whereas avian diversity remains poorly represented in the Mesozoic, many relatively complete bird specimens have been discovered. New taxa have been added to the phylogenetic tree of basal birds, but its overall shape remains constant, suggesting that the broad outlines of early avian evolution are consistently represented: no stage in the Mesozoic is characterized by an overabundance of scrappy fossils compared with more complete specimens. Examples of Neornithes (modern orders) are known from later stages in the Cretaceous, but their fossils are rarer and scrappier than those of basal bird groups, which we suggest is a biological, rather than a geological, signal.

  13. Preservational bias controls the fossil record of pterosaurs.

    PubMed

    Dean, Christopher D; Mannion, Philip D; Butler, Richard J

    2016-01-14

    Pterosaurs, a Mesozoic group of flying archosaurs, have become a focal point for debates pertaining to the impact of sampling biases on our reading of the fossil record, as well as the utility of sampling proxies in palaeodiversity reconstructions. The completeness of the pterosaur fossil specimens themselves potentially provides additional information that is not captured in existing sampling proxies, and might shed new light on the group's evolutionary history. Here we assess the quality of the pterosaur fossil record via a character completeness metric based on the number of phylogenetic characters that can be scored for all known skeletons of 172 valid species, with averaged completeness values calculated for each geological stage. The fossil record of pterosaurs is observed to be strongly influenced by the occurrence and distribution of Lagerstätten. Peaks in completeness correlate with Lagerstätten deposits, and a recovered correlation between completeness and observed diversity is rendered non-significant when Lagerstätten species are excluded. Intervals previously regarded as potential extinction events are shown to lack Lagerstätten and exhibit low completeness values: as such, the apparent low diversity in these intervals might be at least partly the result of poor fossil record quality. A positive correlation between temporal patterns in completeness of Cretaceous pterosaurs and birds further demonstrates the prominent role that Lagerstätten deposits have on the preservation of smaller bodied organisms, contrasting with a lack of correlation with the completeness of large-bodied sauropodomorphs. However, we unexpectedly find a strong correlation between sauropodomorph and pterosaur completeness within the Triassic-Jurassic, but not the Cretaceous, potentially relating to a shared shift in environmental preference and thus preservation style through time. This study highlights the importance of understanding the relationship between various

  14. Preservational bias controls the fossil record of pterosaurs

    PubMed Central

    Dean, Christopher D.; Mannion, Philip D.; Butler, Richard J.

    2016-01-01

    Pterosaurs, a Mesozoic group of flying archosaurs, have become a focal point for debates pertaining to the impact of sampling biases on our reading of the fossil record, as well as the utility of sampling proxies in palaeodiversity reconstructions. The completeness of the pterosaur fossil specimens themselves potentially provides additional information that is not captured in existing sampling proxies, and might shed new light on the group’s evolutionary history. Here we assess the quality of the pterosaur fossil record via a character completeness metric based on the number of phylogenetic characters that can be scored for all known skeletons of 172 valid species, with averaged completeness values calculated for each geological stage. The fossil record of pterosaurs is observed to be strongly influenced by the occurrence and distribution of Lagerstätten. Peaks in completeness correlate with Lagerstätten deposits, and a recovered correlation between completeness and observed diversity is rendered non-significant when Lagerstätten species are excluded. Intervals previously regarded as potential extinction events are shown to lack Lagerstätten and exhibit low completeness values: as such, the apparent low diversity in these intervals might be at least partly the result of poor fossil record quality. A positive correlation between temporal patterns in completeness of Cretaceous pterosaurs and birds further demonstrates the prominent role that Lagerstätten deposits have on the preservation of smaller bodied organisms, contrasting with a lack of correlation with the completeness of large-bodied sauropodomorphs. However, we unexpectedly find a strong correlation between sauropodomorph and pterosaur completeness within the Triassic–Jurassic, but not the Cretaceous, potentially relating to a shared shift in environmental preference and thus preservation style through time. This study highlights the importance of understanding the relationship between various

  15. Testing New Proxies for Photosymbiosis in the Fossil Record

    NASA Astrophysics Data System (ADS)

    Tornabene, C.; Martindale, R. C.; Schaller, M. F.

    2015-12-01

    Photosymbiosis is a mutualistic relationship that many corals have developed with dinoflagellates called zooxanthellae. The dinoflagellates, of the genus Symbiodinium, photosynthesize and provide corals with most of their energy, while in turn coral hosts live in waters where zooxanthellae have optimal exposure to sunlight. Thanks to this relationship, symbiotic corals calcify faster than non-symbiotic corals. Photosymbiosis is therefore considered the evolutionary innovation that allowed corals to become major reef-builders through geological time.This relationship is extremely difficult to study. Zooxanthellae, which are housed in the coral tissue, are not preserved in fossil coral skeletons, thus determining whether corals had symbionts requires a robust proxy. In order to address this critical question, the goal of this research is to test new proxies for ancient photosymbiosis. Currently the project is focused on assessing the nitrogen (δ15N) isotopes of corals' organic matrices, sensu Muscatine et al. (2005), as well as carbon and oxygen (δ13C, δ18O) isotopes of fossil coral skeletons. Samples from Modern, Pleistocene, Oligocene and Triassic coral skeletons were analyzed to test the validity of these proxies. Coral samples comprise both (interpreted) symbiotic and non-symbiotic fossil corals from the Oligocene and Triassic as well as symbiotic fossil corals from the Modern and Pleistocene to corroborate our findings with the results of Muscatine et al. (2005). Samples were tested for diagenesis through petrographic and scanning electron microscope (SEM) analyses to avoid contamination. Additionally, a novel technique that has not yet been applied to the fossil record was tested. The technique aims to recognize dinosterol, a dinoflagellate biomarker, in both modern and fossil coral samples. The premise of this proxy is that symbiotic corals should contain the dinoflagellate biomarker, whereas those lacking symbionts should lack dinosterol. Results from this

  16. Earth's early fossil record: Why not look for similar fossils on Mars?

    NASA Technical Reports Server (NTRS)

    Awramik, Stanley M.

    1989-01-01

    The oldest evidence of life on Earth is discussed with attention being given to the structure and formation of stromatolites and microfossils. Fossilization of microbes in calcium carbonate or chert media is discussed. In searching for fossil remains on Mars, some lessons learned from the study of Earth's earliest fossil record can be applied. Certain sedimentary rock types and sedimentary rock configurations should be targeted for investigation and returned by the Martian rover and ultimately by human explorers. Domical, columnar to wavy laminated stratiform sedimentary rocks that resemble stromatolites should be actively sought. Limestone, other carbonates, and chert are the favored lithology. Being macroscopic, stromatolites might be recognized by an intelligent unmanned rover. In addition, black, waxy chert with conchoidal fracture should be sought. Chert is by far the preferred lithology for the preservation of microbes and chemical fossils. Even under optimal geological conditions (little or no metamorphism or tectonic alteration, excellent outcrops, and good black chert) and using experienced field biogeologists, the chances of finding well preserved microbial remains in chert are very low.

  17. Ancient DNA sheds new light on the Svalbard foraminiferal fossil record of the last millennium.

    PubMed

    Pawłowska, J; Lejzerowicz, F; Esling, P; Szczuciński, W; Zajączkowski, M; Pawlowski, J

    2014-07-01

    Recent palaeogenetic studies have demonstrated the occurrence of preserved ancient DNA (aDNA) in various types of fossilised material. Environmental aDNA sequences assigned to modern species have been recovered from marine sediments dating to the Pleistocene. However, the match between the aDNA and the fossil record still needs to be evaluated for the environmental DNA approaches to be fully exploited. Here, we focus on foraminifera in sediments up to one thousand years old retrieved from the Hornsund fjord (Svalbard). We compared the diversity of foraminiferal microfossil assemblages with the diversity of aDNA sequenced from subsurface sediment samples using both cloning and high-throughput sequencing (HTS). Our study shows that 57% of the species archived in the fossil record were also detected in the aDNA data. However, the relative abundance of aDNA sequence reads and fossil specimens differed considerably. We also found a limited match between the stratigraphic occurrence of some fossil species and their aDNA sequences, especially in the case of rare taxa. The aDNA data comprised a high proportion of non-fossilised monothalamous species, which are known to dominate in modern foraminiferal communities of the Svalbard region. Our results confirm the relevance of HTS for studying past micro-eukaryotic diversity and provide insight into its ability to reflect fossil assemblages. Palaeogenetic studies including aDNA analyses of non-fossilised groups expand the range of palaeoceanographical proxies and therefore may increase the accuracy of palaeoenvironmental reconstructions.

  18. The avian fossil record in Insular Southeast Asia and its implications for avian biogeography and palaeoecology

    PubMed Central

    2014-01-01

    Excavations and studies of existing collections during the last decades have significantly increased the abundance as well as the diversity of the avian fossil record for Insular Southeast Asia. The avian fossil record covers the Eocene through the Holocene, with the majority of bird fossils Pleistocene in age. Fossil bird skeletal remains represent at least 63 species in 54 genera and 27 families, and two ichnospecies are represented by fossil footprints. Birds of prey, owls and swiftlets are common elements. Extinctions seem to have been few, suggesting continuity of avian lineages since at least the Late Pleistocene, although some shifts in species ranges have occurred in response to climatic change. Similarities between the Late Pleistocene avifaunas of Flores and Java suggest a dispersal route across southern Sundaland. Late Pleistocene assemblages of Niah Cave (Borneo) and Liang Bua (Flores) support the rainforest refugium hypothesis in Southeast Asia as they indicate the persistence of forest cover, at least locally, throughout the Late Pleistocene and Holocene. PMID:24688871

  19. Diversity dynamics: molecular phylogenies need the fossil record.

    PubMed

    Quental, Tiago B; Marshall, Charles R

    2010-08-01

    Over the last two decades, new tools in the analysis of molecular phylogenies have enabled study of the diversification dynamics of living clades in the absence of information about extinct lineages. However, computer simulations and the fossil record show that the inability to access extinct lineages severely limits the inferences that can be drawn from molecular phylogenies. It appears that molecular phylogenies can tell us only when there have been changes in diversification rates, but are blind to the true diversity trajectories and rates of origination and extinction that have led to the species that are alive today. We need to embrace the fossil record if we want to fully understand the diversity dynamics of the living biota.

  20. The cambrian fossil record and the origin of the phyla.

    PubMed

    Budd, Graham E

    2003-02-01

    Whilst the "Cambrian Explosion" continues to attract much attention from a wide range of earth and life scientists, the detailed patterns exhibited by the terminal Proterozoic-Early Cambrian biotas remain unclear, for reasons of systematics, biostratigraphy and biogeography. In particular, recent changes in absolute dating of the Cambrian have refined the period of time that the fossil record might be of most help in revealing the dynamics of the undoubted radiation taking place at this time. The famous exceptionally preserved faunas seem to be rather close temporally, and as yet reveal little about the earliest and critical period of evolution, deep in the Cambrian. Nevertheless, the most parsimonious interpretation of the Cambrian fossil record is that it represents a broadly accurate temporal picture of the origins of the bilaterian phyla.

  1. First record of Podocarpoid fossil wood in South China

    PubMed Central

    Li, Long; Jin, Jian-Hua; Quan, Cheng; Oskolski, Alexei A.

    2016-01-01

    A new species of fossil conifer wood, Podocarpoxylon donghuaiense sp. nov., is described from the late Eocene of Nadu Formation in Baise Basin of the Guangxi Province, South China. This fossil wood is characterized by distinct growth rings, circular to oval tracheids in cross section, 1–2-seriate opposite pits on radial tracheid walls, uniseriate (rarely biseriate) rays, smooth end walls of ray parenchyma cells, and the absence of resin ducts, suggesting its affinity to Podocarpaceae. The new species is distinctive from other Cenozoic woods ascribed to this family by the combination of distinctive growth rings, the absence of axial parenchyma, the occurrence of bordered pits on tangential tracheid walls, and the occurrence of 3–4 cuppressoid or taxodioid pits on cross-fields. This represents the first record of podocarpoid fossil wood in South China and provides fossil evidence for the early dispersal and diversification of Podocarpaceae in eastern Asia as well as for mild temperate seasonal climate in this region during the late Eocene. PMID:27571780

  2. The completeness of the fossil record of mesozoic birds: implications for early avian evolution.

    PubMed

    Brocklehurst, Neil; Upchurch, Paul; Mannion, Philip D; O'Connor, Jingmai

    2012-01-01

    Many palaeobiological analyses have concluded that modern birds (Neornithes) radiated no earlier than the Maastrichtian, whereas molecular clock studies have argued for a much earlier origination. Here, we assess the quality of the fossil record of Mesozoic avian species, using a recently proposed character completeness metric which calculates the percentage of phylogenetic characters that can be scored for each taxon. Estimates of fossil record quality are plotted against geological time and compared to estimates of species level diversity, sea level, and depositional environment. Geographical controls on the avian fossil record are investigated by comparing the completeness scores of species in different continental regions and latitudinal bins. Avian fossil record quality varies greatly with peaks during the Tithonian-early Berriasian, Aptian, and Coniacian-Santonian, and troughs during the Albian-Turonian and the Maastrichtian. The completeness metric correlates more strongly with a 'sampling corrected' residual diversity curve of avian species than with the raw taxic diversity curve, suggesting that the abundance and diversity of birds might influence the probability of high quality specimens being preserved. There is no correlation between avian completeness and sea level, the number of fluviolacustrine localities or a recently constructed character completeness metric of sauropodomorph dinosaurs. Comparisons between the completeness of Mesozoic birds and sauropodomorphs suggest that small delicate vertebrate skeletons are more easily destroyed by taphonomic processes, but more easily preserved whole. Lagerstätten deposits might therefore have a stronger impact on reconstructions of diversity of smaller organisms relative to more robust forms. The relatively poor quality of the avian fossil record in the Late Cretaceous combined with very patchy regional sampling means that it is possible neornithine lineages were present throughout this interval but have

  3. The Completeness of the Fossil Record of Mesozoic Birds: Implications for Early Avian Evolution

    PubMed Central

    Brocklehurst, Neil; Upchurch, Paul; Mannion, Philip D.; O'Connor, Jingmai

    2012-01-01

    Many palaeobiological analyses have concluded that modern birds (Neornithes) radiated no earlier than the Maastrichtian, whereas molecular clock studies have argued for a much earlier origination. Here, we assess the quality of the fossil record of Mesozoic avian species, using a recently proposed character completeness metric which calculates the percentage of phylogenetic characters that can be scored for each taxon. Estimates of fossil record quality are plotted against geological time and compared to estimates of species level diversity, sea level, and depositional environment. Geographical controls on the avian fossil record are investigated by comparing the completeness scores of species in different continental regions and latitudinal bins. Avian fossil record quality varies greatly with peaks during the Tithonian-early Berriasian, Aptian, and Coniacian–Santonian, and troughs during the Albian-Turonian and the Maastrichtian. The completeness metric correlates more strongly with a ‘sampling corrected’ residual diversity curve of avian species than with the raw taxic diversity curve, suggesting that the abundance and diversity of birds might influence the probability of high quality specimens being preserved. There is no correlation between avian completeness and sea level, the number of fluviolacustrine localities or a recently constructed character completeness metric of sauropodomorph dinosaurs. Comparisons between the completeness of Mesozoic birds and sauropodomorphs suggest that small delicate vertebrate skeletons are more easily destroyed by taphonomic processes, but more easily preserved whole. Lagerstätten deposits might therefore have a stronger impact on reconstructions of diversity of smaller organisms relative to more robust forms. The relatively poor quality of the avian fossil record in the Late Cretaceous combined with very patchy regional sampling means that it is possible neornithine lineages were present throughout this interval but

  4. The hominin fossil record: taxa, grades and clades

    PubMed Central

    Wood, Bernard; Lonergan, Nicholas

    2008-01-01

    This paper begins by reviewing the fossil evidence for human evolution. It presents summaries of each of the taxa recognized in a relatively speciose hominin taxonomy. These taxa are grouped in grades, namely possible and probable hominins, archaic hominins, megadont archaic hominins, transitional hominins, pre-modern Homo and anatomically modern Homo. The second part of this contribution considers some of the controversies that surround hominin taxonomy and systematics. The first is the vexed question of how you tell an early hominin from an early panin, or from taxa belonging to an extinct clade closely related to the Pan-Homo clade. Secondly, we consider how many species should be recognized within the hominin fossil record, and review the philosophies and methods used to identify taxa within the hominin fossil record. Thirdly, we examine how relationships within the hominin clade are investigated, including descriptions of the methods used to break down an integrated structure into tractable analytical units, and then how cladograms are generated and compared. We then review the internal structure of the hominin clade, including the problem of how many subclades should be recognized within the hominin clade, and we examine the reliability of hominin cladistic hypotheses. The last part of the paper reviews the concepts of a genus, including the criteria that should be used for recognizing genera within the hominin clade. PMID:18380861

  5. Mass extinctions in the fossil record of late Palaeozoic and Mesozoic tetrapods

    NASA Astrophysics Data System (ADS)

    Benton, Michael J.

    The fossil record of tetrapods is very patchy because of the problems of preservation in terrestrial sediments, and because vertebrates are rarely very abundant. However, the fossil record of tetrapods has the advantages that it is easier to establish a phylogenetic taxonomy than for many invertebrate groups (many characters; fast evolution), and there is the potential for more detailed ecological analyses (greater knowledge of modern tetrapod ecology). The diversity of tetrapods increased during the Devonian, the Carboniferous, and the Permian, but it remained generally constant during the Triassic, the Jurassic, and the Early Cretaceous. Overall diversity then began to increase in the Late Cretaceous, and continued to do so during the Tertiary. The rapid radiation of modern tetrapod groups — frogs, salamanders, lizards, snakes, turtles, crocodiles, birds and mammals — was hardly affected by the celebrated end-Cretaceous extinction event.

  6. Maturation experiments reveal bias in the fossil record of feathers

    NASA Astrophysics Data System (ADS)

    McNamara, Maria; Field, Daniel

    2016-04-01

    The evolutionary history of birds and feathers is a major focus in palaeobiology and evolutionary biology. Diverse exceptionally preserved birds and feathered dinosaurs from Jurassic and Cretaceous biotas in China have provided pivotal evidence of early feathers and feather-like integumentary features, but the true nature of many of these fossil soft tissues is still debated. Interpretations of feathers at intermediate developmental stages (i.e. Stages II, III and IV) and of simple quill-like (Stage I) feathers are particularly controversial. This reflects key uncertainties relating to the preservation potential of feathers at different evolutionary-developmental stages, and to the relative preservation potential of diagnostic features of Stage I feathers and hair. To resolve these issues, we used high pressure-high temperature autoclave experiments to simulate the effects of burial on modern feathers from the Black Coucal (Centropus grilii) and Common Starling (Sturnus vulgaris), and on human hair. Our results reveal profound differences in the recalcitrance of feathers of different types during maturation: Stage I and Stage V feathers retain diagnostic morphological and ultrastructural details following maturation, whereas other feather types do not. Further, the morphology and arrangement of certain ultrastructural features diagnostic of Stages III and IV, e.g. barbules, are preferentially lost during maturation. These results indicate a pervasive bias in the fossil record of feathers, whereby preservation of feathers at Stages I and V is favored. Critical stages in the evolution of feathers, i.e. Stages II, III and IV, are less likely to be preserved and more likely to be misinterpreted as feathers at earlier developmental stages. Our discovery has major implications for our understanding of the fidelity of the fossil record of feathers and provides a framework for testing the significance of putative examples of fossil feathers at different developmental

  7. The Quality of the Fossil Record: Populations, Species, and Communities

    NASA Astrophysics Data System (ADS)

    Kidwell, Susan M.; Flessa, Karl W.

    Paleontologists have always been concerned about the documentary quality of the fossil record, and this has also become an important issue for biologists, who increasingly look to accumulations of bones, shells, and plant material as possible ways to extend the time-frame of observation on species and community behaviors. Quantitative data on the postmortem behavior of organic remains in modern environments are providing new insights into death and fossil assemblages as sources of biological information. Important findings include: 1. With the exception of a few circumstances, usually recognizable by independent criteria, transport out of the original life habitat affects few individuals. 2. Most species with preservable hard-parts are in fact represented in the local death assemblage, commonly in correct rank importance. Molluscs are the most durable of modern aquatic groups studied so far, and they show highest fidelity to the original community. 3. Time-averaging of remains from successive generations and communities often prevents the detection of short term (seasons, years) variability but provides an excellent record of the natural range of community composition and structure over longer periods. Thus, although a complex array of processes and circumstances influences preservation, death assemblages of resistant skeletal elements are for many major groups good to excellent records of community composition, morphological variation, and environmental and geographic distribution of species, and such assemblages can record dynamics at ecologically and evolutionarily meaningful scales.

  8. Probabilistic geobiological classification using elemental abundance distributions and lossless image compression in fossils, meteorites, and microorganisms

    NASA Astrophysics Data System (ADS)

    Storrie-Lombardi, Michael C.; Hoover, Richard B.

    2005-09-01

    Last year at this symposium we introduced a strategy for the automated detection of fossils during robotic missions to Mars using both structural and chemical signatures. The strategy employs a measure derived from information theory, lossless compression of photographic images, to estimate the relative complexity of a putative fossil compared to the rock matrix. Following target selection unsupervised multifactor cluster analysis of elemental abundance distributions provides an initial classification of the data. This autonomous classification is then confirmed using a non-linear stochastic neural network to produce a Bayesian estimate of classification accuracy. We have now employed this strategy to explore extant and fossil cyanobacteria from a variety of extreme terrestrial environments and microfossils and abiotic microstructures found in-situ in freshly fractured internal surfaces of carbonaceous meteorite. Elemental abundances (C, N, O, Na, Mg, Al, Si, P, S, Cl, K, Ca, Fe) obtained for both extant and fossil cyanobacteria produce signatures distinguishing them from meteorite targets and from one another. Fossil cyanobacteria exhibit significant loss of C, N, O, P, and Ca and increases in Al, Si, S, and Fe relative to extant organisms. Orgueil structures exhibit decreased abundances for C, N, Na, P, Cl, K, and Ca; and increases in Mg, S, and Fe relative to extant cyanobacteria. Fossil cyanobacteria are distinguished from Orgueil samples by relative increases in Al, Si, and Fe; and by diminished O and Mg. Compression indices verify that variations in random and redundant textural patterns between perceived forms and the background matrix contribute significantly to morphological visual identification. The results provide a quantitative probabilistic methodology for discriminating putatitive fossils from the surrounding rock matrix and from extant organisms using both structural and chemical information. The techniques described appear applicable to the

  9. At the origin of animals: the revolutionary cambrian fossil record.

    PubMed

    Budd, Graham E

    2013-09-01

    The certain fossil record of animals begins around 540 million years ago, close to the base of the Cambrian Period. A series of extraordinary discoveries starting over 100 years ago with Walcott's discovery of the Burgess Shale has accelerated in the last thirty years or so with the description of exceptionally-preserved Cambrian fossils from around the world. Such deposits of "Burgess Shale Type" have been recently complemented by other types of exceptional preservation. Together with a remarkable growth in knowledge about the environments that these early animals lived in, these discoveries have long exerted a fascination and strong influence on views on the origins of animals, and indeed, the nature of evolution itself. Attention is now shifting to the period of time just before animals become common, at the base of the Cambrian and in the preceding Ediacaran Period. Remarkable though the Burgess Shale deposits have been, a substantial gap still exists in our knowledge of the earliest animals. Nevertheless, the fossils from this most remarkable period of evolutionary history continue to exert a strong influence on many aspects of animal evolution, not least recent theories about developmental evolution.

  10. At the Origin of Animals: The Revolutionary Cambrian Fossil Record

    PubMed Central

    Budd, Graham E

    2013-01-01

    The certain fossil record of animals begins around 540 million years ago, close to the base of the Cambrian Period. A series of extraordinary discoveries starting over 100 years ago with Walcott’s discovery of the Burgess Shale has accelerated in the last thirty years or so with the description of exceptionally-preserved Cambrian fossils from around the world. Such deposits of “Burgess Shale Type” have been recently complemented by other types of exceptional preservation. Together with a remarkable growth in knowledge about the environments that these early animals lived in, these discoveries have long exerted a fascination and strong influence on views on the origins of animals, and indeed, the nature of evolution itself. Attention is now shifting to the period of time just before animals become common, at the base of the Cambrian and in the preceding Ediacaran Period. Remarkable though the Burgess Shale deposits have been, a substantial gap still exists in our knowledge of the earliest animals. Nevertheless, the fossils from this most remarkable period of evolutionary history continue to exert a strong influence on many aspects of animal evolution, not least recent theories about developmental evolution. PMID:24396267

  11. Late Paleocene fossils from the Cerrejon Formation, Colombia, are the earliest record of Neotropical rainforest.

    PubMed

    Wing, Scott L; Herrera, Fabiany; Jaramillo, Carlos A; Gómez-Navarro, Carolina; Wilf, Peter; Labandeira, Conrad C

    2009-11-03

    Neotropical rainforests have a very poor fossil record, making hypotheses concerning their origins difficult to evaluate. Nevertheless, some of their most important characteristics can be preserved in the fossil record: high plant diversity, dominance by a distinctive combination of angiosperm families, a preponderance of plant species with large, smooth-margined leaves, and evidence for a high diversity of herbivorous insects. Here, we report on an approximately 58-my-old flora from the Cerrejón Formation of Colombia (paleolatitude approximately 5 degrees N) that is the earliest megafossil record of Neotropical rainforest. The flora has abundant, diverse palms and legumes and similar family composition to extant Neotropical rainforest. Three-quarters of the leaf types are large and entire-margined, indicating rainfall >2,500 mm/year and mean annual temperature >25 degrees C. Despite modern family composition and tropical paleoclimate, the diversity of fossil pollen and leaf samples is 60-80% that of comparable samples from extant and Quaternary Neotropical rainforest from similar climates. Insect feeding damage on Cerrejón fossil leaves, representing primary consumers, is abundant, but also of low diversity, and overwhelmingly made by generalist feeders rather than specialized herbivores. Cerrejón megafossils provide strong evidence that the same Neotropical rainforest families have characterized the biome since the Paleocene, maintaining their importance through climatic phases warmer and cooler than present. The low diversity of both plants and herbivorous insects in this Paleocene Neotropical rainforest may reflect an early stage in the diversification of the lineages that inhabit this biome, and/or a long recovery period from the terminal Cretaceous extinction.

  12. Fossil steroids record the appearance of Demospongiae during the Cryogenian period.

    PubMed

    Love, Gordon D; Grosjean, Emmanuelle; Stalvies, Charlotte; Fike, David A; Grotzinger, John P; Bradley, Alexander S; Kelly, Amy E; Bhatia, Maya; Meredith, William; Snape, Colin E; Bowring, Samuel A; Condon, Daniel J; Summons, Roger E

    2009-02-05

    The Neoproterozoic era (1,000-542 Myr ago) was an era of climatic extremes and biological evolutionary developments culminating in the emergence of animals (Metazoa) and new ecosystems. Here we show that abundant sedimentary 24-isopropylcholestanes, the hydrocarbon remains of C(30) sterols produced by marine demosponges, record the presence of Metazoa in the geological record before the end of the Marinoan glaciation ( approximately 635 Myr ago). These sterane biomarkers are abundant in all formations of the Huqf Supergroup, South Oman Salt Basin, and, based on a new high-precision geochronology, constitute a continuous 100-Myr-long chemical fossil record of demosponges through the terminal Neoproterozoic and into the Early Cambrian epoch. The demosponge steranes occur in strata that underlie the Marinoan cap carbonate (>635 Myr ago). They currently represent the oldest evidence for animals in the fossil record, and are evidence for animals pre-dating the termination of the Marinoan glaciation. This suggests that shallow shelf waters in some late Cryogenian ocean basins (>635 Myr ago) contained dissolved oxygen in concentrations sufficient to support basal metazoan life at least 100 Myr before the rapid diversification of bilaterians during the Cambrian explosion. Biomarker analysis has yet to reveal any convincing evidence for ancient sponges pre-dating the first globally extensive Neoproterozoic glacial episode (the Sturtian, approximately 713 Myr ago in Oman).

  13. Quantifying Uncertainty in Spatio-temporal Forest Composition Changes Inferred from Fossil Pollen Records

    NASA Astrophysics Data System (ADS)

    Dawson, A.; Paciorek, C. J.; McLachlan, J. S.; Goring, S. J.; Williams, J. W.; Jackson, S. T.

    2014-12-01

    Understanding past compositional changes in vegetation provides insight about ecosystem dynamics in response to changing environments. Past vegetation reconstructions rely predominantly on fossil pollen data from sedimentary lake cores, which acts as a proxy record for the surrounding vegetation. Stratigraphic changes in these pollen records allow us to infer changes in composition and species distributions. Pollen records collected from a network of sites allow us to make inference about the spatio-temporal changes in vegetation over thousands of years. However, the complexity of the relationship between pollen deposits and surrounding vegetation, as well as the spatially sparse set of fossil pollen sites are important sources of uncertainty. In addition, uncertainty arises from the carbon dating and age-depth modelling processes. To reconstruct vegetation composition including uncertainty for the Upper Midwestern USA, we build a Bayesian hierarchical model that links vegetation composition to fossil pollen data via a dispersal model. In the calibration phase, we estimate the relationship between vegetation and pollen for the settlement era using Public Land Survey data and a network of pollen records. In the prediction phase, parameter estimates obtained during the calibration phase are used to estimate latent species distributions and relative abundances over the last 2500 years. We account for additional uncertainty in the pollen records by: allowing expert palynologists to identify pre-settlement pollen samples to be included in our calibration data, and through the incorporation of age uncertainty obtained from the Bayesian age-depth model BACON in our prediction data. Resulting spatio-temporal composition and abundance estimates will be used to improve forecasting capabilities of ecosystem models.

  14. Patterns of generic extinction in the fossil record

    NASA Technical Reports Server (NTRS)

    Raup, D. M.; Boyajian, G. E.

    1988-01-01

    Analysis of the stratigraphic records of 19,897 fossil genera indicates that most classes and orders show largely congruent rises and falls in extinction intensity throughout the Phanerozoic. Even an ecologically homogeneous sample of reef genera shows the same basic extinction profile. The most likely explanation for the congruence is that extinction is physically rather than biologically driven and that it is dominated by the effects of geographically widespread environmental perturbations influencing most habitats. Significant departures from the congruence are uncommon but important because they indicate physiological or habitat selectivity. The similarity of the extinction records of reef organisms and the marine biota as a whole confirms that reefs and other faunas are responding to the same history of environmental stress.

  15. The fossil record of evolution: Data on diversification and extinction

    NASA Technical Reports Server (NTRS)

    Sepkoski, J. J., Jr.

    1991-01-01

    Understanding of the evolution of complex life, and of the roles that changing terrestrial and extraterrestrial environments played in life's history, is dependent upon synthetic knowledge of the fossil record. Paleontologists have been describing fossils for more that two centuries. However, much of this information is dispersed in monographs and journal articles published throughout the world. Over the past several years, this literature was surveyed, and a data base on times of origination and extinction of fossil genera was compiled. The data base, which now holds approximately 32,000 genera, covers all taxonomic groups of marine animals, incorporates the most recent taxonomic assignments, and uses a detailed global time framework that can resolve originations and extinctions to intervals averaging three million years in duration. These data can be used to compile patterns of global biodiversity, measure rates of taxic evolution, and test hypotheses concerning adaptive radiations, mass extinctions, etc. Thus far, considerable effort was devoted to using the data to test the hypothesis of periodicity of mass extinction. Rates of extinction measured from the data base have also been used to calibrate models of evolutionary radiations in marine environments. It was observed that new groups, or clades of animals (i.e., orders and classes) tend to reach appreciable diversity first in nearshore environments and then to radiate in more offshore environments; during decline, these clades may disappear from the nearshore while persisting in offshore, deep water habitats. These observations have led to suggestions that there is something special about stressful or perturbed environments that promotes the evolution of novel kinds of animals that can rapidly replace their predecessors. The numerical model that is being investigated to study this phenomenon treats environments along onshore-offshore gradients as if they were discrete habitats. Other aspects of this

  16. The fossil record of evolution: Data on diversification and extinction

    NASA Technical Reports Server (NTRS)

    Sepkoski, J. J., Jr.

    1986-01-01

    Synoptic studies of the fossil record of complex life on Earth indicate increasingly that extinction, and especially mass extinction, were extremely important driving forces in the history of life. Analysis of a new compilation of geologic ranges for 25,000 genera of marine animals suggests that extinction events were much more frequent in occurrence and variable in magnitude than previously suspected. At least 30 well documented and potential mass extinctions were identified in the dataset. The most recent event, distributed over 260 to 0 ma. exhibit a stationary periodicity of 26.1 + or - 1 ma, implicating a cosmological forcing mechanism. Earlier events, especially in the 575 to 450 ma interval, are more frequent, possibly indicating either a breakdown of periodicity in the more distant past; and as yet undemonstrated diminution of the period length; or frequent aperiodic terrestrial perturbations of a less stable biota superimposed upon the cosmological periodicity.

  17. Mass extinctions among tetrapods and the quality of the fossil record.

    PubMed

    Benton, M J

    1989-11-06

    The fossil record of tetrapods is very patchy because of the problems of preservation, in terrestrial sediments in particular, and because vertebrates are rarely very abundant. However, the fossil record of tetrapods has the advantages that it is easier to establish a phylogenetic taxonomy than for many invertebrate groups, and there is the potential for more detailed ecological analyses. The relative incompleteness of a fossil record may be assessed readily, and this can be used to test whether drops in overall diversity are related to mass extinctions or to gaps in our knowledge. Absolute incompleteness cannot be assessed directly, but a historical approach may offer clues to future improvements in our knowledge. One of the key problems facing palaeobiologists is paraphyly, the fact that many higher taxa in common use do not contain all of the descendants of the common ancestor. This may be overcome by cladistic analysis and the identification of monophyletic groups. The diversity of tetrapods increased from the Devonian to the Permian, remained roughly constant during the Mesozoic, and then began to increase in the late Cretaceous, and continued to do so during the Tertiary. The rapid radiation of 'modern' tetrapod groups--frogs, salamanders, lizards, snakes, turtles, crocodilians, birds and mammals--was hardly affected by the celebrated end-Cretaceous extinction event. Major mass extinctions among tetrapods took place in the early Permian, late Permian, early Triassic, late Triassic, late Cretaceous, early Oligocene and late Miocene. Many of these events appear to coincide with the major mass extinctions among marine invertebrates, but the tetrapod record is largely equivocal with regard to the theory of periodicity of mass extinctions.

  18. Nondestructive, in situ, cellular-scale mapping of elemental abundances including organic carbon in permineralized fossils.

    PubMed

    Boyce, C K; Hazen, R M; Knoll, A H

    2001-05-22

    The electron microprobe allows elemental abundances to be mapped at the microm scale, but until now high resolution mapping of light elements has been challenging. Modifications of electron microprobe procedure permit fine-scale mapping of carbon. When applied to permineralized fossils, this technique allows simultaneous mapping of organic material, major matrix-forming elements, and trace elements with microm-scale resolution. The resulting data make it possible to test taphonomic hypotheses for the formation of anatomically preserved silicified fossils, including the role of trace elements in the initiation of silica precipitation and in the prevention of organic degradation. The technique allows one to understand the localization of preserved organic matter before undertaking destructive chemical analyses and, because it is nondestructive, offers a potentially important tool for astrobiological investigations of samples returned from Mars or other solar system bodies.

  19. A 300-million-year record of atmospheric carbon dioxide from fossil plant cuticles

    NASA Astrophysics Data System (ADS)

    Retallack, Gregory J.

    2001-05-01

    To understand better the link between atmospheric CO2 concentrations and climate over geological time, records of past CO2 are reconstructed from geochemical proxies. Although these records have provided us with a broad picture of CO2 variation throughout the Phanerozoic eon (the past 544Myr), inconsistencies and gaps remain that still need to be resolved. Here I present a continuous 300-Myr record of stomatal abundance from fossil leaves of four genera of plants that are closely related to the present-day Ginkgo tree. Using the known relationship between leaf stomatal abundance and growing season CO2 concentrations, I reconstruct past atmospheric CO2 concentrations. For the past 300Myr, only two intervals of low CO2 (<1,000p.p.m.v.) are inferred, both of which coincide with known ice ages in Neogene (1-8Myr) and early Permian (275-290Myr) times. But for most of the Mesozoic era (65-250Myr), CO2 levels were high (1,000-2,000p.p.m.v.), with transient excursions to even higher CO2 (>2,000p.p.m.v.) concentrations. These results are consistent with some reconstructions of past CO2 (refs 1, 2) and palaeotemperature records, but suggest that CO2 reconstructions based on carbon isotope proxies may be compromised by episodic outbursts of isotopically light methane. These results support the role of water vapour, methane and CO2 in greenhouse climate warming over the past 300Myr.

  20. Micritic Peloids: Fossil Record of Biofilms Associated With Methane Seeps

    NASA Astrophysics Data System (ADS)

    Shapiro, R. S.

    2006-12-01

    Biofilms of archaea and bacteria are found where reduced hydrocarbons seep upward to the seafloor. The process of oxidizing the methane coupled with the reduction of seawater sulfate increases the alkalinity in the localized area and promotes the precipitation of carbonate minerals. The biofilms and carbonate deposits are ubiquitous in the modern oceans and the geologic record of hydrocarbon seeps goes back well into the Paleozoic. However, the paleontologic record of the microbes responsible for the production of the carbonates is poorly constrained. The few examples comprise casts and molds of filaments and cocci, framboidal pyrite of assumed biological affinity, organic biomarkers (lipids, hopanoids), and microbialite. Volumetrically, these fossils are insignificant compared with the total bulk of seep carbonate. Research into Mesozoic and Cenozoic seep carbonates from California, Oregon, Colorado, and South Dakota has yielded a new recognition for ancient biofilms. Micrite—the most common lithotype of seeps globally—exists as both peloids and groundmass. Common peloids of micrite average 0.5 mm in diameter (range from 0.1 to 0.7 mm), incorporate some siliciclastic material, and have distinct margins. Opaque minerals, likely sulfides, occur throughout the peloids. The matrix surrounding the peloids is a similar micrite, though in some samples, the peloids are surrounded by cement. Diagenesis leads to blurring of the peloid margins until a homogenous micrite groundmass with scattered sulfide and siliciclastic grains results. Use of a white card helps to outline original peloids. Increased levels of diagenesis can lead to crystal coarsening and obliterate original textures. These peloids are likely fecal pellets. A second population of peloids occur that are smaller (0.05 to 0.10 mm), darker in color, and with more diffuse boundaries. There are generally no siliciclastic grains intermixed with these peloids. These peloids occur in millimeter-scale clusters and

  1. Insect-damaged fossil leaves record food web response to ancient climate change and extinction.

    PubMed

    Wilf, P

    2008-01-01

    Plants and herbivorous insects have dominated terrestrial ecosystems for over 300 million years. Uniquely in the fossil record, foliage with well-preserved insect damage offers abundant and diverse information both about producers and about ecological and sometimes taxonomic groups of consumers. These data are ideally suited to investigate food web response to environmental perturbations, and they represent an invaluable deep-time complement to neoecological studies of global change. Correlations between feeding diversity and temperature, between herbivory and leaf traits that are modulated by climate, and between insect diversity and plant diversity can all be investigated in deep time. To illustrate, I emphasize recent work on the time interval from the latest Cretaceous through the middle Eocene (67-47 million years ago (Ma)), including two significant events that affected life: the end-Cretaceous mass extinction (65.5 Ma) and its ensuing recovery; and globally warming temperatures across the Paleocene-Eocene boundary (55.8 Ma). Climatic effects predicted from neoecology generally hold true in these deep-time settings. Rising temperature is associated with increased herbivory in multiple studies, a result with major predictive importance for current global warming. Diverse floras are usually associated with diverse insect damage; however, recovery from the end-Cretaceous extinction reveals uncorrelated plant and insect diversity as food webs rebuilt chaotically from a drastically simplified state. Calibration studies from living forests are needed to improve interpretation of the fossil data.

  2. The late Middle Pleistocene hominin fossil record of eastern Asia: synthesis and review.

    PubMed

    Bae, Christopher J

    2010-01-01

    Traditionally, Middle Pleistocene hominin fossils that cannot be allocated to Homo erectus sensu lato or modern H. sapiens have been assigned to different specific taxa. For example, in eastern Asia, these hominin fossils have been classified as archaic, early, or premodern H. sapiens. An increasing number of Middle Pleistocene hominin fossils are currently being assigned to H. heidelbergensis. This is particularly the case for the African and European Middle Pleistocene hominin fossil record. There have been suggestions that perhaps the eastern Asian late Middle Pleistocene hominins can also be allocated to the H. heidelbergensis hypodigm. In this article, I review the current state of the late Middle Pleistocene hominin fossil record from eastern Asia and examine the various arguments for assigning these hominins to the different specific taxa. The two primary conclusions drawn from this review are as follows: 1) little evidence currently exists in the eastern Asian Middle Pleistocene hominin fossil record to support their assignment to H. heidelbergensis; and 2) rather than add to the growing list of hominin fossil taxa by using taxonomic names like H. daliensis for northeast Asian fossils and H. mabaensis for Southeast Asian fossils, it is better to err on the side of caution and continue to use the term archaic H. sapiens to represent all of these hominin fossils. What should be evident from this review is the need for an increase in the quality and quantity of the eastern Asian hominin fossil data set. Fortunately, with the increasing number of large-scale multidisciplinary paleoanthropological field and laboratory research projects in eastern Asia, the record is quickly becoming better understood.

  3. 'Citizen science' recording of fossils by adapting existing computer-based biodiversity recording tools

    NASA Astrophysics Data System (ADS)

    McGowan, Alistair

    2014-05-01

    Biodiversity recording activities have been greatly enhanced by the emergence of online schemes and smartphone applications for recording and sharing data about a wide variety of flora and fauna. As a palaeobiologist, one of the areas of research I have been heavily involved in is the question of whether the amount of rock available to sample acts as a bias on our estimates of biodiversity through time. Although great progress has been made on this question over the past ten years by a number of researchers, I still think palaeontology has not followed the lead offered by the 'citizen science' revolution in studies of extant biodiversity. By constructing clearly structured surveys with online data collection support, it should be possible to collect field data on the occurrence of fossils at the scale of individual exposures, which are needed to test competing hypotheses about these effects at relatively small spatial scales. Such data collection would be hard to justify for universities and museums with limited personnel but a co-ordinated citizen science programme would be capable of delivering such a programme. Data collection could be based on the MacKinnon's Lists method, used in rapid conservation assessment work. It relies on observers collecting lists of a fixed length (e.g. 10 species long) but what is important is that it focuses on getting observers to ignore sightings of the same species until that list is complete. This overcomes the problem of 'common taxa being commonly recorded' and encourages observers to seek out and identify the rarer taxa. This gives a targeted but finite task. Rather than removing fossils, participants would be encouraged to take photographs to share via a recording website. The success of iSpot, which allows users to upload photos of plants and animals for other users to help with identifications, offers a model for overcoming the problems of identifying fossils, which can often look nothing like the examples illustrated in

  4. New Palaeogene horntail wasps (Hymenoptera, Siricidae) and a discussion of their fossil record.

    PubMed

    Wedmann, Sonja; Pouillon, Jean-Marc; Nel, André

    2014-09-29

    The phylogenetic placement of siricid hymenopterans and especially the relationships among Siricidae are not resolved, and are in need of further investigation. The fossil record helps to illuminate the evolutionary history of this group. In this paper, Xoanon? eocenicus sp. nov. is newly described from the Eocene Fossillagerstätte Grube Messel (Germany). Although several characters of the wing venation of this fossil are similar to the extant genus Xoanon, there remain some doubts concerning the generic placement. A newly found fossil is attributed to Urocerus ligniticus (Piton, 1940) from the Paloecene Fossillagerstätte Menat (France) and provides more morphological information on this species. An overview of the fossil record of Siricidae in the strict sense is given and the state of knowledge on the different fossils is reviewed.

  5. Late Paleocene fossils from the Cerrejón Formation, Colombia, are the earliest record of Neotropical rainforest

    PubMed Central

    Wing, Scott L.; Herrera, Fabiany; Jaramillo, Carlos A.; Gómez-Navarro, Carolina; Wilf, Peter; Labandeira, Conrad C.

    2009-01-01

    Neotropical rainforests have a very poor fossil record, making hypotheses concerning their origins difficult to evaluate. Nevertheless, some of their most important characteristics can be preserved in the fossil record: high plant diversity, dominance by a distinctive combination of angiosperm families, a preponderance of plant species with large, smooth-margined leaves, and evidence for a high diversity of herbivorous insects. Here, we report on an ≈58-my-old flora from the Cerrejón Formation of Colombia (paleolatitude ≈5 °N) that is the earliest megafossil record of Neotropical rainforest. The flora has abundant, diverse palms and legumes and similar family composition to extant Neotropical rainforest. Three-quarters of the leaf types are large and entire-margined, indicating rainfall >2,500 mm/year and mean annual temperature >25 °C. Despite modern family composition and tropical paleoclimate, the diversity of fossil pollen and leaf samples is 60–80% that of comparable samples from extant and Quaternary Neotropical rainforest from similar climates. Insect feeding damage on Cerrejón fossil leaves, representing primary consumers, is abundant, but also of low diversity, and overwhelmingly made by generalist feeders rather than specialized herbivores. Cerrejón megafossils provide strong evidence that the same Neotropical rainforest families have characterized the biome since the Paleocene, maintaining their importance through climatic phases warmer and cooler than present. The low diversity of both plants and herbivorous insects in this Paleocene Neotropical rainforest may reflect an early stage in the diversification of the lineages that inhabit this biome, and/or a long recovery period from the terminal Cretaceous extinction. PMID:19833876

  6. Old World fossil record of modern-type hummingbirds.

    PubMed

    Mayr, Gerald

    2004-05-07

    I report on tiny skeletons of stem-group hummingbirds from the early Oligocene of Germany that are of essentially modern appearance and exhibit morphological specializations toward nectarivory and hovering flight. These are the oldest fossils of modern-type hummingbirds, which had not previously been reported from the Old World. The findings demonstrate that early hummingbird evolution was not restricted to the New World. They further suggest that bird-flower coevolution dates back to the early Oligocene and open another view on the origin of ornithophily in Old World plants.

  7. Integrating developmental biology and the fossil record of reptiles.

    PubMed

    Skawiński, Tomasz; Tałanda, Mateusz

    2014-01-01

    Numerous new discoveries and new research techniques have influenced our understanding of reptile development from a palaeontological perspective. They suggest for example that transition from mineralized to leathery eggshells and from oviparity to viviparity appeared much more often in the evolution of reptiles than was previously thought. Most marine reptiles evolved from viviparous terrestrial ancestors and had probably genetic sex determination. Fossil forms often display developmental traits absent or rare among modern ones such as polydactyly, hyperphalangy, the presence of ribcage armour, reduction of head ornamentation during ontogeny, extreme modifications of vertebral count or a wide range of feather-like structures. Thus, they provide an empirical background for many morphogenetic considerations.

  8. Environmental Impact on Fossil Record for Palaecological Reconstruction Studies

    NASA Astrophysics Data System (ADS)

    Paraskevi, Chantzi; Elissavet, Dotsika; Brunella, Raco; Konstadinos, Albanakis; Anastasia, Poutouki; Eleni, Samarztidou

    2016-10-01

    Paleoecological studies have an important role in understanding past environmental, dietary and/or societal changes however require the authentic signature of fossil materials. Therefore, a significant part of these studies concerns the isolation of the material authentic matrix. Bone hydroxyapatite from different animal species from the archaeological site of Dispilio in Kastoria Lake basin in northern Greece has been subjected to mineral analysis in order to detect if there are suitable for palaoecological studies. Calcium, phosphorus, oxygen and hydrogen are the main components of bones resulting rigidity, hardness and compressive strength of their structure. However different bone structure resulting different calcium- phosphate phases and different compositions, including Ca/P ratios. These disparities may be attributable to different physiological characteristic, conditions under which the bones were formed or burial environment. Trace element analysis (Ca/P, Sr/P, Fe/Mn) concluded that treated fossil bones retained their biochemical signal without any strong influence by soil remains however without suggesting that no chemical alteration have been occurred.

  9. Contemporaneous trace and body fossils from a late Pleistocene Lakebed in Victoria, Australia, allow assessment of bias in the fossil record.

    PubMed

    Camens, Aaron Bruce; Carey, Stephen Paul

    2013-01-01

    The co-occurrence of vertebrate trace and body fossils within a single geological formation is rare and the probability of these parallel records being contemporaneous (i.e. on or near the same bedding plane) is extremely low. We report here a late Pleistocene locality from the Victorian Volcanic Plains in south-eastern Australia in which demonstrably contemporaneous, but independently accumulated vertebrate trace and body fossils occur. Bite marks from a variety of taxa are also present on the bones. This site provides a unique opportunity to examine the biases of these divergent fossil records (skeletal, footprints and bite marks) that sampled a single fauna. The skeletal record produced the most complete fauna, with the footprint record indicating a markedly different faunal composition with less diversity and the feeding traces suggesting the presence, amongst others, of a predator not represented by either the skeletal or footprint records. We found that the large extinct marsupial predator Thylacoleo was the only taxon apparently represented by all three records, suggesting that the behavioral characteristics of large carnivores may increase the likelihood of their presence being detected within a fossil fauna. In contrast, Diprotodon (the largest-ever marsupial) was represented only by trace fossils at this site and was absent from the site's skeletal record, despite its being a common and easily detected presence in late Pleistocene skeletal fossil faunas elsewhere in Australia. Small mammals absent from the footprint record for the site were represented by skeletal fossils and bite marks on bones.

  10. Contemporaneous Trace and Body Fossils from a Late Pleistocene Lakebed in Victoria, Australia, Allow Assessment of Bias in the Fossil Record

    PubMed Central

    Camens, Aaron Bruce; Carey, Stephen Paul

    2013-01-01

    The co-occurrence of vertebrate trace and body fossils within a single geological formation is rare and the probability of these parallel records being contemporaneous (i.e. on or near the same bedding plane) is extremely low. We report here a late Pleistocene locality from the Victorian Volcanic Plains in south-eastern Australia in which demonstrably contemporaneous, but independently accumulated vertebrate trace and body fossils occur. Bite marks from a variety of taxa are also present on the bones. This site provides a unique opportunity to examine the biases of these divergent fossil records (skeletal, footprints and bite marks) that sampled a single fauna. The skeletal record produced the most complete fauna, with the footprint record indicating a markedly different faunal composition with less diversity and the feeding traces suggesting the presence, amongst others, of a predator not represented by either the skeletal or footprint records. We found that the large extinct marsupial predator Thylacoleo was the only taxon apparently represented by all three records, suggesting that the behavioral characteristics of large carnivores may increase the likelihood of their presence being detected within a fossil fauna. In contrast, Diprotodon (the largest-ever marsupial) was represented only by trace fossils at this site and was absent from the site's skeletal record, despite its being a common and easily detected presence in late Pleistocene skeletal fossil faunas elsewhere in Australia. Small mammals absent from the footprint record for the site were represented by skeletal fossils and bite marks on bones. PMID:23301008

  11. The Future of Fossil Fuels: A Century of Abundance or a Century of Decline?

    NASA Astrophysics Data System (ADS)

    Nelder, C.

    2012-12-01

    Horizontal drilling, hydraulic fracturing, and other advanced technologies have spawned a host of new euphoric forecasts of hydrocarbon abundance. Yet although the world's remaining oil and gas resources are enormous, most of them are destined to stay in the ground due to real-world constraints on price, flow rates, investor appetite, supply chain security, resource quality, and global economic conditions. While laboring under the mistaken belief that it sits atop a 100-year supply of natural gas, the U.S. is contemplating exporting nearly all of its shale gas production even as that production is already flattening due to poor economics. Instead of bringing "energy independence" to the U.S. and making it the top oil exporter, unrestricted drilling for tight oil and in the federal outer continental shelf would cut the lifespan of U.S. oil production in half and make it the world's most desperate oil importer by mid-century. And current forecasts for Canadian tar sands production are as unrealistic as their failed predecessors. Over the past century, world energy production has moved progressively from high quality resources with high production rates and low costs to lower quality resources with lower production rates and higher costs, and that progression is accelerating. Soon we will discover the limits of practical extraction, as production costs exceed consumer price tolerance. Oil and gas from tight formations, shale, bitumen, kerogen, coalbeds, deepwater, and the Arctic are not the stuff of new abundance, but the oil junkie's last dirty fix. This session will highlight the gap between the story the industry tells about our energy future, and the story the data tells about resource size, production rates, costs, and consumer price tolerance. It will show why it's time to put aside unrealistic visions of continued dependence on fossil fuels, face up to a century of decline, and commit ourselves to energy and transportation transition.

  12. Gaps in the Rock and Fossil Records and Implications for the Rate and Mode of Evolution.

    ERIC Educational Resources Information Center

    Smith, Grant Sackett

    1988-01-01

    Examines three types of gaps in the fossil record: real gaps, imaginary gaps, and temporary gaps. Reviews some recent evidence concerning evolution from the paleontological record of microfossils, invertebrates, and vertebrates in order to make some general conclusions regarding the manner in which life evolved on earth. (CW)

  13. Methods for the quantitative comparison of molecular estimates of clade age and the fossil record.

    PubMed

    Clarke, Julia A; Boyd, Clint A

    2015-01-01

    Approaches quantifying the relative congruence, or incongruence, of molecular divergence estimates and the fossil record have been limited. Previously proposed methods are largely node specific, assessing incongruence at particular nodes for which both fossil data and molecular divergence estimates are available. These existing metrics, and other methods that quantify incongruence across topologies including entirely extinct clades, have so far not taken into account uncertainty surrounding both the divergence estimates and the ages of fossils. They have also treated molecular divergence estimates younger than previously assessed fossil minimum estimates of clade age as if they were the same as cases in which they were older. However, these cases are not the same. Recovered divergence dates younger than compared oldest known occurrences require prior hypotheses regarding the phylogenetic position of the compared fossil record and standard assumptions about the relative timing of morphological and molecular change to be incorrect. Older molecular dates, by contrast, are consistent with an incomplete fossil record and do not require prior assessments of the fossil record to be unreliable in some way. Here, we compare previous approaches and introduce two new descriptive metrics. Both metrics explicitly incorporate information on uncertainty by utilizing the 95% confidence intervals on estimated divergence dates and data on stratigraphic uncertainty concerning the age of the compared fossils. Metric scores are maximized when these ranges are overlapping. MDI (minimum divergence incongruence) discriminates between situations where molecular estimates are younger or older than known fossils reporting both absolute fit values and a number score for incompatible nodes. DIG range (divergence implied gap range) allows quantification of the minimum increase in implied missing fossil record induced by enforcing a given set of molecular-based estimates. These metrics are used

  14. The fossil record of ecdysis, and trends in the moulting behaviour of trilobites.

    PubMed

    Daley, Allison C; Drage, Harriet B

    2016-03-01

    Ecdysis, the process of moulting an exoskeleton, is one of the key characters uniting arthropods, nematodes and a number of smaller phyla into Ecdysozoa. The arthropod fossil record, particularly trilobites, eurypterids and decapod crustaceans, yields information on moulting, although the current focus is predominantly descriptive and lacks a broader evolutionary perspective. We here review literature on the fossil record of ecdysis, synthesising research on the behaviour, evolutionary trends, and phylogenetic significance of moulting throughout the Phanerozoic. Approaches vary widely between taxonomic groups, but an overall theme uniting these works suggests that identifying moults in the palaeontological record must take into account the morphology, taphonomy and depositional environment of fossils. We also quantitatively analyse trends in trilobite ecdysis based on a newly generated database of published incidences of moulting behaviour. This preliminary work reveals significant taxonomic and temporal signal in the trilobite moulting fossil record, with free cheek moulting being prevalent across all Orders and throughout the Phanerozoic, and peaks of cephalic moulting in Phacopida during the Ordovician and rostral plate moulting in Redlichiida during the Cambrian. This study and a review of the literature suggest that it is feasible to extract large-scale evolutionary information from the fossil record of moulting.

  15. Discriminating signal from noise in the fossil record of early vertebrates reveals cryptic evolutionary history.

    PubMed

    Sansom, Robert S; Randle, Emma; Donoghue, Philip C J

    2015-02-07

    The fossil record of early vertebrates has been influential in elucidating the evolutionary assembly of the gnathostome bodyplan. Understanding of the timing and tempo of vertebrate innovations remains, however, mired in a literal reading of the fossil record. Early jawless vertebrates (ostracoderms) exhibit restriction to shallow-water environments. The distribution of their stratigraphic occurrences therefore reflects not only flux in diversity, but also secular variation in facies representation of the rock record. Using stratigraphic, phylogenetic and palaeoenvironmental data, we assessed the veracity of the fossil records of the jawless relatives of jawed vertebrates (Osteostraci, Galeaspida, Thelodonti, Heterostraci). Non-random models of fossil recovery potential using Palaeozoic sea-level changes were used to calculate confidence intervals of clade origins. These intervals extend the timescale for possible origins into the Upper Ordovician; these estimates ameliorate the long ghost lineages inferred for Osteostraci, Galeaspida and Heterostraci, given their known stratigraphic occurrences and stem-gnathostome phylogeny. Diversity changes through the Silurian and Devonian were found to lie within the expected limits predicted from estimates of fossil record quality indicating that it is geological, rather than biological factors, that are responsible for shifts in diversity. Environmental restriction also appears to belie ostracoderm extinction and demise rather than competition with jawed vertebrates.

  16. Assessing the fidelity of the fossil record by using marine bivalves

    PubMed Central

    Valentine, James W.; Jablonski, David; Kidwell, Susan; Roy, Kaustuv

    2006-01-01

    Taxa that fail to become incorporated into the fossil record can reveal much about the biases of this record and provide the information needed to correct such biases in empirical analyses of the history of life. Yet little is known about the characteristics of taxa missing from the fossil record. For the marine Bivalvia, which have become a model system for macroevolutionary and macroecological analysis in the fossil record, 308 of the 1,292 living genera and subgenera (herein termed “taxa”) are not recorded as fossils. These missing taxa are not a random sample of the clade, but instead tend to have small body size, reactive shell structures, commensal or parasitic habit, deep-sea distribution, narrow geographic range, restriction to regions exposing few Neogene marine sediments, or recent date of formal taxonomic description in the neontological literature. Most missing taxa show two or more of these features and tend to be concentrated in particular families. When we exclude the smallest taxa (<1 cm) and deep-sea endemics, date of published description and geographic range become the strongest predictors of the missing taxa; other factors are statistically insignificant or have relatively small effects. These biases might influence a variety of analyses including the use of fossil data in support of phylogenetic analyses, molecular clock calibrations, and analyses of spatial and temporal dynamics of clades and biotas. Clade inventories such as these can be used to develop protocols that minimize the biases imposed by sampling and preservation. PMID:16617108

  17. When can decreasing diversification rates be detected with molecular phylogenies and the fossil record?

    PubMed

    Liow, Lee Hsiang; Quental, Tiago B; Marshall, Charles R

    2010-12-01

    Traditionally, patterns and processes of diversification could only be inferred from the fossil record. However, there are an increasing number of tools that enable diversification dynamics to be inferred from molecular phylogenies. The application of these tools to new data sets has renewed interest in the question of the prevalence of diversity-dependent diversification. However, there is growing recognition that the absence of extinct species in molecular phylogenies may prevent accurate inferences about the underlying diversification dynamics. On the other hand, even though the fossil record provides direct data on extinct species, its incompleteness can also mask true diversification processes. Here, using computer-generated diversity-dependent phylogenies, we mimicked molecular phylogenies by eliminating extinct lineages. We also simulated the fossil record by converting the temporal axis into discrete intervals and imposing a variety of preservation processes on the lineages. Given the lack of reliable phylogenies for many fossil marine taxa, we also stripped away phylogenetic information from the computer-generated phylogenies. For the simulated molecular phylogenies, we examined the efficacy of the standard metric (the γ statistic) for identifying decreasing rates of diversification. We find that the underlying decreasing rate of diversification is detected only when the rate of change in the diversification rate is high, and if the molecular phylogeny happens to capture the diversification process as the equilibrium diversity is first reached or shortly thereafter. In contrast, estimating rates of diversification from the simulated fossil record captures the expected zero rate of diversification after equilibrium is reached under a wide range of preservation scenarios. The ability to detect the initial decreasing rate of diversification is lost as the temporal resolution of the fossil record drops and with a decreased quality of preservation. When the

  18. The fossil record of evolution: Analysis of extinction

    NASA Technical Reports Server (NTRS)

    Raup, D. M.

    1986-01-01

    There is increasing evidence that events in space have had direct effects on Earth history and on the history of life on Earth. Nowhere is this more evident than in mass extinction. The biosphere has undergone repeated devastation caused by relatively short-lived environmental stress, with species kill rates up to 80 and 95%. For five of the mass extinctions, geochemical or other evidence was reported suggesting large body impact as the cause of the environmental stress producing the extinctions. It was argued on statistical ground that the major extinction events are uniformly periodic in geological time. If it is true that large body impact is a principal cause of mass extinctions and if the periodicity is real, than a cosmic driving mechanism is inescapable. Paleontological data sets were developed which detail the ranges in geological time of about 4,000 families and 25,000 genera of fossil marine organisms. Analyses to date have concentrated on the most recent 250 million years. Associated with these studies are analyses of other aspects of Earth history which may have signatures indicative of extraterrestrial effects.

  19. Completeness of the fossil record: Estimating losses due to small body size

    NASA Astrophysics Data System (ADS)

    Cooper, Roger A.; Maxwell, Phillip A.; Crampton, James S.; Beu, Alan G.; Jones, Craig M.; Marshall, Bruce A.

    2006-04-01

    Size bias in the fossil record limits its use for interpreting patterns of past biodiversity and ecological change. Using comparative size frequency distributions of exceptionally good regional records of New Zealand Holocene and Cenozoic Mollusca in museum archive collections, we derive first-order estimates of the magnitude of the bias against small body size and the effect of this bias on completeness of the fossil record. Our database of 3907 fossil species represents an original living pool of 9086 species, from which ˜36% have been removed by size culling, 27% from the smallest size class (<5 mm). In contrast, non-size-related losses compose only 21% of the total. In soft rocks, the loss of small taxa can be reduced by nearly 50% through the employment of exhaustive collection and preparation techniques.

  20. Experimental analysis of decay biases in the fossil record of lobopodians

    NASA Astrophysics Data System (ADS)

    Murdock, Duncan; Gabbott, Sarah; Purnell, Mark

    2016-04-01

    If fossils are to realize their full potential in reconstructing the tree of life we must understand how our view of ancient organisms is obscured by taphonomic filters of decay and preservation. In most cases, processes of decay will leave behind either nothing or only the most decay resistant body parts, and even in those rare instances where soft tissues are fossilized we cannot assume that the resulting fossil, however exquisite, represents a faithful anatomical representation of the animal as it was in life.Recent experiments have shown that the biases introduced by decay can be far from random; in chordates, for example, the most phylogenetically informative characters are also the most decay-prone, resulting in 'stemward slippage'. But how widespread is this phenomenon, and are there other non-random biases linked to decay? Intuitively, we make assumptions about the likelihood of different kinds of characters to survive and be preserved, with knock-on effects for anatomical and phylogenetic interpretations. To what extent are these assumptions valid? We combine our understanding of the fossil record of lobopodians with insights from decay experiments of modern onychophorans (velvet worms) to test these assumptions. Our analysis demonstrates that taphonomically informed tests of character interpretations have the potential to improve phylogenetic resolution. This approach is widely applicable to the fossil record - allowing us to ground-truth some of the assumptions involved in describing exceptionally preserved fossil material.

  1. Mass extinction events and the plant fossil record.

    PubMed

    McElwain, Jennifer C; Punyasena, Surangi W

    2007-10-01

    Five mass extinction events have punctuated the geological record of marine invertebrate life. They are characterized by faunal extinction rates and magnitudes that far exceed those observed elsewhere in the geological record. Despite compelling evidence that these extinction events were probably driven by dramatic global environmental change, they were originally thought to have little macroecological or evolutionary consequence for terrestrial plants. New high-resolution regional palaeoecological studies are beginning to challenge this orthodoxy, providing evidence for extensive ecological upheaval, high species-level turnover and recovery intervals lasting millions of years. The challenge ahead is to establish the geographical extent of the ecological upheaval, because reconstructing the vegetation dynamics associated with these events will elucidate the role of floral change in faunal mass extinction and provide a better understanding of how plants have historically responded to global environmental change similar to that anticipated for our future.

  2. Impact theory of mass extinctions and the invertebrate fossil record

    SciTech Connect

    Alvarez, W.; Kauffman, E.G.; Surlyk, F.; Alvarez, L.W.; Asaro, F.; Michel, H.V.

    1984-03-16

    There is much evidence that the Cretaceous-Tertiary boundary was marked by a massive meteorite impact. Theoretical consideration of the consequences of such an impact predicts sharp extinctions in many groups of animals precisely at the boundary. Paleontological data clearly show gradual declines in diversity over the last 1 to 10 million years in various invertebrate groups. Reexamination of data from careful studies of the best sections shows that, in addition to undergoing the decline, four groups (ammonites, cheilostomate bryozoans, brachiopods, and bivalves) were affected by sudden truncations precisely at the iridium anomaly that marks the boundary. The paleontological record thus bears witness to terminal-Cretaceous extinctions on two time scales: a slow decline unrelated to the impact and a sharp truncation synchronous with and probably caused by the impact. 50 references, 4 figures.

  3. Testing the Molecular Clock Using the Best Fossil Record: Case Studies from the Planktic Foraminifera

    NASA Astrophysics Data System (ADS)

    Steel, B. A.; Kucera, M.; Darling, K.

    2004-12-01

    Criticism of molecular clock studies often centres on inadequate calibration and a perceived lack of correlation between reproductive isolation and recognisable morphological evolution. Since many major groups (e.g. birds, mammals, reptiles) have a poor fossil record, it is often difficult to test and refute these limitations. Planktic foraminifera represent an exception to this rule. Deep-sea sediments are super-abundant in foraminifera, and large numbers of specimens and occurrences are easily garnered from Ocean Drilling Programme cores. Planktic foraminifera therefore represent an ideal model group with which to test and refine molecular clock studies. Since the 1990AƒAøAøâ_sA¬Aøâ_zAøs, genetic sequences (principally 18S r-RNA) have been extracted from living planktic foraminifera, and a large genetic library has developed. Our study attempts to contextualise and test molecular data, particularly AƒAøAøâ_sA¬A<Å"molecular clockAƒAøAøâ_sA¬Aøâ_zAø dates, utilising material from two ODP cores (Site 926A (Atlantic) and 806 (Pacific), to examine the evolutionary history of two sibling-species complexes (Globigerinella siphonifera and Globigerinoides ruber, both common shallow-water species and both of considerable palaeoceanographic utility). Recent genetic studies have suggested that these two AƒAøAøâ_sA¬A<Å"super-speciesAƒAøAøâ_sA¬Aøâ_zAø in fact consist of a number of isolated forms, with contrasting ecologies and longevities, which in Recent and sub-Recent sediments can be distinguished either on the basis of pore ultrastructure (Gl. siphonifera) or test colouration (Gs. ruber). In both cases, molecular clock estimates are indicative of ancient (7-11 Ma) intra-species cryptic divergences, which seem to be considerably older than fossil dates. In particular, the calculated molecular split between the two forms of Gs. ruber (AƒAøAøâ_sA¬A<Å"whiteAƒAøAøâ_sA¬Aøâ_zAø and AƒAøAøâ_sA¬A<Å"pinkA

  4. Extant-only comparative methods fail to recover the disparity preserved in the bird fossil record.

    PubMed

    Mitchell, Jonathan S

    2015-09-01

    Most extant species are in clades with poor fossil records, and recent studies of comparative methods show they have low power to infer even highly simplified models of trait evolution without fossil data. Birds are a well-studied radiation, yet their early evolutionary patterns are still contentious. The fossil record suggests that birds underwent a rapid ecological radiation after the end-Cretaceous mass extinction, and several smaller, subsequent radiations. This hypothesized series of repeated radiations from fossil data is difficult to test using extant data alone. By uniting morphological and phylogenetic data on 604 extant genera of birds with morphological data on 58 species of extinct birds from 50 million years ago, the "halfway point" of avian evolution, I have been able to test how well extant-only methods predict the diversity of fossil forms. All extant-only methods underestimate the disparity, although the ratio of within- to between-clade disparity does suggest high early rates. The failure of standard models to predict high early disparity suggests that recent radiations are obscuring deep time patterns in the evolution of birds. Metrics from different models can be used in conjunction to provide more valuable insights than simply finding the model with the highest relative fit.

  5. Do species populations really start small? New perspectives from the Late Neogene fossil record of African mammals.

    PubMed Central

    Vrba, E S; DeGusta, D

    2004-01-01

    This analysis of all known African larger mammals of the past 10 Myr offers new perspectives on the geographical circumstances of speciation. Our central question is: does the fossil evidence support the idea that most new species start as small populations and, if true, how long is the average growth interval until species are established at their mean later size? This simple question is important to unravelling the competing claims of rival models of speciation. We approached it by direct use of fossil data, which, to our knowledge, has not been done previously. We compared the numbers of fossil site records, as a proxy for magnitude of geographical spread, between survivorship intervals across all species. The results show that the average mammal species has indeed started its life in a relatively small population, and thereafter increased rapidly in geographical spread to reach its long-term equilibrium abundance by about 1 million years after origin. Some theoretical implications of these results are discussed. PMID:15101584

  6. Fossil DNA as a Recorder of Ancient Microbial Communities and Palaeoenvironments

    NASA Astrophysics Data System (ADS)

    Coolen, M. J.; Boere, A.; Abbas, B.; Muyzer, G.; Overmann, J.; Wakeham, S. G.; Volkman, J. K.; Sinninghe Damste, J. S.

    2005-12-01

    Fossilized organic components provide an archive of ancient aquatic microbial communities and, hence, can be used to reconstruct climate-induced environmental changes and their impacts on biodiversity. However, the interpretation of these data is complicated by the limited source specificity of some traditional biomarkers, such as lipids and pigments. The ultimate biomarkers are genes encoding for ribosomal RNA (rDNA), which sequences provide information at the species level by phylogenetic comparison but until recently was only applied to identify extant species within environmental samples. With the exception of excellent preservation conditions prevailing in permafrost sediments (3), it was generally believed that DNA becomes rapidly degraded within fossil records. However, we have recently shown that especially in the presence of hydrogen sulfide, DNA can survive in the Holocene fossil record (1, 2). In this presentation we will show how, and to what extent, fossil DNA extracted from Holocene sediments of stratified lakes (the Canadian Mahoney Lake and the Antarctic Ace Lake) and the deep-sea (Black Sea) can be used as a novel proxy to reconstruct the ancient palaeodepositional environments and evolution of past microbial communities. In addition, we will discuss the fate of fossil DNA; quantitative stratigraphic analysis of lipid biomarkers and rDNA from the same biological precursors revealed information on the survival of fossil DNA in comparison to lipid biomarkers. It was shown that most of the DNA was degraded before dead cells reach the bottom but the remaining part was found to be well protected and even less prone to diagenetic alteration compared to certain lipid biomarkers. Base-pair compositions did not change during the Holocene, however, the fossil DNA became fragmented after several thousands of years of deposition but without significantly biasing the qualitative and quantitative molecular biological analysis of at least 10-ka-old fossil DNA

  7. Atmospheric composition as a potential taphonomic filter for the fossil leaf record

    NASA Astrophysics Data System (ADS)

    Bacon, Karen; Haworth, Matthew; McElwain, Jennifer

    2016-04-01

    Controlled environment chambers provide a unique opportunity to investigate plant responses to simulated palaeoatmospheric compositions that reflect previous periods of Earth history. One potentially important role of atmospheric composition that has not been considered in detail, is how it may affect plant preservation in the fossil record. Previous work has shown that plants, particularly angiosperms, have a tendency to increase leaf mass per area (LMA) when grown in above-ambient CO2. We tested the response of six nearest living equivalent taxa for Mesozoic floras to a range of simulated Mesozoic palaeoatmospheric treatments in controlled environment chambers. Exposure to high CO2 (~1,500 ppm) led to a statistically significant (p < 0.001) increase in LMA in four out of 6 species and exposure to high CO2 and low O2 (~13%) led to a statistically significant (p < 0.001) increase in LMA in all six species. These findings suggest that atmospheric composition has a highly significant impact on LMA. If this is also the case in fossil floras, then this suggests that atmospheric composition may influence leaf preservation potential in the fossil record. Based on these results, we put forward the hypothesis that atmospheric composition is an important taphonomic filter of the fossil leaf record. Further research is now required to test the significance of atmospheric composition versus other well-known taphonomic filters.

  8. The origin of animals: Can molecular clocks and the fossil record be reconciled?

    PubMed

    Cunningham, John A; Liu, Alexander G; Bengtson, Stefan; Donoghue, Philip C J

    2017-01-01

    The evolutionary emergence of animals is one of the most significant episodes in the history of life, but its timing remains poorly constrained. Molecular clocks estimate that animals originated and began diversifying over 100 million years before the first definitive metazoan fossil evidence in the Cambrian. However, closer inspection reveals that clock estimates and the fossil record are less divergent than is often claimed. Modern clock analyses do not predict the presence of the crown-representatives of most animal phyla in the Neoproterozoic. Furthermore, despite challenges provided by incomplete preservation, a paucity of phylogenetically informative characters, and uncertain expectations of the anatomy of early animals, a number of Neoproterozoic fossils can reasonably be interpreted as metazoans. A considerable discrepancy remains, but much of this can be explained by the limited preservation potential of early metazoans and the difficulties associated with their identification in the fossil record. Critical assessment of both records may permit better resolution of the tempo and mode of early animal evolution.

  9. Mio-pliocene faunal exchanges and african biogeography: the record of fossil bovids.

    PubMed

    Bibi, Faysal

    2011-02-16

    The development of the Ethiopian biogeographic realm since the late Miocene is here explored with the presentation and review of fossil evidence from eastern Africa. Prostrepsiceros cf. vinayaki and an unknown species of possible caprin affinity are described from the hominid-bearing Asa Koma and Kuseralee Members (∼5.7 and ∼5.2 Ma) of the Middle Awash, Ethiopia. The Middle Awash Prostrepsiceros cf. vinayaki constitutes the first record of this taxon from Africa, previously known from the Siwaliks and Arabia. The possible caprin joins a number of isolated records of caprin or caprin-like taxa recorded, but poorly understood, from the late Neogene of Africa. The identification of these two taxa from the Middle Awash prompts an overdue review of fossil bovids from the sub-Saharan African record that demonstrate Eurasian affinities, including the reduncin Kobus porrecticornis, and species of Tragoportax. The fossil bovid record provides evidence for greater biological continuity between Africa and Eurasia in the late Miocene and earliest Pliocene than is found later in time. In contrast, the early Pliocene (after 5 Ma) saw the loss of any significant proportions of Eurasian-related taxa, and the continental dominance of African-endemic taxa and lineages, a pattern that continues today.

  10. Mio-Pliocene Faunal Exchanges and African Biogeography: The Record of Fossil Bovids

    PubMed Central

    Bibi, Faysal

    2011-01-01

    The development of the Ethiopian biogeographic realm since the late Miocene is here explored with the presentation and review of fossil evidence from eastern Africa. Prostrepsiceros cf. vinayaki and an unknown species of possible caprin affinity are described from the hominid-bearing Asa Koma and Kuseralee Members (∼5.7 and ∼5.2 Ma) of the Middle Awash, Ethiopia. The Middle Awash Prostrepsiceros cf. vinayaki constitutes the first record of this taxon from Africa, previously known from the Siwaliks and Arabia. The possible caprin joins a number of isolated records of caprin or caprin-like taxa recorded, but poorly understood, from the late Neogene of Africa. The identification of these two taxa from the Middle Awash prompts an overdue review of fossil bovids from the sub-Saharan African record that demonstrate Eurasian affinities, including the reduncin Kobus porrecticornis, and species of Tragoportax. The fossil bovid record provides evidence for greater biological continuity between Africa and Eurasia in the late Miocene and earliest Pliocene than is found later in time. In contrast, the early Pliocene (after 5 Ma) saw the loss of any significant proportions of Eurasian-related taxa, and the continental dominance of African-endemic taxa and lineages, a pattern that continues today. PMID:21358825

  11. Fossilized embryos are widespread but the record is temporally and taxonomically biased

    USGS Publications Warehouse

    Donoghue, P.C.J.; Kouchinsky, A.; Waloszek, Dieter; Bengtson, S.; Dong, X.-P.; Val'Kov, A.K.; Cunningham, J.A.; Repetski, J.E.

    2006-01-01

    We report new discoveries of embryos and egg capsules from the Lower Cambrian of Siberia, Middle Cambrian of Australia and Lower Ordovician of North America. Together with existing records, embryos have now been recorded from four of the seven continents. However, the new discoveries highlight secular and systematic biases in the fossil record of embryonic stages. The temporal window within which the embryos and egg capsules are found is of relatively short duration; it ends in the Early Ordovician and is roughly coincident with that of typical "Orsten"-type faunas. The reduced occurrence of such fossils has been attributed to reducing levels of phosphate in marine waters during the early Paleozoic, but may also be owing to the increasing depth of sediment mixing by infaunal metazoans. Furthermore, most records younger than the earliest Cambrian are of a single kind - large eggs and embryos of the priapulid-like scalidophoran Markuelia. We explore alternative explanations for the low taxonomic diversity of embryos recovered thus far, including sampling, size, anatomy, ecology, and environment, concluding that the preponderance of Markuelia embryos is due to its precocious development of cuticle at an embryonic stage, predisposing it to preservation through action as a substrate on which microbially mediated precipitation of authigenic calcium phosphate may occur. The fossil record of embryos may be limited to a late Neoproterozoic to early Ordovician snapshot that is subject to dramatic systematic bias. Together, these biases must be considered seriously in attempts to use the fossil record to arbitrate between hypotheses of developmental and life history evolution implicated in the origin of metazoan clades. ?? 2006 Blackwell Publishing Ltd.

  12. Unlocking the early fossil record of the arthropod central nervous system

    PubMed Central

    Edgecombe, Gregory D.; Ma, Xiaoya; Strausfeld, Nicholas J.

    2015-01-01

    Extant panarthropods (euarthropods, onychophorans and tardigrades) are hallmarked by stunning morphological and taxonomic diversity, but their central nervous systems (CNS) are relatively conserved. The timing of divergences of the ground pattern CNS organization of the major panarthropod clades has been poorly constrained because of a scarcity of data from their early fossil record. Although the CNS has been documented in three-dimensional detail in insects from Cenozoic ambers, it is widely assumed that these tissues are too prone to decay to withstand other styles of fossilization or geologically older preservation. However, Cambrian Burgess Shale-type compressions have emerged as sources of fossilized brains and nerve cords. CNS in these Cambrian fossils are preserved as carbon films or as iron oxides/hydroxides after pyrite in association with carbon. Experiments with carcasses compacted in fine-grained sediment depict preservation of neural tissue for a more prolonged temporal window than anticipated by decay experiments in other media. CNS and compound eye characters in exceptionally preserved Cambrian fossils predict divergences of the mandibulate and chelicerate ground patterns by Cambrian Stage 3 (ca 518 Ma), a dating that is compatible with molecular estimates for these splits. PMID:26554038

  13. Unlocking the early fossil record of the arthropod central nervous system.

    PubMed

    Edgecombe, Gregory D; Ma, Xiaoya; Strausfeld, Nicholas J

    2015-12-19

    Extant panarthropods (euarthropods, onychophorans and tardigrades) are hallmarked by stunning morphological and taxonomic diversity, but their central nervous systems (CNS) are relatively conserved. The timing of divergences of the ground pattern CNS organization of the major panarthropod clades has been poorly constrained because of a scarcity of data from their early fossil record. Although the CNS has been documented in three-dimensional detail in insects from Cenozoic ambers, it is widely assumed that these tissues are too prone to decay to withstand other styles of fossilization or geologically older preservation. However, Cambrian Burgess Shale-type compressions have emerged as sources of fossilized brains and nerve cords. CNS in these Cambrian fossils are preserved as carbon films or as iron oxides/hydroxides after pyrite in association with carbon. Experiments with carcasses compacted in fine-grained sediment depict preservation of neural tissue for a more prolonged temporal window than anticipated by decay experiments in other media. CNS and compound eye characters in exceptionally preserved Cambrian fossils predict divergences of the mandibulate and chelicerate ground patterns by Cambrian Stage 3 (ca 518 Ma), a dating that is compatible with molecular estimates for these splits.

  14. Diversity-dependence brings molecular phylogenies closer to agreement with the fossil record.

    PubMed

    Etienne, Rampal S; Haegeman, Bart; Stadler, Tanja; Aze, Tracy; Pearson, Paul N; Purvis, Andy; Phillimore, Albert B

    2012-04-07

    The branching times of molecular phylogenies allow us to infer speciation and extinction dynamics even when fossils are absent. Troublingly, phylogenetic approaches usually return estimates of zero extinction, conflicting with fossil evidence. Phylogenies and fossils do agree, however, that there are often limits to diversity. Here, we present a general approach to evaluate the likelihood of a phylogeny under a model that accommodates diversity-dependence and extinction. We find, by likelihood maximization, that extinction is estimated most precisely if the rate of increase in the number of lineages in the phylogeny saturates towards the present or first decreases and then increases. We demonstrate the utility and limits of our approach by applying it to the phylogenies for two cases where a fossil record exists (Cetacea and Cenozoic macroperforate planktonic foraminifera) and to three radiations lacking fossil evidence (Dendroica, Plethodon and Heliconius). We propose that the diversity-dependence model with extinction be used as the standard model for macro-evolutionary dynamics because of its biological realism and flexibility.

  15. Towards a morphological metric of assemblage dynamics in the fossil record: a test case using planktonic foraminifera.

    PubMed

    Hsiang, Allison Y; Elder, Leanne E; Hull, Pincelli M

    2016-04-05

    With a glance, even the novice naturalist can tell you something about the ecology of a given ecosystem. This is because the morphology of individuals reflects their evolutionary history and ecology, and imparts a distinct 'look' to communities--making it possible to immediately discern between deserts and forests, or coral reefs and abyssal plains. Once quantified, morphology can provide a common metric for characterizing communities across space and time and, if measured rapidly, serve as a powerful tool for quantifying biotic dynamics. Here, we present and test a new high-throughput approach for analysing community shape in the fossil record using semi-three-dimensional (3D) morphometrics from vertically stacked images (light microscopic or photogrammetric). We assess the potential informativeness of community morphology in a first analysis of the relationship between 3D morphology, ecology and phylogeny in 16 extant species of planktonic foraminifera--an abundant group in the marine fossil record--and in a preliminary comparison of four assemblages from the North Atlantic. In the species examined, phylogenetic relatedness was most closely correlated with ecology, with all three ecological traits examined (depth habitat, symbiont ecology and biogeography) showing significant phylogenetic signal. By contrast, morphological trees (based on 3D shape similarity) were relatively distantly related to both ecology and phylogeny. Although improvements are needed to realize the full utility of community morphometrics, our approach already provides robust volumetric measurements of assemblage size, a key ecological characteristic.

  16. Contrasting behavioral and feeding strategies recorded by tidal-flat bivalve trace fossils from the Upper Carboniferous of eastern Kansas

    USGS Publications Warehouse

    Mangano, M.G.; Buatois, L.A.; West, R.R.; Maples, C.G.

    1998-01-01

    Upper Carboniferous tidal-flat deposits near Waverly, eastern Kansas (Stull Shale Member, Kanwaka Shale Formation), host abundant and very well-preserved trace fossils attributed to the activity of burrowing bivalves. Thin shell lenses with an abundant bivalve fauna area associated with the ichnofossil-bearing beds and afford an unusual opportunity to relate trace fossils to their makers. Two distinctive life and feeding strategies can be reconstructed on the basis of trace fossil analysis and functional morphology. Lockeria siliquaria hyporeliefs commonly are connected with vertical to inclined, truncated endichnial shafts in the absence of horizontal locomotion traces. These structures record vertical and oblique displacement through the sediment, and suggest relatively stable domiciles rather than temporary resting traces as typically considered. Crowded bedding surfaces displaying cross-cutting relationships between specimens of L. siliquaria and differential preservation at the top (concave versus convex epireliefs) record a complex history of successive events of colonization, erosion, deposition, and recolonization (time-averaged assemblages). Irregujlar contours of some large hypichnia indicate the cast of the foot, while other outlines closely match the anterior area of Wilkingia, its suggested tracemaker. Relatively stable, vertical to inclined life positions and dominanit vertical mobility suggest a filter-feeding strategy. Moreover, the elongate shell and pallial sinus of Wilkingia providfe a strong independent line of evidence for an opisthosiphonate, moderately deep-tier inhabitant. Wilingia may represent a pioneer attempt at siphon-feeding in the late Paleozoic, preceding the outcome of the Mesozoic infaunal radiation. A second strategy is represented by Lockeia ornata and association locomotionm and locomotion/feding structures. Lockeia ornata is commonly connected with chevron locomotion traces that record the bifurcated foot of a protobranch

  17. Paleoenvironmental and paleoclimatic control on early diagenetic processes and fossil record in Cretaceous continental sandstones of Brazil

    NASA Astrophysics Data System (ADS)

    Garcia, Antônio J. V.; da Rosa, Átila A. S.; Goldberg, Karin

    2005-08-01

    The Early Cretaceous, pre-rift continental rock sequences of northeastern Brazil (Rio do Peixe, Araripe, Recôncavo-Tucano, and Sergipe-Alagoas basins), deposited in a wide intracontinental basin (Afro-Brazilian Depression), and the Late Cretaceous, post-rift continental deposits of the Paraná Basin (Bauru Group, Minas Gerais) reflect the controlling processes related to the Brazilian record of nonmarine fossil vertebrates. These sequences were deposited in braided fluvial, eolian, and lacustrine environments in a semi-arid to arid climate. Sedimentary and diagenetic processes ascribed to paleoclimatic and paleoenvironmental conditions are among the major factors that control fossil preservation in fluvial deposits. The pre-rift successions contain a rare record of a dinosaur fauna that lived near more humid highlands in the northern portion of the Afro-Brazilian Depression, relative to its southern counterpart, where hardly any fossil remains would have been preserved in the adverse climatic conditions. The Afro-Brazilian Depression is interpreted as a large pathway for dinosaurs before the breakup of Gondwana. Conversely, abundant dinosaur remains (bones, eggs, and teeth) and other vertebrates (turtles, crocodiles, frogs, and fish) are found in the Bauru Group in the Paraná Basin. In this unit, the seasonal paleoclimate provided sufficient conditions for the maintenance of bodies of water that served as nesting and living sites for various vertebrate forms. Paleoclimatic conditions are assumed to account for the different preservation of bones in the Paraná Basin relative to the Afro-Brazilian Depression, because the latter was subject to more arid conditions, and the humid environment was restricted to the northern margin.

  18. Fossil invertebrates records in cave sediments and paleoenvironmental assessments: a study of four cave sites from Romanian Carpathians

    NASA Astrophysics Data System (ADS)

    Moldovan, O. T.; Constantin, S.; Panaiotu, C.; Roban, R. D.; Frenzel, P.; Miko, L.

    2015-06-01

    Fossil invertebrates from cave sediments have been recently described as a potential new proxy for paleoenvironment and used in cross-correlations with alternate proxy records from cave deposits. Here we present the results of a fossil invertebrates study in four caves from two climatically different regions of the Romanian Carpathians, to complement paleoenvironmental data previously reported. Oribatid mites and ostracods are the most common invertebrates in the studied cave sediments. Some of the identified taxa are new for science, and most of them are indicative for either warm/cold stages or dry/wetter oscillations. In two caves the fossil invertebrates records indicate rapid climate oscillations during times known for a relatively stable climate. By corroborating the fossil invertebrates' record with the information given by magnetic properties and sediment structures, complementary data on past vegetation, temperatures, and hydraulic regimes could be gathered. This paper analyses the potential of fossil invertebrate records as a paleoenvironmental proxy, potential problems and pitfalls.

  19. The fossil record, function, and possible origins of shell color patterns in Paleozoic marine invertebrates

    SciTech Connect

    Kobluk, D.R. ); Mapes, R.H. )

    1989-02-01

    Fossil invertebrate shells and carapaces displaying preserved original color patterns are among the rarest fossils. The fossil record of color patterns extends into the Middle Cambrian where the trilobite Anomocare displays a fan-like array of stripes on the pygidium. About 180 Paleozic genera are known with patterns, including trilobites, cephalopods, gastropods, brachiopods, bivalves, crinoids, and crustaceans. Based upon an analysis of these taxa, it appears that patterns and pigments in middle and late Paleozoic invertebrates may have served several functions such as warning displays, light screening, camouflage, or waste disposal. However, the presence of color patterns in fossil invertebrates in the early Paleozoic may have developed prior to the evolution of vision sufficiently sophisticated to see them. This suggests that camouflage and warning displays were not the original functions of color patterns, and that in the earliest Paleozoic they may not have been functional. The authors propose a hypothesis that involves three developmental phases in the evolution of invertebrate color patterns: (1) the incorporation of metabolic by-products, perhaps some pigmented and some not pigmented, into shells and carapaces as a means of disposal of dietary or metabolic wastes, (2) use of these pigments and patterns as an environmental adaptation, such as light screening, and (3) display during and following the evolution of vision in predators sufficiently sophisticated to see the patterns.

  20. Developmental palaeontology in synapsids: the fossil record of ontogeny in mammals and their closest relatives.

    PubMed

    Sánchez-Villagra, Marcelo R

    2010-04-22

    The study of fossilized ontogenies in mammals is mostly restricted to postnatal and late stages of growth, but nevertheless can deliver great insights into life history and evolutionary mechanisms affecting all aspects of development. Fossils provide evidence of developmental plasticity determined by ecological factors, as when allometric relations are modified in species which invaded a new space with a very different selection regime. This is the case of dwarfing and gigantism evolution in islands. Skeletochronological studies are restricted to the examination of growth marks mostly in the cement and dentine of teeth and can provide absolute age estimates. These, together with dental replacement data considered in a phylogenetic context, provide life-history information such as maturation time and longevity. Palaeohistology and dental replacement data document the more or less gradual but also convergent evolution of mammalian growth features during early synapsid evolution. Adult phenotypes of extinct mammals can inform developmental processes by showing a combination of features or levels of integration unrecorded in living species. Some adult features such as vertebral number, easily recorded in fossils, provide indirect information about somitogenesis and hox-gene expression boundaries. Developmental palaeontology is relevant for the discourse of ecological developmental biology, an area of research where features of growth and variation are fundamental and accessible among fossil mammals.

  1. The baryon halo of the milky way: A fossil record of its formation

    PubMed

    Bland-Hawthorn; Freeman

    2000-01-07

    Astronomers believe that the baryon (stellar) halo of the Milky Way retains a fossil imprint of how it was formed. But a vast literature shows that the struggle to interpret the observations within a consistent framework continues. The evidence indicates that the halo has built up through a process of accretion and merging over billions of years, which is still going on at a low level. Future satellite missions to derive three-dimensional space motions and heavy element (metal) abundances for a billion stars will disentangle the existing web and elucidate how galaxies like our own came into existence.

  2. Atmospheric methane isotopic record favors fossil sources flat in 1980s and 1990s with recent increase

    PubMed Central

    Rice, Andrew L.; Butenhoff, Christopher L.; Teama, Doaa G.; Röger, Florian H.; Khalil, M. Aslam K.; Rasmussen, Reinhold A.

    2016-01-01

    Observations of atmospheric methane (CH4) since the late 1970s and measurements of CH4 trapped in ice and snow reveal a meteoric rise in concentration during much of the twentieth century. Since 1750, levels of atmospheric CH4 have more than doubled to current globally averaged concentration near 1,800 ppb. During the late 1980s and 1990s, the CH4 growth rate slowed substantially and was near or at zero between 1999 and 2006. There is no scientific consensus on the drivers of this slowdown. Here, we report measurements of the stable isotopic composition of atmospheric CH4 (13C/12C and D/H) from a rare air archive dating from 1977 to 1998. Together with more modern records of isotopic atmospheric CH4, we performed a time-dependent retrieval of methane fluxes spanning 25 y (1984–2009) using a 3D chemical transport model. This inversion results in a 24 [18, 27] Tg y−1 CH4 increase in fugitive fossil fuel emissions since 1984 with most of this growth occurring after year 2000. This result is consistent with some bottom-up emissions inventories but not with recent estimates based on atmospheric ethane. In fact, when forced with decreasing emissions from fossil fuel sources our inversion estimates unreasonably high emissions in other sources. Further, the inversion estimates a decrease in biomass-burning emissions that could explain falling ethane abundance. A range of sensitivity tests suggests that these results are robust. PMID:27621453

  3. Towards a morphological metric of assemblage dynamics in the fossil record: a test case using planktonic foraminifera

    PubMed Central

    Hsiang, Allison Y.; Elder, Leanne E.; Hull, Pincelli M.

    2016-01-01

    With a glance, even the novice naturalist can tell you something about the ecology of a given ecosystem. This is because the morphology of individuals reflects their evolutionary history and ecology, and imparts a distinct ‘look’ to communities—making it possible to immediately discern between deserts and forests, or coral reefs and abyssal plains. Once quantified, morphology can provide a common metric for characterizing communities across space and time and, if measured rapidly, serve as a powerful tool for quantifying biotic dynamics. Here, we present and test a new high-throughput approach for analysing community shape in the fossil record using semi-three-dimensional (3D) morphometrics from vertically stacked images (light microscopic or photogrammetric). We assess the potential informativeness of community morphology in a first analysis of the relationship between 3D morphology, ecology and phylogeny in 16 extant species of planktonic foraminifera—an abundant group in the marine fossil record—and in a preliminary comparison of four assemblages from the North Atlantic. In the species examined, phylogenetic relatedness was most closely correlated with ecology, with all three ecological traits examined (depth habitat, symbiont ecology and biogeography) showing significant phylogenetic signal. By contrast, morphological trees (based on 3D shape similarity) were relatively distantly related to both ecology and phylogeny. Although improvements are needed to realize the full utility of community morphometrics, our approach already provides robust volumetric measurements of assemblage size, a key ecological characteristic. PMID:26977067

  4. Atmospheric methane isotopic record favors fossil sources flat in 1980s and 1990s with recent increase.

    PubMed

    Rice, Andrew L; Butenhoff, Christopher L; Teama, Doaa G; Röger, Florian H; Khalil, M Aslam K; Rasmussen, Reinhold A

    2016-09-27

    Observations of atmospheric methane (CH4) since the late 1970s and measurements of CH4 trapped in ice and snow reveal a meteoric rise in concentration during much of the twentieth century. Since 1750, levels of atmospheric CH4 have more than doubled to current globally averaged concentration near 1,800 ppb. During the late 1980s and 1990s, the CH4 growth rate slowed substantially and was near or at zero between 1999 and 2006. There is no scientific consensus on the drivers of this slowdown. Here, we report measurements of the stable isotopic composition of atmospheric CH4 ((13)C/(12)C and D/H) from a rare air archive dating from 1977 to 1998. Together with more modern records of isotopic atmospheric CH4, we performed a time-dependent retrieval of methane fluxes spanning 25 y (1984-2009) using a 3D chemical transport model. This inversion results in a 24 [18, 27] Tg y(-1) CH4 increase in fugitive fossil fuel emissions since 1984 with most of this growth occurring after year 2000. This result is consistent with some bottom-up emissions inventories but not with recent estimates based on atmospheric ethane. In fact, when forced with decreasing emissions from fossil fuel sources our inversion estimates unreasonably high emissions in other sources. Further, the inversion estimates a decrease in biomass-burning emissions that could explain falling ethane abundance. A range of sensitivity tests suggests that these results are robust.

  5. Atmospheric methane isotopic record favors fossil sources flat in 1980s and 1990s with recent increase

    NASA Astrophysics Data System (ADS)

    Rice, Andrew L.; Butenhoff, Christopher L.; Teama, Doaa G.; Röger, Florian H.; Khalil, M. Aslam K.; Rasmussen, Reinhold A.

    2016-09-01

    Observations of atmospheric methane (CH4) since the late 1970s and measurements of CH4 trapped in ice and snow reveal a meteoric rise in concentration during much of the twentieth century. Since 1750, levels of atmospheric CH4 have more than doubled to current globally averaged concentration near 1,800 ppb. During the late 1980s and 1990s, the CH4 growth rate slowed substantially and was near or at zero between 1999 and 2006. There is no scientific consensus on the drivers of this slowdown. Here, we report measurements of the stable isotopic composition of atmospheric CH4 (13C/12C and D/H) from a rare air archive dating from 1977 to 1998. Together with more modern records of isotopic atmospheric CH4, we performed a time-dependent retrieval of methane fluxes spanning 25 y (1984-2009) using a 3D chemical transport model. This inversion results in a 24 [18, 27] Tg y-1 CH4 increase in fugitive fossil fuel emissions since 1984 with most of this growth occurring after year 2000. This result is consistent with some bottom-up emissions inventories but not with recent estimates based on atmospheric ethane. In fact, when forced with decreasing emissions from fossil fuel sources our inversion estimates unreasonably high emissions in other sources. Further, the inversion estimates a decrease in biomass-burning emissions that could explain falling ethane abundance. A range of sensitivity tests suggests that these results are robust.

  6. The earliest fossil record of Panorpidae (Mecoptera) from the Middle Jurassic of China

    PubMed Central

    Ding, He; Shih, Chungkun; Bashkuev, Alexei; Zhao, Yunyun; Ren, Dong

    2014-01-01

    Abstract The early history of Panorpidae (Mecoptera) is poorly known due to sparse fossil records. Up to date, only nine fossil species have been described, all from the Paleogene, except the Early Cretaceous Solusipanorpa gibbidorsa Lin, 1980. However, we suggest S. gibbidorsa is too incompletely preserved to permit even family classification. A new genus with two new species, Jurassipanorpa impunctata gen. et sp. n. and Jurassipanorpa sticta sp. n., are described based on four well-preserved specimens from the late Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China. These two new species are the earliest fossil records of Panorpidae. The new genus is erected based on a combination of forewing characters: both R1 and Rs1 with two branches, 1A reaching posterior margin of wing distad of the forking of Rs from R1, and no crossveins or only one crossvein between veins of 1A and 2A. In all four specimens, long and robust setae ranging from 0.09 to 0.38 mm in length and pointing anteriorly, are present on anal veins of forewings. The function of these setae is enigmatic. PMID:25152669

  7. Direct and indirect fossil records of megachilid bees from the Paleogene of Central Europe (Hymenoptera: Megachilidae).

    PubMed

    Wedmann, Sonja; Wappler, Torsten; Engel, Michael S

    2009-06-01

    Aside from pollen and nectar, bees of the subfamily Megachilinae are closely associated with plants as a source of materials for nest construction. Megachilines use resins, masticated leaves, trichomes and other plant materials sometimes along with mud to construct nests in cavities or in soil. Among these, the leafcutter bees (Megachile s.l.) are the most famous for their behaviour to line their brood cells with discs cut from various plants. We report on fossil records of one body fossil of a new non-leafcutting megachiline and of 12 leafcuttings from three European sites-Eckfeld and Messel, both in Germany (Eocene), and Menat, France (Paleocene). The excisions include the currently earliest record of probable Megachile activity and suggest the presence of such bees in the Paleocene European fauna. Comparison with extant leafcuttings permits the interpretation of a minimal number of species that produced these excisions. The wide range of size for the leafcuttings indirectly might suggest at least two species of Megachile for the fauna of Messel in addition to the other megachiline bee described here. The presence of several cuttings on most leaves from Eckfeld implies that the preferential foraging behaviour of extant Megachile arose early in megachiline evolution. These results demonstrate that combined investigation of body and trace fossils complement each other in understanding past biodiversity, the latter permitting the detection of taxa not otherwise directly sampled and inferences on behavioural evolution.

  8. Direct and indirect fossil records of megachilid bees from the Paleogene of Central Europe (Hymenoptera: Megachilidae)

    NASA Astrophysics Data System (ADS)

    Wedmann, Sonja; Wappler, Torsten; Engel, Michael S.

    2009-06-01

    Aside from pollen and nectar, bees of the subfamily Megachilinae are closely associated with plants as a source of materials for nest construction. Megachilines use resins, masticated leaves, trichomes and other plant materials sometimes along with mud to construct nests in cavities or in soil. Among these, the leafcutter bees ( Megachile s.l.) are the most famous for their behaviour to line their brood cells with discs cut from various plants. We report on fossil records of one body fossil of a new non-leafcutting megachiline and of 12 leafcuttings from three European sites—Eckfeld and Messel, both in Germany (Eocene), and Menat, France (Paleocene). The excisions include the currently earliest record of probable Megachile activity and suggest the presence of such bees in the Paleocene European fauna. Comparison with extant leafcuttings permits the interpretation of a minimal number of species that produced these excisions. The wide range of size for the leafcuttings indirectly might suggest at least two species of Megachile for the fauna of Messel in addition to the other megachiline bee described here. The presence of several cuttings on most leaves from Eckfeld implies that the preferential foraging behaviour of extant Megachile arose early in megachiline evolution. These results demonstrate that combined investigation of body and trace fossils complement each other in understanding past biodiversity, the latter permitting the detection of taxa not otherwise directly sampled and inferences on behavioural evolution.

  9. Systematics, phylogeny, and taphonomy of ghost shrimps (Decapoda): a perspective from the fossil record

    PubMed Central

    Klompmaker, Adiël A.

    2016-01-01

    Ghost shrimps of Callianassidae and Ctenochelidae are soft-bodied, usually heterochelous decapods representing major bioturbators of muddy and sandy (sub)marine substrates. Ghost shrimps have a robust fossil record spanning from the Early Cretaceous (~ 133 Ma) to the Holocene and their remains are present in most assemblages of Cenozoic decapod crustaceans. Their taxonomic interpretation is in flux, mainly because the generic assignment is hindered by their insufficient preservation and disagreement in the biological classification. Furthermore, numerous taxa are incorrectly classified within the catch-all taxon Callianassa. To show the historical patterns in describing fossil ghost shrimps and to evaluate taphonomic aspects influencing the attribution of ghost shrimp remains to higher level taxa, a database of all fossil species treated at some time as belonging to the group has been compiled: 250 / 274 species are considered valid ghost shrimp taxa herein. More than half of these taxa (160 species, 58.4%) are known only from distal cheliped elements, i.e., dactylus and / or propodus, due to the more calcified cuticle locally. Rarely, ghost shrimps are preserved in situ in burrows or in direct association with them, and several previously unpublished occurrences are reported herein. For generic assignment, fossil material should be compared to living species because many of them have modern relatives. Heterochely, intraspecific variation, ontogenetic changes and sexual dimorphism are all factors that have to be taken into account when working with fossil ghost shrimps. Distal elements are usually more variable than proximal ones. Preliminary results suggest that the ghost shrimp clade emerged not before the Hauterivian (~ 133 Ma). The divergence of Ctenochelidae and Paracalliacinae is estimated to occur within the interval of Hauterivian to Albian (133–100 Ma). Callichirinae and Eucalliacinae likely diverged later during the Late Cretaceous (100–66 Ma

  10. Sequences, stratigraphy and scenarios: what can we say about the fossil record of the earliest tetrapods?

    PubMed Central

    Friedman, Matt; Brazeau, Martin D.

    2011-01-01

    Past research on the emergence of digit-bearing tetrapods has led to the widely accepted premise that this important evolutionary event occurred during the Late Devonian. The discovery of convincing digit-bearing tetrapod trackways of early Middle Devonian age in Poland has upset this orthodoxy, indicating that current scenarios which link the timing of the origin of digited tetrapods to specific events in Earth history are likely to be in error. Inspired by this find, we examine the fossil record of early digit-bearing tetrapods and their closest fish-like relatives from a statistical standpoint. We find that the Polish trackways force a substantial reconsideration of the nature of the early tetrapod record when only body fossils are considered. However, the effect is less drastic (and often not statistically significant) when other reliably dated trackways that were previously considered anachronistic are taken into account. Using two approaches, we find that 95 per cent credible and confidence intervals for the origin of digit-bearing tetrapods extend into the Early Devonian and beyond, spanning late Emsian to mid Ludlow. For biologically realistic diversity models, estimated genus-level preservation rates for Devonian digited tetrapods and their relatives range from 0.025 to 0.073 per lineage-million years, an order of magnitude lower than species-level rates for groups typically considered to have dense records. Available fossils of early digited tetrapods and their immediate relatives are adequate for documenting large-scale patterns of character acquisition associated with the origin of terrestriality, but low preservation rates coupled with clear geographical and stratigraphic sampling biases caution against building scenarios for the origin of digits and terrestrialization tied to the provenance of particular specimens or faunas. PMID:20739322

  11. Microaerobic steroid biosynthesis and the molecular fossil record of Archean life.

    PubMed

    Waldbauer, Jacob R; Newman, Dianne K; Summons, Roger E

    2011-08-16

    The power of molecular oxygen to drive many crucial biogeochemical processes, from cellular respiration to rock weathering, makes reconstructing the history of its production and accumulation a first-order question for understanding Earth's evolution. Among the various geochemical proxies for the presence of O(2) in the environment, molecular fossils offer a unique record of O(2) where it was first produced and consumed by biology: in sunlit aquatic habitats. As steroid biosynthesis requires molecular oxygen, fossil steranes have been used to draw inferences about aerobiosis in the early Precambrian. However, better quantitative constraints on the O(2) requirement of this biochemistry would clarify the implications of these molecular fossils for environmental conditions at the time of their production. Here we demonstrate that steroid biosynthesis is a microaerobic process, enabled by dissolved O(2) concentrations in the nanomolar range. We present evidence that microaerobic marine environments (where steroid biosynthesis was possible) could have been widespread and persistent for long periods of time prior to the earliest geologic and isotopic evidence for atmospheric O(2). In the late Archean, molecular oxygen likely cycled as a biogenic trace gas, much as compounds such as dimethylsulfide do today.

  12. MicroRNAs resolve an apparent conflict between annelid systematics and their fossil record

    PubMed Central

    Sperling, Erik A.; Vinther, Jakob; Moy, Vanessa N.; Wheeler, Benjamin M.; Sémon, Marie; Briggs, Derek E. G.; Peterson, Kevin J.

    2009-01-01

    Both the monophyly and inter-relationships of the major annelid groups have remained uncertain, despite intensive research on both morphology and molecular sequences. Morphological cladistic analyses indicate that Annelida is monophyletic and consists of two monophyletic groups, the clitellates and polychaetes, whereas molecular phylogenetic analyses suggest that polychaetes are paraphyletic and that sipunculans are crown-group annelids. Both the monophyly of polychaetes and the placement of sipunculans within annelids are in conflict with the annelid fossil record—the former because Cambrian stem taxa are similar to modern polychaetes in possessing biramous parapodia, suggesting that clitellates are derived from polychaetes; the latter because although fossil sipunculans are known from the Early Cambrian, crown-group annelids do not appear until the latest Cambrian. Here we apply a different data source, the presence versus absence of specific microRNAs—genes that encode approximately 22 nucleotide non-coding regulatory RNAs—to the problem of annelid phylogenetics. We show that annelids are monophyletic with respect to sipunculans, and polychaetes are paraphyletic with respect to the clitellate Lumbricus, conclusions that are consistent with the fossil record. Further, sipunculans resolve as the sister group of the annelids, rooting the annelid tree, and revealing the polarity of the morphological change within this diverse lineage of animals. PMID:19755470

  13. Microaerobic steroid biosynthesis and the molecular fossil record of Archean life

    PubMed Central

    Waldbauer, Jacob R.; Newman, Dianne K.; Summons, Roger E.

    2011-01-01

    The power of molecular oxygen to drive many crucial biogeochemical processes, from cellular respiration to rock weathering, makes reconstructing the history of its production and accumulation a first-order question for understanding Earth’s evolution. Among the various geochemical proxies for the presence of O2 in the environment, molecular fossils offer a unique record of O2 where it was first produced and consumed by biology: in sunlit aquatic habitats. As steroid biosynthesis requires molecular oxygen, fossil steranes have been used to draw inferences about aerobiosis in the early Precambrian. However, better quantitative constraints on the O2 requirement of this biochemistry would clarify the implications of these molecular fossils for environmental conditions at the time of their production. Here we demonstrate that steroid biosynthesis is a microaerobic process, enabled by dissolved O2 concentrations in the nanomolar range. We present evidence that microaerobic marine environments (where steroid biosynthesis was possible) could have been widespread and persistent for long periods of time prior to the earliest geologic and isotopic evidence for atmospheric O2. In the late Archean, molecular oxygen likely cycled as a biogenic trace gas, much as compounds such as dimethylsulfide do today. PMID:21825157

  14. Keratin Durability Has Implications for the Fossil Record: Results from a 10 Year Feather Degradation Experiment.

    PubMed

    Moyer, Alison E; Zheng, Wenxia; Schweitzer, Mary H

    2016-01-01

    Keratinous 'soft tissue' structures (i.e. epidermally derived and originally non-biomineralized), include feathers, skin, claws, beaks, and hair. Despite their relatively common occurrence in the fossil record (second only to bone and teeth), few studies have addressed natural degradation processes that must occur in all organic material, including those keratinous structures that are incorporated into the rock record as fossils. Because feathers have high preservation potential and strong phylogenetic signal, in the current study we examine feathers subjected to different burial environments for a duration of ~10 years, using transmission electron microscopy (TEM) and in situ immunofluorescence (IF). We use morphology and persistence of specific immunoreactivity as indicators of preservation at the molecular and microstructural levels. We show that feather keratin is durable, demonstrates structural and microstructural integrity, and retains epitopes suitable for specific antibody recognition in even the harshest conditions. These data support the hypothesis that keratin antibody reactivity can be used to identify the nature and composition of epidermal structures in the rock record, and to address evolutionary questions by distinguishing between alpha- (widely distributed) and beta- (limited to sauropsids) keratin.

  15. Keratin Durability Has Implications for the Fossil Record: Results from a 10 Year Feather Degradation Experiment

    PubMed Central

    Moyer, Alison E.; Zheng, Wenxia; Schweitzer, Mary H.

    2016-01-01

    Keratinous ‘soft tissue’ structures (i.e. epidermally derived and originally non-biomineralized), include feathers, skin, claws, beaks, and hair. Despite their relatively common occurrence in the fossil record (second only to bone and teeth), few studies have addressed natural degradation processes that must occur in all organic material, including those keratinous structures that are incorporated into the rock record as fossils. Because feathers have high preservation potential and strong phylogenetic signal, in the current study we examine feathers subjected to different burial environments for a duration of ~10 years, using transmission electron microscopy (TEM) and in situ immunofluorescence (IF). We use morphology and persistence of specific immunoreactivity as indicators of preservation at the molecular and microstructural levels. We show that feather keratin is durable, demonstrates structural and microstructural integrity, and retains epitopes suitable for specific antibody recognition in even the harshest conditions. These data support the hypothesis that keratin antibody reactivity can be used to identify the nature and composition of epidermal structures in the rock record, and to address evolutionary questions by distinguishing between alpha- (widely distributed) and beta- (limited to sauropsids) keratin. PMID:27384819

  16. First Quaternary Fossil Record of Caecilians from a Mexican Archaeological Site

    NASA Astrophysics Data System (ADS)

    Wake, Thomas A.; Wake, Marvalee H.; Lesure, Richard G.

    1999-07-01

    A single vertebra from an Early Formative period archaeological site in coastal Chiapas, México, is identified as belonging to the amphibian Dermophis mexicanus (Duméril and Bibron) 1841 (Amphibia: Gymnophiona: Caeciliidae). The vertebra was recovered from deposits dated to approximately 1200-1350 B.C. The specimen represents the first Quaternary fossil record for gymnophiones. Its presence suggests the possible role of the species as a bioturbator. Its recovery is further evidence of the utility of fine-grained archaeological recovery techniques.

  17. Assessment of the clumped isotope composition of fossil bone carbonate as a recorder of subsurface temperatures

    NASA Astrophysics Data System (ADS)

    Suarez, Marina B.; Passey, Benjamin H.

    2014-09-01

    Bone is susceptible to early diagenesis, and its carbon and oxygen isotopic compositions have been suggested to reflect conditions in the soil environment and shallow subsurface during fossilization. This implies open-system recrystallization involving mass exchange of carbon and oxygen among bioapatite, soil water, and DIC. Such recrystallization would also redistribute isotopic clumping (including 13C-18O bonds), leading to the possibility that the carbonate clumped isotope compositions of fossil bone record ground temperature during early diagenesis. We assess this possibility by studying Quaternary mammalian fossil bone from subtropical to polar latitudes: if recrystallization is early and pervasive, clumped isotope derived temperatures, T(Δ47), should closely mirror latitudinal gradients in ground temperature. Excluding results from a mummified specimen yielding T(Δ47) = 38 °C (that is, indistinguishable from mammalian body temperature), we find that T(Δ47) values are intermediate between mammalian body temperature and ground temperature, suggesting partial recrystallization of bone carbonate. XRD analyses show that the nature and extent of diagenesis varies among the samples and does not relate in a straightforward manner to T(Δ47). No clear correlation exists between T(Δ47) and mean annual temperature or mean warm season temperature. Furthermore, bone tends to retain the 18O-enriched signature of body water, suggesting incomplete oxygen isotope exchange with meteoric waters. Incomplete carbon and oxygen isotope exchange between bone carbonate and soil waters is also indicated for a set of late Miocene bone-enamel pairs from a sequence of stacked paleosols in northern China. Analysis of bone as old as Early Cretaceous shows that bone carbonate is susceptible to later diagenesis at elevated burial temperatures, although T(Δ47) does not closely conform to maximum burial temperature, again suggesting partial recrystallization, or recrystallization during

  18. Preservation of key biomolecules in the fossil record: current knowledge and future challenges.

    PubMed Central

    Bada, J L; Wang, X S; Hamilton, H

    1999-01-01

    preservation in the fossil record. PMID:10091249

  19. Biology in the Anthropocene: Challenges and insights from young fossil records

    PubMed Central

    Kidwell, Susan M.

    2015-01-01

    With overwhelming evidence of change in habitats, biologists today must assume that few, if any, study areas are natural and that biological variability is superimposed on trends rather than stationary means. Paleobiological data from the youngest sedimentary record, including death assemblages actively accumulating on modern land surfaces and seabeds, provide unique information on the status of present-day species, communities, and biomes over the last few decades to millennia and on their responses to natural and anthropogenic environmental change. Key advances have established the accuracy and resolving power of paleobiological information derived from naturally preserved remains and of proxy evidence for environmental conditions and sample age so that fossil data can both implicate and exonerate human stressors as the drivers of biotic change and permit the effects of multiple stressors to be disentangled. Legacy effects from Industrial and even pre-Industrial anthropogenic extirpations, introductions, (de)nutrification, and habitat conversion commonly emerge as the primary factors underlying the present-day status of populations and communities; within the last 2 million years, climate change has rarely been sufficient to drive major extinction pulses absent other human pressures, which are now manifold. Young fossil records also provide rigorous access to the baseline composition and dynamics of modern-day biota under pre-Industrial conditions, where insights include the millennial-scale persistence of community structures, the dominant role of physical environmental conditions rather than biotic interactions in determining community composition and disassembly, and the existence of naturally alternating states. PMID:25901315

  20. Relict endemism of extant Rhineuridae (Amphisbaenia): testing for phylogenetic niche conservatism in the fossil record.

    PubMed

    Hipsley, Christy A; Müller, Johannes

    2014-03-01

    Rhineurid amphisbaenians are represented by a rich Cenozoic fossil record in North America, but today conisist of a single living species restricted to the Florida Peninsula. Such relict endemism may be the result of phylogenetic niche conservatism (PNC), the retention of ancestral traits preventing expansion into new environments. Most tests of PNC derive ancestral niche preferences from species' extant ecologies, while ignoring valuable paleontological information. To test if PNC contributes to the restricted distribution of modern Rhineura floridana, we compare the species' current environmental preferences (temperature, precipitation and soil) to paleoenvironmental data from the rhineurid fossil record. We find no evidence of PNC in modern R. floridana, as it also occurred in Florida during drier glacial periods. Ancient rhineurids also exhibit tolerance to changing climates, having undergone a shift from subtropical-humid to semi-arid savanna conditions during the Eocene-Oligocene transition. However, rhineurids nearly disappear from North America after the middle Miocene, potentially due to the onset of prolonged freezing temperatures following the mid-Miocene Climatic Optimum. This physiological limit of environmental tolerances could be interpreted as PNC for the entire family, but also characterizes much of Amphisbaenia, emphasizing the relevance of the temporal as well as phylogenetic scale at which PNC is investigated.

  1. Changes to the Fossil Record of Insects through Fifteen Years of Discovery.

    PubMed

    Nicholson, David B; Mayhew, Peter J; Ross, Andrew J

    2015-01-01

    The first and last occurrences of hexapod families in the fossil record are compiled from publications up to end-2009. The major features of these data are compared with those of previous datasets (1993 and 1994). About a third of families (>400) are new to the fossil record since 1994, over half of the earlier, existing families have experienced changes in their known stratigraphic range and only about ten percent have unchanged ranges. Despite these significant additions to knowledge, the broad pattern of described richness through time remains similar, with described richness increasing steadily through geological history and a shift in dominant taxa, from Palaeoptera and Polyneoptera to Paraneoptera and Holometabola, after the Palaeozoic. However, after detrending, described richness is not well correlated with the earlier datasets, indicating significant changes in shorter-term patterns. There is reduced Palaeozoic richness, peaking at a different time, and a less pronounced Permian decline. A pronounced Triassic peak and decline is shown, and the plateau from the mid Early Cretaceous to the end of the period remains, albeit at substantially higher richness compared to earlier datasets. Origination and extinction rates are broadly similar to before, with a broad decline in both through time but episodic peaks, including end-Permian turnover. Origination more consistently exceeds extinction compared to previous datasets and exceptions are mainly in the Palaeozoic. These changes suggest that some inferences about causal mechanisms in insect macroevolution are likely to differ as well.

  2. Changes to the Fossil Record of Insects through Fifteen Years of Discovery

    PubMed Central

    Nicholson, David B.; Mayhew, Peter J.; Ross, Andrew J.

    2015-01-01

    The first and last occurrences of hexapod families in the fossil record are compiled from publications up to end-2009. The major features of these data are compared with those of previous datasets (1993 and 1994). About a third of families (>400) are new to the fossil record since 1994, over half of the earlier, existing families have experienced changes in their known stratigraphic range and only about ten percent have unchanged ranges. Despite these significant additions to knowledge, the broad pattern of described richness through time remains similar, with described richness increasing steadily through geological history and a shift in dominant taxa, from Palaeoptera and Polyneoptera to Paraneoptera and Holometabola, after the Palaeozoic. However, after detrending, described richness is not well correlated with the earlier datasets, indicating significant changes in shorter-term patterns. There is reduced Palaeozoic richness, peaking at a different time, and a less pronounced Permian decline. A pronounced Triassic peak and decline is shown, and the plateau from the mid Early Cretaceous to the end of the period remains, albeit at substantially higher richness compared to earlier datasets. Origination and extinction rates are broadly similar to before, with a broad decline in both through time but episodic peaks, including end-Permian turnover. Origination more consistently exceeds extinction compared to previous datasets and exceptions are mainly in the Palaeozoic. These changes suggest that some inferences about causal mechanisms in insect macroevolution are likely to differ as well. PMID:26176667

  3. Biology in the Anthropocene: Challenges and insights from young fossil records.

    PubMed

    Kidwell, Susan M

    2015-04-21

    With overwhelming evidence of change in habitats, biologists today must assume that few, if any, study areas are natural and that biological variability is superimposed on trends rather than stationary means. Paleobiological data from the youngest sedimentary record, including death assemblages actively accumulating on modern land surfaces and seabeds, provide unique information on the status of present-day species, communities, and biomes over the last few decades to millennia and on their responses to natural and anthropogenic environmental change. Key advances have established the accuracy and resolving power of paleobiological information derived from naturally preserved remains and of proxy evidence for environmental conditions and sample age so that fossil data can both implicate and exonerate human stressors as the drivers of biotic change and permit the effects of multiple stressors to be disentangled. Legacy effects from Industrial and even pre-Industrial anthropogenic extirpations, introductions, (de)nutrification, and habitat conversion commonly emerge as the primary factors underlying the present-day status of populations and communities; within the last 2 million years, climate change has rarely been sufficient to drive major extinction pulses absent other human pressures, which are now manifold. Young fossil records also provide rigorous access to the baseline composition and dynamics of modern-day biota under pre-Industrial conditions, where insights include the millennial-scale persistence of community structures, the dominant role of physical environmental conditions rather than biotic interactions in determining community composition and disassembly, and the existence of naturally alternating states.

  4. Molecular decay of the tooth gene Enamelin (ENAM) mirrors the loss of enamel in the fossil record of placental mammals.

    PubMed

    Meredith, Robert W; Gatesy, John; Murphy, William J; Ryder, Oliver A; Springer, Mark S

    2009-09-01

    Vestigial structures occur at both the anatomical and molecular levels, but studies documenting the co-occurrence of morphological degeneration in the fossil record and molecular decay in the genome are rare. Here, we use morphology, the fossil record, and phylogenetics to predict the occurrence of "molecular fossils" of the enamelin (ENAM) gene in four different orders of placental mammals (Tubulidentata, Pholidota, Cetacea, Xenarthra) with toothless and/or enamelless taxa. Our results support the "molecular fossil" hypothesis and demonstrate the occurrence of frameshift mutations and/or stop codons in all toothless and enamelless taxa. We then use a novel method based on selection intensity estimates for codons (omega) to calculate the timing of iterated enamel loss in the fossil record of aardvarks and pangolins, and further show that the molecular evolutionary history of ENAM predicts the occurrence of enamel in basal representatives of Xenarthra (sloths, anteaters, armadillos) even though frameshift mutations are ubiquitous in ENAM sequences of living xenarthrans. The molecular decay of ENAM parallels the morphological degeneration of enamel in the fossil record of placental mammals and provides manifest evidence for the predictive power of Darwin's theory.

  5. Calcification and silicification: fossilization potential of cyanobacteria from stromatolites of Niuafo'ou's Caldera Lakes (Tonga) and implications for the early fossil record.

    PubMed

    Kremer, Barbara; Kazmierczak, Józef; Lukomska-Kowalczyk, Maja; Kempe, Stephan

    2012-06-01

    Calcification and silicification processes of cyanobacterial mats that form stromatolites in two caldera lakes of Niuafo'ou Island (Vai Lahi and Vai Si'i) were evaluated, and their importance as analogues for interpreting the early fossil record are discussed. It has been shown that the potential for morphological preservation of Niuafo'ou cyanobacteria is highly dependent on the timing and type of mineral phase involved in the fossilization process. Four main modes of mineralization of cyanobacteria organic parts have been recognized: (i) primary early postmortem calcification by aragonite nanograins that transform quickly into larger needle-like crystals and almost totally destroy the cellular structures, (ii) primary early postmortem silicification of almost intact cyanobacterial cells that leave a record of spectacularly well-preserved cellular structures, (iii) replacement by silica of primary aragonite that has already recrystallized and obliterated the cellular structures, (iv) occasional replacement of primary aragonite precipitated in the mucopolysaccharide sheaths and extracellular polymeric substances by Al-Mg-Fe silicates. These observations suggest that the extremely scarce earliest fossil record may, in part, be the result of (a) secondary replacement by silica of primary carbonate minerals (aragonite, calcite, siderite), which, due to recrystallization, had already annihilated the cellular morphology of the mineralized microbiota or (b) relatively late primary silicification of already highly degraded and no longer morphologically identifiable microbial remains.

  6. The taphonomy of unmineralised Palaeozoic fossils preserved as siliciclastic moulds and casts, and their utility in assessing the interaction between environmental change and the fossil record

    NASA Astrophysics Data System (ADS)

    MacGabhann, Breandán; Schiffbauer, James; Hagadorn, James; Van Roy, Peter; Lynch, Edward; Morrsion, Liam; Murray, John

    2015-04-01

    biopolymers, and that these tissues were preferentially fossilised by the formation of an early diagenic mould directly on the organic surfaces. Excess divalent iron ions, produced during decay of more labile tissues by means of bacterial iron reduction, would have adsorbed to anionic functional groups in the biopolymeric tissues. This would have provided a ready substrate for the formation and growth of such an early diagenic mineralised mould, including aluminosilicate minerals produced via reaction with seawater silica and metal ions, and iron sulphide minerals produced via reaction with hydrogen sulphide and free sulphur produced from seawater sulphate through bacterial sulphate reduction associated with further decay. Subsequent weathering would have oxidised such iron sulphides to oxides and oxyhydroxides. This taphonomic model supports the lack of utility of the eldonid palaeobiological record in analysing environmental influence on biological communities, due to the lack of preservation of key anatomical components. However, it also suggests that the very occurrence of fossils preserved in this style is dependent on extrinsic palaeoenvironmental factors - including pH, Eh, and the concentration of other ions in the contemporaneous seawater. Analyses of the distribution of fossils preserved in this style may therefore provide information on ambient conditions which may have affected the distribution of contemporaneous mineralised fossils, potentially allowing a more complete analysis of the effects of palaeoenvironmental change on fossil ecosystems.

  7. Fossil records of subsection Pinus (genus Pinus, Pinaceae) from the Cenozoic in Japan.

    PubMed

    Yamada, Toshihiro; Yamada, Mariko; Tsukagoshi, Minoru

    2014-03-01

    Extant pines of subsection Pinus (section Pinus, genus Pinus, Pinaceae) are predominantly distributed in Eastern Asia. However, the extent of diversification in the section has yet to be fully clarified. We reviewed fossil records of subsection Pinus from Japan and collected permineralized materials, in which anatomical details are preserved for better understanding of the diversification. Our results suggest that this subsection appeared in Japan no earlier than the Middle Eocene, with extant species (i.e., Pinus densiflora and Pinus thunbergii) appearing around the beginning of the Pleistocene. Pinus fujiii (Early Miocene to Early Pleistocene) is inferred to have a close affinity to P. thunbergii based on the medial arrangement of its leaf resin canals. Additionally, P. fujiii has a similar cone morphology to those of extant species living in China, bridging the morphological gap between P. thunbergii and Chinese relatives of P. thunbergii as inferred by molecular phylogenetic analyses. Our results also suggest that taxonomic revisions of Pinus miocenica and Pinus oligolepis are required among the Japanese fossil species reported to date.

  8. Fossil record of stem groups employed in evaluating the chronogram of insects (Arthropoda: Hexapoda)

    PubMed Central

    Wang, Yan-hui; Engel, Michael S.; Rafael, José A.; Wu, Hao-yang; Rédei, Dávid; Xie, Qiang; Wang, Gang; Liu, Xiao-guang; Bu, Wen-jun

    2016-01-01

    Insecta s. str. (=Ectognatha), comprise the largest and most diversified group of living organisms, accounting for roughly half of the biodiversity on Earth. Understanding insect relationships and the specific time intervals for their episodes of radiation and extinction are critical to any comprehensive perspective on evolutionary events. Although some deeper nodes have been resolved congruently, the complete evolution of insects has remained obscure due to the lack of direct fossil evidence. Besides, various evolutionary phases of insects and the corresponding driving forces of diversification remain to be recognized. In this study, a comprehensive sample of all insect orders was used to reconstruct their phylogenetic relationships and estimate deep divergences. The phylogenetic relationships of insect orders were congruently recovered by Bayesian inference and maximum likelihood analyses. A complete timescale of divergences based on an uncorrelated log-normal relaxed clock model was established among all lineages of winged insects. The inferred timescale for various nodes are congruent with major historical events including the increase of atmospheric oxygen in the Late Silurian and earliest Devonian, the radiation of vascular plants in the Devonian, and with the available fossil record of the stem groups to various insect lineages in the Devonian and Carboniferous. PMID:27958352

  9. Balsscallichirus Sakai, 2011 (Decapoda: Axiidea: Callianassidae) in the fossil record: systematics and palaeobiogeography

    PubMed Central

    Hyžný, Matúš

    2016-01-01

    The fossil record of the ghost shrimp genus Balsscallichirus Sakai, 2011 (Crustacea: Decapoda: Callianassidae) is revised. Barnardcallichirus Sakai, 2011 and Tirmizicallichirus Sakai, 2011 are considered subjective synonyms of Balsscallichirus. Based on the examination of extant species it is argued that the morphology of the major cheliped merus, in combination with other hard part morphology characters, is sufficient for assignment of the fossil material into the genus. Main identifying characters are on merus which is keeled along its midline and its lower half is tuberculated; its lower margin possesses broad proximal meral hook continuing into a lobe distally; the entire lower margin is subdivided into numerous irregularly spaced spines. Three species, Callianassa sismondai A. Milne-Edwards, 1860, C. floriana Glaessner, 1928, and Podocallichirus laepaensis Hyžný & Muñiz, 2012, originally described from the Miocene of Italy, Austria and Spain, respectively, are assigned to Balsscallichirus herein. Neocallichirus wellsi Schweitzer, Feldmann & Gingerich, 2004 from the Upper Eocene of Pakistan is tentatively assigned to that genus as well. Spatial and temporal distribution of the genus indicates that at least since the Oligocene, and possibly even sooner (the Late Eocene), the genus has been restricted to the Western Tethys Region. Later, it migrated also into West Atlantic establishing present day communities. PMID:27499568

  10. An ecometric analysis of the fossil mammal record of the Turkana Basin

    PubMed Central

    Žliobaitė, Indrė; Kaya, Ferhat; Bibi, Faysal; Bobe, René; Leakey, Louise; Leakey, Meave; Patterson, David; Rannikko, Janina; Werdelin, Lars

    2016-01-01

    Although ecometric methods have been used to analyse fossil mammal faunas and environments of Eurasia and North America, such methods have not yet been applied to the rich fossil mammal record of eastern Africa. Here we report results from analysis of a combined dataset spanning east and west Turkana from Kenya between 7 and 1 million years ago (Ma). We provide temporally and spatially resolved estimates of temperature and precipitation and discuss their relationship to patterns of faunal change, and propose a new hypothesis to explain the lack of a temperature trend. We suggest that the regionally arid Turkana Basin may between 4 and 2 Ma have acted as a ‘species factory’, generating ecological adaptations in advance of the global trend. We show a persistent difference between the eastern and western sides of the Turkana Basin and suggest that the wetlands of the shallow eastern side could have provided additional humidity to the terrestrial ecosystems. Pending further research, a transient episode of faunal change centred at the time of the KBS Member (1.87–1.53 Ma), may be equally plausibly attributed to climate change or to a top-down ecological cascade initiated by the entry of technologically sophisticated humans. This article is part of the themed issue ‘Major transitions in human evolution’. PMID:27298463

  11. New Biogeographic insight into Bauhinia s.l. (Leguminosae): integration from fossil records and molecular analyses

    PubMed Central

    2014-01-01

    Background Given that most species that have ever existed on earth are extinct, it stands to reason that the evolutionary history can be better understood with fossil taxa. Bauhinia is a typical genus of pantropical intercontinental disjunction among the Asian, African, and American continents. Geographic distribution patterns are better recognized when fossil records and molecular sequences are combined in the analyses. Here, we describe a new macrofossil species of Bauhinia from the Upper Miocene Xiaolongtan Formation in Wenshan County, Southeast Yunnan, China, and elucidate the biogeographic significance through the analyses of molecules and fossils. Results Morphometric analysis demonstrates that the leaf shapes of B. acuminata, B. championii, B. chalcophylla, B. purpurea, and B. podopetala closely resemble the leaf shapes of the new finding fossil. Phylogenetic relationships among the Bauhinia species were reconstructed using maximum parsimony and Bayesian inference, which inferred that species in Bauhinia species are well-resolved into three main groups. Divergence times were estimated by the Bayesian Markov chain Monte Carlo (MCMC) method under a relaxed clock, and inferred that the stem diversification time of Bauhinia was ca. 62.7 Ma. The Asian lineage first diverged at ca. 59.8 Ma, followed by divergence of the Africa lineage starting during the late Eocene, whereas that of the neotropical lineage starting during the middle Miocene. Conclusions Hypotheses relying on vicariance or continental history to explain pantropical disjunct distributions are dismissed because they require mostly Palaeogene and older tectonic events. We suggest that Bauhinia originated in the middle Paleocene in Laurasia, probably in Asia, implying a possible Tethys Seaway origin or an “Out of Tropical Asia”, and dispersal of legumes. Its present pantropical disjunction resulted from disruption of the boreotropical flora by climatic cooling after the Paleocene-Eocene Thermal

  12. Extinction intensity, selectivity and their combined macroevolutionary influence in the fossil record.

    PubMed

    Payne, Jonathan L; Bush, Andrew M; Chang, Ellen T; Heim, Noel A; Knope, Matthew L; Pruss, Sara B

    2016-10-01

    The macroevolutionary effects of extinction derive from both intensity of taxonomic losses and selectivity of losses with respect to ecology, physiology and/or higher taxonomy. Increasingly, palaeontologists are using logistic regression to quantify extinction selectivity because the selectivity metric is independent of extinction intensity and multiple predictor variables can be assessed simultaneously. We illustrate the use of logistic regression with an analysis of physiological buffering capacity and extinction risk in the Phanerozoic marine fossil record. We propose the geometric mean of extinction intensity and selectivity as a metric for the influence of extinction events. The end-Permian mass extinction had the largest influence on the physiological composition of the fauna owing to its combination of high intensity and strong selectivity. In addition to providing a quantitative measure of influence to compare among past events, this approach provides an avenue for quantifying the risk posed by the emerging biodiversity crisis that goes beyond a simple projection of taxonomic losses.

  13. Toward a new synthesis: major evolutionary trends in the angiosperm fossil record.

    PubMed

    Dilcher, D

    2000-06-20

    Angiosperm paleobotany has widened its horizons, incorporated new techniques, developed new databases, and accepted new questions that can now focus on the evolution of the group. The fossil record of early flowering plants is now playing an active role in addressing questions of angiosperm phylogeny, angiosperm origins, and angiosperm radiations. Three basic nodes of angiosperm radiations are identified: (i) the closed carpel and showy radially symmetrical flower, (ii) the bilateral flower, and (iii) fleshy fruits and nutritious nuts and seeds. These are all coevolutionary events and spread out through time during angiosperm evolution. The proposal is made that the genetics of the angiosperms pressured the evolution of the group toward reproductive systems that favored outcrossing. This resulted in the strongest selection in the angiosperms being directed toward the flower, fruits, and seeds. That is why these organs often provide the best systematic characters for the group.

  14. A dinosaurian facial deformity and the first occurrence of ameloblastoma in the fossil record

    PubMed Central

    Dumbravă, Mihai D.; Rothschild, Bruce M.; Weishampel, David B.; Csiki-Sava, Zoltán; Andrei, Răzvan A.; Acheson, Katharine A.; Codrea, Vlad A.

    2016-01-01

    Despite documentation of various types of neoplastic pathologies encountered in the vertebrate fossil record, no ameloblastic tumours have been recognised so far. Ameloblastoma is a benign neoplasic tumour with a strong preponderance for the mandible. Here, we report for the first time the presence of an ameloblastoma neoplasm in the lower jaw of a specimen referred to the derived non-hadrosaurid hadrosauroid dinosaur Telmatosaurus transsylvanicus from the uppermost Cretaceous of the Haeg Basin in Romania. The location, external appearance and internal structure of the pathological outgrowth provide clear evidence for the diagnosis of ameloblastoma in Telmatosaurus. This report extends the range of pathologies encountered in hadrosauroid dinosaurs. In addition, recognition of an ameloblastoma neoplasm in a taxon lying close to the origin of ‘duck-billed’ hadrosaurid dinosaurs confirms the predisposition of this clade towards neoplasia pathologies already in its basal members. PMID:27377317

  15. Fossil invertebrates records in cave sediments and paleoenvironmental assessments - a study of four cave sites from Romanian Carpathians

    NASA Astrophysics Data System (ADS)

    Moldovan, O. T.; Constantin, S.; Panaiotu, C.; Roban, R. D.; Frenzel, P.; Miko, L.

    2016-01-01

    Fossil invertebrates from cave sediments have been recently described as a potential new proxy for paleoenvironment and used in cross-correlations with alternate proxy records from cave deposits. Here we present the results of a fossil invertebrates study in four caves from two climatically different regions of the Romanian Carpathians, to complement paleoenvironmental data previously reported. Oribatid mites and ostracods are the most common invertebrates in the studied cave sediments. Some of the identified taxa are new to science, and most of them are indicative for either warm and/or cold stages or dry and/or wetter oscillations. In two caves the fossil invertebrates records indicate rapid climate oscillations during times known for a relatively stable climate. By corroborating the fossil invertebrates' record with the information given by magnetic properties and sediment structures, complementary data on past vegetation, temperatures and hydraulic regimes could be gathered. This paper analyzes the potential of fossil invertebrate records as a paleoenvironmental proxy, potential problems and pitfalls.

  16. Origin of the Eumetazoa: testing ecological predictions of molecular clocks against the Proterozoic fossil record

    NASA Technical Reports Server (NTRS)

    Peterson, Kevin J.; Butterfield, Nicholas J.

    2005-01-01

    Molecular clocks have the potential to shed light on the timing of early metazoan divergences, but differing algorithms and calibration points yield conspicuously discordant results. We argue here that competing molecular clock hypotheses should be testable in the fossil record, on the principle that fundamentally new grades of animal organization will have ecosystem-wide impacts. Using a set of seven nuclear-encoded protein sequences, we demonstrate the paraphyly of Porifera and calculate sponge/eumetazoan and cnidarian/bilaterian divergence times by using both distance [minimum evolution (ME)] and maximum likelihood (ML) molecular clocks; ME brackets the appearance of Eumetazoa between 634 and 604 Ma, whereas ML suggests it was between 867 and 748 Ma. Significantly, the ME, but not the ML, estimate is coincident with a major regime change in the Proterozoic acritarch record, including: (i) disappearance of low-diversity, evolutionarily static, pre-Ediacaran acanthomorphs; (ii) radiation of the high-diversity, short-lived Doushantuo-Pertatataka microbiota; and (iii) an order-of-magnitude increase in evolutionary turnover rate. We interpret this turnover as a consequence of the novel ecological challenges accompanying the evolution of the eumetazoan nervous system and gut. Thus, the more readily preserved microfossil record provides positive evidence for the absence of pre-Ediacaran eumetazoans and strongly supports the veracity, and therefore more general application, of the ME molecular clock.

  17. Hominin cognitive evolution: identifying patterns and processes in the fossil and archaeological record

    PubMed Central

    Shultz, Susanne; Nelson, Emma; Dunbar, Robin I. M.

    2012-01-01

    As only limited insight into behaviour is available from the archaeological record, much of our understanding of historical changes in human cognition is restricted to identifying changes in brain size and architecture. Using both absolute and residual brain size estimates, we show that hominin brain evolution was likely to be the result of a mix of processes; punctuated changes at approximately 100 kya, 1 Mya and 1.8 Mya are supplemented by gradual within-lineage changes in Homo erectus and Homo sapiens sensu lato. While brain size increase in Homo in Africa is a gradual process, migration of hominins into Eurasia is associated with step changes at approximately 400 kya and approximately 100 kya. We then demonstrate that periods of rapid change in hominin brain size are not temporally associated with changes in environmental unpredictability or with long-term palaeoclimate trends. Thus, we argue that commonly used global sea level or Indian Ocean dust palaeoclimate records provide little evidence for either the variability selection or aridity hypotheses explaining changes in hominin brain size. Brain size change at approximately 100 kya is coincident with demographic change and the appearance of fully modern language. However, gaps remain in our understanding of the external pressures driving encephalization, which will only be filled by novel applications of the fossil, palaeoclimatic and archaeological records. PMID:22734056

  18. New Eocene Coleoid (Cephalopoda) Diversity from Statolith Remains: Taxonomic Assignation, Fossil Record Analysis, and New Data for Calibrating Molecular Phylogenies.

    PubMed

    Neige, Pascal; Lapierre, Hervé; Merle, Didier

    2016-01-01

    New coleoid cephalopods are described from statolith remains from the Middle Eocene (Middle Lutetian) of the Paris Basin. Fifteen fossil statoliths are identified and assigned to the Sepiidae (Sepia boletzkyi sp. nov.,? Sepia pira sp. nov.), Loliginidae (Loligo clarkei sp. nov.), and Ommastrephidae (genus indet.) families. The sediments containing these fossils indicate permanent aquatic settings in the infralittoral domain. These sediments range in age from 46 Mya to 43 Mya. Analysis of the fossil record of statoliths (from findings described here, together with a review of previously published data) indicates marked biases in our knowledge. Fossil statoliths are known from as far back as the Early Jurassic (199.3 to 190.8 Mya) but surprisingly, to the best of our knowledge, no record occurs in the Cretaceous. This is a "knowledge bias" and clearly calls for further studies. Finally, we attempt to compare findings described here with fossils previously used to constrain divergence and/or diversification ages of some coleoid subclades in molecular phylogenies. This comparison clearly indicates that the new records detailed here will challenge some estimated divergence times of coleoid cephalopod subclades.

  19. New Eocene Coleoid (Cephalopoda) Diversity from Statolith Remains: Taxonomic Assignation, Fossil Record Analysis, and New Data for Calibrating Molecular Phylogenies

    PubMed Central

    Neige, Pascal; Lapierre, Hervé; Merle, Didier

    2016-01-01

    New coleoid cephalopods are described from statolith remains from the Middle Eocene (Middle Lutetian) of the Paris Basin. Fifteen fossil statoliths are identified and assigned to the Sepiidae (Sepia boletzkyi sp. nov.,? Sepia pira sp. nov.), Loliginidae (Loligo clarkei sp. nov.), and Ommastrephidae (genus indet.) families. The sediments containing these fossils indicate permanent aquatic settings in the infralittoral domain. These sediments range in age from 46 Mya to 43 Mya. Analysis of the fossil record of statoliths (from findings described here, together with a review of previously published data) indicates marked biases in our knowledge. Fossil statoliths are known from as far back as the Early Jurassic (199.3 to 190.8 Mya) but surprisingly, to the best of our knowledge, no record occurs in the Cretaceous. This is a “knowledge bias” and clearly calls for further studies. Finally, we attempt to compare findings described here with fossils previously used to constrain divergence and/or diversification ages of some coleoid subclades in molecular phylogenies. This comparison clearly indicates that the new records detailed here will challenge some estimated divergence times of coleoid cephalopod subclades. PMID:27192490

  20. Recording of climate and diagenesis through sedimentary DNA and fossil pigments at Laguna Potrok Aike, Argentina

    NASA Astrophysics Data System (ADS)

    Vuillemin, Aurèle; Ariztegui, Daniel; Leavitt, Peter R.; Bunting, Lynda; The Pasado Science Team

    2016-04-01

    Aquatic sediments record past climatic conditions while providing a wide range of ecological niches for microorganisms. In theory, benthic microbial community composition should depend on environmental features and geochemical conditions of surrounding sediments, as well as ontogeny of the subsurface environment as sediment degraded. In principle, DNA in sediments should be composed of ancient and extant microbial elements persisting at different degrees of preservation, although to date few studies have quantified the relative influence of each factor in regulating final composition of total sedimentary DNA assemblage. Here geomicrobiological and phylogenetic analyses of a Patagonian maar lake were used to indicate that the different sedimentary microbial assemblages derive from specific lacustrine regimes during defined climatic periods. Two climatic intervals (Mid-Holocene, 5 ka BP; Last Glacial Maximum, 25 ka BP) whose sediments harbored active microbial populations were sampled for a comparative environmental study based on fossil pigments and 16S rRNA gene sequences. The genetic assemblage recovered from the Holocene record revealed a microbial community displaying metabolic complementarities that allowed prolonged degradation of organic matter to methane. The series of Archaea identified throughout the Holocene record indicated an age-related stratification of these populations brought on by environmental selection during early diagenesis. These characteristics were associated with sediments resulting from endorheic lake conditions and stable pelagic regime, high evaporative stress and concomitant high algal productivity. In contrast, sulphate-reducing bacteria and lithotrophic Archaea were predominant in sediments dated from the Last Glacial Maximum, in which pelagic clays alternated with fine volcanic material characteristic of a lake level highstand and freshwater conditions, but reduced water column productivity. Comparison of sedimentary DNA composition

  1. Atlantic Multidecadal Oscillation recorded in fossil corals during the last Interglacial

    NASA Astrophysics Data System (ADS)

    Vàsquez-Bedoya, L.; Cohen, A. L.; Oppo, D.; Thompson, W. G.; Blanchon, P.

    2013-05-01

    The Atlantic Multidecadal Oscillation (AMO) is a mode of sea surface temperature variability occurring in the North Atlantic Ocean, whose warm phase correlates strongly with Atlantic hurricane activity. While support for this mode originates in historical observations and models, controversy exists with regard to the attribution of sea surface temperature change to natural or anthropogenic forcing. Previously, we showed that long-lived colonies of the massive Caribbean coral Siderastrea siderea (Ellis & Solander, 1786) on the Yucatan Peninsula capture AMO-like variability in their annual growth bands (Vásquez-Bedoya et al., 2012) allowing us to extend the record of Atlantic multidecadal variability back to 1775 AD. Here we report an analysis of skeletal growth bands of a fossil coral of the same species, dated by U-series (122.24±0.19 kyr) to the Last Interglacial (LIG). MultiTaper spectral analysis of the LIG coral record reveals significant concentrations of power (99% confidence level) at intervals centered at 45-67 and 50-67 years respectively, consistent with the AMO spectrum, which is centered in intervals of 60-70 years. Thus our analysis provides the first evidence of AMO mode during the LIG and supports the hypotheses of a persistent, naturally-forced multidecadal mode of SST variability in the North Atlantic.

  2. Strong coupling of predation intensity and diversity in the Phanerozoic fossil record.

    PubMed

    Huntley, John Warren; Kowalewski, Michal

    2007-09-18

    The importance of ecological interactions in driving the evolution of animals has been the focus of intense debate among paleontologists, evolutionary biologists, and macroecologists. To test whether the intensity of such interactions covaries with the secular evolutionary trend in global biodiversity, we compiled a species-level database of predation intensity, as measured by the frequency of common predation traces (drillings and repair scars ranging in age from Ediacaran to Holocene). The results indicate that the frequency of predation traces increased notably by the Ordovician, and not in the mid-Paleozoic as suggested by multiple previous studies. Importantly, these estimates of predation intensity and global diversity of marine metazoans correlate throughout the Phanerozoic fossil record regardless of corrections and methods applied. This concordance may represent (i) an ecological signal: long-term coupling of diversity and predation; (ii) a diversity-driven diffusion of predatory behaviors: an increased probability of more complex predatory strategies to appear at higher diversity levels; or (iii) a spurious concordance in signal capture: an artifact where rare species and less-frequent (e.g., trace-producing) predatory behaviors are both more detectable at times when sampling improves. The coupling of predation and diversity records suggests that macroevolutionary and macroecological patterns share common causative mechanisms that may reflect either historical processes or sampling artifacts.

  3. Two new fossil genera and species of Cerocephalinae (Hymenoptera, Chalcidoidea, Pteromalidae), including the first record from the Eocene.

    PubMed

    Bläser, Marcel; Krogmann, Lars; Peters, Ralph S

    2015-01-01

    Cerocephalinae (Chalcidoidea, Pteromalidae) is a small group of parasitoid wasps characterized by a number of derived diagnostic features. Their hosts are endophytic beetles. So far, 43 species of Cerocephalinae have been described, including one fossil species from the Miocene. In this study, we add two new genera and species from Baltic and Dominican amber to the fossil record. Tenuicornus dominicus gen. et sp. n. is the second genus described from Dominican amber, and Pteropilosa lailarabanorum gen. et sp. n., described from Baltic amber, represents the oldest record of the subfamily, pushing the minimum age of Cerocephalinae back to the Eocene. Diagnostic characters of both species are discussed in comparison with other Cerocephalinae. An updated key to extant and fossil Cerocephalinae is presented.

  4. Introducing Evolution to Non-Biology Majors via the Fossil Record: A Case Study from the Israeli High School System.

    ERIC Educational Resources Information Center

    Dodick, Jeff; Orion, Nir

    2003-01-01

    Discusses challenges faced in the teaching and learning of evolution. Presents a curricular program and a case study on evolutionary biology. Investigates students' conceptual knowledge after exposure to the program "From Dinosaurs to Darwin," which focuses on fossil records as evidence of evolution. (Contains 32 references.) (YDS)

  5. Molecular Decay of the Tooth Gene Enamelin (ENAM) Mirrors the Loss of Enamel in the Fossil Record of Placental Mammals

    PubMed Central

    Meredith, Robert W.; Gatesy, John; Murphy, William J.; Ryder, Oliver A.; Springer, Mark S.

    2009-01-01

    Vestigial structures occur at both the anatomical and molecular levels, but studies documenting the co-occurrence of morphological degeneration in the fossil record and molecular decay in the genome are rare. Here, we use morphology, the fossil record, and phylogenetics to predict the occurrence of “molecular fossils” of the enamelin (ENAM) gene in four different orders of placental mammals (Tubulidentata, Pholidota, Cetacea, Xenarthra) with toothless and/or enamelless taxa. Our results support the “molecular fossil” hypothesis and demonstrate the occurrence of frameshift mutations and/or stop codons in all toothless and enamelless taxa. We then use a novel method based on selection intensity estimates for codons (ω) to calculate the timing of iterated enamel loss in the fossil record of aardvarks and pangolins, and further show that the molecular evolutionary history of ENAM predicts the occurrence of enamel in basal representatives of Xenarthra (sloths, anteaters, armadillos) even though frameshift mutations are ubiquitous in ENAM sequences of living xenarthrans. The molecular decay of ENAM parallels the morphological degeneration of enamel in the fossil record of placental mammals and provides manifest evidence for the predictive power of Darwin's theory. PMID:19730686

  6. Caught in the act: the first record of copulating fossil vertebrates.

    PubMed

    Joyce, Walter G; Micklich, Norbert; Schaal, Stephan F K; Scheyer, Torsten M

    2012-10-23

    The behaviour of fossil organisms can typically be inferred only indirectly, but rare fossil finds can provide surprising insights. Here, we report from the Eocene Messel Pit Fossil Site between Darmstadt and Frankfurt, Germany numerous pairs of the fossil carettochelyid turtle Allaeochelys crassesculpta that represent for the first time among fossil vertebrates couples that perished during copulation. Females of this taxon can be distinguished from males by their relatively shorter tails and development of plastral kinesis. The preservation of mating pairs has important taphonomic implications for the Messel Pit Fossil Site, as it is unlikely that the turtles would mate in poisonous surface waters. Instead, the turtles initiated copulation in habitable surface waters, but perished when their skin absorbed poisons while sinking into toxic layers. The mating pairs from Messel are therefore more consistent with a stratified, volcanic maar lake with inhabitable surface waters and a deadly abyss.

  7. Iridium abundance measurements across bio-event horizons in the fossil record

    SciTech Connect

    Orth, C.J.; Attrep, M. Jr.; Quintana, L.R. )

    1989-01-01

    Geochemical measurements have been performed on thousands of rock samples collected across bio-event horizons using Instrumental Neutron Activation Analysis (INAA) for about 40 common and trace elements and radiochemical isolation procedures for Ir. On selected samples, Os, Pt and Au were also radiochemically determined. These studies have encompassed the time interval from the Precambrian-Cambrian transition to the Late Eocene impact (microspherule) horizons. Our early work strengthened the Alvarez impact hypothesis by finding the Ir (PGE) anomaly at the K-T boundary in continental sedimentary sequences. In collaborations with paleontologists, weak to moderately string Ir anomalies have been discovered at the Frasnian-Famennian boundary in Australia, in the Early Mississippian of Oklahoma, at the Mississipian-Pennsylvanian boundary of Oklahoma and Texas, and in the Late Cenomanian throughout the western interior of North America and on the south coast of England to date. We have found no compelling evidence for an impact related cause for these anomalies although PGE impact signatures in the two Late Cenomanian anomalies could be masked by the strong terrestrial mafic to ultramafic overprint. Thus far, our evidence for extinction events older than the terminal Cretaceous does not support recent hypotheses which suggest that impacts from cyclic swarms of comets in the inner Solar system were responsible for the periodic mass extinctions. 50 refs., 7 figs., 3 tabs.

  8. Piscivory in a Miocene Cetotheriidae of Peru: first record of fossilized stomach content for an extinct baleen-bearing whale

    NASA Astrophysics Data System (ADS)

    Collareta, Alberto; Landini, Walter; Lambert, Olivier; Post, Klaas; Tinelli, Chiara; Di Celma, Claudio; Panetta, Daniele; Tripodi, Maria; Salvadori, Piero A.; Caramella, Davide; Marchi, Damiano; Urbina, Mario; Bianucci, Giovanni

    2015-12-01

    Instead of teeth, modern mysticetes bear hair-fringed keratinous baleen plates that permit various bulk-filtering predation techniques (from subsurface skimming to lateral benthic suction and engulfment) devoted to various target prey (from small invertebrates to schooling fish). Current knowledge about the feeding ecology of extant cetaceans is revealed by stomach content analyses and observations of behavior. Unfortunately, no fossil stomach contents of ancient mysticetes have been described so far; the investigation of the diet of fossil baleen whales, including the Neogene family Cetotheriidae, remains thus largely speculative. We report on an aggregate of fossil fish remains found within a mysticete skeleton belonging to an undescribed late Miocene (Tortonian) cetotheriid from the Pisco Formation (Peru). Micro-computed tomography allowed us to interpret it as the fossilized content of the forestomach of the host whale and to identify the prey as belonging to the extant clupeiform genus Sardinops. Our discovery represents the first direct evidence of piscivory in an ancient edentulous mysticete. Since among modern mysticetes only Balaenopteridae are known to ordinarily consume fish, this fossil record may indicate that part of the cetotheriids experimented some degree of balaenopterid-like engulfment feeding. Moreover, this report corresponds to one of the geologically oldest records of Sardinops worldwide, occurring near the Tortonian peak of oceanic primary productivity and cooling phase. Therefore, our discovery evokes a link between the rise of Cetotheriidae; the setup of modern coastal upwelling systems; and the radiation of epipelagic, small-sized, schooling clupeiform fish in such highly productive environments.

  9. Piscivory in a Miocene Cetotheriidae of Peru: first record of fossilized stomach content for an extinct baleen-bearing whale.

    PubMed

    Collareta, Alberto; Landini, Walter; Lambert, Olivier; Post, Klaas; Tinelli, Chiara; Di Celma, Claudio; Panetta, Daniele; Tripodi, Maria; Salvadori, Piero A; Caramella, Davide; Marchi, Damiano; Urbina, Mario; Bianucci, Giovanni

    2015-12-01

    Instead of teeth, modern mysticetes bear hair-fringed keratinous baleen plates that permit various bulk-filtering predation techniques (from subsurface skimming to lateral benthic suction and engulfment) devoted to various target prey (from small invertebrates to schooling fish). Current knowledge about the feeding ecology of extant cetaceans is revealed by stomach content analyses and observations of behavior. Unfortunately, no fossil stomach contents of ancient mysticetes have been described so far; the investigation of the diet of fossil baleen whales, including the Neogene family Cetotheriidae, remains thus largely speculative. We report on an aggregate of fossil fish remains found within a mysticete skeleton belonging to an undescribed late Miocene (Tortonian) cetotheriid from the Pisco Formation (Peru). Micro-computed tomography allowed us to interpret it as the fossilized content of the forestomach of the host whale and to identify the prey as belonging to the extant clupeiform genus Sardinops. Our discovery represents the first direct evidence of piscivory in an ancient edentulous mysticete. Since among modern mysticetes only Balaenopteridae are known to ordinarily consume fish, this fossil record may indicate that part of the cetotheriids experimented some degree of balaenopterid-like engulfment feeding. Moreover, this report corresponds to one of the geologically oldest records of Sardinops worldwide, occurring near the Tortonian peak of oceanic primary productivity and cooling phase. Therefore, our discovery evokes a link between the rise of Cetotheriidae; the setup of modern coastal upwelling systems; and the radiation of epipelagic, small-sized, schooling clupeiform fish in such highly productive environments.

  10. The proterozoic and earliest cambrian trace fossil record; patterns, problems and perspectives.

    PubMed

    Jensen, Sören

    2003-02-01

    The increase in trace fossil diversity across the Neoproterozoic-Cambrian boundary often is presented in terms of tabulations of ichnogenera. However, a clearer picture of the increase in diversity and complexity can be reached by combining trace fossils into broad groups defined both on morphology and interpretation. This also focuses attention on looking for similarites between Neoproterozoic and Cambrian trace fossils. Siliciclastic sediments of the Neoproterozoic preserve elongate tubular organisms and structures of probable algal origin, many of which are very similar to trace fossils. Such enigmatic structures include Palaeopascichnus and Yelovichnus, previously thought to be trace fossils in the form of tight meanders.A preliminary two or tripartite terminal Neoproterozoic trace fossil zonation can be be recognized. Possibly the earliest trace fossils are short unbranched forms, probably younger than about 560 Ma. Typical Neoproterozoic trace fossils are unbranched and essentially horizontal forms found associated with diverse assemblages of Ediacaran organisms. In sections younger than about 550 Ma a modest increase in trace fossil diversity occurs, including the appearance of rare three-dimensional burrow systems (treptichnids), and traces with a three-lobed lower surfaces.

  11. Paleovegetation changes recorded by n-alkyl lipids bound in macromolecules of plant fossils and kerogens from the Cretaceous sediments in Japan

    NASA Astrophysics Data System (ADS)

    Miyata, Y.; Sawada, K.; Nakamura, H.; Takashima, R.; Takahashi, M.

    2014-12-01

    Resistant macromolecules composing living plant tissues tend to be preserved through degradation and diagenesis, hence constituate major parts of sedimentary plant-derived organic matter (kerogen), and their monomer compositions vary widely among different plant taxa, organs and growth stages. Thus, analysis of such macromolecule may serve as new technique for paleobotanical evaluation distinctive from classical paleobotnical studies depends on morphological preservation of fossils. In the present study, we analyzed plant fossils and kerogens in sediments from the Cretaceous strata in Japan to examine chemotaxonomic characteristics of fossil macromolecules and to reconstruct paleovegetation change by kerogen analysis. The kerogens were separated from the powdered sediments of Cretaceous Yezo Group, Hokkaido, Japan. All kerogens have been confirmed to be mostly originated from land plant tissues by microscopic observation. Mummified angiosperm and gymnosperm fossil leaves were separated from carbonaceous sandstone of the Cretaceous Ashizawa Formation, Futaba Group. The kerogens and plant fossils were extracted with methanol and dichloromethane, and were subsequently refluxed under 110°C to remove free compounds completely. The residues are hydrolyzed by KOH/methanol under 110°C. These released compounds are analyzed by GC-MS. As main hydrolyzed products (ester-bound molecular units) from all kerogens, C10-C28 n-alkanoic acids and C10-C30 n-alkanols were detected. Recent studies on the hydrolysis products of plant tissues suggested the long chain (>C20) n-alkanols were predominantly abundant in deciduous broadleaved angiosperms. Correspondingly, the stratigraphic variation of the ratios of long chain (>C20) n-alkanols to fatty acids was concordant with the variation of angiosperm/gymnosperm ratios recorded by land plant-derived terpenoid biomarkers. In addition, we found that the long chain n-alkanols/fatty acids ratio in the angiosperm fossil leaf was

  12. A multi-calibrated mitochondrial phylogeny of extant Bovidae (Artiodactyla, Ruminantia) and the importance of the fossil record to systematics

    PubMed Central

    2013-01-01

    Background Molecular phylogenetics has provided unprecedented resolution in the ruminant evolutionary tree. However, molecular age estimates using only one or a few (often misapplied) fossil calibration points have produced a diversity of conflicting ages for important evolutionary events within this clade. I here identify 16 fossil calibration points of relevance to the phylogeny of Bovidae and Ruminantia and use these, individually and together, to construct a dated molecular phylogeny through a reanalysis of the full mitochondrial genome of over 100 ruminant species. Results The new multi-calibrated tree provides ages that are younger overall than found in previous studies. Among these are young ages for the origin of crown Ruminantia (39.3–28.8 Ma), and crown Bovidae (17.3–15.1 Ma). These are argued to be reasonable hypotheses given that many basal fossils assigned to these taxa may in fact lie on the stem groups leading to the crown clades, thus inflating previous age estimates. Areas of conflict between molecular and fossil dates do persist, however, especially with regard to the base of the rapid Pecoran radiation and the sister relationship of Moschidae to Bovidae. Results of the single-calibrated analyses also show that a very wide range of molecular age estimates are obtainable using different calibration points, and that the choice of calibration point can influence the topology of the resulting tree. Compared to the single-calibrated trees, the multi-calibrated tree exhibits smaller variance in estimated ages and better reflects the fossil record. Conclusions The use of a large number of vetted fossil calibration points with soft bounds is promoted as a better approach than using just one or a few calibrations, or relying on internal-congruency metrics to discard good fossil data. This study also highlights the importance of considering morphological and ecological characteristics of clades when delimiting higher taxa. I also illustrate how

  13. First forensic records of termite activity on non-fossilized human bones in Brazil.

    PubMed

    Queiroz, R A; Soriano, E P; Carvalho, M V D; Caldas-Junior, A F; Souza, E H A; Coelho-Junior, L G T M; Campello, R I C; Almeida, A C; Farias, R C A P; Vasconcellos, A

    2016-07-25

    The aim of this study was to describe the first records of termite activity on non-fossilized human bones in Brazil. The cases reported in this study resulted from forensic analysis of six human skeletons found in northeastern Brazil between 2012 and 2014. Traces of tunnels and nests commonly produced by termites were found on several human bone surfaces as well as the specimens and characteristic signs of osteophagic activity. In four cases, the species were identified: Amitermes amifer Silvestri, 1901, Nasutitermes corniger (Motschulsky, 1855) (on two skeletons), and Microcerotermes indistinctus Mathews, 1977. In two other cases, the activity of termites on bone surfaces was evidenced by remains of nests and tunnels produced by these insects. At least in the samples of human remains available for this report, the number of termites collected was greater on bones found during autumn, the rainy season in the Northeast of Brazil. The human bones examined showed termites like insects with lots of strength at bone degradation, capable of continuing the process of decomposition of human remains even in completely skeletonized bodies.

  14. Review of the monotreme fossil record and comparison of palaeontological and molecular data.

    PubMed

    Musser, A M

    2003-12-01

    Monotremes have traditionally been considered a remnant group of mammals descended from archaic Mesozoic stock, surviving to the present day on the relatively isolated Australian continent. Challenges to this orthodoxy have been spurred by discoveries of 'advanced' Cretaceous monotremes (Steropodon galmani, Archer, M., et al., 1985. First Mesozoic mammal from Australia-an Early Cretaceous monotreme, Nature. 318, 363-366) as well as by results from molecular data linking monotremes to therian mammals (specifically to marsupials in some studies). This paper reviews the monotreme fossil record and briefly discusses significant new information from additional Cretaceous Australian material. Mesozoic monotremes (including S. galmani) were a diverse group as evidenced by new material from the Early Cretaceous of New South Wales and Victoria currently under study. Although most of these new finds are edentulous jaws (limiting dental comparisons and determination of dietary niches), a range of sizes and forms has been determined. Some of these Cretaceous jaws exhibit archaic features-in particular evidence for the presence of a splenial bone in S. galmani-not seen in therian mammals or in post-Mesozoic (Tertiary and Quaternary) monotreme taxa. Tertiary monotremes were either archaic ornithorhynchids (toothed platypuses in the genera Monotrematum and Obdurodon) or tachyglossids (large echidnas in the genera Megalibgwilia and Zaglossus). Quaternary ornithorhynchid material is referable to the sole living platypus species Ornithorhynchus anatinus. Quaternary echidnas, however, were moderately diverse and several forms are known (Megalibgwilia species; 'Zaglossus' hacketti; Zaglossus species and Tachyglossus aculeatus).

  15. Nacre tablet thickness records formation temperature in modern and fossil shells

    NASA Astrophysics Data System (ADS)

    Gilbert, Pupa U. P. A.; Bergmann, Kristin D.; Myers, Corinne E.; Marcus, Matthew A.; DeVol, Ross T.; Sun, Chang-Yu; Blonsky, Adam Z.; Tamre, Erik; Zhao, Jessica; Karan, Elizabeth A.; Tamura, Nobumichi; Lemer, Sarah; Giuffre, Anthony J.; Giribet, Gonzalo; Eiler, John M.; Knoll, Andrew H.

    2017-02-01

    Nacre, the iridescent outer lining of pearls and inner lining of many mollusk shells, is composed of periodic, parallel, organic sheets alternating with aragonite (CaCO3) tablet layers. Nacre tablet thickness (TT) generates both nacre's iridescence and its remarkable resistance to fracture. Despite extensive studies on how nacre forms, the mechanisms controlling TT remain unknown, even though they determine the most conspicuous of nacre's characteristics, visible even to the naked eye. Thermodynamics predicts that temperature (T) will affect both physical and chemical components of biomineralized skeletons. The chemical composition of biominerals is well-established to record environmental parameters, and has therefore been extensively used in paleoclimate studies. The physical structure, however, has been hypothesized but never directly demonstrated to depend on the environment. Here we observe that the physical TT in nacre from modern and fossil shallow-water shells of the bivalves Pinna and Atrina correlates with T as measured by the carbonate clumped isotope thermometer. Based on the observed TT vs. T correlation, we anticipate that TT will be used as a paleothermometer, useful to estimate paleotemperature in shallow-water paleoenvironments. Here we successfully test the proposed new nacre TT thermometer on two Jurassic Pinna shells. The increase of TT with T is consistent with greater aragonite growth rate at higher T, and with greater metabolic rate at higher T. Thus, it reveals a complex, T-dependent biophysical mechanism for nacre formation.

  16. Species-energy relationship in the deep sea: A test using the Quaternary fossil record

    USGS Publications Warehouse

    Hunt, G.; Cronin, T. M.; Roy, K.

    2005-01-01

    Little is known about the processes regulating species richness in deep-sea communities. Here we take advantage of natural experiments involving climate change to test whether predictions of the species-energy hypothesis hold in the deep sea. In addition, we test for the relationship between temperature and species richness predicted by a recent model based on biochemical kinetics of metabolism. Using the deep-sea fossil record of benthic foraminifera and statistical meta-analyses of temperature-richness and productivity-richness relationships in 10 deep-sea cores, we show that temperature but not productivity is a significant predictor of species richness over the past c. 130 000 years. Our results not only show that the temperature-richness relationship in the deep-sea is remarkably similar to that found in terrestrial and shallow marine habitats, but also that species richness tracks temperature change over geological time, at least on scales of c. 100 000 years. Thus, predicting biotic response to global climate change in the deep sea would require better understanding of how temperature regulates the occurrences and geographical ranges of species. ??2005 Blackwell Publishing Ltd/CNRS.

  17. Colloquium paper: dynamics of origination and extinction in the marine fossil record.

    PubMed

    Alroy, John

    2008-08-12

    The discipline-wide effort to database the fossil record at the occurrence level has made it possible to estimate marine invertebrate extinction and origination rates with much greater accuracy. The new data show that two biotic mechanisms have hastened recoveries from mass extinctions and confined diversity to a relatively narrow range over the past 500 million years (Myr). First, a drop in diversity of any size correlates with low extinction rates immediately afterward, so much so that extinction would almost come to a halt if diversity dropped by 90%. Second, very high extinction rates are followed by equally high origination rates. The two relationships predict that the rebound from the current mass extinction will take at least 10 Myr, and perhaps 40 Myr if it rivals the Permo-Triassic catastrophe. Regardless, any large event will result in a dramatic ecological and taxonomic restructuring of the biosphere. The data also confirm that extinction and origination rates both declined through the Phanerozoic and that several extinctions in addition to the Permo-Triassic event were particularly severe. However, the trend may be driven by taxonomic biases and the rates vary in accord with a simple log normal distribution, so there is no sharp distinction between background and mass extinctions. Furthermore, the lack of any significant autocorrelation in the data is inconsistent with macroevolutionary theories of periodicity or self-organized criticality.

  18. Climate refugia: joint inference from fossil records, species distribution models and phylogeography.

    PubMed

    Gavin, Daniel G; Fitzpatrick, Matthew C; Gugger, Paul F; Heath, Katy D; Rodríguez-Sánchez, Francisco; Dobrowski, Solomon Z; Hampe, Arndt; Hu, Feng Sheng; Ashcroft, Michael B; Bartlein, Patrick J; Blois, Jessica L; Carstens, Bryan C; Davis, Edward B; de Lafontaine, Guillaume; Edwards, Mary E; Fernandez, Matias; Henne, Paul D; Herring, Erin M; Holden, Zachary A; Kong, Woo-seok; Liu, Jianquan; Magri, Donatella; Matzke, Nicholas J; McGlone, Matt S; Saltré, Frédérik; Stigall, Alycia L; Tsai, Yi-Hsin Erica; Williams, John W

    2014-10-01

    Climate refugia, locations where taxa survive periods of regionally adverse climate, are thought to be critical for maintaining biodiversity through the glacial-interglacial climate changes of the Quaternary. A critical research need is to better integrate and reconcile the three major lines of evidence used to infer the existence of past refugia - fossil records, species distribution models and phylogeographic surveys - in order to characterize the complex spatiotemporal trajectories of species and populations in and out of refugia. Here we review the complementary strengths, limitations and new advances for these three approaches. We provide case studies to illustrate their combined application, and point the way towards new opportunities for synthesizing these disparate lines of evidence. Case studies with European beech, Qinghai spruce and Douglas-fir illustrate how the combination of these three approaches successfully resolves complex species histories not attainable from any one approach. Promising new statistical techniques can capitalize on the strengths of each method and provide a robust quantitative reconstruction of species history. Studying past refugia can help identify contemporary refugia and clarify their conservation significance, in particular by elucidating the fine-scale processes and the particular geographic locations that buffer species against rapidly changing climate.

  19. Anatomical Correlates to Nectar Feeding among the Strepsirrhines of Madagascar: Implications for Interpreting the Fossil Record

    PubMed Central

    Muchlinski, Magdalena N.; Perry, Jonathan M. G.

    2011-01-01

    One possible ecological scenario for the origin of primates is the archaic pollination and coevolution hypothesis. Its proponents contend that the consumption of nectar by some early primates and the resulting cross-pollination is an example of coevolution that drove adaptive radiations in some primates. This hypothesis is perhaps ecologically sound, but it lacks the morphology-behavior links that would allow us to test it using the fossil record. Here we attempt to identify cranial adaptations to nectar feeding among the strepsirrhines of Madagascar in order to provide such links. Many Malagasy strepsirrhines are considered effective cross-pollinators of the flowers they feed from, and nectar consumption represents as much as 75% of total feeding time. Previous studies identified skeletal correlates to nectar feeding in the crania of nonprimate mammals; from these, nine cranial measurements were chosen to be the focus of the present study. Results indicate that Cheirogaleus, Varecia, and Eulemur mirror other nectar-feeding mammals in having elongated crania and/or muzzles. These strepsirrhines might be effective cross-pollinators, lending support to the coevolution hypothesis. PMID:22567292

  20. Fossil bryophytes as recorders of ancient CO2 levels: Experimental evidence and a Cretaceous case study

    NASA Astrophysics Data System (ADS)

    Fletcher, Benjamin J.; Beerling, David J.; Brentnall, Stuart J.; Royer, Dana L.

    2005-09-01

    Biological and geochemical CO2 proxies provide critical constraints on understanding the role of atmospheric CO2 in driving climate change during Earth history. As no single existing CO2 proxy is without its limitations, there is a clear need for new approaches to reconstructing past CO2 concentrations. Here we develop a new pre-Quaternary CO2 proxy based on the stable carbon isotope composition (δ13C) of astomatous land plants. In a series of CO2-controlled laboratory experiments, we show that the carbon isotope discrimination (Δ13C) of a range of bryophyte (liverwort and moss) species increases with atmospheric CO2 across the range 375 to 6000 ppm. Separate experiments establish that variations in growth temperature, water content and substrate type have minor impacts on the Δ13C of liverworts but not mosses, indicating the greater potential of liverworts to faithfully record past variations in CO2. A mechanistic model for calculating past CO2 concentrations from bryophyte Δ13C (White et al., 1994) is extended and calibrated using our experimental results. The potential for fossil liverworts to record past CO2 changes is investigated by analyzing the δ13C of specimens collected from Alexander Island, Antarctica dating to the "greenhouse" world of the mid-Cretaceous. Our analysis and isotopic model yield mid-Cretaceous CO2 concentrations of 1000-1400 ppm, in general agreement with independent proxy data and long-term carbon cycle models. The exceptionally long evolutionary history of bryophytes offers the possibility of reconstructing CO2 concentrations back to the mid-Ordovician, pre-dating all currently used quantitative CO2 proxies.

  1. New historical records and relationships among 14C production rates, abundance and color of low latitude auroras and sunspot abundance

    NASA Astrophysics Data System (ADS)

    Abbott, Dallas; Juhl, Robert

    2016-12-01

    Incursions of high-energy particles from space, specifically solar energetic particles and galactic cosmic rays, have significant effects on the Earth, including disruption of the Earth's magnetic field, generation of electric fields strong enough to damage electronic devices as well as the production of auroras at low-latitudes, within 45° of the magnetic equator. We examine the relationships among 14C production, auroral abundance, auroral color and sunspot abundance using existing data supplemented by a new dataset. The new dataset, based on Chinese and Korean records from A.D. 1100-1700, includes 46 new or revised records of sunspots and 279 records of low-latitude auroras. Low-latitude auroras are predominantly red (66%, 835 events) with lesser proportions of white (20%, 253 events) and black auroras (6%, 67 events). All other auroral colors (green, yellow, multicolored, blue and purple) aggregate to a total of 100 events (8%). Overall, white auroras are more frequent during times of higher 14C production. We use two empirical methods of evaluating the flux of high-energy particles: modeled peaks and lows in 14C production and peaks and lows in the 14C calibration curve. We find that comparison to modeled 14C production gives significant results. White auroras are significantly more abundant (98% probability) at times of high production of 14C. Red auroras are somewhat more abundant (88% probability) at times of low production of 14C. The abundances of black, multicolored, green, yellow, and blue auroras between times of low and high 14C production are not significantly different. Violet/purple auroras are significantly more abundant (98% probability) at times of low 14C production. The positive correlation of violet/purple auroras with times of low14C production rate and the lack of correlation of blue auroras with times of high14C production is surprising, for this portion of the visible spectrum contains strong emission lines and some lines with high

  2. Recording of climate and diagenesis through fossil pigments and sedimentary DNA at Laguna Potrok Aike, Argentina

    NASA Astrophysics Data System (ADS)

    Vuillemin, A.; Ariztegui, D.; Leavitt, P. R.; Bunting, L.; Pasado Science Team

    2015-11-01

    Aquatic sediments record past climatic conditions while providing a wide range of ecological niches for microorganisms. Although marine sedimentary microbial assemblages are often defined by their surrounding geochemical conditions, the influence of environmental features upon microbial development and post-depositional survival remains largely unknown in the lacustrine realm. Due to long-term microbial activity, the composition of environmental DNA can be expected to evolve with sediment depth and over time and therefore should reflect both ancient and extant microbial populations, but this hypothesis has rarely been tested using a multiproxy approach. Here geomicrobiological and phylogenetic analyses of a Patagonian maar lake were used to indicate that the different sedimentary microbial assemblages derive from specific lacustrine regimes during defined climatic periods. Two well defined climatic intervals whose sediments harboured active microbial populations and measurable ATP were sampled for a comparative environmental study based on fossil pigments and 16S rRNA gene sequences. Bacterial and archaeal 16S rRNA gene sequences recovered from the Holocene record revealed a microbial community adapted to subsaline conditions actively producing methane during organic matter degradation. These characteristics were associated with sediments resulting from endorheic lake conditions with high evaporative stress and concomitant high algal productivity. Moreover, archaeal clone libraries established throughout the Holocene record indicate an age-related stratification of these populations, consistent with a gradual use of organic substrates after deposition. In contrast, sulphate-reducing bacteria and lithotrophic Archaea were predominant in sediments dated from the Last Glacial Maximum, in which pelagic clays alternated with fine volcanic material characteristic of a lake level highstand and freshwater conditions, but reduced water column productivity. These patterns

  3. Limitations of a morphological criterion of adaptive inference in the fossil record.

    PubMed

    Ravosa, Matthew J; Menegaz, Rachel A; Scott, Jeremiah E; Daegling, David J; McAbee, Kevin R

    2016-11-01

    Experimental analyses directly inform how an anatomical feature or complex functions during an organism's lifetime, which serves to increase the efficacy of comparative studies of living and fossil taxa. In the mammalian skull, food material properties and feeding behaviour have a pronounced influence on the development of the masticatory apparatus. Diet-related variation in loading magnitude and frequency induce a cascade of changes at the gross, tissue, cellular, protein and genetic levels, with such modelling and remodelling maintaining the integrity of oral structures vis-à-vis routine masticatory stresses. Ongoing integrative research using rabbit and rat models of long-term masticatory plasticity offers unique insight into the limitations of functional interpretations of fossilised remains. Given the general restriction of the palaeontological record to bony elements, we argue that failure to account for the disparity in the hierarchical network of responses of hard versus soft tissues may overestimate the magnitude of the adaptive divergence that is inferred from phenotypic differences. Second, we note that the developmental onset and duration of a loading stimulus associated with a given feeding behaviour can impart large effects on patterns of intraspecific variation that can mirror differences observed among taxa. Indeed, plasticity data are relevant to understanding evolutionary transformations because rabbits raised on different diets exhibit levels of morphological disparity comparable to those found between closely related primate species that vary in diet. Lastly, pronounced variation in joint form, and even joint function, can also characterise adult conspecifics that differ solely in age. In sum, our analyses emphasise the importance of a multi-site and hierarchical approach to understanding determinants of morphological variation, one which incorporates critical data on performance.

  4. Trace metals as biomarkers for eumelanin pigment in the fossil record.

    PubMed

    Wogelius, R A; Manning, P L; Barden, H E; Edwards, N P; Webb, S M; Sellers, W I; Taylor, K G; Larson, P L; Dodson, P; You, H; Da-qing, L; Bergmann, U

    2011-09-16

    Well-preserved fossils of pivotal early bird and nonavian theropod species have provided unequivocal evidence for feathers and/or downlike integuments. Recent studies have reconstructed color on the basis of melanosome structure; however, the chemistry of these proposed melanosomes has remained unknown. We applied synchrotron x-ray techniques to several fossil and extant organisms, including Confuciusornis sanctus, in order to map and characterize possible chemical residues of melanin pigments. Results show that trace metals, such as copper, are present in fossils as organometallic compounds most likely derived from original eumelanin. The distribution of these compounds provides a long-lived biomarker of melanin presence and density within a range of fossilized organisms. Metal zoning patterns may be preserved long after melanosome structures have been destroyed.

  5. Palaeontology: The Point of No Return in the Fossil Record of Eusociality.

    PubMed

    Rust, Jes; Wappler, Torsten

    2016-02-22

    The evolution of eusociality is one of the major transitions in the history of life, particularly in the insects. Now, fossil termites and ants from Burmese amber offer insights into early stages of eusociality in the Lower Cretaceous.

  6. Evolutionary History of the Asian Horned Frogs (Megophryinae): Integrative Approaches to Timetree Dating in the Absence of a Fossil Record.

    PubMed

    Mahony, Stephen; Foley, Nicole M; Biju, S D; Teeling, Emma C

    2017-03-01

    Molecular dating studies typically need fossils to calibrate the analyses. Unfortunately, the fossil record is extremely poor or presently nonexistent for many species groups, rendering such dating analysis difficult. One such group is the Asian horned frogs (Megophryinae). Sampling all generic nomina, we combined a novel ∼5 kb dataset composed of four nuclear and three mitochondrial gene fragments to produce a robust phylogeny, with an extensive external morphological study to produce a working taxonomy for the group. Expanding the molecular dataset to include out-groups of fossil-represented ancestral anuran families, we compared the priorless RelTime dating method with the widely used prior-based Bayesian timetree method, MCMCtree, utilizing a novel combination of fossil priors for anuran phylogenetic dating. The phylogeny was then subjected to ancestral phylogeographic analyses, and dating estimates were compared with likely biogeographic vicariant events. Phylogenetic analyses demonstrated that previously proposed systematic hypotheses were incorrect due to the paraphyly of genera. Molecular phylogenetic, morphological, and timetree results support the recognition of Megophryinae as a single genus, Megophrys, with a subgenus level classification. Timetree results using RelTime better corresponded with the known fossil record for the out-group anuran tree. For the priorless in-group, it also outperformed MCMCtree when node date estimates were compared with likely influential historical biogeographic events, providing novel insights into the evolutionary history of this pan-Asian anuran group. Given a relatively small molecular dataset, and limited prior knowledge, this study demonstrates that the computationally rapid RelTime dating tool may outperform more popular and complex prior reliant timetree methodologies.

  7. †Kenyaichthyidae fam. nov. and †Kenyaichthys gen. nov. - First Record of a Fossil Aplocheiloid Killifish (Teleostei, Cyprinodontiformes).

    PubMed

    Altner, Melanie; Reichenbacher, Bettina

    2015-01-01

    The extant Cyprinodontiformes (killifishes) with their two suborders Cyprinodontoidei and Aplocheiloidei represent a diverse and well-studied group of fishes. However, their fossil record is comparatively sparse and has so far yielded members of the Cyprinodontoidei only. Here we report on cyprinodontiform fossils from the upper Miocene Lukeino Formation in the Tugen Hills of the Central Rift Valley of Kenya, which represent the first fossil record of an aplocheiloid killifish. A total of 169 specimens - mostly extraordinarily well preserved - and a sample of ten extant cyprinodontiform species were studied on the basis of morphometrics, meristics and osteology. A phylogenetic analysis using PAUP was also conducted for the fossils. Both the osteological data and the phylogenetic analysis provide strong evidence for the assignment of the fossils to the Aplocheiloidei, and justify the definition of the new family †Kenyaichthyidae, the new genus †Kenyaichthys and the new species †K. kipkechi sp. nov. The phylogenetic analysis unexpectedly places †Kenyaichthys gen. nov. in a sister relationship to the Rivulidae (a purely Neotropical group), a probable explanation might be lack of available synapomorphies for the Rivulidae, Nothobranchiidae and Aplocheilidae. The specimens of †K. kipkechi sp. nov. show several polymorphic characters and large overlap in meristic traits, which justifies their interpretation as a species flock in statu nascendi. Patterns of variation in neural and haemal spine dimensions in the caudal vertebrae of †Kenyaichthys gen. nov. and the extant species studied indicate that some previously suggested synapomorphies of the Cyprinodontoidei and Aplocheiloidei need to be revised.

  8. Late Cretaceous Extreme Polar Warmth recorded by Vertebrate Fossils from the High Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Vandermark, D.; Tarduno, J. A.; Brinkman, D.

    2006-12-01

    A vertebrate fossil assemblage from Late Cretaceous (Coniacian-Turonian, ~92 to 86 Ma) rocks on Axel Heiberg Island in the High Canadian Arctic reflects what was once a diverse community of freshwater fishes and reptiles. Paleomagnetic data indicate a paleolatitude of ~71° N for the site; the fossils are from non-migratory fauna, so they can provide insight into Late Cretaceous polar climate. The fossil assemblage includes large (> 2.4 m long) champsosaurs (extinct crocodilelike reptiles). The presence of large champsosaurs suggests a mean annual temperature > 14 °C (and perhaps as great as 25 °C). Here we summarize findings and analyses following the discovery of the fossil-bearing strata in 1996. Examination of larger fish elements, isolated teeth and SEM studies of microstructures indicates the presence of lepisosteids, amiids and teleosts (Friedman et al., 2003) Interestingly, the only other known occurrence of amiids and lepisosteids, fossil or recent, are from intervals of extreme warmth during the Tertiary. Turtles present in the assemblage include Boreralochelys axelheibergensis, a generically indeterminate eucryptodire and a trioychid (Brinkman and Tarduno, 2005). The level of turtle diversity is also comparable to mid-latitude assemblages with a mean annual paleotemperature of at least 14 °C. A large portion of the champsosaur fossil assemblage is comprised of elements from subadults. This dominance of subadults is similar to that seen from low latitude sites. Because of the sensitivity of juveniles to ice formation, the make-up of the Arctic champsosaur population further indicates that the Late Cretaceous saw an interval of extreme warmth and low seasonality. We note the temporal coincidence of these fossils with volcanism at large igneous provinces (including high Arctic volcanism) and suggest that a pulse in volcanic carbon dioxide emissions helped cause the global warmth.

  9. Molecular and isotopic composition of lipids in modern and fossil bivalve shells: Records of paleoenvironmental change?

    SciTech Connect

    CoBabe, E.A.

    1995-12-31

    Suites of lipids residing in situ in modern and fossil bivalve shells offer new possibilities for the study of paleoecology and paleoclimatology. Distributions of carbon isotopic compositions of modem shell lipids suggests that many of these compounds, including alkanes, sterols, fatty acids, ketones and phytadienes, are derived from the bivalves and not directly from the surrounding environment. The occurrence of fatty acids in modem and fossil shell material opens up the possibility that saturation levels of these compounds may be used as paleothermometers. To date, the utility of fatty acids in paleoclimate studies has been limited because of the swift breakdown of these compounds in sediment. However, initial results indicate that fatty acids in bivalve shells retain their original structure for at least several million years. Comparison of modem bivalve shell fatty acids from tropical, temperate and polar nearshore marine systems will be presented, along with analogous fossil data.

  10. Ghost shrimp Calliax de Saint Laurent, 1973 (Decapoda: Axiidea: Callianassidae) in the fossil record: systematics, palaeoecology and palaeobiogeography

    PubMed Central

    HYŽNÝ, MATÚŠ; GAŠPARIČ, ROK

    2015-01-01

    Ghost shrimps of the family Callianassidae are very common in the fossil record, but mostly as isolated cheliped elements only. The assignment to biologically defined genera, diagnosed on the basis of soft part morphology, is thus rather difficult. In this respect, proxy characters present on chelipeds that are the most durable ghost shrimp remains are needed to ascribe fossil material to extant genera. The genus Calliax de Saint Laurent, 1973 has been particularly obscure in this respect. Thorough comparison of extant members of the genus resulted in evaluation of characters present on chelipeds being taxonomically important on the genus level, specifically: 1) rectangular major P1 propodus with two ridges on the base of the fixed finger extending onto manus; 2) major P1 fingers relatively short; and 3) minor P1 chela with dactylus longer than fixed finger and possessing a wide gap between fingers. On this basis, Callianassa michelottii A. Milne Edwards, 1860, from the Oligocene and Miocene of Europe is herein reassigned to Calliax. Further re-examination of the ghost shrimp fossil record revealed that C. szobensis Müller, 1984, from the Middle Miocene of Hungary represents the same animal as C. michelottii and they are synomymised herein. The known geographic distribution of C. michelottii is expanded by the first confirmed occurrence of the species in Slovakia. All occurrences of C. michelottii known to date are reviewed and documented. The presence of Calliax michelottii comb. nov. may be considered an indicator of deeper marine settings. Based on the scarce fossil record known to date, Calliax has a Tethyan origin; it supposedly migrated westward to establish present day communities in the Caribbean sometime before the Middle Miocene. PMID:24989725

  11. Ghost shrimp Calliax de Saint Laurent, 1973 (Decapoda: Axiidea: Callianassidae) in the fossil record: systematics, palaeoecology and palaeobiogeography.

    PubMed

    Hyžný, Matúš; Gašparič, Rok

    2014-06-19

    Ghost shrimps of the family Callianassidae are very common in the fossil record, but mostly as isolated cheliped elements only. The assignment to biologically defined genera, diagnosed on the basis of soft part morphology, is thus rather difficult. In this respect, proxy characters present on chelipeds that are the most durable ghost shrimp remains are needed to ascribe fossil material to extant genera. The genus Calliax de Saint Laurent, 1973 has been particularly obscure in this respect. Thorough comparison of extant members of the genus resulted in evaluation of characters present on chelipeds being taxonomically important on the genus level, specifically: 1) rectangular major P1 propodus with two ridges on the base of the fixed finger extending onto manus; 2) major P1 fingers relatively short; and 3) minor P1 chela with dactylus longer than fixed finger and possessing a wide gap between fingers. On this basis, Callianassa michelottii A. Milne Edwards, 1860, from the Oligocene and Miocene of Europe is herein reassigned to Calliax. Further re-examination of the ghost shrimp fossil record revealed that C. szobensis Müller, 1984, from the Middle Miocene of Hungary represents the same animal as C. michelottii and they are synomymised herein. The known geographic distribution of C. michelottii is expanded by the first confirmed occurrence of the species in Slovakia. All occurrences of C. michelottii known to date are reviewed and documented. The presence of Calliax michelottii comb. nov. may be considered an indicator of deeper marine settings. Based on the scarce fossil record known to date, Calliax has a Tethyan origin; it supposedly migrated westward to establish present day communities in the Caribbean sometime before the Middle Miocene.

  12. Calcium-phosphate biomineralization induced by alkaline phosphatase activity in Escherichia coli: localization, kinetics and potential signatures in the fossil record

    NASA Astrophysics Data System (ADS)

    Cosmidis, Julie; Benzerara, Karim; Guyot, François; Skouri-Panet, Fériel; Duprat, Elodie; Férard, Céline; Guigner, Jean-Michel; Babonneau, Florence; Coelho, Cristina

    2015-12-01

    Bacteria are thought to play an important role in the formation of calcium-phosphate minerals composing marine phosphorites, as supported by the common occurrence of fossil microbes in these rocks. Phosphatase enzymes may play a key role in this process. Indeed, they may increase the supersaturation with respect to Ca-phosphates by releasing orthophosphate ions following hydrolysis of organic phosphorus. However, several questions remain unanswered about the cellular-level mechanisms involved in this model, and its potential signatures in the mineral products. We studied Ca-phosphate precipitation by different strains of Escherichia coli which were genetically modified to differ in the abundance and cellular localization of the alkaline phosphatase (PHO A) produced. The mineral precipitated by either E. coli or purified PHO A was invariably identified as a carbonate-free non-stoichiometric hydroxyapatite. However, the bacterial precipitates could be discriminated from the ones formed by purified PHO A at the nano-scale. PHO A localization was shown to influence the pattern of Ca-phosphate nucleation and growth. Finally, the rate of calcification was proved to be consistent with the PHO A enzyme kinetics. Overall, this study provides mechanistic keys to better understand phosphogenesis in the environment, and experimental references to better interpret the microbial fossil record in phosphorites.

  13. Exceptionally preserved North American Paleogene metatherians: adaptations and discovery of a major gap in the opossum fossil record.

    PubMed

    Sánchez-Villagra, Marcelo; Ladevèze, Sandrine; Horovitz, Inés; Argot, Christine; Hooker, Jeremy J; Macrini, Thomas E; Martin, Thomas; Moore-Fay, Scott; de Muizon, Christian; Schmelzle, Thomas; Asher, Robert J

    2007-06-22

    A major gap in our knowledge of the evolution of marsupial mammals concerns the Paleogene of the northern continents, a critical time and place to link the early history of metatherians in Asia and North America with the more recent diversification in South America and Australia. We studied new exceptionally well-preserved partial skeletons of the Early Oligocene fossil Herpetotherium from the White River Formation in Wyoming, which allowed us to test the relationships of this taxon and examine its adaptations. Herpetotheriidae, with a fossil record extending from the Cretaceous to the Miocene, has traditionally been allied with opossums (Didelphidae) based on fragmentary material, mainly dentitions. Analysis of the new material reveals that several aspects of the cranial and postcranial anatomy, some of which suggests a terrestrial lifestyle, distinguish Herpetotherium from opossums. We found that Herpetotherium is the sister group to the crown group Marsupialia and is not a stem didelphid. Combination of the new palaeontological data with molecular divergence estimates, suggests the presence of a long undocumented gap in the fossil record of opossums extending some 45Myr from the Early Miocene to the Cretaceous.

  14. A first record of Cretaceous aphids (Hemiptera, Sternorrhyncha, Aphidomorpha) in Australia, from the Lower Cretaceous Koonwarra Fossil Bed, Victoria.

    PubMed

    Martin, Sarah K; Skidmore, Luke I; Stilwell, Jeffrey D

    2016-07-08

    This paper describes the first species of aphid from the Lower Cretaceous Koonwarra Fossil Bed of the Gippsland Basin, southeastern Victoria, Australia. This aphid, herein named Koonwarraphis rotundafrons gen. & sp. nov., is assigned to the cosmopolitan Cretaceous superfamily Tajmyraphidoidea, which has been previously described from the Lebanese, Taimyrian, Canadian, Myanmar (Burmese), and Spanish ambers. Koonwarraphis rotundafrons is the first aphid recorded from the eastern Gondwanan landmass during the Cretaceous, and represents the only tajmyraphidoid preserved as a compression fossil, rather than as an amber inclusion. Due to the nature of the fossil's preservation, Koonwarraphis cannot be firmly placed in any of the described tajmyraphidoid families; however, all observable morphological features suggest that the genus is broadly typical of the superfamily and Cretaceous aphids in general. Koonwarraphis' shortened rostrum, a feature also seen in other tajmyraphidoids, suggests an association with the more herbaceous aspects of the Early Cretaceous Victorian flora. Considering the modern aphid preference for angiosperm plants, it is possible that this aphid was living upon the herbaceous early angiosperms recorded previously from the Koonwarra macrofloral assemblage.

  15. The First Occurrence in the Fossil Record of an Aquatic Avian Twig-Nest with Phoenicopteriformes Eggs: Evolutionary Implications

    PubMed Central

    Grellet-Tinner, Gerald; Murelaga, Xabier; Larrasoaña, Juan C.; Silveira, Luis F.; Olivares, Maitane; Ortega, Luis A.; Trimby, Patrick W.; Pascual, Ana

    2012-01-01

    Background We describe the first occurrence in the fossil record of an aquatic avian twig-nest with five eggs in situ (Early Miocene Tudela Formation, Ebro Basin, Spain). Extensive outcrops of this formation reveal autochthonous avian osteological and oological fossils that represent a single taxon identified as a basal phoenicopterid. Although the eggshell structure is definitively phoenicopterid, the characteristics of both the nest and the eggs are similar to those of modern grebes. These observations allow us to address the origin of the disparities between the sister taxa Podicipedidae and Phoenicopteridae crown clades, and traces the evolution of the nesting and reproductive environments for phoenicopteriforms. Methodology/Principal Findings Multi-disciplinary analyses performed on fossilized vegetation and eggshells from the eggs in the nest and its embedding sediments indicate that this new phoenicopterid thrived under a semi-arid climate in an oligohaline (seasonally mesohaline) shallow endorheic lacustine environment. High-end microcharacterizations including SEM, TEM, and EBSD techniques were pivotal to identifying these phoenicopterid eggshells. Anatomical comparisons of the fossil bones with those of Phoenicopteriformes and Podicipediformes crown clades and extinct palaelodids confirm that this avian fossil assemblage belongs to a new and basal phoenicopterid. Conclusions/Significance Although the Podicipediformes-Phoenicopteriformes sister group relationship is now well supported, flamingos and grebes exhibit feeding, reproductive, and nesting strategies that diverge significantly. Our multi-disciplinary study is the first to reveal that the phoenicopteriform reproductive behaviour, nesting ecology and nest characteristics derived from grebe-like type strategies to reach the extremely specialized conditions observed in modern flamingo crown groups. Furthermore, our study enables us to map ecological and reproductive characters on the

  16. Deep-sea foraging behavior: its bathymetric potential in the fossil record.

    PubMed

    Kitchell, J A; Kitchell, J F; Clark, D L; Dangeard, L

    1978-06-16

    Spiral and meander foraging traces in the deep sea are not distributed in proportion to assumed food availability. Data collected by means of deep-sea photography failed to reveal a bathymetric gradient in behavioral complexity or sensitivity. The foraging paradigm developed by numerous trace fossil studies does not adequately predict the modern environment.

  17. New records and species of Crepidodera Chevrolat (Coleoptera: Chrysomelidae) in Eocene European amber, with a brief review of described fossil beetles from Bitterfeld amber.

    PubMed

    Bukejs, Andris; Biondi, Maurizio; Alekseev, Vitalii I

    2016-11-15

    Based on six relatively well-preserved specimens from Eocene Baltic amber, Crepidodera tertiotertiaria sp. nov. is described. The new species is illustrated and compared with morphologically similar extant and fossil relatives. It is the third described fossil species of Crepidodera Chevrolat. In addition to the new taxon, new fossil records of C. decolorata Nadein & Perkovsky from Baltic and Bitterfeld amber are presented. A key to species of Crepidodera described from fossil resins is provided, and a checklist of Coleoptera described from Bitterfeld amber is compiled.

  18. High-Resolution pCO2 Record for the Cenomanian-Turonian OAE2 based on Fossil Plant Cuticle

    NASA Astrophysics Data System (ADS)

    Barclay, R. S.; Sageman, B. B.; McElwain, J. C.

    2008-12-01

    The Cenomanian-Turonian oceanic anoxic event 2 (OAE2) represents a major perturbation to the ocean- atmosphere-terrestrial system that lasted at least 600 ka. Marine extinction associated with OAE2 is thought to have occurred due to global marine anoxia, and increased primary production is the likely driver. However, the causal factors leading to increased production have remained poorly resolved. Recent research indicates that a pulse of submarine volcanism occurred in association with OAE2, and it has been suggested that this event led to overturn of the stratified ocean, possibly bringing P-rich deep waters to the surface. 208/204Pbinitial ratios taken from the Bonarelli horizon suggest that CO2 expelled by the volcanic event may have come from the Caribbean LIP. This is supported by a rapid negative shift in both 186/187Os and 87/86Sr isotopes just prior to OAE2, suggesting a marine source for the CO2 pulse. Some prior studies suggested that OAE2 resulted in a major drawdown of high ambient pCO2 levels. Only recently has a volcanic-sourced CO2 pulse been suggested for the event and its implications have yet to be fully explored. Two previous studies attempted to reconstruct pCO2 levels through OAE2 using geochemical proxy methods. Both studies show a decline in pCO2 at the onset of the δ13C excursion, but with decreases ranging from 140 to at least 400ppmV. Since neither study extended analyses to the interval preceding onset of the δ13C excursion it is difficult to assess the longer term trend. In addition, marine-based proxy methods contain large uncertainties that may be avoided in a non-marine proxy of pCO2, such as the stomatal frequency record of fossil plant cuticles. The stomatal based paleo-CO2 proxy relies on a genetically controlled inverse relationship between pCO2 and stomatal frequency in terrestrial plant leaves. Abundant plant cuticle is preserved in the paralic sections of the Dakota SS in SW Utah, which has been correlated to the Cenomanian

  19. Phylogeography of Douglas-fir based on mitochondrial and chloroplast DNA sequences: testing hypotheses from the fossil record.

    PubMed

    Gugger, Paul F; Sugita, Shinya; Cavender-Bares, Jeannine

    2010-05-01

    The integration of fossil and molecular data can provide a synthetic understanding of the ecological and evolutionary history of an organism. We analysed range-wide maternally inherited mitochondrial DNA and paternally inherited chloroplast DNA sequence data with coalescent simulations and traditional population genetic methods to test hypotheses of population divergence generated from the fossil record of Douglas-fir (Pseudotsuga menziesii), an ecologically and economically important western North American conifer. Specifically, we tested (i) the hypothesis that the Pliocene orogeny of the Cascades and Sierra Nevada caused the divergence of coastal and Rocky Mountain Douglas-fir varieties; and (ii) the hypothesis that multiple glacial refugia existed on the coast and in the Rocky Mountains. We found that Douglas-fir varieties diverged about 2.11 Ma (4.37 Ma-755 ka), which could be consistent with a Pliocene divergence. Rocky Mountain Douglas-fir probably resided in three or more glacial refugia. More variable molecular markers would be required to detect the two coastal refugia suggested in the fossil record. Comparison of mitochondrial DNA and chloroplast DNA variation revealed that gene flow via pollen linked populations isolated from seed exchange. Postglacial colonization of Canada from coastal and Rocky Mountain refugia near the ice margin at the Last Glacial Maximum produced a wide hybrid zone among varieties that formed almost exclusively by pollen exchange and chloroplast DNA introgression, not seed exchange. Postglacial migration rates were 50-165 m/year, insufficient to track projected 21st century warming in some regions. Although fossil and genetic data largely agree, each provides unique insights.

  20. The consequences of time averaging for measuring temporal species turnover in the fossil record

    NASA Astrophysics Data System (ADS)

    Tomašových, Adam; Kidwell, Susan

    2010-05-01

    Modeling time averaging effects with simple simulations allows us to evaluate the magnitude of change in temporal species turnover that is expected to occur in long (paleoecological) time series with fossil assemblages. Distinguishing different modes of metacommunity dynamics (such as neutral, density-dependent, or trade-off dynamics) with time-averaged fossil assemblages requires scaling-up time-averaging effects because the decrease in temporal resolution and the decrease in temporal inter-sample separation (i.e., the two main effects of time averaging) substantially increase community stability relative to assemblages without or with weak time averaging. Large changes in temporal scale that cover centuries to millennia can lead to unprecedented effects on temporal rate of change in species composition. Temporal variation in species composition monotonically decreases with increasing duration of time-averaging in simulated fossil assemblages. Time averaging is also associated with the reduction of species dominance owing to the temporal switching in the identity of dominant species. High degrees of time averaging can cause that community parameters of local fossil assemblages converge to parameters of metacommunity rather that to parameters of individual local non-averaged communities. We find that the low variation in species composition observed among mollusk and ostracod subfossil assemblages can be explained by time averaging alone, and low temporal resolution and reduced temporal separation among assemblages in time series can thus explain a substantial part of the reduced variation in species composition relative to unscaled predictions of neutral model (i.e., species do not differ in birth, death, and immigration rates on per capita basis). The structure of time-averaged assemblages can thus provide important insights into processes that act over larger temporal scales, such as evolution of niches and dispersal, range-limit dynamics, taxon cycles, and

  1. Cercopithecoid humeri from Taung support the distinction of major papionin clades in the South African fossil record.

    PubMed

    Gilbert, Christopher C; Takahashi, Maressa Q; Delson, Eric

    2016-01-01

    Associated cercopithecoid postcrania are rare in the Plio-Pleistocene fossil record, particularly in the case of South African karst cave sites. However, as clear postcranial differences between major papionin clades have been documented, it should be possible to assign isolated papionin postcrania to the Cercocebus/Mandrillus and Papio/Lophocebus/Theropithecus groups wherever sufficient anatomy is preserved. Here, we demonstrate that two partial humeri preserved at Taung, UCMP 56693 and UCMP 125898, are most likely attributable to the Cercocebus/Mandrillus and Papio/Lophocebus/Theropithecus clades, respectively. Univariate analyses (ANOVAs and t-tests) and multivariate analyses (discriminant function analyses) of humeral features, combined with a phylogenetic analysis of 24 humeral characters, all support our assessment. Given that the overwhelming number of craniodental specimens at Taung are attributable to two papionin taxa, Procercocebus antiquus (a member of the Cercocebus/Mandrillus clade) and Papio izodi (a purported fossil species of the modern genus Papio), we assign UCMP 56693 to Pr. antiquus and UCMP 125868 to P. izodi with a high degree of confidence. Implications for cercopithecoid evolution and biogeography are discussed, with a particular emphasis on these two fossil taxa.

  2. El Niño during the Last Interglacial Period recorded by a fossil coral from Indonesia

    NASA Astrophysics Data System (ADS)

    Hughen, Konrad A.; Schrag, Daniel P.; Jacobsen, Stein B.; Hantoro, Wahyoe

    Measurements of oxygen isotopes and elemental ratios in a fossil coral that grew 124,000 years ago in North Sulawesi, Indonesia, reflect interannual variability in precipitation and sea surface temperature (SST) due to the El Niño/Southern Oscillation (ENSO). This indicates that ENSO was robust during the last interglacial period, a time when global climate was slightly warmer than the present. The pattern of ENSO frequency behavior in the past is similar to variability in modern instrumental records, but distinct from the most recent period since the mid-1970s, supporting the hypothesis that ENSO behavior in recent decades is anomalous with respect to natural variability.

  3. A Fossil DNA Based High Resolution Record of Holocene Planktonic Taxa and Environmental Change in the Black Sea

    NASA Astrophysics Data System (ADS)

    Coolen, M. J.; Saenz, J. P.; Trowbridge, N.; Eglinton, T.

    2007-12-01

    A standard approach to study past planktonic taxa which carry information about past environments and climate variability is the microscopic determination and enumeration of microfossils. However, most planktonic taxa are soft-bodied and in cases where microfossils are absent or difficult to identify, chemical fossils (lipid biomarkers) can be used as paleoecological tools. Nevertheless, most lipids are not very specific, multiple sources are possible, or their biological source remains unknown. Recently, we and others have shown that under excellent preservation conditions, the analysis of preserved genetic signatures (fossil DNA) offers great potential to study past planktonic communities, including soft-bodied species, at the unprecedented species- and even strain-level (this work). Given the dramatic shifts in hydrography and the present anoxia that permeates most of the water column which promotes preservation of cellular materials, the Black Sea is an excellent setting to study the ancient species composition based on fossil DNA. We developed a high temporal resolution (50-100 yr) fossil DNA and lipid biomarker based stratigraphic record of planktonic community structure in the Black Sea spanning the complete Holocene development from the first post-glacial input of Mediterranean waters in the paleo-lacustrine Black Sea to the present. Preserved genetic markers for microbial communities dwelling at the surface (algal primary producers and zooplankton), the suboxic layer (marine Crenarchaeota), and the sulfidic chemocline (green sulfur bacteria) were targeted to provide information on past environmental change in the Black Sea. Specifically, we targeted markers that contributed to our understanding of past surface water temperature, salinity and stratification. Where possible, a side-by-side phylogenetic and lipid biomarker analyses was performed in order to carefully assess the validity of utilizing the former as proxies of a given biological input. As the

  4. Individual to community-level faunal responses to environmental change from a marine fossil record of Early Miocene global warming.

    PubMed

    Belanger, Christina L

    2012-01-01

    Modern climate change has a strong potential to shift earth systems and biological communities into novel states that have no present-day analog, leaving ecologists with no observational basis to predict the likely biotic effects. Fossil records contain long time-series of past environmental changes outside the range of modern observation, which are vital for predicting future ecological responses, and are capable of (a) providing detailed information on rates of ecological change, (b) illuminating the environmental drivers of those changes, and (c) recording the effects of environmental change on individual physiological rates. Outcrops of Early Miocene Newport Member of the Astoria Formation (Oregon) provide one such time series. This record of benthic foraminiferal and molluscan community change from continental shelf depths spans a past interval environmental change (≈ 20.3-16.7 mya) during which the region warmed 2.1-4.5°C, surface productivity and benthic organic carbon flux increased, and benthic oxygenation decreased, perhaps driven by intensified upwelling as on the modern Oregon coast. The Newport Member record shows that (a) ecological responses to natural environmental change can be abrupt, (b) productivity can be the primary driver of faunal change during global warming, (c) molluscs had a threshold response to productivity change while foraminifera changed gradually, and (d) changes in bivalve body size and growth rates parallel changes in taxonomic composition at the community level, indicating that, either directly or indirectly through some other biological parameter, the physiological tolerances of species do influence community change. Ecological studies in modern and fossil records that consider multiple ecological levels, environmental parameters, and taxonomic groups can provide critical information for predicting future ecological change and evaluating species vulnerability.

  5. Individual to Community-Level Faunal Responses to Environmental Change from a Marine Fossil Record of Early Miocene Global Warming

    PubMed Central

    Belanger, Christina L.

    2012-01-01

    Modern climate change has a strong potential to shift earth systems and biological communities into novel states that have no present-day analog, leaving ecologists with no observational basis to predict the likely biotic effects. Fossil records contain long time-series of past environmental changes outside the range of modern observation, which are vital for predicting future ecological responses, and are capable of (a) providing detailed information on rates of ecological change, (b) illuminating the environmental drivers of those changes, and (c) recording the effects of environmental change on individual physiological rates. Outcrops of Early Miocene Newport Member of the Astoria Formation (Oregon) provide one such time series. This record of benthic foraminiferal and molluscan community change from continental shelf depths spans a past interval environmental change (∼20.3-16.7 mya) during which the region warmed 2.1–4.5°C, surface productivity and benthic organic carbon flux increased, and benthic oxygenation decreased, perhaps driven by intensified upwelling as on the modern Oregon coast. The Newport Member record shows that (a) ecological responses to natural environmental change can be abrupt, (b) productivity can be the primary driver of faunal change during global warming, (c) molluscs had a threshold response to productivity change while foraminifera changed gradually, and (d) changes in bivalve body size and growth rates parallel changes in taxonomic composition at the community level, indicating that, either directly or indirectly through some other biological parameter, the physiological tolerances of species do influence community change. Ecological studies in modern and fossil records that consider multiple ecological levels, environmental parameters, and taxonomic groups can provide critical information for predicting future ecological change and evaluating species vulnerability. PMID:22558424

  6. Vegetation response to climate change in Alaska: examples from the fossil record

    USGS Publications Warehouse

    Ager, Thomas A.

    2007-01-01

    Preface: This report was presented as an invited paper at the Fish & Wildlife Service Climate Forum held in Anchorage, Alaska on February 21-23, 2007. The purpose of the talk was to provide some examples of past climate changes that appear to have caused significant responses in Alaskan vegetation. These examples are based on interpretations of dated fossil assemblages (pollen, spores and plant macrofossils) collected and interpreted by U.S. Geological Survey and collaborating scientists from other scientific organizations during the past several decades.

  7. Leaf fossil record suggests limited influence of atmospheric CO2 on terrestrial productivity prior to angiosperm evolution

    PubMed Central

    Boyce, C. Kevin; Zwieniecki, Maciej A.

    2012-01-01

    Declining CO2 over the Cretaceous has been suggested as an evolutionary driver of the high leaf vein densities (7–28 mm mm−2) that are unique to the angiosperms throughout all of Earth history. Photosynthetic modeling indicated the link between high vein density and productivity documented in the modern low-CO2 regime would be lost as CO2 concentrations increased but also implied that plants with very low vein densities (less than 3 mm mm−2) should experience substantial disadvantages with high CO2. Thus, the hypothesized relationship between CO2 and plant evolution can be tested through analysis of the concurrent histories of alternative lineages, because an extrinsic driver like atmospheric CO2 should affect all plants and not just the flowering plants. No such relationship is seen. Regardless of CO2 concentrations, low vein densities are equally common among nonangiosperms throughout history and common enough to include forest canopies and not just obligate shade species that will always be of limited productivity. Modeling results can be reconciled with the fossil record if maximum assimilation rates of nonflowering plants are capped well below those of flowering plants, capturing biochemical and physiological differences that would be consistent with extant plants but previously unrecognized in the fossil record. Although previous photosynthetic modeling suggested that productivity would double or triple with each Phanerozoic transition from low to high CO2, productivity changes are likely to have been limited before a substantial increase accompanying the evolution of flowering plants. PMID:22689947

  8. Phylogenomic Dating-A Method of Constraining the Age of Microbial Taxa That Lack a Conventional Fossil Record

    NASA Astrophysics Data System (ADS)

    Blank, Carrine E.

    2009-03-01

    A phylogenomic dating approach was used to identify potential age constraints for multiple archaeal groups, many of which have no fossil, isotopic, or biomarker record. First, well-resolved phylogenetic trees were inferred with the use of multiple gene sequences obtained from whole genome sequences. Next, the ability to use oxygen as a terminal electron acceptor was coded into characters, and ancestral state reconstruction was used to identify clades with taxa that metabolize oxygen and likely had an aerobic ancestor. Next, the habitat of the ancestor was inferred. If the local presence of Cyanobacteria could be excluded from the putative ancestral habitat, then these clades would have originated after the rise in atmospheric oxygen 2.32 Ga. With this method, an upper age of 2.32 Ga (an "oxygen age constraint") is proposed for four major archaeal clades: the Sulfolobales, Thermoplasmatales, Thermoproteus neutrophilus/Pyrobaculum spp., and the Thermoproteales. It was also shown that the halophilic archaea likely had an aerobic common ancestor, yet the possibility of local oxygen oases before oxygenation of the atmosphere could not be formally rejected. Thus, an oxygen age constraint was not assessed for this group. This work suggests that many archaeal groups are not as ancient as many in the research community have previously assumed, and it provides a new method for establishing upper age constraints for major microbial groups that lack a conventional fossil record.

  9. Revisiting the origin and diversification of vascular plants through a comprehensive Bayesian analysis of the fossil record.

    PubMed

    Silvestro, Daniele; Cascales-Miñana, Borja; Bacon, Christine D; Antonelli, Alexandre

    2015-07-01

    Plants have a long evolutionary history, during which mass extinction events dramatically affected Earth's ecosystems and its biodiversity. The fossil record can shed light on the diversification dynamics of plant life and reveal how changes in the origination-extinction balance have contributed to shaping the current flora. We use a novel Bayesian approach to estimate origination and extinction rates in plants throughout their history. We focus on the effect of the 'Big Five' mass extinctions and on estimating the timing of origin of vascular plants, seed plants and angiosperms. Our analyses show that plant diversification is characterized by several shifts in origination and extinction rates, often matching the most important geological boundaries. The estimated origin of major plant clades predates the oldest macrofossils when considering the uncertainties associated with the fossil record and the preservation process. Our findings show that the commonly recognized mass extinctions have affected each plant group differently and that phases of high extinction often coincided with major floral turnovers. For instance, after the Cretaceous-Paleogene boundary we infer negligible shifts in diversification of nonflowering seed plants, but find significantly decreased extinction in spore-bearing plants and increased origination rates in angiosperms, contributing to their current ecological and evolutionary dominance.

  10. Late glacial climate estimates for southern Nevada: The ostracode fossil record

    SciTech Connect

    Forester, R.M.; Smith, A.J.

    1995-10-01

    Climate change plays an important role in determining as possible long term hydrological performance of the potential high level nuclear waste repository within Yucca Mountain, Nevada. Present-day global circulation results in this region having an arid to semi-arid climate characterized by hot and relatively dry summers. Global circulation during the late glacial (about 14 to 20 ka) was very different from the present-day. Preliminary study of late-glacial fossil ostracodes from {open_quotes}marsh deposits{close_quotes} in the upper Las Vegas Valley suggests mean annual precipitation may have been four times higher, while mean annual temperature may have been about 10{degrees}C cooler than today. A major difference between present-day and late-glacial climate was likely the existence of cooler, cloudier, and wetter summers in the past.

  11. High-resolution leaf-fossil record spanning the Cretaceous/Tertiary boundary

    USGS Publications Warehouse

    Johnson, K.R.; Nichols, D.J.; Attrep, M.; Orth, C.J.

    1989-01-01

    THEORIES that explain the extinctions characterizing the Cretaceous/Tertiary (K/T) boundary1-3 need to be tested by analyses of thoroughly sampled biotas. Palynological studies are the primary means for stratigraphic placement of the terrestrial boundary and for estimates of plant extinction4-12, but have not been combined with quantitative analyses of fossil leaves (megaflora). Megafloral studies complement palynology by representing local floras with assemblages capable of high taxonomic resolution13, but have previously lacked the sample size and stratigraphic spacing needed to resolve latest Cretaceous floral history5,14-18. We have now combined megafloral data from a 100-m-thick composite K/T boundary section in North Dakota with detailed palynological analysis. Here the boundary is marked by a 30% palynofloral extinction coincident with iridium and shocked-mineral anomalies and lies ???2 m above the highest dinosaur remains. The megaflora undergoes a 79% turnover across the boundary, and smaller changes 17- and 25-m below it. This pattern is consistent with latest Cretaceous climatic warming preceding a bolide impact. ?? 1989 Nature Publishing Group.

  12. Was Australopithecus anamensis ancestral to A. afarensis? A case of anagenesis in the hominin fossil record.

    PubMed

    Kimbel, William H; Lockwood, Charles A; Ward, Carol V; Leakey, Meave G; Rak, Yoel; Johanson, Donald C

    2006-08-01

    We tested the hypothesis that early Pliocene Australopithecus anamensis was ancestral to A. afarensis by conducting a phylogenetic analysis of four temporally successive fossil samples assigned to these species (from earliest to latest: Kanapoi, Allia Bay, Laetoli, Hadar) using polarized character-state data from 20 morphological characters of the dentition and jaws. If the hypothesis that A. anamensis is ancestral to A. afarensis is true, then character-state changes between the temporally ordered site-samples should be congruent with hypothesized polarity transformations based on outgroup (African great ape) conditions. The most parsimonious reconstruction of character-state evolution suggests that each of the hominin OTUs shares apomorphies only with geologically younger OTUs, as predicted by the hypothesis of ancestry (tree length=31; Consistency Index=0.903). This concordance of stratigraphic and character-state data supports the idea that the A. anamensis and A. afarensis samples represent parts of an anagenetically evolving lineage, or evolutionary species. Each site-sample appears to capture a different point along this evolutionary trajectory. We discuss the implications of this conclusion for the taxonomy and adaptive evolution of these early-middle Pliocene hominins.

  13. Fossil pollen records indicate that Patagonian desertification was not solely a consequence of Andean uplift.

    PubMed

    Palazzesi, L; Barreda, V D; Cuitiño, J I; Guler, M V; Tellería, M C; Ventura Santos, R

    2014-03-28

    The Patagonian steppe-a massive rain-shadow on the lee side of the southern Andes-is assumed to have evolved ~15-12 Myr as a consequence of the southern Andean uplift. However, fossil evidence supporting this assumption is limited. Here we quantitatively estimate climatic conditions and plant richness for the interval ~10-6 Myr based on the study and bioclimatic analysis of terrestrially derived spore-pollen assemblages preserved in well-constrained Patagonian marine deposits. Our analyses indicate a mesothermal climate, with mean temperatures of the coldest quarter between 11.4 °C and 16.9 °C (presently ~3.5 °C) and annual precipitation rarely below 661 mm (presently ~200 mm). Rarefied richness reveals a significantly more diverse flora during the late Miocene than today at the same latitude but comparable with that approximately 2,000 km further northeast at mid-latitudes on the Brazilian coast. We infer that the Patagonian desertification was not solely a consequence of the Andean uplift as previously insinuated.

  14. Fossil Horses

    NASA Astrophysics Data System (ADS)

    MacFadden, Bruce J.

    1994-06-01

    The family Equidae have an extensive fossil record spanning the past 58 million years, and the evolution of the horse has frequently been used as a classic example of long-term evolution. In recent years, however, there have been many important discoveries of fossil horses, and these, in conjunction with such new methods as cladistics, and techniques such as precise geochronology, have allowed us to achieve a much greater understanding of the evolution and biology of this important group. This book synthesizes the large body of data and research relevant to an understanding of fossil horses from several disciplines including biology, geology and paleontology. Using horses as the central theme, the author weaves together in the text such topics as modern geochronology, paleobiogeography, climate change, evolution and extinction, functional morphology, and population biology during the Cenozoic period. This book will be exciting reading for researchers and graduate students in vertebrate paleontology, evolution, and zoology.

  15. Trace fossils and substrates of the terminal Proterozoic-Cambrian transition: implications for the record of early bilaterians and sediment mixing.

    PubMed

    Droser, Mary L; Jensen, Sören; Gehling, James G

    2002-10-01

    The trace fossil record is important in determining the timing of the appearance of bilaterian animals. A conservative estimate puts this time at approximately equal 555 million years ago. The preservational potential of traces made close to the sediment-water interface is crucial to detecting early benthic activity. Our studies on earliest Cambrian sediments suggest that shallow tiers were preserved to a greater extent than typical for most of the Phanerozoic, which can be attributed both directly and indirectly to the low levels of sediment mixing. The low levels of sediment mixing meant that thin event beds were preserved. The shallow depth of sediment mixing also meant that muddy sediments were firm close to the sediment-water interface, increasing the likelihood of recording shallow-tier trace fossils in muddy sediments. Overall, trace fossils can provide a sound record of the onset of bilaterian benthic activity.

  16. THE VERY FAINT END OF THE UV LUMINOSITY FUNCTION OVER COSMIC TIME: CONSTRAINTS FROM THE LOCAL GROUP FOSSIL RECORD

    SciTech Connect

    Weisz, Daniel R.; Johnson, Benjamin D.; Conroy, Charlie

    2014-10-10

    We present a new technique to estimate the evolution of the very faint end of the UV luminosity function (LF) out to z ∼ 5. Measured star formation histories (SFHs) from the fossil record of Local Group (LG) galaxies are used to reconstruct the LF down to M {sub UV} ∼–5 at z ∼ 5 and M {sub UV} ∼–1.5 at z < 1. Such faint limits are well beyond the current observational limits and are likely to remain beyond the limits of next-generation facilities. The reconstructed LFs, when combined with direct measurements of the LFs at higher luminosity, are well-fit by a standard Schechter function with no evidence of a break to the faintest limits probed by this technique. The derived faint-end slope, α, steepens from ≈ – 1.2 at z < 1 to ≈ – 1.6 at 4 < z < 5. We test the effects of burstiness in the SFHs and find the recovered LFs to be only modestly affected. Incompleteness corrections for the faintest LG galaxies and the (unlikely) possibility of significant luminosity-dependent destruction of dwarf galaxies between high redshift and the present epoch are important uncertainties. These and other uncertainties can be mitigated with more detailed modeling and future observations. The reconstructed faint end LF from the fossil record can therefore be a powerful and complementary probe of the high-redshift faint galaxies believed to play a key role in the reionization of the universe.

  17. The fossil record of phenotypic integration and modularity: A deep-time perspective on developmental and evolutionary dynamics.

    PubMed

    Goswami, Anjali; Binder, Wendy J; Meachen, Julie; O'Keefe, F Robin

    2015-04-21

    Variation is the raw material for natural selection, but the factors shaping variation are still poorly understood. Genetic and developmental interactions can direct variation, but there has been little synthesis of these effects with the extrinsic factors that can shape biodiversity over large scales. The study of phenotypic integration and modularity has the capacity to unify these aspects of evolutionary study by estimating genetic and developmental interactions through the quantitative analysis of morphology, allowing for combined assessment of intrinsic and extrinsic effects. Data from the fossil record in particular are central to our understanding of phenotypic integration and modularity because they provide the only information on deep-time developmental and evolutionary dynamics, including trends in trait relationships and their role in shaping organismal diversity. Here, we demonstrate the important perspective on phenotypic integration provided by the fossil record with a study of Smilodon fatalis (saber-toothed cats) and Canis dirus (dire wolves). We quantified temporal trends in size, variance, phenotypic integration, and direct developmental integration (fluctuating asymmetry) through 27,000 y of Late Pleistocene climate change. Both S. fatalis and C. dirus showed a gradual decrease in magnitude of phenotypic integration and an increase in variance and the correlation between fluctuating asymmetry and overall integration through time, suggesting that developmental integration mediated morphological response to environmental change in the later populations of these species. These results are consistent with experimental studies and represent, to our knowledge, the first deep-time validation of the importance of developmental integration in stabilizing morphological evolution through periods of environmental change.

  18. Tectonometamorphic record in a fossilized subduction channel: insights from the Cycladic Blueschist Unit (Cyclades, Greece)

    NASA Astrophysics Data System (ADS)

    Laurent, Valentin; Roche, Vincent; Jolivet, Laurent; Lanari, Pierre; Augier, Romain; Scaillet, Stéphane

    2016-04-01

    The comprehension of subduction dynamics is partly based on the reconstruction of detailed Pressure-Temperature-time-deformation paths of HP-LT metamorphic rocks, which have undergone a complete burial-exhumation cycle. The Cycladic Blueschist Unit (CBU), located in the Aegean domain (Greece), is one of the best examples of a fossilized subduction channel. The tectonometamorphic history of this domain can be summarized in two successive episodes: (1) From the Paleocene to the Eocene, the formation of the Hellenides-Taurides belt due to the convergence between Eurasia and Africa. During this episode, the entrance of the Apulian crust in the subduction zone led to an episode of crustal thickening and formation-exhumation of HP-LT metamorphic units like the CBU. (2) From the Early Oligocene, consecutively to the retreat of the African slab, back-arc extension affected the previously thickened crust and the Aegean Sea started to form. Syros and Sifnos islands are worldwide known for their excellent preservation of HP-LT parageneses in the CBU, providing one of the best case-studies to understand the tectonometamorphic evolution of a subduction channel. This study aims to decipher the P-T-t-d path of the CBU using for the first time on Syros, Raman spectroscopy of carbonaceous material to constrain metamorphic peak temperature (Beyssac et al., 2002) and a quantitative X-ray micro-mapping approach together with the program XMapTools (Lanari et al., 2014). The micro-mapping tools allowed extracting local chemical compositions observed in zoned garnets to calculate the local effective bulk composition. Forward models are then created to constrain P-T conditions of crystallization of these local assemblages. This study brings new data on the debated metamorphic peak conditions of the CBU, which undoubtedly attained at least 20 ± 2 kbar / 530 ± 50°C. Additionally, the geological and metamorphic maps of Syros and Sifnos have been totally redrawn in order to decipher the

  19. Neotropical mammal diversity and the Great American Biotic Interchange: spatial and temporal variation in South America's fossil record

    PubMed Central

    Carrillo, Juan D.; Forasiepi, Analía; Jaramillo, Carlos; Sánchez-Villagra, Marcelo R.

    2015-01-01

    The vast mammal diversity of the Neotropics is the result of a long evolutionary history. During most of the Cenozoic, South America was an island continent with an endemic mammalian fauna. This isolation ceased during the late Neogene after the formation of the Isthmus of Panama, resulting in an event known as the Great American Biotic Interchange (GABI). In this study, we investigate biogeographic patterns in South America, just before or when the first immigrants are recorded and we review the temporal and geographical distribution of fossil mammals during the GABI. We performed a dissimilarity analysis which grouped the faunal assemblages according to their age and their geographic distribution. Our data support the differentiation between tropical and temperate assemblages in South America during the middle and late Miocene. The GABI begins during the late Miocene (~10–7 Ma) and the putative oldest migrations are recorded in the temperate region, where the number of GABI participants rapidly increases after ~5 Ma and this trend continues during the Pleistocene. A sampling bias toward higher latitudes and younger records challenges the study of the temporal and geographic patterns of the GABI. PMID:25601879

  20. Neotropical mammal diversity and the Great American Biotic Interchange: spatial and temporal variation in South America's fossil record.

    PubMed

    Carrillo, Juan D; Forasiepi, Analía; Jaramillo, Carlos; Sánchez-Villagra, Marcelo R

    2014-01-01

    The vast mammal diversity of the Neotropics is the result of a long evolutionary history. During most of the Cenozoic, South America was an island continent with an endemic mammalian fauna. This isolation ceased during the late Neogene after the formation of the Isthmus of Panama, resulting in an event known as the Great American Biotic Interchange (GABI). In this study, we investigate biogeographic patterns in South America, just before or when the first immigrants are recorded and we review the temporal and geographical distribution of fossil mammals during the GABI. We performed a dissimilarity analysis which grouped the faunal assemblages according to their age and their geographic distribution. Our data support the differentiation between tropical and temperate assemblages in South America during the middle and late Miocene. The GABI begins during the late Miocene (~10-7 Ma) and the putative oldest migrations are recorded in the temperate region, where the number of GABI participants rapidly increases after ~5 Ma and this trend continues during the Pleistocene. A sampling bias toward higher latitudes and younger records challenges the study of the temporal and geographic patterns of the GABI.

  1. The Terrestrial Fossil Organic Matter Record of Global Carbon Cycling: A Late Paleozoic through Early Mesozoic Perspective

    NASA Astrophysics Data System (ADS)

    Montanez, I. P.

    2006-12-01

    The carbon isotope composition of terrestrial fossil organic matter (δ13Corg) has been widely used as a proxy of global carbon cycling and to reconstruct perturbations to the ocean-atmosphere carbon budget. The degree to which terrestrial δ13Corg records local to regional environmental conditions versus the evolution of the global carbon cycle has been highly debated. The high-resolution (104 to 106 m.y.) terrestrial δ13Corg record presented here defines a long-term trend through the latest Devonian to Late Triassic that reveals significant and systematic variations that track independently inferred changes in climate, paleo-atmospheric pCO2, and major restructuring in paleotropical flora. This newly derived record is based on 350 carbon isotope analyses of compressed and permineralized plants, cuticle, charcoal and coal (including vitrinite and fusinite) collected from paleo-wetland mudstones and claystones, claystone-filled abandoned fluvial channels, floodplain mudstones, and ephemeral lacustrine deposits at paleo-tropical to paleo-temperate latitudes. Morphologic and geochemical analysis of contemporaneous paleosols and fluvial-alluvial deposits allow for correlation of terrestrial δ13Corg values to reconstructed paleo-environmental conditions. Terrestrial δ13Corg values of contemporaneous fossil organic matter exhibit systematic inter- and intra-basinal variation of up to 2‰ associated with differences in paleo-precipitation and burial history, and geomorphic position within depositional basins and paleo-fluvial systems. Variation in δ13Corg by organic matter type is minimal to less than 1.5‰; specifically, charcoal δ13Corg values overlap to are slightly less negative than those of thermally less mature organic components analyzed. Overall, variation within contemporaneous populations is significantly less than defined by the long-term terrestrial δ13Corg record. Moreover, paleo-floral pi/pa ratios, an established proxy of water-use efficiency of

  2. Arthropod eyes: The early Cambrian fossil record and divergent evolution of visual systems.

    PubMed

    Strausfeld, Nicholas J; Ma, Xiaoya; Edgecombe, Gregory D; Fortey, Richard A; Land, Michael F; Liu, Yu; Cong, Peiyun; Hou, Xianguang

    2016-03-01

    evolution of sessile eyes equipped with optics typical of extant xiphosurans. Observations of fossil material, including that of trilobites and eurypterids, support the proposition that the ancestral compound eye was the apposition type. Cambrian arthropods include possible precursors of mandibulate eyes. The latter are the modified compound eyes, now sessile, and their underlying optic lobes exemplified by scutigeromorph chilopods, and the mobile stalked compound eyes and more elaborate optic lobes typifying Pancrustacea. Radical divergence from an ancestral apposition type is demonstrated by the evolution of chelicerate eyes, from doublet sessile-eyed stem-group taxa to special apposition eyes of xiphosurans, the compound eyes of eurypterids, and single-lens eyes of arachnids. Different eye types are discussed with respect to possible modes of life of the extinct species that possessed them, comparing these to extant counterparts and the types of visual centers the eyes might have served.

  3. Fossil records of high level of 60Fe in chondrules from unequilibrated chondrites

    NASA Astrophysics Data System (ADS)

    Mishra, Ritesh Kumar; Chaussidon, Marc

    2014-07-01

    The short-lived now-extinct nuclide (SLN) 60Fe, which decays to 60Ni with a half-life of 2.62 Ma, is uniquely of stellar origin. Hence, its Solar System initial abundance yields information about the source of SLNs and the astrophysical environment in which the Solar System was born. Only a few chondrules (∼19) from unequilibrated ordinary chondrites have reported resolved 60Ni excesses using in situ secondary ion mass spectrometry implying Fe60/Fe56>∼0.6×10-7 in the early Solar System, and among these very few (3) have higher excesses implying Fe60/Fe56∼7×10-7 (Mishra et al., 2010; Mishra and Goswami, 2014; Telus et al., 2012). At variance, multi-collector inductively coupled plasma mass spectrometer studies of bulk samples and mineral separates from differentiated meteorites, angrites, achondrites, and chondrules suggest a low abundance of 60Fe/56Fe of ∼1.4×10-8 which would rule out the need for an external seeding of the early Solar with stellar 60Fe (Quitté et al., 2011; Tang and Dauphas, 2012). Two Semarkona chondrules and one Efremovka chondrule analyzed in the present study have mass fractionation corrected excess of up to ∼75 permil (‰) and give 60Fe isochrons with initial 60Fe/56Fe ratios of (7.8±3.7)×10-7, (3.8±1.6)×10-7, and (2.2±1.1)×10-7 (2σ), for Efremovka Ch 1, Semarkona Ch 12, and Semarkona Ch J5 respectively. The higher values of 60Fe/56Fe ratios seen in the chondrules of these least altered meteorites samples concur with and lend greater credence to the suggestion of a massive star as the source of 60Fe, and possibly of other short-lived nuclides, to the early Solar System. However, no definitive explanation (e.g. sample bias, effects of metamorphism, 60Fe heterogeneity) to the apparent disagreement with studies of bulk chondrules and chondrule fragments has been found.

  4. Iridium abundance measurements across bio-event horizons in the geological record

    NASA Technical Reports Server (NTRS)

    Orth, C. J.; Attrep, M., Jr.

    1988-01-01

    Geochemical studies have been performed on thousands of rock samples collected across bio-event horizons in the fossil record using INAA for about 40 common and trace elements and radiochemical isolation procedures for Os, Ir, Pt, and Au on selected samples. These studies were begun soon after the Alvarez team announced their discovery of the Cretaceous-Tertiary (K-T) Ir anomaly in marine rock sequences in Europe. With their encouragement the Authors searched for the anomaly in nearby continental (freshwater coal swamp) deposits. In collaboration with scientists from the U.S.G.S. in Denver, the anomaly was located and it was observed that a floral crisis occurred at the same stratigraphic position as the Ir spike. Further work in the Raton Basin has turned up numerous well-preserved K-T boundary sections. Although the Authors have continued to study the K-T boundary and provide geochemical measurements for other groups trying to precisely locate it, the primary effort was turned to examining the other bio-events in the Phanerozoic, especially to those that are older than the terminal Cretaceous. A list of horizons that were examined in collaboration with paleontologists and geologists is given. Results are also given and discussed.

  5. Novel application of confocal laser scanning microscopy and 3D volume rendering toward improving the resolution of the fossil record of charcoal.

    PubMed

    Belcher, Claire M; Punyasena, Surangi W; Sivaguru, Mayandi

    2013-01-01

    Variations in the abundance of fossil charcoals between rocks and sediments are assumed to reflect changes in fire activity in Earth's past. These variations in fire activity are often considered to be in response to environmental, ecological or climatic changes. The role that fire plays in feedbacks to such changes is becoming increasingly important to understand and highlights the need to create robust estimates of variations in fossil charcoal abundance. The majority of charcoal based fire reconstructions quantify the abundance of charcoal particles and do not consider the changes in the morphology of the individual particles that may have occurred due to fragmentation as part of their transport history. We have developed a novel application of confocal laser scanning microscopy coupled to image processing that enables the 3-dimensional reconstruction of individual charcoal particles. This method is able to measure the volume of both microfossil and mesofossil charcoal particles and allows the abundance of charcoal in a sample to be expressed as total volume of charcoal. The method further measures particle surface area and shape allowing both relationships between different size and shape metrics to be analysed and full consideration of variations in particle size and size sorting between different samples to be studied. We believe application of this new imaging approach could allow significant improvement in our ability to estimate variations in past fire activity using fossil charcoals.

  6. New Early Triassic trace fossil records from South China: implications for biotic recovery following the end-Permian mass extinction

    NASA Astrophysics Data System (ADS)

    Luo, M.; George, A. D.; Chen, Z.; Zhang, Y.

    2013-12-01

    New Early Triassic trace fossil assemblages are documented from the Susong and Tianshengqiao areas in South China to evaluate the mode and tempo of biotic recovery of epifaunal and infaunal organisms following the end-Permian mass extinction. The Susong succession is exposed in Anhui area of the Lower Yangtze region and comprises mudstone and carbonate facies that record overall shallowing from offshore to supratidal settings. The Tianshengqiao succession crops out in the Luoping area, Yuannan Province of the Upper Yangtze region, and consists of mixed carbonate and siliciclastic facies which were deposited in shallow marine to offshore settings. Bivalve and conodont biostratigraphy helps constrain the chronostratigraphic framework of the Lower Triassic successions in these two sections. Griesbachian to Dieneria ichnological records in both successions are characterized by low ichnodiversity, low ichnofabric indices (ii=1-2) and low bedding plane bioturbation indices (bpbi=1-2). Higher ii (ii= 3 and 4) corresponding to densely populated diminutive Skolithos in the Tianshengqiao succession suggest an opportunistic strategy during earliest Triassic deposition. Ichnological data from the Susong succession show an increase in ichnodiversity during the Smithian. A total of 12 ichnogenera including Arenicolites, Chondrites, Gyrochorte, Laevicyclus, Monocraterion, Palaeophycus, Phycodes, Plaolites, Thalassinoides, Treptichnus, Trichichnus and one problematic trace are identified. Ichnofabric indices (ii) and bpbi increase to moderate to high levels (ii = 4-5, bpbi= 3-5). Although complex traces such as Rhizocorallium are in Spathian strata in this section, the low levels of ichnodiversity, ichnofabric indices and diminutive Planolites suggest a decline in recovery. In the Tianshengqiao succession, ichnofabric indices exhibit a moderate to high value (ii= 3 to 5), however, only six ichnogenera are found and Planolites burrows are consistently small (average diameter at 3

  7. Biotic immigration events, speciation, and the accumulation of biodiversity in the fossil record

    NASA Astrophysics Data System (ADS)

    Stigall, Alycia L.; Bauer, Jennifer E.; Lam, Adriane R.; Wright, David F.

    2017-01-01

    Biotic Immigration Events (BIMEs) record the large-scale dispersal of taxa from one biogeographic area to another and have significantly impacted biodiversity throughout geologic time. BIMEs associated with biodiversity increases have been linked to ecologic and evolutionary processes including niche partitioning, species packing, and higher speciation rates. Yet substantial biodiversity decline has also been documented following BIMEs due to elevated extinction and/or reduced speciation rates. In this review, we develop a conceptual model for biodiversity accumulation that links BIMEs and geographic isolation with local (α) diversity, regional (β) diversity, and global (γ) diversity metrics. Within the model, BIME intervals are characterized by colonization of existing species within new geographic regions and a lack of successful speciation events. Thus, there is no change in γ-diversity, and α-diversity increases at the cost of β-diversity. An interval of regional isolation follows in which lineage splitting results in successful speciation events and diversity increases across all three metrics. Alternation of these two regimes can result in substantial biodiversity accumulation. We tested this conceptual model using a series of case studies from the paleontological record. We primarily focus on two intervals during the Middle through Late Ordovician Period (470-458 Ma): the globally pervasive BIMEs during the Great Ordovician Biodiversification Event (GOBE) and a regional BIME, the Richmondian Invasion. We further test the conceptual model by examining the Great Devonian Interchange, Neogene mollusk migrations and diversification, and the Great American Biotic Interchange. Paleontological data accord well with model predictions. Constraining the mechanisms of biodiversity accumulation provides context for conservation biology. Because α-, β-, and γ-diversity are semi-independent, different techniques should be considered for sustaining various

  8. When Did Carcharocles megalodon Become Extinct? A New Analysis of the Fossil Record

    PubMed Central

    Pimiento, Catalina; Clements, Christopher F.

    2014-01-01

    Carcharocles megalodon (“Megalodon”) is the largest shark that ever lived. Based on its distribution, dental morphology, and associated fauna, it has been suggested that this species was a cosmopolitan apex predator that fed on marine mammals from the middle Miocene to the Pliocene (15.9–2.6 Ma). Prevailing theory suggests that the extinction of apex predators affects ecosystem dynamics. Accordingly, knowing the time of extinction of C. megalodon is a fundamental step towards understanding the effects of such an event in ancient communities. However, the time of extinction of this important species has never been quantitatively assessed. Here, we synthesize the most recent records of C. megalodon from the literature and scientific collections and infer the date of its extinction by making a novel use of the Optimal Linear Estimation (OLE) model. Our results suggest that C. megalodon went extinct around 2.6 Ma. Furthermore, when contrasting our results with known ecological and macroevolutionary trends in marine mammals, it became evident that the modern composition and function of modern gigantic filter-feeding whales was established after the extinction of C. megalodon. Consequently, the study of the time of extinction of C. megalodon provides the basis to improve our understanding of the responses of marine species to the removal of apex predators, presenting a deep-time perspective for the conservation of modern ecosystems. PMID:25338197

  9. When did Carcharocles megalodon become extinct? A new analysis of the fossil record.

    PubMed

    Pimiento, Catalina; Clements, Christopher F

    2014-01-01

    Carcharocles megalodon ("Megalodon") is the largest shark that ever lived. Based on its distribution, dental morphology, and associated fauna, it has been suggested that this species was a cosmopolitan apex predator that fed on marine mammals from the middle Miocene to the Pliocene (15.9-2.6 Ma). Prevailing theory suggests that the extinction of apex predators affects ecosystem dynamics. Accordingly, knowing the time of extinction of C. megalodon is a fundamental step towards understanding the effects of such an event in ancient communities. However, the time of extinction of this important species has never been quantitatively assessed. Here, we synthesize the most recent records of C. megalodon from the literature and scientific collections and infer the date of its extinction by making a novel use of the Optimal Linear Estimation (OLE) model. Our results suggest that C. megalodon went extinct around 2.6 Ma. Furthermore, when contrasting our results with known ecological and macroevolutionary trends in marine mammals, it became evident that the modern composition and function of modern gigantic filter-feeding whales was established after the extinction of C. megalodon. Consequently, the study of the time of extinction of C. megalodon provides the basis to improve our understanding of the responses of marine species to the removal of apex predators, presenting a deep-time perspective for the conservation of modern ecosystems.

  10. A search for evidence of large body Earth impacts associated with biological crisis zones in the fossil record

    NASA Technical Reports Server (NTRS)

    Orth, C. J.; Gilmore, J. S.; Knight, J. D.

    1985-01-01

    The natural history of the Earth, how the present plant and animal species developed, how others completely died out, etc., was studied. The rock strata sampled and studied were at the time of deposition at sea bottom. It was found that, exactly at the stratigraphic level corresponding to the extinction, a thin clay layer was greatly enriched in the the rare element iridium. It was hypothesized that the excess irridium at the boundary came from a large steroid like object that hit the earth, and that the impact of this object threw up a dust cloud dense enough and long lasting enough to bring about the extinction of a wide variety of plants and animals, producing the unique break in in the fossil record, the cretaceous-tertiary boundary. The same iridium and platinum metals enrichement are found in a thin clay layer that corresponds with the boundary as difined by sudden radical changes in plant populations. The irridium enrichement is confirmed at other fresh water origin rites in the Raton Basin.

  11. An analysis of pterosaurian biogeography: implications for the evolutionary history and fossil record quality of the first flying vertebrates.

    PubMed

    Upchurch, Paul; Andres, Brian; Butler, Richard J; Barrett, Paul M

    2015-08-18

    The biogeographical history of pterosaurs has received very little treatment. Here, we present the first quantitative analysis of pterosaurian biogeography based on an event-based parsimony method (Treefitter). This approach was applied to a phylogenetic tree comprising the relationships of 108 in-group pterosaurian taxa, spanning the full range of this clade's stratigraphical and geographical extent. The results indicate that there is no support for the impact of vicariance or coherent dispersal on pterosaurian distributions. However, this group does display greatly elevated levels of sympatry. Although sampling biases and taxonomic problems might have artificially elevated the occurrence of sympatry, we argue that our results probably reflect a genuine biogeographical signal. We propose a novel model to explain pterosaurian distributions: pterosaurs underwent a series of 'sweep-stakes' dispersal events (across oceanic barriers in most cases), resulting in the founding of sympatric clusters of taxa. Examination of the spatiotemporal distributions of pterosaurian occurrences indicates that their fossil record is extremely patchy. Thus, while there is likely to be genuine information on pterosaurian diversity and biogeographical patterns in the current data-set, caution is required in its interpretation.

  12. An analysis of pterosaurian biogeography: implications for the evolutionary history and fossil record quality of the first flying vertebrates

    PubMed Central

    Upchurch, Paul; Andres, Brian; Butler, Richard J.; Barrett, Paul M.

    2015-01-01

    The biogeographical history of pterosaurs has received very little treatment. Here, we present the first quantitative analysis of pterosaurian biogeography based on an event-based parsimony method (Treefitter). This approach was applied to a phylogenetic tree comprising the relationships of 108 in-group pterosaurian taxa, spanning the full range of this clade's stratigraphical and geographical extent. The results indicate that there is no support for the impact of vicariance or coherent dispersal on pterosaurian distributions. However, this group does display greatly elevated levels of sympatry. Although sampling biases and taxonomic problems might have artificially elevated the occurrence of sympatry, we argue that our results probably reflect a genuine biogeographical signal. We propose a novel model to explain pterosaurian distributions: pterosaurs underwent a series of ‘sweep-stakes’ dispersal events (across oceanic barriers in most cases), resulting in the founding of sympatric clusters of taxa. Examination of the spatiotemporal distributions of pterosaurian occurrences indicates that their fossil record is extremely patchy. Thus, while there is likely to be genuine information on pterosaurian diversity and biogeographical patterns in the current data-set, caution is required in its interpretation. PMID:26339122

  13. Grazing trails formed by soldier fly larvae (Diptera: Stratiomyidae) and their paleoenvironmental and paleoecological implications for the fossil record

    USGS Publications Warehouse

    Mangano, M.G.; Buatois, L.A.; Claps, G.L.

    1996-01-01

    Recent trails formed by soldier fly larvae (Diptera: Stratiomyidae) were examined in a shallow pond in the floodplain of a braided river in Jujuy Province, northwestern Argentina. Collected specimens were identified as Stratiomys convexa van der Wulp. Simple, irregularly meandering trails were produced across the surface of a muddy-silty substrate. Since soldier fly larvae extend their caudal respiratory tube to the water-air interface, they are restricted to extremely shallow water. The presence of benthic algal remains within the mouthparts of the larvae suggests a feeding habit of algal grazing. If preserved, these trails would be included in the ichnogenus Helminthopsis, a common element in ancient freshwater ichnofaunas. Helminthopsis preserved in pond and lacustrine margin deposits younger than Late Jurassic is regarded as one possible trace fossil analogue of the trails documented herein. Additionally, it is suggested that larvae of many aquatic Diptera with similar ecologic restrictions are potential tracemakers of Helminthopsis and other simple trails in these environments, particularly in post-Paleozoic deposits. Studies of modern shallow aquatic habitats and reexamination of the ichnologic record stress the importance of fly larvae as tracemakers in lake margin and pond ecosystems. Ecologic requirements of soldier fly larvae make them inappropriate analogues of Helminthopsis tracemakers in deeper water, lacustrine settings. ?? 1996 OPA (Overseas Publishers Association) Amsterdam B.V. Published in The Netherlands by Harwood Academic Publishers GmbH.

  14. Major adaptive radiation in neritopsine gastropods estimated from 28S rRNA sequences and fossil records.

    PubMed Central

    Kano, Yasunori; Chiba, Satoshi; Kase, Tomoki

    2002-01-01

    A well-supported phylogeny of the Neritopsina, a gastropod superorder archaic in origin, radiated ecologically and diverse in morphology, is reconstructed based on partial 28S rRNA sequences. The result (Neritopsidae (Hydrocenidae (Helicinidae + Neritiliidae) (Neritidae + Phenacolepadidae))) is highly congruent with the fossil records and the character distribution of reproductive tracts in extant taxa. We suggest that the Neritopsina originated in subtidal shallow waters, invaded the land and became fully terrestrial at least three times in different clades, by the extinct Dawsonellidae in the Late Palaeozoic and by the Helicinidae and Hydrocenidae in the Mesozoic. Invasion of fresh- and brackish waters is prevalent among the Neritopsina as the Jurassic and freshwater ancestory is most probable for helicinids. The Phenacolepadidae, a group exclusively inhabiting dysoxic environments, colonized deep-sea hydrothermal vents and seeps in the Late Cretaceous or Early Cenozoic. Submarine caves have served as refuges for the archaic Neritopsidae since the Early to Middle Cenozoic, and the marine neritopsine slug Titiscania represents a highly specialized but relatively recent offshoot of this family. The Neritiliidae is another clade to be found utilizing submarine caves as shelter by the Oligocene; once adapted to the completely dark environment, but some neritiliids have immigrated to surface freshwater habitats. PMID:12495489

  15. Inferring the nature of anthropogenic threats from long-term abundance records.

    PubMed

    Shoemaker, Kevin T; Akçakaya, H Resit

    2015-02-01

    Diagnosing the processes that threaten species persistence is critical for recovery planning and risk forecasting. Dominant threats are typically inferred by experts on the basis of a patchwork of informal methods. Transparent, quantitative diagnostic tools would contribute much-needed consistency, objectivity, and rigor to the process of diagnosing anthropogenic threats. Long-term census records, available for an increasingly large and diverse set of taxa, may exhibit characteristic signatures of specific threatening processes and thereby provide information for threat diagnosis. We developed a flexible Bayesian framework for diagnosing threats on the basis of long-term census records and diverse ancillary sources of information. We tested this framework with simulated data from artificial populations subjected to varying degrees of exploitation and habitat loss and several real-world abundance time series for which threatening processes are relatively well understood: bluefin tuna (Thunnus maccoyii) and Atlantic cod (Gadus morhua) (exploitation) and Red Grouse (Lagopus lagopus scotica) and Eurasian Skylark (Alauda arvensis) (habitat loss). Our method correctly identified the process driving population decline for over 90% of time series simulated under moderate to severe threat scenarios. Successful identification of threats approached 100% for severe exploitation and habitat loss scenarios. Our method identified threats less successfully when threatening processes were weak and when populations were simultaneously affected by multiple threats. Our method selected the presumed true threat model for all real-world case studies, although results were somewhat ambiguous in the case of the Eurasian Skylark. In the latter case, incorporation of an ancillary source of information (records of land-use change) increased the weight assigned to the presumed true model from 70% to 92%, illustrating the value of the proposed framework in bringing diverse sources of

  16. Fossil fuel and wood combustion as recorded by carbon particles in Lake Erie sediments 1850-1998.

    PubMed

    Kralovec, Andrew C; Christensen, Erik R; Van Camp, Ryan P

    2002-04-01

    Carbon particle analysis was performed on a dated sediment core from Lake Erie in order to explore the inputs of pollution from incomplete combustion of coal, oil, and wood. Carbon particles were isolated from the sediment by chemical digestion, and elemental carbon content was determined by CHN analysis. The type of carbon particle (from burning coal, oil, and wood) and particle size and relative abundance were determined using scanning electron microscopy on 100 particles from each core section. The elemental carbon content in the Lake Erie core ranges from 2.5 to 7.4 mg of carbon/g of sediment (1850-1998), and the maximum carbon content in the sediment occurs in the late 1960s to early 1970s. It is shown that particle mass is a better predictor than particle number of historical energy consumption records. This is especially clear for wood where variable particle volumes play a significant role in determining the record of elemental carbon mass from wood burning. Lake Erie core's content of total carbon and carbon particle type is in agreement with U.S. energy consumption records, except that a wood maximum occurs during 1905-1917, about 36 yr after the U.S. consumption maximum from 1870 to 1880.

  17. Review of the fossil matamata turtles: earliest well-dated record and hypotheses on the origin of their present geographical distribution

    NASA Astrophysics Data System (ADS)

    Ferreira, Gabriel S.; Rincón, Ascanio D.; Solórzano, Andrés; Langer, Max C.

    2016-04-01

    The matamata ( Chelus fimbriatus) is a highly aquatic chelid turtle known exclusively from northern South America. Due to its extremely modified morphology, it is well circumscribed among living taxa, but that is not the case of the two extinct species ascribed to the taxon, Chelus colombianus and Chelus lewisi. These were originally described for the Miocene of Colombia and Venezuela, respectively, and are known mostly from post-cranial material. Few traits have been considered diagnostic for these fossil taxa, and their shared geographic and temporal distributions raise doubts about their distinctiveness. Here, we describe new turtle remains from the early Miocene Castillo Formation, at Cerro la Cruz, northwestern Venezuela, assigning them to C. colombianus. We also review the taxonomy and diagnostic features of the fossil species of Chelus, comparing them with the variation recognized within C. fimbriatus. All alleged differences between the fossil Chelus species were found in our sample of the extant species, and may represent intraspecific variation of a single fossil species. Further, we reviewed the fossil record of Chelus spp. and proposed a paleobiogeographic hypothesis to explain its present geographic range.

  18. Review of the fossil matamata turtles: earliest well-dated record and hypotheses on the origin of their present geographical distribution.

    PubMed

    Ferreira, Gabriel S; Rincón, Ascanio D; Solórzano, Andrés; Langer, Max C

    2016-04-01

    The matamata (Chelus fimbriatus) is a highly aquatic chelid turtle known exclusively from northern South America. Due to its extremely modified morphology, it is well circumscribed among living taxa, but that is not the case of the two extinct species ascribed to the taxon, Chelus colombianus and Chelus lewisi. These were originally described for the Miocene of Colombia and Venezuela, respectively, and are known mostly from post-cranial material. Few traits have been considered diagnostic for these fossil taxa, and their shared geographic and temporal distributions raise doubts about their distinctiveness. Here, we describe new turtle remains from the early Miocene Castillo Formation, at Cerro la Cruz, northwestern Venezuela, assigning them to C. colombianus. We also review the taxonomy and diagnostic features of the fossil species of Chelus, comparing them with the variation recognized within C. fimbriatus. All alleged differences between the fossil Chelus species were found in our sample of the extant species, and may represent intraspecific variation of a single fossil species. Further, we reviewed the fossil record of Chelus spp. and proposed a paleobiogeographic hypothesis to explain its present geographic range.

  19. Where's the glass? Biomarkers, molecular clocks, and microRNAs suggest a 200-Myr missing Precambrian fossil record of siliceous sponge spicules

    NASA Astrophysics Data System (ADS)

    Sperling, E. A.; Robinson, J.; Pisani, D.; Peterson, K.

    2010-12-01

    The earliest evidence for animal life comes from the fossil record of 24-isopropylcholestane, a sterane found in Cryogenian deposits, and whose precursors are found in modern demosponges, but not choanoflagellates, calcareans, hexactinellids, or eumetazoans. However, many modern demosponges are also characterized by the presence of siliceous spicules, and there are no convincing demosponge spicules in strata older than the Cambrian. This temporal disparity highlights a problem with our understanding of the Precambrian fossil record - either these supposed demosponge-specific biomarkers were derived from the sterols of some other organism and are simply retained in modern demosponges, or spicules do not primitively characterize crown-group demosponges. Resolving this issue requires resolving the phylogenetic placement of another group of sponges, the hexactinellids, which not only make a spicule thought to be homologous to the spicules of demosponges, but also make their first appearance near the Precambrian/Cambrian boundary. Using two independent analytical approaches and data sets - traditional molecular phylogenetic analyses and the presence or absence of specific microRNA genes - we show that demosponges are monophyletic, and that hexactinellids are their sister group (together forming the Silicea). Thus, spicules must have evolved before the last common ancestor of all living siliceans, suggesting the presence of a significant gap in the silicean spicule fossil record. Molecular divergence estimates date the origin of this last common ancestor well within the Cryogenian, consistent with the biomarker record, and strongly suggests that siliceous spicules were present during the Precambrian but were not preserved.

  20. Where's the glass? Biomarkers, molecular clocks, and microRNAs suggest a 200-Myr missing Precambrian fossil record of siliceous sponge spicules.

    PubMed

    Sperling, E A; Robinson, J M; Pisani, D; Peterson, K J

    2010-01-01

    The earliest evidence for animal life comes from the fossil record of 24-isopropylcholestane, a sterane found in Cryogenian deposits, and whose precursors are found in modern demosponges, but not choanoflagellates, calcareans, hexactinellids, or eumetazoans. However, many modern demosponges are also characterized by the presence of siliceous spicules, and there are no convincing demosponge spicules in strata older than the Cambrian. This temporal disparity highlights a problem with our understanding of the Precambrian fossil record--either these supposed demosponge-specific biomarkers were derived from the sterols of some other organism and are simply retained in modern demosponges, or spicules do not primitively characterize crown-group demosponges. Resolving this issue requires resolving the phylogenetic placement of another group of sponges, the hexactinellids, which not only make a spicule thought to be homologous to the spicules of demosponges, but also make their first appearance near the Precambrian/Cambrian boundary. Using two independent analytical approaches and data sets--traditional molecular phylogenetic analyses and the presence or absence of specific microRNA genes--we show that demosponges are monophyletic, and that hexactinellids are their sister group (together forming the Silicea). Thus, spicules must have evolved before the last common ancestor of all living siliceans, suggesting the presence of a significant gap in the silicean spicule fossil record. Molecular divergence estimates date the origin of this last common ancestor well within the Cryogenian, consistent with the biomarker record, and strongly suggests that siliceous spicules were present during the Precambrian but were not preserved.

  1. The first fossil record of the Emesinae genus Emesopsis Uhler (Hemiptera: Heteroptera, Reduviidae) from Eocene Baltic amber.

    PubMed

    Popov, Yuri A; Chłond, Dominik

    2015-11-06

    Two new fossil representatives of the assassin bug family Reduviidae are described as new from Baltic amber (Upper Eocene), belonging to the genus Emesopsis of the tribe Ploiariolini (Emesinae): Emesopsis putshkovi sp. nov. and E. similis sp. nov. These representatives of the Emesinae are the oldest fossil bugs of the genus Emesopsis known so far, and reported for the first time. This genus is also briefly diagnosed.

  2. †Kenyaichthyidae fam. nov. and †Kenyaichthys gen. nov. – First Record of a Fossil Aplocheiloid Killifish (Teleostei, Cyprinodontiformes)

    PubMed Central

    Altner, Melanie; Reichenbacher, Bettina

    2015-01-01

    The extant Cyprinodontiformes (killifishes) with their two suborders Cyprinodontoidei and Aplocheiloidei represent a diverse and well-studied group of fishes. However, their fossil record is comparatively sparse and has so far yielded members of the Cyprinodontoidei only. Here we report on cyprinodontiform fossils from the upper Miocene Lukeino Formation in the Tugen Hills of the Central Rift Valley of Kenya, which represent the first fossil record of an aplocheiloid killifish. A total of 169 specimens - mostly extraordinarily well preserved - and a sample of ten extant cyprinodontiform species were studied on the basis of morphometrics, meristics and osteology. A phylogenetic analysis using PAUP was also conducted for the fossils. Both the osteological data and the phylogenetic analysis provide strong evidence for the assignment of the fossils to the Aplocheiloidei, and justify the definition of the new family †Kenyaichthyidae, the new genus †Kenyaichthys and the new species †K. kipkechi sp. nov. The phylogenetic analysis unexpectedly places †Kenyaichthys gen. nov. in a sister relationship to the Rivulidae (a purely Neotropical group), a probable explanation might be lack of available synapomorphies for the Rivulidae, Nothobranchiidae and Aplocheilidae. The specimens of †K. kipkechi sp. nov. show several polymorphic characters and large overlap in meristic traits, which justifies their interpretation as a species flock in statu nascendi. Patterns of variation in neural and haemal spine dimensions in the caudal vertebrae of †Kenyaichthys gen. nov. and the extant species studied indicate that some previously suggested synapomorphies of the Cyprinodontoidei and Aplocheiloidei need to be revised. PMID:25923654

  3. Reassessment of Olduvai Bed I cercopithecoids: A new biochronological and biogeographical link to the South African fossil record.

    PubMed

    Gilbert, Christopher C; Frost, Stephen R; Delson, Eric

    2016-03-01

    Fossil monkeys have long been used as important faunal elements in studies of African Plio-Pleistocene biochronology, particularly in the case of the South African karst cave sites. Cercopithecoid fossils have been known from Tanzania's Olduvai Gorge for nearly a century, with multiple taxa documented including Theropithecus oswaldi and Cercopithecoides kimeui, along with papionins and colobines less clearly attributable to species. A small number of large papionin fossils, including a partial male cranium and partial female skull, have been previously identified as an early form of Papio, but noted as distinct from extant baboons as well as other fossil Papio species. In 2013 we reviewed the Olduvai cercopithecoid material at the National Museum of Tanzania, with a particular focus on the specimens from Beds I-IV. Quantitative and qualitative comparisons of the Olduvai papionins largely confirmed previous observations, with one notable exception. The large papionin taxon from Bed I previously recognized as Papio sp. is more properly recognized as Gorgopithecus major, a taxon previously known only from South Africa. Features shared between the Olduvai specimens and G. major include relatively short and concavo-convex tubular nasals, antero-posteriorly curved upper incisor roots, downwardly curved brow ridges in the midline, and robust zygomatic arches. The recognition of G. major at Olduvai Bed I, a well-known horizon with precise radiometric dates, provides an important biochronological and biogeographical link with South African localities Kromdraai A, Swartkrans Member 1 and possibly Swartkrans Members 2-3 and Cooper's A and D.

  4. Influence of changes in climate, sea level, and depositional systems on the fossil record of the Neoproterozoic-early Cambrian metazoan radiation, Australia

    SciTech Connect

    Mount, J.F.; McDonald, C. )

    1992-11-01

    On the Australian continent the fossil record of the initial appearance and radiation of higher metazoans is strongly influenced by the distribution of facies suitable for fossil preservation. The limited stratigraphic range of the [open quotes]Ediacaran[close quotes] fauna, the seemingly abrupt appearance and radiation of Cambrian-aspect traces, and the apparently late appearance of skeletogenous organisms are all functions of the spatial and temporal distributions of key habitats. The principal controls on the formation of these habitats appear to have been changes in climate and siliciclastic sediment supply coupled with cyclic changes in sea level. Aspects of the artifactual bias documented in Australia are recognized (but rarely documented) in Precambrian-Cambrian boundary sections worldwide. This bias may ultimately form a major stumbling block to detailed reconstruction of early metazoan evolution. 43 refs., 3 figs.

  5. Reconstructing Carotenoid-Based and Structural Coloration in Fossil Skin.

    PubMed

    McNamara, Maria E; Orr, Patrick J; Kearns, Stuart L; Alcalá, Luis; Anadón, Pere; Peñalver, Enrique

    2016-04-25

    Evidence of original coloration in fossils provides insights into the visual communication strategies used by ancient animals and the functional evolution of coloration over time [1-7]. Hitherto, all reconstructions of the colors of reptile integument and the plumage of fossil birds and feathered dinosaurs have been of melanin-based coloration [1-6]. Extant animals also use other mechanisms for producing color [8], but these have not been identified in fossils. Here we report the first examples of carotenoid-based coloration in the fossil record, and of structural coloration in fossil integument. The fossil skin, from a 10 million-year-old colubrid snake from the Late Miocene Libros Lagerstätte (Teruel, Spain) [9, 10], preserves dermal pigment cells (chromatophores)-xanthophores, iridophores, and melanophores-in calcium phosphate. Comparison with chromatophore abundance and position in extant reptiles [11-15] indicates that the fossil snake was pale-colored in ventral regions; dorsal and lateral regions were green with brown-black and yellow-green transverse blotches. Such coloration most likely functioned in substrate matching and intraspecific signaling. Skin replicated in authigenic minerals is not uncommon in exceptionally preserved fossils [16, 17], and dermal pigment cells generate coloration in numerous reptile, amphibian, and fish taxa today [18]. Our discovery thus represents a new means by which to reconstruct the original coloration of exceptionally preserved fossil vertebrates.

  6. The Origin and Early Evolution of Sauria: Reassessing the Permian Saurian Fossil Record and the Timing of the Crocodile-Lizard Divergence

    PubMed Central

    Ezcurra, Martín D.; Scheyer, Torsten M.; Butler, Richard J.

    2014-01-01

    Sauria is the crown-group of Diapsida and is subdivided into Lepidosauromorpha and Archosauromorpha, comprising a high percentage of the diversity of living and fossil tetrapods. The split between lepidosauromorphs and archosauromorphs (the crocodile-lizard, or bird-lizard, divergence) is considered one of the key calibration points for molecular analyses of tetrapod phylogeny. Saurians have a very rich Mesozoic and Cenozoic fossil record, but their late Paleozoic (Permian) record is problematic. Several Permian specimens have been referred to Sauria, but the phylogenetic affinity of some of these records remains questionable. We reexamine and review all of these specimens here, providing new data on early saurian evolution including osteohistology, and present a new morphological phylogenetic dataset. We support previous studies that find that no valid Permian record for Lepidosauromorpha, and we also reject some of the previous referrals of Permian specimens to Archosauromorpha. The most informative Permian archosauromorph is Protorosaurus speneri from the middle Late Permian of Western Europe. A historically problematic specimen from the Late Permian of Tanzania is redescribed and reidentified as a new genus and species of basal archosauromorph: Aenigmastropheus parringtoni. The supposed protorosaur Eorasaurus olsoni from the Late Permian of Russia is recovered among Archosauriformes and may be the oldest known member of the group but the phylogenetic support for this position is low. The assignment of Archosaurus rossicus from the latest Permian of Russia to the archosauromorph clade Proterosuchidae is supported. Our revision suggests a minimum fossil calibration date for the crocodile-lizard split of 254.7 Ma. The occurrences of basal archosauromorphs in the northern (30°N) and southern (55°S) parts of Pangea imply a wider paleobiogeographic distribution for the group during the Late Permian than previously appreciated. Early archosauromorph growth

  7. From Fossil Parasitoids to Vectors: Insects as Parasites and Hosts.

    PubMed

    Nagler, Christina; Haug, Joachim T

    2015-01-01

    Within Metazoa, it has been proposed that as many as two-thirds of all species are parasitic. This propensity towards parasitism is also reflected within insects, where several lineages independently evolved a parasitic lifestyle. Parasitic behaviour ranges from parasitic habits in the strict sense, but also includes parasitoid, phoretic or kleptoparasitic behaviour. Numerous insects are also the host for other parasitic insects or metazoans. Insects can also serve as vectors for numerous metazoan, protistan, bacterial and viral diseases. The fossil record can report this behaviour with direct (parasite associated with its host) or indirect evidence (insect with parasitic larva, isolated parasitic insect, pathological changes of host). The high abundance of parasitism in the fossil record of insects can reveal important aspects of parasitic lifestyles in various evolutionary lineages. For a comprehensive view on fossil parasitic insects, we discuss here different aspects, including phylogenetic systematics, functional morphology and a direct comparison of fossil and extant species.

  8. Characterization of fossil organic matter with Fourier-Transform Infrared (FTIR) Spectroscopy: an attempt to record extraterrestrial life .

    NASA Astrophysics Data System (ADS)

    Guido, A.; Mastandrea, A.; Tosti, F.; Demasi, F.; Blanco, A.; D'Elia, M.; Orofino, V.; Fonti, S.; Russo, F.

    The characterization of the insoluble macromolecular fraction of organic matter preserved in carbonate sediments allows the identification of fossil organisms otherwise not recognizable. This approach represents a new tool for the detection of extraterrestrial traces of life even in their primitive form, one of the primary goals of exobiological studies on Mars. Considering the deep connection between carbonate sediments and biological activities on Earth, we checked if it was possible to characterize the organic matter remains dispersed within these rocks, with Fourier transform infrared (FTIR) spectroscopy. The experiment was performed on ancient and well preserved carbonates, belonging to the Calcare di Base Formation outcropping in Northern Calabria (Rossano Basin). The origin of these Miocene deposits is problematic, due to the absence of skeletal fossils. The results demonstrate that FTIR is a reliable method for the characterization of the organic matter preserved in carbonates, and generally in all types of sedimentary rocks.

  9. Vascularization of the Selaginella rhizophore: anatomical fingerprints of polar auxin transport with implications for the deep fossil record.

    PubMed

    Matsunaga, Kelly K S; Cullen, Nevin P; Tomescu, Alexandru M F

    2017-02-22

    The Selaginella rhizophore is a unique and enigmatic organ whose homology with roots, shoots, or neither of the two remains unresolved. Nevertheless, rhizophore-like organs have been documented in several fossil lycophytes. Here we test the homology of these organs through comparisons with the architecture of rhizophore vascularization in Selaginella. We document rhizophore vascularization in nine Selaginella species using cleared whole-mounts and histological sectioning combined with three-dimensional reconstruction. Three patterns of rhizophore vascularization are present in Selaginella and each is comparable to those observed in rhizophore-like organs of fossil lycophytes. More compellingly, we found that all Selaginella species sampled exhibit tracheids that arc backward from the stem and side branch into the rhizophore base. This tracheid curvature is consistent with acropetal auxin transport previously documented in the rhizophore and is indicative of the redirection of basipetal auxin from the shoot into the rhizophore during development. The tracheid curvature observed in Selaginella rhizophores provides an anatomical fingerprint for the patterns of auxin flow that underpin rhizophore development. Similar tracheid geometry may be present and should be searched for in fossils to address rhizophore homology and the conservation of auxin-related developmental mechanisms from early stages of lycophyte evolution.

  10. "Fossil" Forecasting.

    ERIC Educational Resources Information Center

    Brody, Michael J.; deOnis, Ann

    2001-01-01

    Presents a density study in which students calculate the density of limestone substrate to determine if the specimen contains any fossils. Explains how to make fossils and addresses national standards. (YDS)

  11. A Record of Moisture History in Hawaii since the Arrival of Humans Inferred from Testate Amoebae and Cladocera Fossils Preserved in Bog Sediments

    NASA Astrophysics Data System (ADS)

    Barrett, K.; Kim, S. H.; Hotchkiss, S.

    2015-12-01

    Around AD 800, Polynesians arrived on the Hawaiian Islands where they expanded and intensified distinct agricultural practices in the islands' wet and dry regions. Dryland farming productivity in particular would have been sensitive to atmospheric rearrangements of the ENSO and PDO systems that affect rainfall in Hawaii. The few detailed terrestrial paleoclimate records in Hawaii are mainly derived from vegetation proxies (e.g. pollen, seeds, fruits, and plant biomarkers) which are heavily influenced by widespread landscape modification following human arrival. Here we present initial results of an independent paleomoisture proxy: fossil remains of moisture-sensitive testate amoebae (Protozoa: Rhizopoda) and cladocera (water fleas) preserved in continuous bog sediments on Kohala Volcano uplsope of the ancient Kohala agricultural field system, one of the largest dryland field systems in Hawaii. Hydrologic conditions inferred from testate amoebae and cladoceran fossil assemblages correlate with observed decadal moisture regimes in Hawaii and state changes of the PDO system during the last century. Testate ameoabe and cladoceran fossils in older sediments reveal an alternating history of very wet, lake-forming conditions on the bog surface to periods when bog soils were much drier than today's, demonstrating that this method can be paired with vegetation proxies to provide a better understanding of hydroclimate variability in prehistoric Hawaii.

  12. First Fossil Record of Alphonsea Hk. f. & T. (Annonaceae) from the Late Oligocene Sediments of Assam, India and Comments on Its Phytogeography

    PubMed Central

    Srivastava, Gaurav; Mehrotra, Rakesh C.

    2013-01-01

    A new fossil leaf impression of Alphonsea Hk. f. & T. of the family Annonaceae is described from the Late Oligocene sediments of Makum Coalfield, Assam, India. This is the first authentic record of the fossil of Alphonsea from the Tertiary rocks of South Asia. The Late Oligocene was the time of the last significant globally warm climate and the fossil locality was at 10°–15°N palaeolatitude. The known palaeoflora and sedimentological studies indicate a fluvio-marine deltaic environment with a mosaic of mangrove, fluvial, mire and lacustrine depositional environments. During the depositional period the suturing between the Indian and Eurasian plates was not complete to facilitate the plant migration. The suturing was over by the end of the Late Oligocene/beginning of Early Miocene resulting in the migration of the genus to Southeast Asia where it is growing profusely at present. The present study is in congruence with the earlier published palaeofloral and molecular phylogenetic data. The study also suggests that the Indian plate was not only a biotic ferry during its northward voyage from Gondwana to Asia but also a place for the origin of several plant taxa. PMID:23349701

  13. First fossil record of Alphonsea Hk. f. & T. (Annonaceae) from the Late Oligocene sediments of Assam, India and comments on its phytogeography.

    PubMed

    Srivastava, Gaurav; Mehrotra, Rakesh C

    2013-01-01

    A new fossil leaf impression of Alphonsea Hk. f. & T. of the family Annonaceae is described from the Late Oligocene sediments of Makum Coalfield, Assam, India. This is the first authentic record of the fossil of Alphonsea from the Tertiary rocks of South Asia. The Late Oligocene was the time of the last significant globally warm climate and the fossil locality was at 10°-15°N palaeolatitude. The known palaeoflora and sedimentological studies indicate a fluvio-marine deltaic environment with a mosaic of mangrove, fluvial, mire and lacustrine depositional environments. During the depositional period the suturing between the Indian and Eurasian plates was not complete to facilitate the plant migration. The suturing was over by the end of the Late Oligocene/beginning of Early Miocene resulting in the migration of the genus to Southeast Asia where it is growing profusely at present. The present study is in congruence with the earlier published palaeofloral and molecular phylogenetic data. The study also suggests that the Indian plate was not only a biotic ferry during its northward voyage from Gondwana to Asia but also a place for the origin of several plant taxa.

  14. Abundant climatic information in water stable isotope record from a maritime glacier on southeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Zhao, Huabiao; Xu, Baiqing; Li, Zhen; Wang, Mo; Li, Jiule; Zhang, Xiaolong

    2017-02-01

    Climatic significance of ice core stable isotope record in the Himalayas and southern Tibetan Plateau (TP), where the climate is alternately influenced by Indian summer monsoon and mid-latitude westerlies, is still debated. A newly drilled Zuoqiupu ice core from a temperate maritime glacier on the southeastern TP covering 1942-2011 is investigated in terms of the relationships between δ18O and climate parameters. Distinct seasonal variation of δ18O is observed due to high precipitation amount in this area. Thus the monsoon (June to September) and non-monsoon (October to May) δ18O records are reconstructed, respectively. The temperature effect is identified in the annual δ18O record, which is predominantly contributed by temperature control on the non-monsoon precipitation δ18O record. Conversely, the negative correlation between annual δ18O record and precipitation amount over part of Northeast India is mostly contributed by the monsoon precipitation δ18O record. The variation of monsoon δ18O record is greatly impacted by the Indian summer monsoon strength, while that of non-monsoon δ18O record is potentially associated with the mid-latitude westerly activity. The relationship between Zuoqiupu δ18O record and Sea Surface Temperature (SST) is found to be inconsistent before and after the climate shift of 1976/1977. In summer monsoon season, the role of SST in the monsoon δ18O record is more important in eastern equatorial Pacific Ocean and tropical Indian Ocean before and after the shift, respectively. In non-monsoon season, however, the Atlantic Multidecadal Oscillation has a negative impact before but positive impact after the climate shift on the non-monsoon δ18O record.

  15. Fossil Explorers

    ERIC Educational Resources Information Center

    Moran, Sean; McLaughlin, Cheryl; MacFadden, Bruce; Jacobbe, Elizabeth; Poole, Michael

    2015-01-01

    Many young learners are fascinated with fossils, particularly charismatic forms such as dinosaurs and giant sharks. Fossils provide tangible, objective evidence of life that lived millions of years ago. They also provide a timescale of evolution not typically appreciated by young learners. Fossils and the science of paleontology can, therefore,…

  16. Marquee Fossils

    ERIC Educational Resources Information Center

    Clary, Renee; Wandersee, James

    2008-01-01

    Professors of an online graduate-level paleontology class developed the concept of marquee fossils--fossils that have one or more unique characteristics that capture the attention and direct observation of students. In the classroom, Marquee fossils integrate the geology, biology, and environmental science involved in the study of fossilized…

  17. Abundance not linked to survival across the end-Cretaceous mass extinction: patterns in North American bivalves.

    PubMed

    Lockwood, Rowan

    2003-03-04

    Ecological studies suggest that rare taxa are more likely to go extinct than abundant ones, but the influence of abundance on survivorship in the fossil record has received little attention. An analysis of Late Maastrichtian bivalve subgenera from the North American Coastal Plain found no evidence that survivorship is tied to abundance across the end-Cretaceous mass extinction (65 million years ago), regardless of abundance metric or spatial scale examined. The fact that abundance does not promote survivorship in end-Cretaceous bivalves suggests that the factors influencing survivorship during mass extinctions in the fossil record may differ from those operating during intervals of background extinction.

  18. First record of fossil wood and phytolith assemblages of the Late Pleistocene in El Palmar National Park (Argentina)

    NASA Astrophysics Data System (ADS)

    Zucol, A. F.; Brea, M.; Scopel, A.

    2005-10-01

    Two paleoxylologic assemblages and two phytolith assemblages were recovered from Late Pleistocene sediments of El Palmar Formation. These deposits are found in outcrops along the western margin of the Uruguay River. The spectra of taxa obtained in both sets by different methods is complementary. The fossil remains are characterized in terms of floristic composition and paleoclimate. Seven families are recognized: Podostemaceae, Myrtaceae, Anacardiaceae, Mimosoideae, Arecaceae, Poaceace, and Cyperaceae. Sponge siliceous spicules also have been found in these assemblages. The state of preservation of the phytoliths and their weathering degree is analyzed. These studies can be used as a potential paleoecological tool for alluvial sediments. The comparison of fossil assemblages with modern analogs clarifies the paleoecological requirements and composition of two paleocommunities, one dominated by woody forests and the other by palms. The climatic conditions inferred from the reconstructed vegetation and sedimentary deposits indicate a temperate-warm, humid climate. The results constitute the first evidence of the floral diversity of the vegetation in El Palmar National Park during the Late Pleistocene.

  19. Parasites in the fossil record: a Cretaceous fauna with isopod-infested decapod crustaceans, infestation patterns through time, and a new ichnotaxon.

    PubMed

    Klompmaker, Adiël A; Artal, Pedro; van Bakel, Barry W M; Fraaije, René H B; Jagt, John W M

    2014-01-01

    Parasites are common in modern ecosystems and are also known from the fossil record. One of the best preserved and easily recognisable examples of parasitism in the fossil record concerns isopod-induced swellings in the branchial chamber of marine decapod crustaceans. However, very limited quantitative data on the variability of infestation percentages at the species, genus, and family levels are available. Here we provide this type of data for a mid-Cretaceous (upper Lower Cretaceous, upper Albian) reef setting at Koskobilo, northern Spain, on the basis of 874 specimens of anomurans and brachyurans. Thirty-seven specimens (4.2%), arranged in ten species, are infested. Anomurans are more heavily infested than brachyurans, variability can be high within genera, and a relationship may exist between the number of specimens and infestation percentage per taxon, possibly suggesting host-specificity. We have also investigated quantitative patterns of infestation through geological time based on 88 infested species (25 anomurans, 55 brachyurans, seven lobsters, and one shrimp), to show that the highest number of infested species can be found in the Late Jurassic, also when corrected for the unequal duration of epochs. The same Late Jurassic peak is observed for the percentage of infested decapod species per epoch. This acme is caused entirely by infested anomurans and brachyurans. Biases (taphonomic and otherwise) and causes of variability with regard to the Koskobilo assemblage and infestation patterns through time are discussed. Finally, a new ichnogenus and -species, Kanthyloma crusta, are erected to accommodate such swellings or embedment structures (bioclaustrations).

  20. Palaeolithic use of fossil combustible linked to singular environmental conditions : the long term el Kowm record (Syria).

    NASA Astrophysics Data System (ADS)

    Courty, M.-A.; Le Tensorer, J.-M.; Boëda, E.; Muhesen, S.; Alsakhel, E.; Wegmüller, F.

    2012-04-01

    Identifying the adaptation of hunter-gatherer communities to particular situations that provided natural resources is a major concern for multidisciplinary team studying archaeological contexts. This challenge is illustrated in the desertic El Kowm basin in central Syria by data from Hummal and El Kowm Paleolithic sites. The sites form prominent mounds at artesian springs resulting from recurrent episodes of lacustrine, limnic and aeolian sedimentation in pseudo-karstic depressions. The few meter sequences provide semi-continuous succession of archaeological levels from the Oldest Palaeolithic (Oldowan) to the early Neolithic period. This long term continuity of occupation is partly due to attracting conditions due to the profusion of water from epithermal artesian wells during periods of high water recharge. In addition, we document here the unique potential of this endoreic basin to have accumulated singular fossil combustible of high energy value during particular environmental episodes. The latter are represented by the recurrence of distinctive black organogenic facies showing a contrasting micro stratification formed of interlayered grey calcareous silty clay, dark brown organic rich clay and dull orange clay. Spatial excavation has shown the unique preservation of Palaeolithic occupation surfaces in association to the microstratified facies. High resolution sampling and multi-proxy analysis have allowed explaining the formation of the microstratified facies from rapid changes of environmental conditions in response to contrasting fluctuations of atmospheric dust loading, precipitation events, rainwater quality and evapotranspiration. Organogenic microfacies formed at different time periods share common compositional assemblage and structural behaviour: occurrence of exotic fine sand-sized debris formed of metal-rich carbonaceous components with polymer, fine charcoal, vitrous carbon, carbon fibres, and exotic rock clasts with a metal-rich carbonaceous

  1. A diverse Rancholabrean vertebrate microfauna from southern California includes the first fossil record of ensatina ( Ensatina eschscholtzii: Plethodontidae)

    NASA Astrophysics Data System (ADS)

    Wake, Thomas A.; Roeder, Mark A.

    2009-11-01

    Analysis of late Pleistocene fossils recovered from near the Huntington Beach, California (USA), pier (site LACM 7679) has revealed a diverse fauna dating to approximately 40 14C ka BP. Extinct megafauna (three genera) are present; however, a microfauna including three genera of fish, five genera of amphibians, twelve genera of reptiles, two genera of birds, and ten genera of small mammals dominates the assemblage in terms of diversity. Additional identification of seven genera of non-marine mollusks and various macro- and microscopic plant remains including grasses, three families of herbs, and seven genera of trees provides a wealth of information concerning the past ecology of what is currently a coastal dune field complex. During the Rancholabrean Period, the LACM 7679 locality was approximately 10 km inland from the Pleistocene coastline and contained lush riparian zones interspersed with coastal sage scrub, a few trees, and grasslands teeming with a variety of small and large animals.

  2. Consequences of elevated temperature and pCO2 on insect folivory at the ecosystem level: perspectives from the fossil record.

    PubMed

    Currano, Ellen D; Laker, Rachel; Flynn, Andrew G; Fogt, Kari K; Stradtman, Hillary; Wing, Scott L

    2016-07-01

    Paleoecological studies document the net effects of atmospheric and climate change in a natural laboratory over timescales not accessible to laboratory or ecological studies. Insect feeding damage is visible on well-preserved fossil leaves, and changes in leaf damage through time can be compared to environmental changes. We measured percent leaf area damaged on four fossil leaf assemblages from the Bighorn Basin, Wyoming, that range in age from 56.1 to 52.65 million years (Ma). We also include similar published data from three US sites 49.4 to ~45 Ma in our analyses. Regional climate was subtropical or warmer throughout this period, and the second oldest assemblage (56 Ma) was deposited during the Paleocene-Eocene Thermal Maximum (PETM), a geologically abrupt global warming event caused by massive release of carbon into the atmosphere. Total and leaf-chewing damage are highest during the PETM, whether considering percent area damaged on the bulk flora, the average of individual host plants, or a single plant host that occurs at multiple sites. Another fossil assemblage in our study, the 52.65 Ma Fifteenmile Creek paleoflora, also lived during a period of globally high temperature and pCO 2, but does not have elevated herbivory. Comparison of these two sites, as well as regression analyses conducted on the entire dataset, demonstrates that, over long timescales, temperature and pCO 2 are uncorrelated with total insect consumption at the ecosystem level. Rather, the most important factor affecting herbivory is the relative abundance of plants with nitrogen-fixing symbionts. Legumes dominate the PETM site; their prevalence would have decreased nitrogen limitation across the ecosystem, buffering generalist herbivore populations against decreased leaf nutritional quality that commonly occurs at high pCO 2. We hypothesize that nitrogen concentration regulates the opposing effects of elevated temperature and CO 2 on insect abundance and thereby total insect consumption

  3. How fragmented was the British Holocene wildwood? Perspectives on the “Vera” grazing debate from the fossil beetle record

    NASA Astrophysics Data System (ADS)

    Whitehouse, Nicki J.; Smith, David

    2010-02-01

    The reconstruction and structure of the European Holocene "wildwood" has been the focus of considerable academic debate. The ability of palaeoecological data and particularly pollen analysis to accurately reflect the density of wildwood canopy has also been widely discussed. Fossil insects, as a proxy for vegetation and landscape structure, provide a potential approach to address this argument. Here, we present a review and re-analysis of 36 early and mid-Holocene (9500-2000 cal BC) sub-fossil beetle assemblages from Britain, examining percentage values of tree, open ground and dung beetles as well as tree host data to gain an insight into vegetation structure, the role of grazing animals in driving such structure and establish independently the importance of different types of trees and associated shading in the early Holocene "wildwood". Open indicator beetle species are persistently present over the entire review period, although they fluctuate in importance. During the early Holocene (9500-6000 cal BC), these indicators are initially high, at levels which are not dissimilar to modern data from pasture woodland. However, during the latter stages of this and the next period, 6000-4000 cal BC, open ground and pasture indicators decline and are generally low compared with previously. Alongside this pattern, we see woodland indicators generally increase in importance, although there are significant local fluctuations. Levels of dung beetles are mostly low over these periods, with some exceptions to this pattern, especially towards the end of the Mesolithic and in floodplain areas. Host data associated with the fossil beetles indicate that trees associated with lighter canopy conditions such as oak, pine, hazel and birch are indeed important components of the tree canopy during the earlier Holocene (c. 9500-6000 cal BC), in accordance with much of the current pollen literature. Beetles associated with more shade-tolerant trees (such as lime and elm) become more

  4. The Effect Of microbial Mats In The Decay Of Anurans With Implications For Understanding Taphonomic Processes In The Fossil Record

    PubMed Central

    Iniesto, M.; Villalba, I.; Buscalioni, A. D.; Guerrero, M. C.; López-Archilla, A. I.

    2017-01-01

    The pattern and sequence of the decomposition of the Pipidae African dwarf frog (Hymenochirus boettgeri) is tracked in an experiment with microbial mats in order to explore soft tissue preservation over three years. Frog decay in microbial mats is preceded by rapid entombment (25–30 days) and mediated by the formation of a sarcophagus, which is built by a complex microbial community. The frog carcasses maintained a variety of soft tissues for years. Labile organic structures show greater durability within the mat, cells maintain their general shape (bone marrow cells and adipocytes), and muscles and connective tissues (adipose and fibrous tendons) exhibit their original organic structures. In addition, other soft tissues are promptly mineralized (day 540) in a Ca-rich carbonate phase (encephalic tectum) or enriched in sulphur residues (integumentary system). The result is coherent with a bias in soft-tissue preservation, as some tissues are more likely to be conserved than others. The outcomes support observations of exceptionally preserved fossil anurans (adults and tadpoles). Decomposition in mats shows singular conditions of pH and dissolved oxygen. Mineralization processes could be more diverse than in simple heterotrophic biofilms, opening new taphonomic processes that have yet to be explored. PMID:28338095

  5. Microbial fossil record of rocks from the Ross Desert, Antarctica: implications in the search for past life on Mars

    NASA Astrophysics Data System (ADS)

    Wierzchos, Jacek; Ascaso, Carmen

    2002-01-01

    Cryptoendolithic microbial communities living within Antarctic rocks are an example of survival in an extremely cold and dry environment. The extinction of these micro-organisms formerly colonizing sandstone in the Mount Fleming area (Ross Desert), was probably provoked by the hostile environment. This is considered to be a good terrestrial analogue of the first stage of the disappearance of possible life on early Mars. To date, only macroscopically observed indirect biomarkers of the past activity of cryptoendoliths in Antarctic rocks have been described. The present paper confirms, for the first time, the existence of cryptoendolith microbial fossils within these sandstone rocks. The novel in situ application of scanning electron microscopy with backscattered electron imaging and simultaneous use of X-ray energy dispersive spectroscopy allowed the clear detection of microfossils left behind by Antarctic endoliths. Careful interpretation of the morphological features of cells, such as preserved cell walls in algae, fungi and bacteria, cytoplasm elements such as chloroplast membranes in algae and organic matter traces, mineral associations, and the spatial context of these structures all point to their identification as cryptoendolith microfossils. This type of investigation will prompt the development of research strategies aimed at locating and identifying the signs that Martian microbiota, probably only bacteria if they existed, may have been left for us to see.

  6. A Prejudiced Review of Ancient Parasites and Their Host Echinoderms: CSI Fossil Record or Just an Excuse for Speculation?

    PubMed

    Donovan, Stephen K

    2015-01-01

    Recognizing the presence of a parasite and identifying it is a relatively straightforward task for the twenty-first century parasitologist. Not so the pursuit of ancient parasites in fossil organisms, a much more difficult proposition. Herein, Boucot's seven-tiered scheme of reliability classes is applied as a measure of confidence of the recognition of putative parasitism in two echinoderm classes, Upper Palaeozoic crinoids and a Cretaceous echinoid (high confidence is 1, low confidence 7). Of the five examples, the parasitic(?) organism is preserved in only two of them. A zaphrentoid coral on the camerate crinoid Amphoracrinus may have robbed food from the arms (Category 1 or 2B). A pit in what appears to be a carefully selected site on the disparid crinoid Synbathocrinus is associated with a growth deformity of the cup (Category 4). Multiple pits in an Amphoracrinus theca are also associated with a deformed cup, but it is more difficult to interpret (Category 4 or 7). Some specimens of the camerate crinoid Neoplatycrinites have circular grooves or depressions posteriorly, presumably produced by coprophagic/parasitic platyceratid gastropods (Category 1). Site selectivity of pits in the echinoid Hemipneustes places them preferentially adjacent to respiratory tube feet (Category 4). From these examples it is deduced that sparse infestations of borings or epizoozoic organisms permit a more confident interpretation of organism/organism interactions; dense accumulations, possibly following multiple spatfalls, mask such patterns.

  7. Fossil Fuels.

    ERIC Educational Resources Information Center

    Crank, Ron

    This instructional unit is one of 10 developed by students on various energy-related areas that deals specifically with fossil fuels. Some topics covered are historic facts, development of fuels, history of oil production, current and future trends of the oil industry, refining fossil fuels, and environmental problems. Material in each unit may…

  8. Ediacara Fossils

    ERIC Educational Resources Information Center

    Science Teacher, 2005

    2005-01-01

    Now, a research team from Virginia Tech and Nanjing Institute of Geology and Paleontology has discovered uniquely well-preserved fossil forms from 550-million-year-old rocks of the Ediacaran Period. The research appears in the Proceedings of the National Academy of Sciences. The discovery of these unusually preserved fossils reveals unprecedented…

  9. Osteological associations with unique tooth development in manatees (Trichechidae, Sirenia): a detailed look at modern Trichechus and a review of the fossil record.

    PubMed

    Beatty, Brian Lee; Vitkovski, Taisia; Lambert, Olivier; Macrini, Thomas E

    2012-09-01

    Modern manatees have a unique type of tooth development, continually forming identical new molars in the posterior end of each quadrant of their mouths, and then progressively moving teeth anteriorly, only to reabsorb roots and spit out worn crowns. This process is not only developmentally complex, but requires space in the oral cavity that imposes its own limitations on other uses of that space. To gain a clearer understanding of the anatomical constraints on the evolution of this unique developmental process, we identified the specialized craniodental features in modern Trichechus that permit this specialization using visual observation and CT. Furthermore, to better understand the evolution of these traits, we review the fossil record of trichechids for these traits, including CT analysis of the skull of Miosiren kocki, a possible early member of the family from the Early Miocene of Belgium.

  10. Parasites in the Fossil Record: A Cretaceous Fauna with Isopod-Infested Decapod Crustaceans, Infestation Patterns through Time, and a New Ichnotaxon

    PubMed Central

    Klompmaker, Adiël A.; Artal, Pedro; van Bakel, Barry W. M.; Fraaije, René H. B.; Jagt, John W. M.

    2014-01-01

    Parasites are common in modern ecosystems and are also known from the fossil record. One of the best preserved and easily recognisable examples of parasitism in the fossil record concerns isopod-induced swellings in the branchial chamber of marine decapod crustaceans. However, very limited quantitative data on the variability of infestation percentages at the species, genus, and family levels are available. Here we provide this type of data for a mid-Cretaceous (upper Lower Cretaceous, upper Albian) reef setting at Koskobilo, northern Spain, on the basis of 874 specimens of anomurans and brachyurans. Thirty-seven specimens (4.2%), arranged in ten species, are infested. Anomurans are more heavily infested than brachyurans, variability can be high within genera, and a relationship may exist between the number of specimens and infestation percentage per taxon, possibly suggesting host-specificity. We have also investigated quantitative patterns of infestation through geological time based on 88 infested species (25 anomurans, 55 brachyurans, seven lobsters, and one shrimp), to show that the highest number of infested species can be found in the Late Jurassic, also when corrected for the unequal duration of epochs. The same Late Jurassic peak is observed for the percentage of infested decapod species per epoch. This acme is caused entirely by infested anomurans and brachyurans. Biases (taphonomic and otherwise) and causes of variability with regard to the Koskobilo assemblage and infestation patterns through time are discussed. Finally, a new ichnogenus and -species, Kanthyloma crusta, are erected to accommodate such swellings or embedment structures (bioclaustrations). PMID:24667587

  11. A high-elevation, multi-proxy biotic and environmental record of MIS 6-4 from the Ziegler Reservoir fossil site, Snowmass Village, Colorado, USA

    USGS Publications Warehouse

    Miller, Ian M.; Pigati, Jeffrey S.; Anderson, R. Scott; Johnson, Kirk R.; Mahan, Shannon; Ager, Thomas A.; Baker, Richard G.; Blaauw, Maarten; Bright, Jordon; Brown, Peter M.; Bryant, Bruce; Calamari, Zachary T.; Carrara, Paul E.; Michael D., Cherney; Demboski, John R.; Elias, Scott A.; Fisher, Daniel C.; Gray, Harrison J.; Haskett, Danielle R.; Honke, Jeffrey S.; Jackson, Stephen T.; Jiménez-Moreno, Gonzalo; Kline, Douglas; Leonard, Eric M.; Lifton, Nathaniel A.; Lucking, Carol; McDonald, H. Gregory; Miller, Dane M.; Muhs, Daniel R.; Nash, Stephen E.; Newton, Cody; Paces, James B.; Petrie, Lesley; Plummer, Mitchell A.; Porinchu, David F.; Rountrey, Adam N.; Scott, Eric; Sertich, Joseph J. W.; Sharpe, Saxon E.; Skipp, Gary L.; Strickland, Laura E.; Stucky, Richard K.; Thompson, Robert S.; Wilson, Jim

    2014-01-01

    In North America, terrestrial records of biodiversity and climate change that span Marine Oxygen Isotope Stage (MIS) 5 are rare. Where found, they provide insight into how the coupling of the ocean–atmosphere system is manifested in biotic and environmental records and how the biosphere responds to climate change. In 2010–2011, construction at Ziegler Reservoir near Snowmass Village, Colorado (USA) revealed a nearly continuous, lacustrine/wetland sedimentary sequence that preserved evidence of past plant communities between ~ 140 and 55 ka, including all of MIS 5. At an elevation of 2705 m, the Ziegler Reservoir fossil site also contained thousands of well-preserved bones of late Pleistocene megafauna, including mastodons, mammoths, ground sloths, horses, camels, deer, bison, black bear, coyotes, and bighorn sheep. In addition, the site contained more than 26,000 bones from at least 30 species of small animals including salamanders, otters, muskrats, minks, rabbits, beavers, frogs, lizards, snakes, fish, and birds. The combination of macro- and micro-vertebrates, invertebrates, terrestrial and aquatic plant macrofossils, a detailed pollen record, and a robust, directly dated stratigraphic framework shows that high-elevation ecosystems in the Rocky Mountains of Colorado are climatically sensitive and varied dramatically throughout MIS 5.

  12. A high-elevation, multi-proxy biotic and environmental record of MIS 6–4 from the Ziegler Reservoir fossil site, Snowmass Village, Colorado, USA

    SciTech Connect

    Ian M. Miller; Mitchell A. Plummer; Various Others

    2014-10-01

    In North America, terrestrial records of biodiversity and climate change that span Marine Oxygen Isotope Stage (MIS) 5 are rare. Where found, they provide insight into how the coupling of the ocean–atmosphere system is manifested in biotic and environmental records and how the biosphere responds to climate change. In 2010–2011, construction at Ziegler Reservoir near Snowmass Village, Colorado (USA) revealed a nearly continuous, lacustrine/wetland sedimentary sequence that preserved evidence of past plant communities between ~140 and 55 ka, including all of MIS 5. At an elevation of 2705 m, the Ziegler Reservoir fossil site also contained thousands of well-preserved bones of late Pleistocene megafauna, including mastodons, mammoths, ground sloths, horses, camels, deer, bison, black bear, coyotes, and bighorn sheep. In addition, the site contained more than 26,000 bones from at least 30 species of small animals including salamanders, otters, muskrats, minks, rabbits, beavers, frogs, lizards, snakes, fish, and birds. The combination of macro- and micro-vertebrates, invertebrates, terrestrial and aquatic plant macrofossils, a detailed pollen record, and a robust, directly dated stratigraphic framework shows that high-elevation ecosystems in the Rocky Mountains of Colorado are climatically sensitive and varied dramatically throughout MIS 5

  13. The Late Pleistocene-Holocene community development in Central and SE-Europe in direct fossil record: scope of the approach, common patterns and inter-regional differences.

    NASA Astrophysics Data System (ADS)

    Horacek, Ivan; Lozek, Vojen

    2010-05-01

    The information provided by modern instrumental approaches (molecular phylogeography, ancient DNA analyses, large scale radiocarbon datings etc.) refined the knowledge on Late Quaternary faunal development and range history of particular taxa in essential way. Nevertheless, the direct fossil record remains still an essential substrate in study of that topics, and to reveal all the information, that it may provide, and integrate it with the outputs of the other approaches presents one of the essential aim of the present meeting. Unfortunately, the immediate use of fossil record for the paleoecologic and paleobiogeographic inferences is often limited by its fragmentarity (both in temporal and spatial respects), taphonomic influences and/or locally specific post-sedimentary effects which all may bias it in a considerable degree. Hence, each particular record is to be carefully reexamined in respect to all factor which may bias it - unfortunately, often it is not too easy to respond that task, particularly when the record is retrived from secondary sources. It should also be remembered that the records representing narrow time slices without a robust lithostratigraphic context do not provide any information on the historical and contextual setting of the respective faunal situation. Such information that is essential for reconstructions of paleobiogeography of community development and similar locally-sensitive phenomena can only be retrived from the continuous sedimentary series which establish the sequence of particular faunal events by direct superposition. A sufficiently dense network of such series provides than a possibility of direct inter-regional comparisons and a high resolution information on the paleobiogeography of the Late Pleistocene-Holocene rearrangements of mammalian communities, local variation in history of particular species and its community context. We illustrate productivity of such approach on with aid of the fossil record obtained from

  14. Influence of hydro-sedimentary factors on mollusc death assemblages in a temperate mixed tide-and-wave dominated coastal environment: Implications for the fossil record

    NASA Astrophysics Data System (ADS)

    Poirier, Clément; Sauriau, Pierre-Guy; Chaumillon, Eric; Bertin, Xavier

    2010-10-01

    Mollusc death assemblages were recovered in 98 subtidal sampling stations on the seafloor of the shallow Pertuis Charentais Sea (Atlantic coast of France). Taxonomic composition and spatial distribution of death assemblages were investigated, as well as their response to sediment grain size (field data), bottom shear stress (coupled tide and wave hydrodynamic modelling), and sediment budget (bathymetric difference map). Results showed that molluscs are likely to be reliable paleoenvironmental indicators since death assemblages were able to acquire ecological changes within years (decadal-scale taphonomic inertia), and live-dead agreement inferred from existing data on living benthic communities was high, except close to river mouths and intertidal mudflats that provide terrestrial and intertidal species to subtidal death assemblages, respectively. Taxonomic composition of these within-habitat death assemblages strongly depended on sediment grain size and bottom shear stress, similarly to living subtidal communities. Post-mortem dispersal of shells, owing to relatively low bottom shear stress in the area, was only of a few 10s to 100s of meters, which shows that death assemblages preserved environmental gradients even at a fine spatial scale. Sediment budget had also a significant influence on death assemblages. Thick-shelled epifaunal species were correlated with erosion areas on one side, and thin-shelled infaunal species with deposition on the other, showing that mollusc fossil assemblages could be used as indicators of paleo-sedimentation rate. This new proxy was successfully tested on a previously published Holocene mollusc fossil record from the same area. It was possible to refine the paleoenvironmental interpretation already proposed, in accordance with existing stratigraphic and sedimentological data.

  15. The extinct river shark Glyphis pagoda from the Miocene of Myanmar and a review of the fossil record of the genus Glyphis (Carcharhiniformes: Carcharhinidae).

    PubMed

    Shimada, Kenshu; Egi, Naoko; Tsubamoto, Takehisa; Maung-Maung, Maung-Maung; Thaung-Htike, Thaung-Htike; Zin-Maung-Maung-Thein, Zin-Maung-Maung-Thein; Nishioka, Yuichiro; Sonoda, Teppei; Takai, Masanaru

    2016-09-05

    We redescribe an extinct river shark, Glyphis pagoda (Noetling), on the basis of 20 teeth newly collected from three different Miocene localities in Myanmar. One locality is a nearshore marine deposit (Obogon Formation) whereas the other two localities represent terrestrial freshwater deposits (Irrawaddy sediments), suggesting that G. pagoda from the Irrawaddy sediments was capable of tolerating low salinity like the extant Glyphis. Glyphis pagoda likely reached up to at least 185 cm in total body length and was probably piscivorous. The fossil species occurs in rocks of Myanmar and eastern and western India and stratigraphically ranges at least from the Lower Miocene (Aquitanian) to the lower Upper Miocene (mid-Tortonian). It has been classified under at least eight other genera to date, along with numerous taxonomic synonyms largely stemming from the lack of understanding of the heterodonty in extant Glyphis in the original description. Our literature review suggests that known Miocene shark faunas, particularly those in India, are manifested with unreliable taxonomic identifications and outdated classifications that warrant the need for a comprehensive taxonomic review in order to evaluate the evolutionary history and diversity pattern of Miocene shark faunas. The genus Glyphis has a roughly 23-million-year-long history, and its success may be related to the evolution of its low salinity tolerance. While extant Glyphis spp. are considered to be particularly vulnerable to habitat degradation and overfishing, the fossil record of G. pagoda provides renewed perspective on the natural history of the genus that can be taken into further consideration for conservation biology of the extant forms.

  16. New records and detailed distribution and abundance of selected arthropod species collected between 1999 and 2011 in Azorean native forests

    PubMed Central

    Gaspar, Clara; Crespo, Luís Carlos Fonseca; Rigal, François; Cardoso, Pedro; Pereira, Fernando; Rego, Carla; Amorim, Isabel R.; Melo, Catarina; Aguiar, Carlos; André, Genage; Mendonça, Enésima P.; Ribeiro, Sérvio; Hortal, Joaquín; Santos, Ana M.C.; Barcelos, Luís; Enghoff, Henrik; Mahnert, Volker; Pita, Margarida T.; Ribes, Jordi; Baz, Arturo; Sousa, António B.; Vieira, Virgílio; Wunderlich, Jörg; Parmakelis, Aristeidis; Whittaker, Robert J.; Quartau, José Alberto; Serrano, Artur R.M.; Triantis, Kostas A.

    2016-01-01

    Abstract Background In this contribution we present detailed distribution and abundance data for arthropod species identified during the BALA – Biodiversity of Arthropods from the Laurisilva of the Azores (1999-2004) and BALA2 projects (2010-2011) from 18 native forest fragments in seven of the nine Azorean islands (all excluding Graciosa and Corvo islands, which have no native forest left). New information Of the total 286 species identified, 81% were captured between 1999 and 2000, a period during which only 39% of all the samples were collected. On average, arthropod richness for each island increased by 10% during the time frame of these projects. The classes Arachnida, Chilopoda and Diplopoda represent the most remarkable cases of new island records, with more than 30% of the records being novelties. This study stresses the need to expand the approaches applied in these projects to other habitats in the Azores, and more importantly to other less surveyed taxonomic groups (e.g. Diptera and Hymenoptera). These steps are fundamental for getting a more accurate assessment of biodiversity in the archipelago. PMID:28174509

  17. An expansion of age constraints for microbial clades that lack a conventional fossil record using phylogenomic dating.

    PubMed

    Blank, Carrine E

    2011-10-01

    Most microbial taxa lack a conventional microfossil or biomarker record, and so we currently have little information regarding how old most microbial clades and their associated traits are. Building on the previously published oxygen age constraint, two new age constraints are proposed based on the ability of microbial clades to metabolize chitin and aromatic compounds derived from lignin. Using the archaeal domain of life as a test case, phylogenetic analyses, along with published metabolic and genetic data, showed that members of the Halobacteriales and Thermococcales are able to metabolize chitin. Ancestral state reconstruction combined with phylogenetic analysis of the genes underlying chitin degradation predicted that the ancestors of these two groups were also likely able to metabolize chitin or chitin-related compounds. These two clades were therefore assigned a maximum age of 1.0 Ga (when chitin likely first appeared). Similar analyses also predicted that the ancestor to the Sulfolobus solfataricus-Sulfolobus islandicus clade was able to metabolize phenol using catechol dioxygenase, so this clade was assigned a maximum age of 475 Ma. Inferred ages of archaeal clades using relaxed molecular clocks with the new age constraints were consistent with those inferred with the oxygen age constraints. This work expands our current toolkit to include Paleoproterozoic, Neoproterozoic, and Paleozoic age constraints, and should aid in our ability to phylogenetically reconstruct the antiquity of a wide array of microbial clades and their associated morphological and biogeochemical traits, spanning deep geologic time. Such hypotheses-although built upon evolutionary inferences-are fundamentally testable.

  18. Correlation of Plio Pleistocene Tephra in Ethiopian and Kenyan rift basins: Temporal calibration of geological features and hominid fossil records

    NASA Astrophysics Data System (ADS)

    WoldeGabriel, Giday; Hart, William K.; Katoh, Shigehiro; Beyene, Yonas; Suwa, Gen

    2005-10-01

    The 200-m-thick fossiliferous Konso Formation and overlying terrace deposits, which crop out at the end of the southern sector of the Main Ethiopian Rift (MER), contain more than 30 distal tephra layers. Local and regional tephra correlations of more than 20 tephra units were established using major and trace element data of discrete and purified bulk glass samples within the Konso study area. Eleven correlative marker tuffs were recognized in stratigraphic sections of both the Konso Formation and the Omo-Turkana Basin sediments in southern Ethiopia and northern Kenya. The Turoha, Hope, Ivory, Bright White, and Boleshe Tuffs in the Konso Formation, and the Upper White Tuff in the overlying terrace deposits are securely correlated with the KBS, Akait, Lokapetamoi, Chari, Lower Nariokotome, and Silbo Tuffs of the Omo-Turkana Basin, using least mobile major elements (CaO, Fe 2O 3*, and TiO 2) and geochronology. Preliminary correlations are also suggested between the Konso Formation distal tephra and proximal units of the Quaternary caldera-forming silicic centers in the central sector of the MER. The strongly peralkaline tuffs of the Konso Formation are compositionally similar to proximal eruptions mostly located along the Quaternary axial rift zone of the southern, central, and northern sectors of the MER. The tephra correlation provides information about the temporal and spatial features of the volcanic and tectonic processes recorded in the evolving basins. Thickness and sedimentation rate were determined for both the Konso Formation and the Omo-Turkana Basin sections, measured between the Turoha (=KBS; 1.91 ± 0.03 Ma) and the Bright White (=Chari; 1.40 ± 0.02 Ma) Tuffs. Although the lithostratigraphic sequence at the Konso study area is younger, sedimentation rate within the Konso Formation was comparable to that of the Koobi Fora Formation, higher in the Nachukui Formation, and lower in the Shungura Formation. Local and regional differences in thickness and

  19. Middle Pleistocene Climate Change Recorded in Fossil Mammal Teeth from Tarija, Bolivia, and Upper Limit of the Ensenadan Land-Mammal Age

    NASA Astrophysics Data System (ADS)

    MacFadden, Bruce J.

    2000-07-01

    Fossiliferous middle Pleistocene sediments of the Tarija basin of southern Bolivia contain a classic Ensenadan land-mammal fauna. New carbon isotopic data reported here for 50 specimens of the grazing mammals Equus (horse) and Cuvieronius (mastodon), documented from eight stratigraphic levels at Tarija, vary significantly in the δ13C values of their teeth. The pattern of variation appears to reflect the proportion of C3 and C4 grasses eaten during colder (more C3) and warmer (more C4) times. Within age limits set by associated magnetostratigraphy, the cold periods can be correlated with particular even-numbered stages in the marine oxygen-isotope record, and the warm periods can be correlated with odd-numbered stages. The oldest fossil teeth analyzed from the Tarija section can thereby be assigned to stage 29, and the youngest to stages 17 or 15, that is; the teeth range in age from about 1.1 myr to as young as 0.7 myr. Based on correlation of the upper part of the Tarija beds to the isotopic stages, the upper limit of the Ensenadan land-mammal age is between 0.7 and 0.6 myr, which is younger than stated in most previous studies.

  20. First record of Microscapha LeConte from Baltic amber with description of a new species and list of fossil Melandryidae (Coleoptera: Tenebrionoidea).

    PubMed

    Bukejs, Andris; Alekseev, Vitalii I

    2015-09-03

    Microscapha andrzeji sp. nov., the first fossil representative of the genus is described from Eocene Baltic amber. An updated list of fossil Melandryidae (Coleoptera: Tenebrionoidea) is provided. The presence of Microscapha within Baltic amber suggests some potential for palaeoenvironmental inferences based on the melandryid assemblage within the deposit.

  1. Growth-Dependent Calibration of Coral Sr/Ca-SST From Multiple Colonies Provides Potential for Long SST Records from Fossil Corals

    NASA Astrophysics Data System (ADS)

    Goodkin, N. F.

    2005-12-01

    Extended reconstructions of sea surface temperature (SST) are critical to examining long-term climate variability not captured in instrumental records. Coral skeleton, which continuously accretes in annual density bands, preserves unique, multi-century archives of sub-annual resolution SST. Despite the promise of coral proxies, however, SSTs derived from corals are often several degrees cooler than those derived from other archives. Here we present strontium to calcium ratios (Sr/Ca) for four brain corals (Diploria labyrinthiformis) collected from the south shore of Bermuda that are strongly correlated with both instrumental SST (Hydrostation S, 30km southeast) and annual skeletal extension rate. High Sr/Ca ratios correspond with cold SSTs and slow skeletal growth rate, and vice versa. Over a ~25 year calibration period, the four corals have distinct average growth rates (2.57, 2.68, 3.55 and 4.03 mm/yr). For each colony, we provide a quantitative calibration of annual Sr/Ca to annual extension rate and annual SST along the axis of maximum growth and derive an individual growth dependent Sr/Ca-SST calibration equation: Sr/Ca = m*(SST) + n*(annual growth rate)*(SST) + b The slopes and intercepts of the four equations are found to be linearly related to the average growth-rate during the calibration periods of each colony, and a final multi-variant regression is performed to establish one final Sr/Ca-Growth Rate-SST calibration, in the form: Sr/Ca = m*(SST) + n*(annual growth rate)*(SST) + o*(average colony growth rate)*(SST) + b This growth-dependent calibration is shown to be applicable to a fossil coral of the same species in order to reconstruct SSTs at Bermuda for 223 years. A reconstruction excluding the influence of growth yields SSTs that exaggerate both cool and warm periods. SST anomalies near the end of the Little Ice Age (~1850) that are derived using a non-growth dependent calibration are exaggerated by a factor of two relative to those from a growth

  2. Darwin's Enigma: The Fossil Record.

    ERIC Educational Resources Information Center

    Sunderland, Luther D.

    In December of 1978 the New York State Board of Regents ordered the New York State Education Department to conduct a detailed study of the way in which the subject of origins should be treated in a revised version of the Regents Biology Syllabus. The author was invited to supply scientific information to the Bureau of Science Education, which was…

  3. A rich fossil record yields calibrated phylogeny for Acanthaceae (Lamiales) and evidence for marked biases in timing and directionality of intercontinental disjunctions.

    PubMed

    Tripp, Erin A; McDade, Lucinda A

    2014-09-01

    More than a decade of phylogenetic research has yielded a well-sampled, strongly supported hypothesis of relationships within the large ( > 4000 species) plant family Acanthaceae. This hypothesis points to intriguing biogeographic patterns and asymmetries in sister clade diversity but, absent a time-calibrated estimate for this evolutionary history, these patterns have remained unexplored. Here, we reconstruct divergence times within Acanthaceae using fossils as calibration points and experimenting with both fossil selection and effects of invoking a maximum age prior related to the origin of Eudicots. Contrary to earlier reports of a paucity of fossils of Lamiales (an order of ∼ 23,000 species that includes Acanthaceae) and to the expectation that a largely herbaceous to soft-wooded and tropical lineage would have few fossils, we recovered 51 reports of fossil Acanthaceae. Rigorous evaluation of these for accurate identification, quality of age assessment and utility in dating yielded eight fossils judged to merit inclusion in analyses. With nearly 10 kb of DNA sequence data, we used two sets of fossils as constraints to reconstruct divergence times. We demonstrate differences in age estimates depending on fossil selection and that enforcement of maximum age priors substantially alters estimated clade ages, especially in analyses that utilize a smaller rather than larger set of fossils. Our results suggest that long-distance dispersal events explain present-day distributions better than do Gondwanan or northern land bridge hypotheses. This biogeographical conclusion is for the most part robust to alternative calibration schemes. Our data support a minimum of 13 Old World (OW) to New World (NW) dispersal events but, intriguingly, only one in the reverse direction. Eleven of these 13 were among Acanthaceae s.s., which comprises > 90% of species diversity in the family. Remarkably, if minimum age estimates approximate true history, these 11 events occurred within

  4. Recognition of deep-water benthic assemblages in the fossil record: Taphonomy and community characteristics of Louisiana continental slope petroleum seep assemblages

    SciTech Connect

    Callender, W.R.

    1992-01-01

    Chemoautotrophic benthic assemblages associated with petroleum seepage form the only substantial shell accumulations below storm wave base on the northern Gulf of Mexico shelf and slope. Five biofacies are associated with petroleum seepage, dominated respectively by vestimentiferan tubeworms, lucinid, thyasirid and vesicomyid clams and mytilid mussels. The taphonomy of petroleum seep death assemblages includes dissolution as the most pervasive mode of shell alteration. The dominant species in each assemblage reflect the taphonomic signature of the assemblage they dominate. The taphonomic attributes of petroleum seep death assemblages are similar to those of ancient autochthonous benthic assemblages. Paleoecological characteristics representative of cold seep assemblages include: high density-low diversity molluscan assemblages dominated by large individuals, high molluscan biomass concentrations aligned in linear trends, carbons with depleted [delta][sup 13]C values associated with faunally depauperate shales, laminated or massive sedimentary structures, variable articulation frequencies, poor shell preservation, and a trophic structure dominated by one trophic group. The Campanian Tepee Buttes share many paleoecological characteristics with recognized ancient seep assemblages. Methane and hydrogen sulfide-rich fluids from underlying strata were transported along fault conduits to supply a localized nutrient source for lucinid-dominated benthic communities. The Tepee Butte assemblages were dominated by dense accumulations of Nymphalucina occidentalis with moderate to high articulation frequencies. The lucinids probably used H[sub 2]S as a nutrient source. Cold seeps can be recognized in the fossil record, based on criteria developed by the study of modern cold seep death assemblages, because the paleoecological characteristics of cold seep assemblages are very conservative.

  5. Mud fossils

    USGS Publications Warehouse

    ,

    1997-01-01

    At the close of the 18th century, the haze of fantasy and mysticism that tended to obscure the true nature of the Earth was being swept away. Careful studies by scientists showed that rocks had diverse origins. Some rock layers, containing clearly identifiable fossil remains of fish and other forms of aquatic animal and plant life, originally formed in the ocean. Other layers, consisting of sand grains winnowed clean by the pounding surf, obviously formed as beach deposits that marked the shorelines of ancient seas.

  6. Long-term Records of Pacific Salmon Abundance From Sediment Core Analysis: Relationships to Past Climatic Change, and Implications for the Future

    NASA Astrophysics Data System (ADS)

    Finney, B.

    2002-12-01

    The response of Pacific salmon to future climatic change is uncertain, but will have large impacts on the economy, culture and ecology of the North Pacific Rim. Relationships between sockeye salmon populations and climatic change can be determined by analyzing sediment cores from lakes where sockeye return to spawn. Sockeye salmon return to their natal lake system to spawn and subsequently die following 2 - 3 years of feeding in the North Pacific Ocean. Sockeye salmon abundance can be reconstructed from stable nitrogen isotope analysis of lake sediment cores as returning sockeye transport significant quantities of N, relatively enriched in N-15, from the ocean to freshwater systems. Temporal changes in the input of salmon-derived N, and hence salmon abundance, can be quantified through downcore analysis of N isotopes. Reconstructions of sockeye salmon abundance from lakes in several regions of Alaska show similar temporal patterns, with variability occurring on decadal to millennial timescales. Over the past 2000 years, shifts in sockeye salmon abundance far exceed the historical decadal-scale variability. A decline occurred from about 100 BC - 800 AD, but salmon were consistently more abundant 1200 - 1900 AD. Declines since 1900 AD coincide with the period of extensive commercial fishing. Correspondence between these records and paleoclimatic data suggest that changes in salmon abundance are related to large scale climatic changes over the North Pacific. For example, the increase in salmon abundance c.a. 1200 AD corresponds to a period of glacial advance in southern Alaska, and a shift to drier conditions in western North America. Although the regionally coherent patterns in reconstructed salmon abundance are consistent with the hypothesis that climate is an important driver, the relationships do not always follow patterns observed in the 20th century. A main feature of recorded climate variability in this region is the alternation between multi-decade periods of

  7. Cycles in fossil diversity

    SciTech Connect

    Rohde, Robert A.; Muller, Richard A.

    2004-10-20

    It is well-known that the diversity of life appears to fluctuate during the course the Phanerozoic, the eon during which hard shells and skeletons left abundant fossils (0-542 Ma). Using Sepkoski's compendium of the first and last stratigraphic appearances of 36380 marine genera, we report a strong 62 {+-} 3 Myr cycle, which is particularly strong in the shorter-lived genera. The five great extinctions enumerated by Raup and Sepkoski may be an aspect of this cycle. Because of the high statistical significance, we also consider contributing environmental factors and possible causes.

  8. Cycles in fossil diversity.

    PubMed

    Rohde, Robert A; Muller, Richard A

    2005-03-10

    It is well known that the diversity of life appears to fluctuate during the course of the Phanerozoic, the eon during which hard shells and skeletons left abundant fossils (0-542 million years ago). Here we show, using Sepkoski's compendium of the first and last stratigraphic appearances of 36,380 marine genera, a strong 62 +/- 3-million-year cycle, which is particularly evident in the shorter-lived genera. The five great extinctions enumerated by Raup and Sepkoski may be an aspect of this cycle. Because of the high statistical significance we also consider the contributions of environmental factors, and possible causes.

  9. Fossilization of melanosomes via sulfurization.

    PubMed

    McNamara, Maria E; van Dongen, Bart E; Lockyer, Nick P; Bull, Ian D; Orr, Patrick J

    2016-05-01

    Fossil melanin granules (melanosomes) are an important resource for inferring the evolutionary history of colour and its functions in animals. The taphonomy of melanin and melanosomes, however, is incompletely understood. In particular, the chemical processes responsible for melanosome preservation have not been investigated. As a result, the origins of sulfur-bearing compounds in fossil melanosomes are difficult to resolve. This has implications for interpretations of original colour in fossils based on potential sulfur-rich phaeomelanosomes. Here we use pyrolysis gas chromatography mass spectrometry (Py-GCMS), fourier transform infrared spectroscopy (FTIR) and time of flight secondary ion mass spectrometry (ToF-SIMS) to assess the mode of preservation of fossil microstructures, confirmed as melanosomes based on the presence of melanin, preserved in frogs from the Late Miocene Libros biota (NE Spain). Our results reveal a high abundance of organosulfur compounds and non-sulfurized fatty acid methyl esters in both the fossil tissues and host sediment; chemical signatures in the fossil tissues are inconsistent with preservation of phaeomelanin. Our results reflect preservation via the diagenetic incorporation of sulfur, i.e. sulfurization (natural vulcanization), and other polymerization processes. Organosulfur compounds and/or elevated concentrations of sulfur have been reported from melanosomes preserved in various invertebrate and vertebrate fossils and depositional settings, suggesting that preservation through sulfurization is likely to be widespread. Future studies of sulfur-rich fossil melanosomes require that the geochemistry of the host sediment is tested for evidence of sulfurization in order to constrain interpretations of potential phaeomelanosomes and thus of original integumentary colour in fossils.

  10. The largest fossil rodent

    PubMed Central

    Rinderknecht, Andrés; Blanco, R. Ernesto

    2008-01-01

    The discovery of an exceptionally well-preserved skull permits the description of the new South American fossil species of the rodent, Josephoartigasia monesi sp. nov. (family: Dinomyidae; Rodentia: Hystricognathi: Caviomorpha). This species with estimated body mass of nearly 1000 kg is the largest yet recorded. The skull sheds new light on the anatomy of the extinct giant rodents of the Dinomyidae, which are known mostly from isolated teeth and incomplete mandible remains. The fossil derives from San José Formation, Uruguay, usually assigned to the Pliocene–Pleistocene (4–2 Myr ago), and the proposed palaeoenvironment where this rodent lived was characterized as an estuarine or deltaic system with forest communities. PMID:18198140

  11. The largest fossil rodent.

    PubMed

    Rinderknecht, Andrés; Blanco, R Ernesto

    2008-04-22

    The discovery of an exceptionally well-preserved skull permits the description of the new South American fossil species of the rodent, Josephoartigasia monesi sp. nov. (family: Dinomyidae; Rodentia: Hystricognathi: Caviomorpha). This species with estimated body mass of nearly 1000kg is the largest yet recorded. The skull sheds new light on the anatomy of the extinct giant rodents of the Dinomyidae, which are known mostly from isolated teeth and incomplete mandible remains. The fossil derives from San José Formation, Uruguay, usually assigned to the Pliocene-Pleistocene (4-2Myr ago), and the proposed palaeoenvironment where this rodent lived was characterized as an estuarine or deltaic system with forest communities.

  12. Biomineralization and biosignatures of coralloid-type speleothems from lava tubes of Galapagos Islands: evidences on the fossil record of prokaryotes

    NASA Astrophysics Data System (ADS)

    Miller, Ana Z.; Garcia-Sanchez, Angela M.; Pereira, Manuel F. C.; Gazquez, Fernando; Calaforra, José M.; Forti, Paolo; Toulkeridis, Theofilos; Martínez-Frías, Jesús; Saiz-Jimenez, Cesareo

    2016-04-01

    , whereas the final stage mainly consists of low crystalline calcite. FESEM-EDS analysis revealed mineralized bacterial filaments rich in Si on the coralloid samples, as well as minerals precipitation associated with extracellular polymeric substances (EPS), which serve as nuclei for preferential precipitation on the extracellular sheaths. This suggests that biological activity played a major role in the development of these speleothems. In addition, imprints of filamentous cells and microboring readily preserved on siliceous minerals were observed on the coralloid speleothems. These features are recognized as biosignatures valuable for astrobiology and may represent modern analogs of the fossil record of prokaryotes. DNA-based analyses showed that bacteria belonging to Actinobacteria (31%) Gemmatimonadetes (25%) and Proteobacteria (24%) phyla dominated in this cave ecosystem, followed by Acidobacteria, Firmicutes and Nitrospirae. Most of the identified phylotypes were affiliated to chemoautotrophs, including thermophilic bacteria such as Ferrithrix thermotolerans, and other mineral utilizing microorganisms like Aciditerrimonas ferrireducens, Desulfuromonas sp. and Desulfovibrio sp., indicating that Galapagos lava tubes host highly specialized subsurface biosphere dominated by microorganisms able to interact with minerals and promote biomineralization. Acknowledgments: This work has been supported by the project PC-65-14 from the Ministry of Environment of Ecuador. AZM acknowledges the support from the Marie Curie Fellowship of the 7th EC Framework Programme (PIEF-GA-2012-328689-DECAVE). The authors acknowledge the Spanish Ministry of Economy and Competitiveness (project CGL2013-41674-P) and FEDER funds for financial support.

  13. Patterns of tooth crown size and shape variation in great apes and humans and species recognition in the hominid fossil record.

    PubMed

    Scott, Jeremiah E; Lockwood, Charles A

    2004-12-01

    It has been suggested that patterns of craniodental variation in living hominids (Gorilla, Homo, Pan, and Pongo) may be useful for evaluating variation in fossil hominid assemblages. Using this approach, a fossil sample exhibiting a pattern of variation that deviates from one shared among living taxa would be regarded as taxonomically heterogeneous. Here we examine patterns of tooth crown size and shape variation in great apes and humans to determine 1) if these taxa share a pattern of dental variation, and 2) if such a pattern can reliably discriminate between samples that contain single species and those that contain multiple species. We use parametric and nonparametric correlation methods to establish the degree of pattern similarity among taxa, and randomization tests to assess their statistical significance. The results of this study show that extant hominids do not share a pattern of dental size variation, and thus these taxa cannot be used to generate expectations for patterns of size variation in fossil hominid species. The hominines (Gorilla, Homo, and Pan) do share a pattern of shape variation in the mandibular dentition; however, Pongo is distinct, and thus it is unclear which, if either, pattern should be expected in fossil hominids. Moreover, in this case, most combined-species samples exhibit patterns of shape variation that are similar to those for single hominine species samples. Thus, although a common pattern of shape variation is present in the mandibular dentition, it is not useful for recognizing taxonomically mixed paleontological samples.

  14. Sustainability of Fossil Fuels

    NASA Astrophysics Data System (ADS)

    Lackner, K. S.

    2002-05-01

    effects of injecting excess carbon into the environment need to be eliminated before fossil fuels can be considered sustainable. Sustainable fossil fuel use would likely rely on abundant, low-grade hydrocarbons like coal, tar, and shale. It would require a closed cycle approach in which carbon is extracted from the ground, processed for its energy content, and returned into safe and stable sinks for permanent disposal. Such sequestration technologies already exist and more advanced approaches that could maintain access to fossil energy for centuries are on the drawing boards. I will review these options and outline a pathway towards a zero emission fossil fuel based economy that could provide energy at prices comparable to those of today for several centuries. A successful implementation will depend not only on technological advances but also on the development of economic institutions that allow one to pay for the required carbon management. If done correctly the markets will decide whether renewable energy, or sustainable fossil energy provides a better choice.

  15. Are the oldest 'fossils', fossils

    NASA Technical Reports Server (NTRS)

    Schopf, J. W.

    1976-01-01

    A comparative statistical study has been carried out on populations of modern algae, Precambrian algal microfossils, the 'organized elements' of the Orgueil carbonaceous meteorite, and the oldest microfossil-like objects now known (spheroidal bodies from the Fig Tree and Onverwacht Groups of the Swaziland Supergroup, South Africa). The distribution patterns exhibited by the more than 3000 m.y.-old Swaziland microstructures bear considerable resemblance to those of the abiotic 'organized elements' but differ rather markedly from those exhibited by younger, assuredly biogenic, populations. Based on these comparisons, it is concluded that the Swaziland spheroids could be, at least in part, of nonbiologic origin; these oldest known fossil-like microstructures should not be regarded as constituting firm evidence of Archean life.

  16. Fossil Leaves and Fossil Leaf n-Alkanes: Reconstructing the First Closed Canopied Rainforests

    NASA Astrophysics Data System (ADS)

    Graham, H. V.; Freeman, K. H.

    2013-12-01

    characteristics associated with canopy effect. A biomass flux-weighted model of alkane chain-length distribution and δ13Cleaf indicate n-alkanes extracted from bulk rock are consistent with inputs integrated over time from plants represented by fossil leaves. In a modern rainforest, we found leaf lipid amounts markedly higher in the shaded and moist understory, consistent with studies that show alkanes proffer fungal protection. Shade tolerance is associated with higher plant orders and, consistent with this, literature data for modern plants from 30 plant orders shows alkane production in asterids and rosids is 2 to 3 times greater than in basal angiosperms or gymnosperms. The lower clades tend to contain greater amounts of terpenoids and novel benzylisoquinoline alkaloids, rather than alkanes. For our three fossil floras, alkane abundance is strongly influenced by depositional setting, with preservation best in the lacustrine setting. Within each site, abundance patterns are potentially influenced by both taxonomic affiliation and by canopy structure as measured by δ13Cleaf values, and such relationships shed light on the combined influences of plant evolution, canopy structure and the function of biochemical resources on the geochemical record of the first rainforests.

  17. Will My Fossil Float?

    ERIC Educational Resources Information Center

    Riesser, Sharon; Airey, Linda

    1993-01-01

    Explains how young students can be introduced to fossils. Suggests books to read and science activities including "Fossils to Eat" where students make fossils from peanut butter, honey, and powdered milk. (PR)

  18. Major Radiations in the Evolution of Caviid Rodents: Reconciling Fossils, Ghost Lineages, and Relaxed Molecular Clocks

    PubMed Central

    Pérez, María Encarnación; Pol, Diego

    2012-01-01

    Background Caviidae is a diverse group of caviomorph rodents that is broadly distributed in South America and is divided into three highly divergent extant lineages: Caviinae (cavies), Dolichotinae (maras), and Hydrochoerinae (capybaras). The fossil record of Caviidae is only abundant and diverse since the late Miocene. Caviids belongs to Cavioidea sensu stricto (Cavioidea s.s.) that also includes a diverse assemblage of extinct taxa recorded from the late Oligocene to the middle Miocene of South America (“eocardiids”). Results A phylogenetic analysis combining morphological and molecular data is presented here, evaluating the time of diversification of selected nodes based on the calibration of phylogenetic trees with fossil taxa and the use of relaxed molecular clocks. This analysis reveals three major phases of diversification in the evolutionary history of Cavioidea s.s. The first two phases involve two successive radiations of extinct lineages that occurred during the late Oligocene and the early Miocene. The third phase consists of the diversification of Caviidae. The initial split of caviids is dated as middle Miocene by the fossil record. This date falls within the 95% higher probability distribution estimated by the relaxed Bayesian molecular clock, although the mean age estimate ages are 3.5 to 7 Myr older. The initial split of caviids is followed by an obscure period of poor fossil record (refered here as the Mayoan gap) and then by the appearance of highly differentiated modern lineages of caviids, which evidentially occurred at the late Miocene as indicated by both the fossil record and molecular clock estimates. Conclusions The integrated approach used here allowed us identifying the agreements and discrepancies of the fossil record and molecular clock estimates on the timing of the major events in cavioid evolution, revealing evolutionary patterns that would not have been possible to gather using only molecular or paleontological data alone. PMID

  19. Statistical Models for Inferring Vegetation Composition from Fossil Pollen

    NASA Astrophysics Data System (ADS)

    Paciorek, C.; McLachlan, J. S.; Shang, Z.

    2011-12-01

    Fossil pollen provide information about vegetation composition that can be used to help understand how vegetation has changed over the past. However, these data have not traditionally been analyzed in a way that allows for statistical inference about spatio-temporal patterns and trends. We build a Bayesian hierarchical model called STEPPS (Spatio-Temporal Empirical Prediction from Pollen in Sediments) that predicts forest composition in southern New England, USA, over the last two millenia based on fossil pollen. The critical relationships between abundances of tree taxa in the pollen record and abundances in actual vegetation are estimated using modern (Forest Inventory Analysis) data and (witness tree) data from colonial records. This gives us two time points at which both pollen and direct vegetation data are available. Based on these relationships, and incorporating our uncertainty about them, we predict forest composition using fossil pollen. We estimate the spatial distribution and relative abundances of tree species and draw inference about how these patterns have changed over time. Finally, we describe ongoing work to extend the modeling to the upper Midwest of the U.S., including an approach to infer tree density and thereby estimate the prairie-forest boundary in Minnesota and Wisconsin. This work is part of the PalEON project, which brings together a team of ecosystem modelers, paleoecologists, and statisticians with the goal of reconstructing vegetation responses to climate during the last two millenia in the northeastern and midwestern United States. The estimates from the statistical modeling will be used to assess and calibrate ecosystem models that are used to project ecological changes in response to global change.

  20. First fossil record of Discocephalinae (Insecta, Pentatomidae): a new genus from the middle Eocene of Río Pichileufú, Patagonia, Argentina

    PubMed Central

    Petrulevičius, Julián F.; Popov, Yuri A.

    2014-01-01

    Abstract A new genus and species of Discocephalini, Acanthocephalonotum martinsnetoi gen. n. et sp. n. is described from Río Pichileufú, middle Eocene of Patagonia, Argentina at palaeolatitude ~ 46°S. The new species is the first fossil representative of the Discocephalinae. This taxon is extant in equatorial to subtropical America, and some species reach warm temperate latitudes (Buenos Aires province). The new genus is distinguished from the other genera of Discocephalini by the combination of these characters: interocular width greater than head length; head massive and quadrangular with the anterior margin almost straight; juga touching each other; labrum thick and curved; triangular ante-ocular process extending beyond the eye; broad spine-like antero-lateral process of the pronotum; pronotum explanate and bean shaped; scutellum triangular with a circular tongue reaching the anterior side of abdominal segment 7; and wings well developed with membrane just surpassing end of abdomen. PMID:25061387

  1. Fossil Shorelines Record Multiple Sea Level Highstands and Surface Deformation on Million Year Timescales at Cape Range National Park, Northwestern Australia

    NASA Astrophysics Data System (ADS)

    Sandstrom, R. M.; O'Leary, M.; Barham, M.; Cai, Y.; Jacome, A. P.; Raymo, M. E.

    2015-12-01

    Correcting fossil shorelines for vertical displacement subsequent to deposition is a vital consideration in estimating sea level and ice volume during past warm periods. Field observations of paleo-sea level indicators must be adjusted for local tectonic deformation, subsequent sediment loading, dynamic topography (DT), and glacial isostatic adjustment (GIA). Dynamic topography is often the most difficult of these corrections to determine, especially on million year timescales, but is essential when providing constraints on sea level and ice volume changes. GIA effects from high latitude ice sheets minimally impact northwestern Australia, making this region well suited for observing surface displacement due to mantle and tectonic processes. This study presents centimeter accuracy paleo-shoreline data from four distinct marine terraces in the Cape Range National Park, Australia, which document vertical displacement history along 100 kilometers of coastline. The mapped region has an anticlinal structure in the center that has been slowly uplifting the three older reef complexes over the Neogene, constraining the timing of deformation. These neotectonics are probably caused by reactivation of ancient fault zones normal to the principal horizontal compressive stress, resulting in the warping of overlaying units. The elevation data also suggests minimal vertical displacement since the last interglacial highstand. Well-preserved fossil coral were collected from each terrace and will be geochemically dated using Sr isotope and U-series dating methods. This dataset provides a better understanding of DT and neotectonic deformation in this region (useful for improving mantle viscosity models), and offers a means for improving past sea level reconstructions in northwestern Australia.

  2. Congruent phylogenetic and fossil signatures of mammalian diversification dynamics driven by Tertiary abiotic change.

    PubMed

    Cantalapiedra, Juan L; Hernández Fernández, Manuel; Azanza, Beatriz; Morales, Jorge

    2015-11-01

    Computational methods for estimating diversification rates from extant species phylogenetic trees have become abundant in evolutionary research. However, little evidence exists about how their outcome compares to a complementary and direct source of information: the fossil record. Furthermore, there is virtually no direct test for the congruence of evolutionary rates based on these two sources. This task is only achievable in clades with both a well-known fossil record and a complete phylogenetic tree. Here, we compare the evolutionary rates of ruminant mammals as estimated from their vast paleontological record--over 1200 species spanning 50 myr--and their living-species phylogeny. Significantly, our results revealed that the ruminant's fossil record and phylogeny reflect congruent evolutionary processes. The concordance is especially strong for the last 25 myr, when living groups became a dominant part of ruminant diversity. We found empirical support for previous hypotheses based on simulations and neontological data: The pattern captured by the tree depends on how clade specific the processes are and which clades are involved. Also, we report fossil evidence for a postradiation speciation slowdown coupled with constant, moderate extinction in the Miocene. The recent deceleration in phylogenetic rates is connected to rapid extinction triggered by recent climatic fluctuations.

  3. Fossil echinoid (Echinoidea, Echinodermata) diversity of the Early Cretaceous (Hauterivian) in the Paris Basin (France)

    PubMed Central

    Benetti, Sophie; Saucède, Thomas; David, Bruno

    2013-01-01

    Abstract This dataset inventories occurrence records of fossil echinoid specimens collected in the Calcaires à Spatangues Formation (CSF) that crops out in the southeast of the Paris Basin (France), and is dated from the Acanthodiscus radiatus chronozone (ca. 132 Ma, early Hauterivian, Early Cretaceous). Fossil richness and abundance of the CSF has attracted the attention of palaeontologists since the middle of the nineteenth century. This dataset compiles occurrence data (referenced by locality names and geographic coordinates with decimal numbers) of fossil echinoids both collated from the literature published over a century and a half, and completed by data from collection specimens. The dataset also gives information on taxonomy (from species to order and higher taxonomic levels), which has been checked for reliability and consistency. It compiles a total of 628 georeferenced occurrence data of 26 echinoid species represented by 22 genera, 14 families, and 9 orders. PMID:24003321

  4. Clinal morphological variation along a depth gradient in the living scleractinian reef coral Favia pallida: Effects on perceived evolutionary tempos in the fossil record

    SciTech Connect

    Cuffey, R.J. ); Pachut, J.F. )

    1990-12-01

    The Holocene reef-building coral Favia pallida was sampled at 4.5 m depth increments (to 40 m) from two reefs on Enewetak Atoll to examine intraspecific environmental effects. An exposed outer reef was massive and wall-like, whereas a sheltered lagoonal reef grew as a slender pinnacle. Corallite diameter and growth rate, two attributes retrievable in fossil corals, were measured with data partitioned into shallow (<20 m), intermediate (20 to 29 m), and deep-water (>29 m) subsets. Highly significant differences between depth zone populations were found for both corallite diameters and growth rates in analyses of individual and combined reef data sets. Canonical variates analyses (CVA) separated populations from depth zones along single, highly significant, functions. Centroids and 95% confidence intervals, calculated from CVA scores of colonies in each population, are widely separated for the lagoon reef and combined data sets. Conversely, populations from shallow and intermediate depths on the outer reef display overlapping confidence bars indicative of more gradational morphologic changes. When CV's were used to classify specimens to groups, misassignments of intermediate depth specimens to shallow or deep-water populations underscored the gradational nature of the environment. Completely intergrading populations of Favia pallida collected from different depths can be morphologically separated into statistically distinct groupings. A stratigraphic succession of such morphotypes might be interpreted as abruptly appearing separate species if sampling were not as uniform, systematic, and detailed as was possible on modern reefs. Analyses of evolutionary patterns must carefully assess potential effects of clinal variation if past evolutionary patterns are to be interpreted correctly.

  5. First record of the fossil snakefly genus Mesoraphidia (Insecta: Raphidioptera: Mesoraphidiidae) from the Middle Jurassic of China, with description of a new species.

    PubMed

    Lü, Ya-Nan; Liu, Xingyue; Dong, Ren

    2015-08-12

    Mesoraphidia daohugouensis sp. nov. is described from the Middle Jurassic Jiulongshan Formation of Inner Mongolia, China. It is diagnosed by the following character states: subquadrate pronotum, narrowly elliptical forewing, distally darkened pterostigma closed respectively by a proximal costal crossvein and a distal radial veinlet, absence of pterostigmal crossvein. The new species represents the first record of Mesoraphidiinae from the Middle Jurassic of China.

  6. C-isotope composition of fossil sedges and grasses

    NASA Astrophysics Data System (ADS)

    Kurschner, Wolfram M.

    2010-05-01

    C4 plants differ from C3 plants regarding their anatomy and their C-isotope composition. Both features can be used in the geological record to determine the presence of C4 plants. Yet, the evolution of the C4 pathway in the fossil record is enigmatic as palaeobotanical and geological evidence for C4 plants is sparse. The oldest structural evidence for Kranz anatomy has been found in Late Miocene permineralized grass leaf remains. But studies on the C-isotope composition of sedimentary organic matter indicate that abundant C4 biomass was present in N-America and Asia throughout the Miocene in expanding savannahs and grasslands. The success of C4 plants appears to be related also to an increasing seasonal aridity in the tropical climate belts and the co-evolution of grazers. However, C- isotope composition of palaeosols or vertebrate teeth only allows to estimate the abundance of C4 plant biomass in the vegetation or in the diet without further taxonomical specification which plant groups would have had C4 metabolism. In this contribution the first extensive C-isotope analysis of fossil seeds of sedges and a few grasses are presented. The age of the carpological material ranges from Late Eocene to Pliocene and was collected from several central European brown coal deposits. The 52 different taxa studied include several species of Carex, Cladiocarya, Eriopherum, Eleocharis, Scirpus, Sparganium. Most of them representing herbaceous elements of a (sub)tropical vegetation growing near the edge of a lake. The C-isotope composition of the fossil seeds varies between -30 and -23 o/oo indicating C3 photosynthesis. This first systematic inventory shows that C4 plants were absent in the European (sub)tropical brown coal forming wetland vegetation during the Tertiary. These preliminary data are in agreement with phylogenetic studies which predict the origin of C4 plants outside the European realm.

  7. Summary of the Snowmastodon Project Special Volume. A high-elevation, multi-proxy biotic and environmental record of MIS 6-4 from the Ziegler Reservoir fossil site, Snowmass Village, Colorado, USA

    NASA Astrophysics Data System (ADS)

    Miller, Ian M.; Pigati, Jeffrey S.; Scott Anderson, R.; Johnson, Kirk R.; Mahan, Shannon A.; Ager, Thomas A.; Baker, Richard G.; Blaauw, Maarten; Bright, Jordon; Brown, Peter M.; Bryant, Bruce; Calamari, Zachary T.; Carrara, Paul E.; Cherney, Michael D.; Demboski, John R.; Elias, Scott A.; Fisher, Daniel C.; Gray, Harrison J.; Haskett, Danielle R.; Honke, Jeffrey S.; Jackson, Stephen T.; Jiménez-Moreno, Gonzalo; Kline, Douglas; Leonard, Eric M.; Lifton, Nathaniel A.; Lucking, Carol; Gregory McDonald, H.; Miller, Dane M.; Muhs, Daniel R.; Nash, Stephen E.; Newton, Cody; Paces, James B.; Petrie, Lesley; Plummer, Mitchell A.; Porinchu, David F.; Rountrey, Adam N.; Scott, Eric; Sertich, Joseph J. W.; Sharpe, Saxon E.; Skipp, Gary L.; Strickland, Laura E.; Stucky, Richard K.; Thompson, Robert S.; Wilson, Jim

    2014-11-01

    In North America, terrestrial records of biodiversity and climate change that span Marine Oxygen Isotope Stage (MIS) 5 are rare. Where found, they provide insight into how the coupling of the ocean-atmosphere system is manifested in biotic and environmental records and how the biosphere responds to climate change. In 2010-2011, construction at Ziegler Reservoir near Snowmass Village, Colorado (USA) revealed a nearly continuous, lacustrine/wetland sedimentary sequence that preserved evidence of past plant communities between ~ 140 and 55 ka, including all of MIS 5. At an elevation of 2705 m, the Ziegler Reservoir fossil site also contained thousands of well-preserved bones of late Pleistocene megafauna, including mastodons, mammoths, ground sloths, horses, camels, deer, bison, black bear, coyotes, and bighorn sheep. In addition, the site contained more than 26,000 bones from at least 30 species of small animals including salamanders, otters, muskrats, minks, rabbits, beavers, frogs, lizards, snakes, fish, and birds. The combination of macro- and micro-vertebrates, invertebrates, terrestrial and aquatic plant macrofossils, a detailed pollen record, and a robust, directly dated stratigraphic framework shows that high-elevation ecosystems in the Rocky Mountains of Colorado are climatically sensitive and varied dramatically throughout MIS 5.

  8. Late Quaternary vegetation and environments in the Verkhoyansk Mountains region (NE Asia) reconstructed from a 50-kyr fossil pollen record from Lake Billyakh

    NASA Astrophysics Data System (ADS)

    Müller, Stefanie; Tarasov, Pavel E.; Andreev, Andrei A.; Tütken, Thomas; Gartz, Steffi; Diekmann, Bernhard

    2010-08-01

    Here we present a detailed radiocarbon-dated 936 cm long pollen record from Lake Billyakh (65°17'N, 126°47'E; 340 m a.s.l.) situated in the western part of the Verkhoyansk Mountains, about 140 km south of the Arctic Circle. A set of 53 surface pollen samples representing tundra, cold deciduous forest and taiga was collected in northern and central Yakutia communities to verify the accuracy of the quantitative biome reconstruction method and to obtain a more precise attribution of the identified pollen taxa to the main regional biomes. The adjusted method is then applied to the pollen record from Lake Billyakh to gain a reconstruction of vegetation and environments since about 50.7 kyr BP. The results of the pollen analysis and pollen-based biome reconstruction suggest that herbaceous tundra and steppe communities dominated the area from 50.7 to 13.5 kyr BP. Relatively low pollen concentrations and high percentages of herbaceous pollen taxa (mainly Cyperaceae, Poaceae and Artemisia) likely indicate a reduced vegetation cover and/or lower pollen production. On the other hand, extremely low percentages of drought-tolerant taxa, such as Chenopodiaceae and Ephedra, and the constant presence of various mesophyllous herbaceous ( Thalictrum, Rosaceae, Asteraceae) and shrubby taxa ( Betula sect. Nanae/Fruticosae, Duschekia fruticosa, Salix) in the pollen assemblages prevent an interpretation of the last glacial environments around Lake Billyakh as extremely arid. The lowest pollen percentages of woody taxa and the highest values of Artemisia pollen attest that the 31-15 kyr BP period as the driest and coldest interval of the entire record. A relative high content of taxa representing shrub tundra communities and the presence of larch pollen recorded prior to 31 kyr and after 13.5 kyr BP likely indicate interstadial climate amelioration associated with the middle and latest parts of the last glacial. An increase in pollen percentages of herbaceous taxa around 12 kyr BP

  9. Fossilized bioelectric wire - the trace fossil Trichichnus.

    PubMed

    Kędzierski, M; Uchman, A; Sawlowicz, Z; Briguglio, A

    2015-04-16

    The trace fossil Trichichnus is proposed as an indicator of fossil bioelectric bacterial activity at the oxic-anoxic interface zone of marine sediments. This fulfils the idea that such processes, commonly found in the modern realm, should be also present in the geological past. Trichichnus is an exceptional trace fossil due to its very thin diameter (mostly less than 1 mm) and common pyritic filling. It is ubiquitous in some fine-grained sediments, where it has been interpreted as a burrow formed deeper than any other trace fossils, below the redox boundary. Trichichnus, formerly referred to as deeply burrowed invertebrates, has been found as remnant of a fossilized intrasediment bacterial mat that is pyritized. As visualized in 3-D by means of X-ray computed microtomography scanner, Trichichnus forms dense filamentous fabric, which reflects that it is produced by modern large, mat-forming, sulfide-oxidizing bacteria, belonging mostly to Thioploca-related taxa, which are able to house a complex bacterial consortium. Several stages of Trichichnus formation, including filamentous, bacterial mat and its pyritization, are proposed to explain an electron exchange between oxic and suboxic/anoxic layers in the sediment. Therefore, Trichichnus can be considered a fossilized "electric wire".

  10. Fossilized bioelectric wire - the trace fossil Trichichnus

    NASA Astrophysics Data System (ADS)

    Kędzierski, M.; Uchman, A.; Sawlowicz, Z.; Briguglio, A.

    2014-12-01

    The trace fossil Trichichnus is proposed as an indicator of fossil bioelectric bacterial activity at the interface oxic - anoxic zone of marine sediments. This fulfils the idea that such processes, commonly found in the modern realm, should be also present in the geological past. Trichichnus is an exceptional trace fossil due to its very thin diameter (mostly less than 1 mm) and common pyritic filling. It is ubiquitous in some fine-grained sediments, where it has been interpreted as a burrow formed deeper than any other trace fossils, below the redox boundary. Trichichnus formerly referred to as deeply burrowed invertebrates, has been found as remnant of a fossilized intrasediment bacterial mat that is pyritized. As visualized in 3-D by means of X-ray computed microtomography scanner, Trichichnus forms dense filamentous fabric, which reflects that produced by modern large, mat-forming, sulphide-oxidizing bacteria, belonging mostly to Trichichnus-related taxa, which are able to house a complex bacterial consortium. Several stages of Trichichnus formation, including filamentous, bacterial mat and its pyritization, are proposed to explain an electron exchange between oxic and suboxic/anoxic layers in the sediment. Therefore, Trichichnus can be considered a fossilized "electric wire".

  11. Fossilized bioelectric wire - the trace fossil Trichichnus

    NASA Astrophysics Data System (ADS)

    Kędzierski, M.; Uchman, A.; Sawlowicz, Z.; Briguglio, A.

    2015-04-01

    The trace fossil Trichichnus is proposed as an indicator of fossil bioelectric bacterial activity at the oxic-anoxic interface zone of marine sediments. This fulfils the idea that such processes, commonly found in the modern realm, should be also present in the geological past. Trichichnus is an exceptional trace fossil due to its very thin diameter (mostly less than 1 mm) and common pyritic filling. It is ubiquitous in some fine-grained sediments, where it has been interpreted as a burrow formed deeper than any other trace fossils, below the redox boundary. Trichichnus, formerly referred to as deeply burrowed invertebrates, has been found as remnant of a fossilized intrasediment bacterial mat that is pyritized. As visualized in 3-D by means of X-ray computed microtomography scanner, Trichichnus forms dense filamentous fabric, which reflects that it is produced by modern large, mat-forming, sulfide-oxidizing bacteria, belonging mostly to Thioploca-related taxa, which are able to house a complex bacterial consortium. Several stages of Trichichnus formation, including filamentous, bacterial mat and its pyritization, are proposed to explain an electron exchange between oxic and suboxic/anoxic layers in the sediment. Therefore, Trichichnus can be considered a fossilized "electric wire".

  12. The ancient sun: Fossil record in the earth, moon and meteorites; Proceedings of the Conference, Boulder, CO, October 16-19, 1979

    NASA Technical Reports Server (NTRS)

    Pepin, R. O. (Editor); Eddy, J. A.; Merrill, R. B.

    1980-01-01

    Papers are presented concerning theories of solar variability and their consequences for luminosity, particle emission and magnetic field changes within the past 4.5 billion years, and on the records of such solar behavior in lunar, meteoritic and terrestrial materials. Specific topics include the neutrino luminosity of the sun, the relation of sunspots to the terrestrial climate of the past 100 years, solar modulation of galactic cosmic rays, the historical record of solar activity, C-14 variations in terrestrial and marine reservoirs, and solar particle fluxes as indicated by track, thermoluminescence and solar wind measurements in lunar rocks. Attention is also given to the spin-down of the solar interior through circulation currents and fluid instabilities, grain surface exposure models in planetary regoliths, rare gases in the solar wind, nitrogen isotopic variations in the lunar regolith, the influence of solar UV radiation on climate, and the pre-main sequence evolution of the sun and evidence of the primordial solar wind in the electromagnetic induction heating of the asteroids and moon.

  13. A 12-year record of intertidal barnacle recruitment in Atlantic Canada (2005-2016): relationships with sea surface temperature and phytoplankton abundance.

    PubMed

    Scrosati, Ricardo A; Ellrich, Julius A

    2016-01-01

    On the Gulf of St. Lawrence coast of Nova Scotia (Canada), recruitment of the barnacle Semibalanus balanoides occurs in May and June. Every year in June between 2005 and 2016, we recorded recruit density for this barnacle at the same wave-exposed rocky intertidal location on this coast. During these 12 years, mean recruit density was lowest in 2015 (198 recruits dm(-2)) and highest in 2007 (969 recruits dm(-2)). The highest recruit density observed in a single quadrat was 1,457 recruits dm(-2) (in 2011) and the lowest was 34 recruits dm(-2) (in 2015). Most barnacle recruits appear during May, which suggests that most pelagic larvae (which develop over 5-6 weeks before benthic settlement) are in the water column in April. An AICc-based model selection approach identified sea surface temperature (SST) in April and the abundance of phytoplankton (food for barnacle larvae, measured as chlorophyll-a concentration -Chl-a-) in April as good explanatory variables. Together, April SST and April Chl-a explained 51% of the observed interannual variation in recruit density, with an overall positive influence. April SST was positively related to March-April air temperature (AT). April Chl-a was negatively related to the April ratio between the number of days with onshore winds (which blow from phytoplankton-limited offshore waters) and the number of days with alongshore winds (phytoplankton is more abundant on coastal waters). Therefore, this study suggests that climatic processes affecting April SST and April Chl-a indirectly influence intertidal barnacle recruitment by influencing larval performance.

  14. A 12-year record of intertidal barnacle recruitment in Atlantic Canada (2005–2016): relationships with sea surface temperature and phytoplankton abundance

    PubMed Central

    2016-01-01

    On the Gulf of St. Lawrence coast of Nova Scotia (Canada), recruitment of the barnacle Semibalanus balanoides occurs in May and June. Every year in June between 2005 and 2016, we recorded recruit density for this barnacle at the same wave-exposed rocky intertidal location on this coast. During these 12 years, mean recruit density was lowest in 2015 (198 recruits dm−2) and highest in 2007 (969 recruits dm−2). The highest recruit density observed in a single quadrat was 1,457 recruits dm−2 (in 2011) and the lowest was 34 recruits dm−2 (in 2015). Most barnacle recruits appear during May, which suggests that most pelagic larvae (which develop over 5–6 weeks before benthic settlement) are in the water column in April. An AICc-based model selection approach identified sea surface temperature (SST) in April and the abundance of phytoplankton (food for barnacle larvae, measured as chlorophyll-a concentration –Chl-a–) in April as good explanatory variables. Together, April SST and April Chl-a explained 51% of the observed interannual variation in recruit density, with an overall positive influence. April SST was positively related to March–April air temperature (AT). April Chl-a was negatively related to the April ratio between the number of days with onshore winds (which blow from phytoplankton-limited offshore waters) and the number of days with alongshore winds (phytoplankton is more abundant on coastal waters). Therefore, this study suggests that climatic processes affecting April SST and April Chl-a indirectly influence intertidal barnacle recruitment by influencing larval performance. PMID:27812421

  15. Modes of fossil preservation

    USGS Publications Warehouse

    Schopf, J.M.

    1975-01-01

    The processes of geologic preservation are important for understanding the organisms represented by fossils. Some fossil differences are due to basic differences in organization of animals and plants, but the interpretation of fossils has also tended to be influenced by modes of preservation. Four modes of preservation generally can be distinguished: (1) Cellular permineralization ("petrifaction") preserves anatomical detail, and, occasionally, even cytologic structures. (2) Coalified compression, best illustrated by structures from coal but characteristic of many plant fossils in shale, preserves anatomical details in distorted form and produces surface replicas (impressions) on enclosing matrix. (3) Authigenic preservation replicates surface form or outline (molds and casts) prior to distortion by compression and, depending on cementation and timing, may intergrade with fossils that have been subject to compression. (4) Duripartic (hard part) preservation is characteristic of fossil skeletal remains, predominantly animal. Molds, pseudomorphs, or casts may form as bulk replacements following dissolution of the original fossil material, usually by leaching. Classification of the kinds of preservation in fossils will aid in identifying the processes responsible for modifying the fossil remains of both animals and plants. ?? 1975.

  16. Fidelity of fossil n-alkanes from leaf to paleosol and applications to the Paleocene-Eocene Thermal Maximum

    NASA Astrophysics Data System (ADS)

    Bush, R. T.; McInerney, F. A.; Baczynski, A. A.; Wing, S. L.

    2011-12-01

    Long chain n-alkanes (C21-C35) are well-known as biomarkers of terrestrial plants. They can be preserved across a wide range of terrestrial and marine environments, survive in the sedimentary record for millions of years, and can serve as proxies for ancient environments. Most n-alkane records are derived from sediments rather than directly from fossil leaves. However, little is known about the fidelity of the n-alkane record: how and where leaf preservation relates to n-alkane preservation and how patterns of n-alkane carbon isotope ratios (δ13C) compare to living relatives. To examine these questions, we analyzed n-alkanes from fluvial sediments and individual leaf fossils collected in the Bighorn Basin, Wyoming, across the Paleocene-Eocene Thermal Maximum (PETM) carbon isotope excursion. We assessed the fidelity of the n-alkane signature from individual fossil leaves via three separate means. 1) Spatial variations were assessed by comparing n-alkane concentrations on a fossil leaf and in sediments both directly adjacent to the leaf and farther away. Absolute concentrations were greater within the compression fossil than in the directly adjacent sediment, which were in turn greater than in more distant sediment. 2) n-Alkane abundances and distributions were examined in fossil leaves having a range of preservational quality, from fossils with intact cuticle to carbonized fossils lacking cuticle and higher-order venation. The best preserved fossils preserved a higher concentration of n-alkanes and showed the most similar n-alkane distribution to living relatives. However, a strong odd over even predominance suggests a relatively unmodified plant source occurred in all samples regardless of preservation state. 3) n-Alkane δ13C values were measured for both fossil leaves and their living relatives. Both the saw-tooth pattern of δ13C values between odd and even chain lengths and the general decrease in δ13C values with increasing chain length are consistent with

  17. The first recorded decline of the Malvinokaffric Devonian fauna in the Paraná Basin (southern Brazil) and its cause; taphonomic and fossil evidences

    NASA Astrophysics Data System (ADS)

    Bosetti, Elvio Pinto; Grahn, Yngve; Horodyski, Rodrigo Scalise; Mauller, Paula Mendlowicz

    2012-08-01

    The first recorded decline of the Malvinokaffric Devonian fauna in the Paraná Basin, south Brazil, occurred between early and early late Emsian. The event is recognized on biostratigraphic implications, and it coincides with a regional hiatus resulting from tectonic activity during a Precordilleran epeirogeny. The Emsian beds, dated with palynomorphs, indicate a late Pragian - early Emsian (PoW Su spore Zone) age below, and an early late Emsian (upper FD - lower AP spore Zones) age above the hiatus. The extinctions that occurred between the late Pragian - early Emsian regression, and the initial transgression in the early late Emsian, were extensive and more dramatic than elsewhere on the globe. In the Paraná Basin invertebrates 4 classes, 25 families, 41 genera, and 54 species become extinct. The Emsian sedimentation in the Paraná Basin was realized under constant oscillation of sea level punctuated by storm events, probably due to Milankovitch orbital cycles. It is known that the eccentricity cycles are the most striking in regions at higher latitudes, which was the case of the ParanáBasin during the Emsian. This was, however, not a factor of major importance for the large decline of the fauna. The decline of the shelly fauna was an effect of the late Pragian - early Emsian regression, and the early late Emsian transgression introduced a reduced and less provincial shelly fauna.

  18. Calibrating the Tree of Life: fossils, molecules and evolutionary timescales

    PubMed Central

    Forest, Félix

    2009-01-01

    Background Molecular dating has gained ever-increasing interest since the molecular clock hypothesis was proposed in the 1960s. Molecular dating provides detailed temporal frameworks for divergence events in phylogenetic trees, allowing diverse evolutionary questions to be addressed. The key aspect of the molecular clock hypothesis, namely that differences in DNA or protein sequence between two species are proportional to the time elapsed since they diverged, was soon shown to be untenable. Other approaches were proposed to take into account rate heterogeneity among lineages, but the calibration process, by which relative times are transformed into absolute ages, has received little attention until recently. New methods have now been proposed to resolve potential sources of error associated with the calibration of phylogenetic trees, particularly those involving use of the fossil record. Scope and Conclusions The use of the fossil record as a source of independent information in the calibration process is the main focus of this paper; other sources of calibration information are also discussed. Particularly error-prone aspects of fossil calibration are identified, such as fossil dating, the phylogenetic placement of the fossil and the incompleteness of the fossil record. Methods proposed to tackle one or more of these potential error sources are discussed (e.g. fossil cross-validation, prior distribution of calibration points and confidence intervals on the fossil record). In conclusion, the fossil record remains the most reliable source of information for the calibration of phylogenetic trees, although associated assumptions and potential bias must be taken into account. PMID:19666901

  19. Identification of immunoreactive material in mammoth fossils.

    PubMed

    Schweitzer, Mary; Hill, Christopher L; Asara, John M; Lane, William S; Pincus, Seth H

    2002-12-01

    The fossil record represents a history of life on this planet. Attempts to obtain molecular information from this record by analysis of nucleic acids found within fossils of extreme age have been unsuccessful or called into question. However, previous studies have demonstrated the long-term persistence of peptides within fossils and have used antibodies to extant proteins to demonstrate antigenic material. In this study we address two questions: Do immunogenic/antigenic materials persist in fossils? and; Can fossil material be used to raise antibodies that will cross-react with extant proteins? We have used material extracted from a well-preserved 100000-300000-year-old mammoth skull to produce antisera. The specificity of the antisera was tested by ELISA, western blotting, and immunohistochemistry. It was demonstrated that antisera reacted specifically with the fossils and not the surrounding sediments. Reactivity of antisera with modern proteins and tissues was also demonstrated, as was the ability to detect evolutionary relationships via antibody-antigen interactions. Mass spectrometry demonstrated the presence of amino acids and specific peptides within the fossil. Peptides were purified by anion-exchange chromatography and sequenced by tandem mass spectrometry. The collagen-derived peptides may have been the source of at least some of the immunologic reactivity, but the antisera identified molecules that were not observed by mass spectrometry, indicating that immunologic methods may have greater sensitivity. Although the presence of peptides and amino acids was demonstrated, the exact nature of the antigenic material was not fully clarified. This report demonstrates that antibodies may be used to obtain information from the fossil record.

  20. Restoring Fossil Creek

    ERIC Educational Resources Information Center

    Flaccus, Kathleen; Vlieg, Julie; Marks, Jane C.; LeRoy, Carri J.

    2004-01-01

    Fossil Creek had been dammed for the past 90 years, and plans were underway to restore the stream. The creek runs through Central Arizona and flows from the high plateaus to the desert, cutting through the same formations that form the Grand Canyon. This article discusses the Fossil Creek monitoring project. In this project, students and teachers…

  1. Late Pleistocene Vertebrates and Other Fossils from Epiguruk, Northwestern Alaska

    NASA Astrophysics Data System (ADS)

    Hamilton, Thomas D.; Ashley, Gall M.; Reed, Katherine M.; Schweger, Charles E.

    1993-05-01

    Sediments exposed at Epiguruk, a large cutbank on the Kobuk River about 170 km inland from Kotzebue Sound, record multiple episodes of glacial-age alluviation followed by interstadial downcutting and formation of paleosols. Vertebrate remains from Epiguruk include mammoth, bison, caribou, an equid, a canid, arctic ground squirrel, lemmings, and voles. Radiocarbon ages of bone validated by concordant ages of peat and wood span the interval between about 37,000 and 14,000 yr B.P. The late Pleistocene pollen record is dominated by Cyperaceae, with Artemisia, Salix, Betula, and Gramineae also generally abundant. The fossil record from Epiguruk indicates that the Kobuk River valley supported tundra vegetation with abundant riparian willows during middle and late Wisconsin time. Large herbivores were present during the height of late Wisconsin glaciation as well as during its waning stage and the preceding interstadial interval. The Kobuk River valley would have been a favorable refugium for plants, animals, and possibly humans throughout the last glaciation.

  2. Late Pleistocene Vertebrates and Other Fossils from Epiguruk, Northwestern Alaska

    USGS Publications Warehouse

    Hamilton, T.D.; Ashley, G.M.; Reed, K.M.; Schweger, C.E.

    1993-01-01

    Sediments exposed at Epiguruk, a large cutbank on the Kobuk River about 170 km inland from Kotzebue Sound, record multiple episodes of glacial-age alluviation followed by interstadial downcutting and formation of paleosols. Vertebrate remains from Epiguruk include mammoth, bison, caribou, an equid, a canid, arctic ground squirrel, lemmings, and voles. Radiocarbon ages of bone validated by concordant ages of peat and wood span the interval between about 37,000 and 14,000 yr B.P. The late Pleistocene pollen record is dominated by Cyperaceae, with Artemisia, Salix, Betula, and Gramineae also generally abundant. The fossil record from Epiguruk indicates that the Kobuk River valley supported tundra vegetation with abundant riparian willows during middle and late Wisconsin time. Large herbivores were present during the height of late Wisconsin glaciation as well as during its waning stage and the preceding interstadial interval. The Kobuk River valley would have been a favorable refugium for plants, animals, and possibly humans throughout the last glaciation.

  3. Landscape planning for the future: using fossil records to independently validate potential threats, opportunities and likely future range-shifts for socio-economically valuable plant species in Europe and sub-Saharan Africa

    NASA Astrophysics Data System (ADS)

    Macias Fauria, M.; Willis, K. J.

    2011-12-01

    Bioclimatic Envelope Models (BEMs) for a set of socio-economically important tree species in Europe were independently validated using a hindcasting approach and fossil pollen records spanning the last 1000 years, including the Medieval Warm Period (MWP), the Little Ice Age (LIA) and the 20th Century warming (PRES). The aim was to determine the accuracy of combining BEMs and palaeoecological data to predict continental-scale changes in distribution, and the availability of fossil data to hindcast economically important species. Eight types of BEMs were implemented in this study, covering most state-of-the-art modelling techniques. Present and palaeoclimatic data were obtained from the Atmosphere-Ocean Global Circulation Model ECHO-G. Last millenium was divided into three climatically distinct periods: MWP (AD 900-1300), LIA (AD 1600-1850) and PRES (AD 1900-2000). Models were calibrated for each period and validated with climatic and pollen data from the remaining periods. Successfully validated models were projected onto a 1-degree European grid, allowing the reconstruction of past modelled species distributions. BEMs were successfully validated with independent data. Strong model performance suggested high potential for BEMs to be used to model future species distributions, and highlighted the importance of palaeoecological data to independently validate these models, taking into account the scales at which this data operates. Although valid, BEMs showed poorer performance with species heavily managed and/or growing in heterogeneous terrain or with discontinuous distributions. Last millennium in Europe was characterized by an increase of crop woody species and a decline of forest species, suggesting an increasing land use by humans. The same approach was then implemented to a set of sub-Saharan plant species of high importance as a source of food, wood, and other ecosystem services such as carbon storage or erosion protection. The African study covered most of the

  4. Fossil fuels -- future fuels

    SciTech Connect

    1998-03-01

    Fossil fuels -- coal, oil, and natural gas -- built America`s historic economic strength. Today, coal supplies more than 55% of the electricity, oil more than 97% of the transportation needs, and natural gas 24% of the primary energy used in the US. Even taking into account increased use of renewable fuels and vastly improved powerplant efficiencies, 90% of national energy needs will still be met by fossil fuels in 2020. If advanced technologies that boost efficiency and environmental performance can be successfully developed and deployed, the US can continue to depend upon its rich resources of fossil fuels.

  5. Globular cluster formation - The fossil record

    NASA Technical Reports Server (NTRS)

    Murray, Stephen D.; Lin, Douglas N. C.

    1992-01-01

    Properties of globular clusters which have remained unchanged since their formation are used to infer the internal pressures, cooling times, and dynamical times of the protocluster clouds immediately prior to the onset of star formation. For all globular clusters examined, it is found that the cooling times are much less than the dynamical times, implying that the protoclusters must have been maintained in thermal equilibrium by external heat sources, with fluxes consistent with those found in previous work, and giving the observed rho-T relation. Self-gravitating clouds cannot be stably heated, so that the Jeans mass forms an upper limit to the cluster masses. The observed dependence of protocluster pressure upon galactocentric position implies that the protocluster clouds were in hydrostatic equilibrium after their formation. The pressure dependence is well fitted by that expected for a quasi-statically evolving background hot gas, shock heated to its virial temperature. The observations and inferences are combined with previous theoretical work to construct a picture of globular cluster formation.

  6. Fossil Record of Precambrian Life on Land

    NASA Technical Reports Server (NTRS)

    Knauth, Paul

    2000-01-01

    The argument that the earth's early ocean was up to two times modern salinity was published in 'Nature' and presented at the 1998 Annual Meeting of the Geological Society of America in Toronto. The argument is bolstered by chemical data for fluid inclusions in Archean black smokers. The inclusions were 1.7 times the modern salinity causing the authors to interpret the parent fluids as evaporite brines (in a deep marine setting). I reinterpreted the data in terms of the predicted value of high Archean salinities. If the arguments I presented are on track, early life was either halophilic or non-marine. Halophiles are not among the most primitive organisms based on RNA sequencing, so here is an a priori argument that non-marine environments may have been the site of most early biologic evolution. This result carries significant implications for the issue of past life on Mars or current life on the putative sub-ice oceans on Europa and possibly Callisto. If the Cl/H2O ratio on these objects is similar to that of the earth, then oceans and oceanic sediments are probably not the preferred sites for early life. On Mars, this means that non-marine deposits such as caliche in basalt may be an overlooked potential sample target.

  7. Infrared Spectra of Fossils,

    DTIC Science & Technology

    fossil’s surface is accessible to the analyzing beams. The technique is potentially valuable for the examination of special samples of palaeontological and archaeological interest. Keywords include: Photothermal effect.

  8. Natural Product Molecular Fossils.

    PubMed

    Falk, Heinz; Wolkenstein, Klaus

    2017-01-01

    The natural products synthesized by organisms that were living a long time ago gave rise to their molecular fossils. These can consist of either the original unchanged compounds or they may undergo peripheral transformations in which their skeletons remain intact. In cases when molecular fossils can be traced to their organismic source, they are termed "geological biomarkers".This contribution describes apolar and polar molecular fossils and, in particular biomarkers, along the lines usually followed in organic chemistry textbooks, and points to their bioprecursors when available. Thus, the apolar compounds are divided in linear and branched alkanes followed by alicyclic compounds and aromatic and heterocyclic molecules, and, in particular, the geoporphyrins. The polar molecular fossils contain as functional groups or constituent units ethers, alcohols, phenols, carbonyl groups, flavonoids, quinones, and acids, or are polymers like kerogen, amber, melanin, proteins, or nucleic acids. The final sections discuss the methodology used and the fundamental processes encountered by the biomolecules described, including diagenesis, catagenesis, and metagenesis.

  9. Fossils of reionization in the local group

    SciTech Connect

    Gnedin, Nickolay Y.; Kravtsov, Andrey V.; /KICP, Chicago /Chicago U., EFI /Chicago U., Astron. Astrophys. Ctr.

    2006-01-01

    We use a combination of high-resolution gas dynamics simulations of high-redshift dwarf galaxies and dissipationless simulations of a Milky Way sized halo to estimate the expected abundance and spatial distribution of the dwarf satellite galaxies that formed most of their stars around z {approx} 8 and evolved only little since then. Such galaxies can be considered as fossils of the reionization era, and studying their properties could provide a direct window into the early, pre-reionization stages of galaxy formation. We show that 5-15% of the objects existing at z {approx} 8 do indeed survive until the present in the MW like environment without significant evolution. This implies that it is plausible that the fossil dwarf galaxies do exist in the Local Group. Because such galaxies form their stellar systems early during the period of active merging and accretion, they should have spheroidal morphology regardless of their current distance from the host galaxy. We show that both the expected luminosity function and spatial distribution of dark matter halos which are likely to host fossil galaxies agree reasonably well with the observed distributions of the luminous (L{sub V} > 10{sup 6} Lsun) Local Group fossil candidates near the host galaxy (d<200 kpc). However, the predicted abundance is substantially larger (by a factor of 2-3) for fainter galaxies (L{sub V} < 10{sup 6} Lsun) at larger distances (d>300 kpc). We discuss several possible explanations for this discrepancy.

  10. Fossil Simulation in the Classroom

    ERIC Educational Resources Information Center

    Hoehn, Robert G.

    1977-01-01

    Describes classroom science demonstrations and experiments that simulate the process of fossil formation. Lists materials, procedures and suggestions for successful activities. Includes ten student activities (coral fossils, leaf fossils, leaf scars, carbonization, etc.). Describes a fossil game in which students work in pairs. (CS)

  11. An early Oligocene fossil demonstrates treeshrews are slowly evolving "living fossils".

    PubMed

    Li, Qiang; Ni, Xijun

    2016-01-14

    Treeshrews are widely considered a "living model" of an ancestral primate, and have long been called "living fossils". Actual fossils of treeshrews, however, are extremely rare. We report a new fossil species of Ptilocercus treeshrew recovered from the early Oligocene (~34 Ma) of China that represents the oldest definitive fossil record of the crown group of treeshrews and nearly doubles the temporal length of their fossil record. The fossil species is strikingly similar to the living Ptilocercus lowii, a species generally recognized as the most plesiomorphic extant treeshrew. It demonstrates that Ptilocercus treeshrews have undergone little evolutionary change in their morphology since the early Oligocene. Morphological comparisons and phylogenetic analysis support the long-standing idea that Ptilocercus treeshrews are morphologically conservative and have probably retained many characters present in the common stock that gave rise to archontans, which include primates, flying lemurs, plesiadapiforms and treeshrews. This discovery provides an exceptional example of slow morphological evolution in a mammalian group over a period of 34 million years. The persistent and stable tropical environment in Southeast Asia through the Cenozoic likely played a critical role in the survival of such a morphologically conservative lineage.

  12. Genetic and Fossil Evidence for the Origin of Modern Humans.

    ERIC Educational Resources Information Center

    Stringer, C. B.; Andrews, P.

    1988-01-01

    Discusses how genetic data on present human population relationships and data from the Pleistocene fossil hominid record are being used to compare two contrasting models for the origin of modern humans. (TW)

  13. Spider crabs of the Western Atlantic with special reference to fossil and some modern Mithracidae

    PubMed Central

    Portell, Roger W.; Klier, Aaron T.; Prueter, Vanessa; Tucker, Alyssa L.

    2015-01-01

    Spider crabs (Majoidea) are well-known from modern oceans and are also common in the western part of the Atlantic Ocean. When spider crabs appeared in the Western Atlantic in deep time, and when they became diverse, hinges on their fossil record. By reviewing their fossil record, we show that (1) spider crabs first appeared in the Western Atlantic in the Late Cretaceous, (2) they became common since the Miocene, and (3) most species and genera are found in the Caribbean region from the Miocene onwards. Furthermore, taxonomic work on some modern and fossil Mithracidae, a family that might have originated in the Western Atlantic, was conducted. Specifically, Maguimithrax gen. nov. is erected to accommodate the extant species Damithrax spinosissimus, while Damithrax cf. pleuracanthus is recognized for the first time from the fossil record (late Pliocene–early Pleistocene, Florida, USA). Furthermore, two new species are described from the lower Miocene coral-associated limestones of Jamaica (Mithrax arawakum sp. nov. and Nemausa windsorae sp. nov.). Spurred by a recent revision of the subfamily, two known species from the same deposits are refigured and transferred to new genera: Mithrax donovani to Nemausa, and Mithrax unguis to Damithrax. The diverse assemblage of decapods from these coral-associated limestones underlines the importance of reefs for the abundance and diversity of decapods in deep time. Finally, we quantitatively show that these crabs possess allometric growth in that length/width ratios drop as specimens grow, a factor that is not always taken into account while describing and comparing among taxa. PMID:26557432

  14. Alkane distribution and carbon isotope composition in fossil leaves: An interpretation of plant physiology in the geologic past

    NASA Astrophysics Data System (ADS)

    Graham, H. V.; Freeman, K. H.

    2014-12-01

    The relative chain-length distribution and carbon-isotope composition of n-alkanes extracted from sedimentary rocks are important geochemical tools for investigating past terrestrial ecosystems. Alkanes preserved in ancient sediments are assumed to be contemporaneous, derived from the same ecosystem, and integrated from the biomass present on the landscape at the time of deposition. Further, there is an underlying assumption that ancient plants exhibited the same metabolic and physiological responses to climate conditions that are observed for modern plants. Interpretations of alkane abundances and isotopic signatures are complicated by the strong influence of phylogenetic affiliation and ecological factors, such as canopy structure. A better understanding of how ecosystem and taxa influence alkane properties, including homologue abundance patterns and leaf-lipid carbon isotope fractionation would help strengthen paleoecological interpretations based on these widely employed plant biomarkers. In this study, we analyze the alkane chain-length distribution and carbon-isotope composition of phytoleim and alkanes (d13Cleaf and d13Clipid) extracted from a selection of Cretaceous and Paleocene fossil leaves from the Guaduas and Cerrejon Formations of Colombia. These data were compared with data for the same families in a modern analogue biome. Photosynthetic and biosynthetic fractionation (∆leaf and elipid) values determined from the fossil material indicate carbon metabolism patterns were similar to modern plants. Fossil data were incorporated in a biomass-weighted mixing model to represent the expected lipid complement of sediment arising from this ecosystem and compared with alkane measurements from the rock matrix. Modeled and observed isotopic and abundance patterns match well for alkane homologs most abundant in plants (i.e., n-C27 to n-C33). The model illustrates the importance of understanding biases in litter flux and taphonomic pressures inherent in the

  15. Microbial Cretaceous park: biodiversity of microbial fossils entrapped in amber

    NASA Astrophysics Data System (ADS)

    Martín-González, Ana; Wierzchos, Jacek; Gutiérrez, Juan C.; Alonso, Jesús; Ascaso, Carmen

    2009-05-01

    Microorganisms are the most ancient cells on this planet and they include key phyla for understanding cell evolution and Earth history, but, unfortunately, their microbial records are scarce. Here, we present a critical review of fossilized prokaryotic and eukaryotic microorganisms entrapped in Cretaceous ambers (but not exclusively from this geological period) obtained from deposits worldwide. Microbiota in ambers are rather diverse and include bacteria, fungi, and protists. We comment on the most important microbial records from the last 25 years, although it is not an exhaustive bibliographic compilation. The most frequently reported eukaryotic microfossils are shells of amoebae and protists with a cell wall or a complex cortex. Likewise, diverse dormant stages (palmeloid forms, resting cysts, spores, etc.) are abundant in ambers. Besides, viral and protist pathogens have been identified inside insects entrapped in amber. The situation regarding filamentous bacteria and fungi is quite confusing because in some cases, the same record was identified consecutively as a member of these phylogenetically distant groups. To avoid these identification errors in the future, we propose to apply a more resolute microscopic and analytical method in amber studies. Also, we discuss the most recent findings about ancient DNA repair and bacterial survival in remote substrates, which support the real possibility of ancient DNA amplification and bacterial resuscitation from Cretaceous resins.

  16. Microbial Cretaceous park: biodiversity of microbial fossils entrapped in amber.

    PubMed

    Martín-González, Ana; Wierzchos, Jacek; Gutiérrez, Juan C; Alonso, Jesús; Ascaso, Carmen

    2009-05-01

    Microorganisms are the most ancient cells on this planet and they include key phyla for understanding cell evolution and Earth history, but, unfortunately, their microbial records are scarce. Here, we present a critical review of fossilized prokaryotic and eukaryotic microorganisms entrapped in Cretaceous ambers (but not exclusively from this geological period) obtained from deposits worldwide. Microbiota in ambers are rather diverse and include bacteria, fungi, and protists. We comment on the most important microbial records from the last 25 years, although it is not an exhaustive bibliographic compilation. The most frequently reported eukaryotic microfossils are shells of amoebae and protists with a cell wall or a complex cortex. Likewise, diverse dormant stages (palmeloid forms, resting cysts, spores, etc.) are abundant in ambers. Besides, viral and protist pathogens have been identified inside insects entrapped in amber. The situation regarding filamentous bacteria and fungi is quite confusing because in some cases, the same record was identified consecutively as a member of these phylogenetically distant groups. To avoid these identification errors in the future, we propose to apply a more resolute microscopic and analytical method in amber studies. Also, we discuss the most recent findings about ancient DNA repair and bacterial survival in remote substrates, which support the real possibility of ancient DNA amplification and bacterial resuscitation from Cretaceous resins.

  17. Advanced fossil energy utilization

    SciTech Connect

    Shekhawat, D.; Berry, D.; Spivey, J.; Pennline, H.; Granite, E.

    2010-01-01

    This special issue of Fuel is a selection of papers presented at the symposium ‘Advanced Fossil Energy Utilization’ co-sponsored by the Fuels and Petrochemicals Division and Research and New Technology Committee in the 2009 American Institute of Chemical Engineers (AIChE) Spring National Meeting Tampa, FL, on April 26–30, 2009.

  18. Trace Fossil Analysis

    NASA Astrophysics Data System (ADS)

    Hasiotis, Stephen T.

    2009-05-01

    Today, the study of trace fossils—ichnology—is an important subdiscipline of geology at the interface of paleontology and sedimentology, mostly because of the efforts of Adolf Seilacher. His ability to synthesize various aspects of ichnology and produce a hierarchy of marine ichna and sedimentary facies has made ichnology useful worldwide in interpreting paleodiversity, rates of sedimentation, oxygenation of bottom water and sediment pore water, and depositional energy. Seilacher's book Trace Fossil Analysis provides a glimpse into the mind, methodology, and insights of the father of modern ichnology, generated from his course notes as a professor and a guest lecturer. The title sounds misleading—readers looking for up-to-date principles and approaches to trace fossil analysis in marine and continental strata will be disappointed. In his preface, however, Seilacher clearly gives direction for the use of his text: “This is a course book—meaning that it is intended to confer not knowledge, but skill.” Thus, it is not meant as a total compilation of all trace fossils, ichnotaxonomy, ichnological interpretations, applications, or the most relevant and up-to-date references. Rather, it takes the reader on a personal journey, explaining how trace fossils are understood in the context of their three-dimensional (3-D) morphology and sedimentary facies.

  19. Macroevolutionary developmental biology: Embryos, fossils, and phylogenies.

    PubMed

    Organ, Chris L; Cooper, Lisa Noelle; Hieronymus, Tobin L

    2015-10-01

    The field of evolutionary developmental biology is broadly focused on identifying the genetic and developmental mechanisms underlying morphological diversity. Connecting the genotype with the phenotype means that evo-devo research often considers a wide range of evidence, from genetics and morphology to fossils. In this commentary, we provide an overview and framework for integrating fossil ontogenetic data with developmental data using phylogenetic comparative methods to test macroevolutionary hypotheses. We survey the vertebrate fossil record of preserved embryos and discuss how phylogenetic comparative methods can integrate data from developmental genetics and paleontology. Fossil embryos provide limited, yet critical, developmental data from deep time. They help constrain when developmental innovations first appeared during the history of life and also reveal the order in which related morphologies evolved. Phylogenetic comparative methods provide a powerful statistical approach that allows evo-devo researchers to infer the presence of nonpreserved developmental traits in fossil species and to detect discordant evolutionary patterns and processes across levels of biological organization.

  20. Fossil Crustaceans as Parasites and Hosts.

    PubMed

    Klompmaker, Adiël A; Boxshall, Geoff A

    2015-01-01

    Numerous crustacean lineages have independently moved into parasitism as a mode of life. In modern marine ecosystems, parasitic crustaceans use representatives from many metazoan phyla as hosts. Crustaceans also serve as hosts to a rich diversity of parasites, including other crustaceans. Here, we show that the fossil record of such parasitic interactions is sparse, with only 11 examples, one dating back to the Cambrian. This may be due to the limited preservation potential and small size of parasites, as well as to problems with ascribing traces to parasitism with certainty, and to a lack of targeted research. Although the confirmed stratigraphic ranges are limited for nearly every example, evidence of parasitism related to crustaceans has become increasingly more complete for isopod-induced swellings in decapods so that quantitative analyses can be carried out. Little attention has yet been paid to the origin of parasitism in deep time, but insight can be generated by integrating data on fossils with molecular studies on modern parasites. In addition, there are other traces left by parasites that could fossilize, but have not yet been recognized in the fossil record.

  1. High abundance of salps in the coastal Gulf of Alaska during 2011: A first record of bloom occurrence for the northern Gulf

    NASA Astrophysics Data System (ADS)

    Li, Kaizhi; Doubleday, Ayla J.; Galbraith, Moira D.; Hopcroft, Russell R.

    2016-10-01

    Atypical high abundances of two salp species occurred in the coastal Gulf of Alaska during 2011. Salpa aspera dominated numerically in aggregate form during spring, and became uncommon during summer, while Cyclosalpa bakeri increased from low during spring to high abundance during summer. Both species were absent, or nearly so, by fall. C. bakeri abundance was positively correlated to surface temperature in spring and summer, and both species abundances were negatively correlated to chlorophyll a. The proportion of aggregate forms of both species was higher than that of solitary forms during spring and summer. The length-frequency of S. aspera aggregate individuals ranged primarily from 10 to 50 mm, and solitary forms reached 130 mm, while C. bakeri aggregates were 10-25 mm, with solitary forms up to 75 mm. Estimated biomass of S. aspera was 0.35±0.64 mg C m-3 in southeastern Alaska during spring then decreased to 0.03±0.12 mg C m-3 during summer. Estimated biomass of C. bakeri was 0.03±0.06 mg C m-3 over the entire sampling domain during spring, then rose to 0.15±0.25 mg C m-3 during summer. The volume of water filtered daily by S. aspera was estimated to be up to 17% of the 200 m water column at some stations during spring, but only up to ~3.5% during summer. Substantially higher grazing impact was possible if animals were largely confined to the surface mixed layer (typically 20-30 m thick). The average volume filtrated was higher during spring for S. aspera, but for C. bakeri it was higher during summer. We propose that the combined effect of the northward transport of seed populations, their rapid biomass increase through asexual reproduction, and the high clearance rate of salps contributed to atypically low chlorophyll a in the Gulf of Alaska during spring and summer of 2011. This unusual event impacted ecosystem function during 2011, and might be expected to increase in frequency as the Gulf continues to respond to climate variations.

  2. Synthesizing and databasing fossil calibrations: divergence dating and beyond.

    PubMed

    Ksepka, Daniel T; Benton, Michael J; Carrano, Matthew T; Gandolfo, Maria A; Head, Jason J; Hermsen, Elizabeth J; Joyce, Walter G; Lamm, Kristin S; Patané, José S L; Phillips, Matthew J; Polly, P David; Van Tuinen, Marcel; Ware, Jessica L; Warnock, Rachel C M; Parham, James F

    2011-12-23

    Divergence dating studies, which combine temporal data from the fossil record with branch length data from molecular phylogenetic trees, represent a rapidly expanding approach to understanding the history of life. National Evolutionary Synthesis Center hosted the first Fossil Calibrations Working Group (3-6 March, 2011, Durham, NC, USA), bringing together palaeontologists, molecular evolutionists and bioinformatics experts to present perspectives from disciplines that generate, model and use fossil calibration data. Presentations and discussions focused on channels for interdisciplinary collaboration, best practices for justifying, reporting and using fossil calibrations and roadblocks to synthesis of palaeontological and molecular data. Bioinformatics solutions were proposed, with the primary objective being a new database for vetted fossil calibrations with linkages to existing resources, targeted for a 2012 launch.

  3. Synthesizing and databasing fossil calibrations: divergence dating and beyond

    PubMed Central

    Ksepka, Daniel T.; Benton, Michael J.; Carrano, Matthew T.; Gandolfo, Maria A.; Head, Jason J.; Hermsen, Elizabeth J.; Joyce, Walter G.; Lamm, Kristin S.; Patané, José S. L.; Phillips, Matthew J.; Polly, P. David; Van Tuinen, Marcel; Ware, Jessica L.; Warnock, Rachel C. M.; Parham, James F.

    2011-01-01

    Divergence dating studies, which combine temporal data from the fossil record with branch length data from molecular phylogenetic trees, represent a rapidly expanding approach to understanding the history of life. National Evolutionary Synthesis Center hosted the first Fossil Calibrations Working Group (3–6 March, 2011, Durham, NC, USA), bringing together palaeontologists, molecular evolutionists and bioinformatics experts to present perspectives from disciplines that generate, model and use fossil calibration data. Presentations and discussions focused on channels for interdisciplinary collaboration, best practices for justifying, reporting and using fossil calibrations and roadblocks to synthesis of palaeontological and molecular data. Bioinformatics solutions were proposed, with the primary objective being a new database for vetted fossil calibrations with linkages to existing resources, targeted for a 2012 launch. PMID:21525049

  4. Fossil Carder Bee's Nest from the Hominin Locality of Taung, South Africa.

    PubMed

    Parker, Jennifer F; Hopley, Philip J; Kuhn, Brian F

    The Buxton-Norlim Limeworks southwest of Taung, South Africa, is renowned for the discovery of the first Australopithecus africanus fossil, the 'Taung Child'. The hominin was recovered from a distinctive pink calcrete that contains an abundance of invertebrate ichnofauna belonging to the Coprinisphaera ichnofacies. Here we describe the first fossil bee's nest, attributed to the ichnogenus Celliforma, from the Plio-Pleistocene of Africa. Petrographic examination of a cell lining revealed the preservation of an intricate organic matrix lined with the calcitic casts of numerous plant trichomes-a nesting behaviour unique to the modern-day carder bees (Anthidiini). The presence of Celliforma considered alongside several other recorded ichnofossils can be indicative of a dry, savannah environment, in agreement with recent work on the palaeoenvironment of Plio-Pleistocene southern Africa. Moreover, the occurrence of ground-nesting bees provides further evidence that the pink calcrete deposits are of pedogenic origin, rather than speleogenic origin as has previously been assumed. This study demonstrates the potential value of insect trace fossils as palaeoenvironmental indicators.

  5. Fossil Carder Bee's Nest from the Hominin Locality of Taung, South Africa

    PubMed Central

    Parker, Jennifer F.; Hopley, Philip J.; Kuhn, Brian F.

    2016-01-01

    The Buxton-Norlim Limeworks southwest of Taung, South Africa, is renowned for the discovery of the first Australopithecus africanus fossil, the ‘Taung Child’. The hominin was recovered from a distinctive pink calcrete that contains an abundance of invertebrate ichnofauna belonging to the Coprinisphaera ichnofacies. Here we describe the first fossil bee’s nest, attributed to the ichnogenus Celliforma, from the Plio-Pleistocene of Africa. Petrographic examination of a cell lining revealed the preservation of an intricate organic matrix lined with the calcitic casts of numerous plant trichomes–a nesting behaviour unique to the modern-day carder bees (Anthidiini). The presence of Celliforma considered alongside several other recorded ichnofossils can be indicative of a dry, savannah environment, in agreement with recent work on the palaeoenvironment of Plio-Pleistocene southern Africa. Moreover, the occurrence of ground-nesting bees provides further evidence that the pink calcrete deposits are of pedogenic origin, rather than speleogenic origin as has previously been assumed. This study demonstrates the potential value of insect trace fossils as palaeoenvironmental indicators. PMID:27682845

  6. Exceptional fossil preservation and the cambrian explosion.

    PubMed

    Butterfield, Nicholas J

    2003-02-01

    Exceptionally preserved, non-biomineralizing fossils contribute importantly to resolving details of the Cambrian explosion, but little to its overall patterns. Six distinct "types" of exceptional preservation are identified for the terminal Proterozoic-Cambrian interval, each of which is dependent on particular taphonomic circumstances, typically restricted both in space and time. Taphonomic pathways yielding exceptional preservation were particularly variable through the Proterozoic-Cambrian transition, at least in part a consequence of contemporaneous evolutionary innovations. Combined with the reasonably continuous record of "Doushantuo-type preservation," and the fundamentally more robust records of shelly fossils, phytoplankton cysts and trace fossils, these taphonomic perturbations contribute to the documentation of major evolutionary and biogeochemical shifts through the terminal Proterozoic and early Cambrian.Appreciation of the relationship between taphonomic pathway and fossil expression serves as a useful tool for interpreting exceptionally preserved, often problematic, early Cambrian fossils. In shale facies, for example, flattened non-biomineralizing structures typically represent the remains of degradation-resistant acellular and extracellular "tissues" such as chaetae and cuticles, whereas three-dimensional preservation represents labile cellular tissues with a propensity for attracting and precipitating early diagenetic minerals. Such distinction helps to identify the acuticular integument of hyolithids, the chaetae-like nature of Wiwaxia sclerites, the chaetognath-like integument of Amiskwia, the midgut glands of various Burgess Shale arthropods, and the misidentification of deposit-feeding arthropods in the Chengjiang biota. By the same reasoning, putative lobopods in the Sirius Passet biota and putative deuterostomes in the Chengiang biota are better interpreted as arthropods.

  7. Linking Fossil Fish Cyclicity and Paleoenvironmental Proxies in the mid-Devonian

    NASA Astrophysics Data System (ADS)

    Grogan, D.; Whiteside, J. H.; Trewin, N. H.; Johnson, J. E.

    2009-12-01

    The significant radiation of fishes throughout the Devonian, combined with the abundance of well-preserved fossil fish assemblages from this period, provides for a high-resolution record of prevalent fish taxa in the Orcadian basin of North Scotland. In addition to their ability to serve as a lake-level and lake-chemistry proxy, the waxing and waning of dominant fish taxa exhibit a pronounced cyclicity, suggesting they respond to broader climate rhythms. Recent studies of mid-Devonian lacustrine sedimentary sequences have quantitatively demonstrated the presence of Milankovitch cyclicity in geochemical and gamma ray proxy records. Spectral analysis of gamma ray data show a strong obliquity peak usually associated with ice-house conditions; this obliquity signal is unexpected as tropical latitudes in the mid-Devonian are traditionally thought to have been in a greenhouse climate. Geochemical data include the measurement of bulk carbon and nitrogen stable isotopes, molecule-specific carbon isotopes of plant biomarkers, and depth ranks from eight sections of the Caithness Flagstone Group of the Orcadian Basin. Evidence for orbital forcing of climate change paired with the fossil fish record provides a unique opportunity to establish an astronomically calibrated timescale for the mid-Devonian, as well as to make a quantitative assessment of the validity of a greenhouse climate existing in the mid-Devonian.

  8. Fossilization Processes in Thermal Springs

    NASA Technical Reports Server (NTRS)

    Farmer, Jack D.; Cady, Sherry; Desmarais, David J.; Chang, Sherwood (Technical Monitor)

    1995-01-01

    To create a comparative framework for the study of ancient examples, we have been carrying out parallel studies of the microbial biosedimentology, taphonomy and geochemistry of modem and sub-Recent thermal spring deposits. One goal of the research is the development of integrated litho- and taphofacies models for siliceous and travertline sinters. Thermal springs are regarded as important environments for the origin and early evolution of life on Earth, and we seek to utilize information from the fossil record to reconstruct the evolution of high temperature ecosystems. Microbial contributions to the fabric of thermal spring sinters occur when population growth rates keep pace with, or exceed rates of inorganic precipitation, allowing for the development of continuous biofilms or mats. In siliceous thermal springs, microorganisms are typically entombed while viable. Modes of preservation reflect the balance between rates of organic matter degradation, silica precipitation and secondary infilling. Subaerial sinters are initially quite porous and permeable and at temperatures higher than about 20 C, organic materials are usually degraded prior to secondary infilling of sinter frameworks. Thus, organically-preserved microfossils are rare and fossil information consists of characteristic biofabrics formed by the encrustation and underplating of microbial mat surfaces. This probably accounts for the typically low total organic carbon values observed in thermal spring deposits. In mid-temperature, (approx. 35 - 59 C) ponds and outflows, the surface morphology of tufted Phormidium mats is preserved through mat underplating by thin siliceous: crusts. Microbial taxes lead to clumping of ceils and/or preferred filament orientations that together define higher order composite fabrics in thermal spring stromatolites (e.g. network, coniform, and palisade). At lower temperatures (less than 35 C), Calothrix mats cover shallow terracette pools forming flat carpets or pustular

  9. Late Holocene vegetation and historic grazing impacts at Capital Reef National Park reconstructed using fossil packrat middens

    SciTech Connect

    Cole, K.L.

    1995-06-01

    Late Holocene vegetation change from a high desert site in southern Utah was reconstructed using fossil plant macrofossils and pollen from packrat middens. Presettlement middens consistently contained abundant macrofossils of plant species palatable to livestock that are now absent or reduced such as: Ceratoides lanata, Stipa hymenoides, Pinus edulis, and Artemisia spp.. In contrast, species typical of overgrazed range, such as: Chrysothamnus visidiflorus, Sarcobatus vermiculatus, and Gutterezia sarothrae, are now more abundant than prior to the historic introduction of grazing animals. Similar changes are evident in the fossil pollen from the packrat middens. Pine and sagebrush pollen is now far lower than prior to settlement, while Salsola sp. is first recorded following settlement. Ordination of the plant records using Detrended Correspondence Analysis demonstrates that the modem assemblages are substantially different from the presettlement assemblages and that the rates of vegetation change accompanying settlement are far greater than any recorded during the previous 5000 years. These results suggest that the plant communities and rates of vegetation change observed during this century are unlike previous natural communities and rates of vegetation change.

  10. Fossil diatoms and neogene paleolimnology

    USGS Publications Warehouse

    Platt, Bradbury J.

    1988-01-01

    Diatoms have played an important role in the development of Neogene continental biostratigraphy and paleolimnology since the mid-19th Century. The history of progress in Quaternary diatom biostratigraphy has developed as a result of improved coring techniques that enable sampling sediments beneath existing lakes coupled with improved chronological control (including radiometric dating and varve enumeration), improved statistical treatment of fossil diatom assemblages (from qualitative description to influx calculations of diatom numbers or volumes), and improved ecological information about analogous living diatom associations. The last factor, diatom ecology, is the most critical in many ways, but progresses slowly. Fortunately, statistical comparison of modern diatom assemblages and insightful studies of the nutrient requirements of some common freshwater species are enabling diatom paleolimnologists to make more detailed interpretations of the Quaternary record than had been possible earlier, and progress in the field of diatom biology and ecology will continue to refine paleolimnological studies. The greater age and geologic setting of Tertiary diatomaceous deposits has prompted their study in the contexts of geologic history, biochronology and evolution. The distribution of diatoms of marine affinities in continental deposits has given geologists insights about tectonism and sea-level change, and the distribution of distinctive (extinct?) diatoms has found utilization both in making stratigraphic correlations between outcrops of diatomaceous deposits and in various types of biochronological studies that involve dating deposits in different areas. A continental diatom biochronologic scheme will rely upon evolution, such as the appearance of new genera within a family, in combination with regional environmental changes that are responsible for the wide distribution of distinctive diatom species. The increased use of the scanning electron microscope for the

  11. Late Miocene fossils from shallow marine sediments in Brunei Darussalam: systematics, palaeoenvironment and ecology.

    NASA Astrophysics Data System (ADS)

    Roslim, Amajida; Briguglio, Antonino; Kocsis, László; Ćorić, Stjepan; Razak, Hazirah

    2016-04-01

    The geology of Brunei Darussalam is fascinating but difficult to approach: rainforests and heavy precipitation tend to erode and smoothen the landscape limiting rocks exposure, whereas abundant constructions sites and active quarries allow the creation of short time available outcrop, which have to be immediately sampled. The stratigraphy of Brunei Darussalam comprises mainly Neogene sediments deposited in a wave to tide dominated shallow marine environment in a pure siliciclastic system. Thick and heavily bioturbated sandstone layers alternate to claystone beds which occasionally yield an extraordinary abundance and diversity of fossils. The sandstones, when not bioturbated, are commonly characterized by a large variety of sedimentary structures (e.g., ripple marks, planar laminations and cross beddings). In this study, we investigate the sediments and the fossil assemblages to record the palaeoenvironmental evolution of the shallow marine environment during the late Miocene, in terms of sea level change, chemostratigraphy and sedimentation rate. The study area is one of the best in terms of accessibility, extension, abundance and preservation of fossils; it is located in the region -'Bukit Ambug' (Ambug Hill), Tutong District. The fossils fauna collected encompasses mollusks, decapods, otoliths, shark and ray teeth, amber, foraminifera and coccolithophorids. In this investigation, sediment samples were taken along a section which measures 62.5 meters. A thick clay layer of 9 meters was sampled each 30 cm to investigate microfossils occurrences. Each sample was treated in peroxide and then sieved trough 63 μm, 150μm, 250μm, 450μm, 600μm, 1mm and 2mm sieves. Results point on the changes in biodiversity of foraminifera along the different horizons collected reflecting sea level changes and sediment production. The most abundant taxa identified are Pseoudorotalia schroeteriana, Ampistegina lessonii, Elphidium advenum, Quinqueloculina sp., Bolivina sp

  12. Fossil evidence of water lilies (Nymphaeales) in the Early Cretaceous.

    PubMed

    Friis, E M; Pedersen, K R; Crane, P R

    2001-03-15

    Phylogenetic analyses have identified the water lilies (Nymphaeales: Cabombaceae and Nymphaeaceae), together with four other small groups of flowering plants (the 'ANITA clades': Amborellaceae, Illiciales, Trimeniaceae, Austrobaileyaceae), as the first diverging lineages from the main branch of the angiosperm phylogenetic tree, but evidence of these groups in the earliest phases of the angiosperm fossil record has remained elusive. Here we report the earliest unequivocal evidence, based on fossil floral structures and associated pollen, of fossil plants related to members of the ANITA clades. This extends the history of the water lilies (Nymphaeales) back to the Early Cretaceous (125-115 million years) and into the oldest fossil assemblages that contain unequivocal angiosperm stamens and carpels. This discovery adds to the growing congruence between results from molecular-based analyses of relationships among angiosperms and the palaeobotanical record. It is also consistent with previous observations that the flowers of early angiosperms were generally very small compared with those of their living relatives.

  13. Organic preservation of fossil musculature with ultracellular detail

    PubMed Central

    McNamara, Maria; Orr, Patrick J.; Kearns, Stuart L.; Alcalá, Luis; Anadón, Pere; Peñalver-Mollá, Enrique

    2010-01-01

    The very labile (decay-prone), non-biomineralized, tissues of organisms are rarely fossilized. Occurrences thereof are invaluable supplements to a body fossil record dominated by biomineralized tissues, which alone are extremely unrepresentative of diversity in modern and ancient ecosystems. Fossil examples of extremely labile tissues (e.g. muscle) that exhibit a high degree of morphological fidelity are almost invariably replicated by inorganic compounds such as calcium phosphate. There is no consensus as to whether such tissues can be preserved with similar morphological fidelity as organic remains, except when enclosed inside amber. Here, we report fossilized musculature from an approximately 18 Myr old salamander from lacustrine sediments of Ribesalbes, Spain. The muscle is preserved organically, in three dimensions, and with the highest fidelity of morphological preservation yet documented from the fossil record. Preserved ultrastructural details include myofilaments, endomysium, layering within the sarcolemma, and endomysial circulatory vessels infilled with blood. Slight differences between the fossil tissues and their counterparts in extant amphibians reflect limited degradation during fossilization. Our results provide unequivocal evidence that high-fidelity organic preservation of extremely labile tissues is not only feasible, but likely to be common. This is supported by the discovery of similarly preserved tissues in the Eocene Grube Messel biota. PMID:19828545

  14. Biodesulfurization of fossil fuels.

    PubMed

    Gray, Kevin A; Mrachko, Gregory T; Squires, Charles H

    2003-06-01

    Biotechnological techniques enabling the specific removal of sulfur from fossil fuels have been developed. In the past three years there have been important advances in the elucidation of the mechanisms of biodesulfurization; some of the most significant relate to the role of a flavin reductase, DszD, in the enzymology of desulfurization, and to the use of new tools that enable enzyme enhancement via DNA manipulation to influence both the rate and the substrate range of Dsz. Also, a clearer understanding of the unique desulfinase step in the pathway has begun to emerge.

  15. Atmospheric CO2 from fossil plant cuticles.

    PubMed

    Kerp, Hans

    2002-01-03

    Plants respond to changes in atmospheric carbon dioxide levels by regulating the number of stomata in their leaves. In his reconstruction of a continuous, 300-million-year record of atmospheric CO2, Retallack bases his curve on stomatal counts of fossil plant cuticles taken from published micrographs. However, the preservation of cuticles from Permian times is generally too fragmentary for the stomatal index to be reliably determined, the micrographs used could have biased the results, and there are important errors in the supplementary data - all of which cast doubt on the Permian part of Retallack's record.

  16. Fossil Diatoms in a New Carbonaceous Meteorite

    NASA Astrophysics Data System (ADS)

    Wickramasinghe, N. C.; Wallis, J.; Wallis, D. H.; Samaranayake, Anil

    2013-01-01

    We report the discovery for the first time of diatom frustules in a carbonaceous meteorite that fell in the North Central Province of Sri Lanka on 29 December 2012. Contamination is excluded by the circumstance that the elemental abundances within the structures match closely with those of the surrounding matrix. There is also evidence of structures morphologically similar to red rain cells that may have contributed to the episode of red rain that followed within days of the meteorite fall. The new data on "fossil" diatoms provide strong evidence to support the theory of cometary panspermia.

  17. Fossilized spermatozoa preserved in a 50-Myr-old annelid cocoon from Antarctica

    PubMed Central

    Bomfleur, Benjamin; Mörs, Thomas; Ferraguti, Marco; Reguero, Marcelo A.; McLoughlin, Stephen

    2015-01-01

    The origin and evolution of clitellate annelids—earthworms, leeches and their relatives—is poorly understood, partly because body fossils of these delicate organisms are exceedingly rare. The distinctive egg cases (cocoons) of Clitellata, however, are relatively common in the fossil record, although their potential for phylogenetic studies has remained largely unexplored. Here, we report the remarkable discovery of fossilized spermatozoa preserved within the secreted wall layers of a 50-Myr-old clitellate cocoon from Antarctica, representing the oldest fossil animal sperm yet known. Sperm characters are highly informative for the classification of extant Annelida. The Antarctic fossil spermatozoa have several features that point to affinities with the peculiar, leech-like ‘crayfish worms' (Branchiobdellida). We anticipate that systematic surveys of cocoon fossils coupled with advances in non-destructive analytical methods may open a new window into the evolution of minute, soft-bodied life forms that are otherwise only rarely observed in the fossil record. PMID:26179804

  18. Fossil Microorganisms in Archaean

    NASA Technical Reports Server (NTRS)

    Astafleva, Marina; Hoover, Richard; Rozanov, Alexei; Vrevskiy, A.

    2006-01-01

    Ancient Archean and Proterozoic rocks are the model objects for investigation of rocks comprising astromaterials. The first of Archean fossil microorganisms from Baltic shield have been reported at the last SPIE Conference in 2005. Since this confeence biomorphic structures have been revealed in Archean rocks of Karelia. It was determined that there are 3 types of such bion structures: 1. structures found in situ, in other words microorganisms even-aged with rock matrix, that is real Archean fossils biomorphic structures, that is to say forms inhabited early formed rocks, and 3. younger than Archean-Protherozoic minerali microorganisms, that is later contamination. We made attempt to differentiate these 3 types of findings and tried to understand of burial of microorganisms. The structures belongs (from our point of view) to the first type, or real Archean, forms were under examination. Practical investigation of ancient microorganisms from Green-Stone-Belt of Northern Karelia turns to be very perspective. It shows that even in such ancient time as Archean ancient diverse world existed. Moreover probably such relatively highly organized cyanobacteria and perhaps eukaryotic formes existed in Archean world.

  19. Further records of Amphipoda from Baltic Eocene amber with first evidence of prae-copulatory behaviour in a fossil amphipod and remarks on the taxonomic position of Palaeogammarus Zaddach, 1864.

    PubMed

    Jażdżewski, Krzysztof; Grabowski, Michał; Kupryjanowicz, Janusz

    2014-02-20

    Two pieces of Baltic amber with amphipod inclusions were studied. One of them contained approximately twenty individuals identified as belonging to the extinct genus Palaeogammarus and described as P. debroyeri sp. nov. Interestingly, among the individuals there are two pairs preserved in an evident prae-copula position. This is the first finding of such mating behaviour in fossil amphipods. Based on this behavioural trait and on the observed morphological features, we conclude that the genus Palaeogammarus should be placed in Gammaridae and not in Crangonyctidae. The second amber piece contains two individuals identified as belonging to the still extant genus Synurella and described as S. aliciae sp. nov. 

  20. Radioactivity in fossils at the Hagerman Fossil Beds National Monument.

    PubMed

    Farmer, C Neal; Kathren, Ronald L; Christensen, Craig

    2008-08-01

    Since 1996, higher than background levels of naturally occurring radioactivity have been documented in both fossil and mineral deposits at Hagerman Fossil Beds National Monument in south-central Idaho. Radioactive fossil sites occur primarily within an elevation zone of 900-1000 m above sea level and are most commonly found associated with ancient river channels filled with sand. Fossils found in clay rich deposits do not exhibit discernable levels of radioactivity. Out of 300 randomly selected fossils, approximately three-fourths exhibit detectable levels of natural radioactivity ranging from 1 to 2 orders of magnitude above ambient background levels when surveyed with a portable hand held Geiger-Muller survey instrument. Mineral deposits in geologic strata also show above ambient background levels of radioactivity. Radiochemical lab analysis has documented the presence of numerous natural radioactive isotopes. It is postulated that ancient groundwater transported radioactive elements through sand bodies containing fossils which precipitated out of solution during the fossilization process. The elevated levels of natural radioactivity in fossils may require special precautions to ensure that exposures to personnel from stored or displayed items are kept as low as reasonably achievable (ALARA).

  1. Shotgun microbial profiling of fossil remains.

    PubMed

    Der Sarkissian, C; Ermini, L; Jónsson, H; Alekseev, A N; Crubezy, E; Shapiro, B; Orlando, L

    2014-04-01

    Millions to billions of DNA sequences can now be generated from ancient skeletal remains thanks to the massive throughput of next-generation sequencing platforms. Except in cases of exceptional endogenous DNA preservation, most of the sequences isolated from fossil material do not originate from the specimen of interest, but instead reflect environmental organisms that colonized the specimen after death. Here, we characterize the microbial diversity recovered from seven c. 200- to 13 000-year-old horse bones collected from northern Siberia. We use a robust, taxonomy-based assignment approach to identify the microorganisms present in ancient DNA extracts and quantify their relative abundance. Our results suggest that molecular preservation niches exist within ancient samples that can potentially be used to characterize the environments from which the remains are recovered. In addition, microbial community profiling of the seven specimens revealed site-specific environmental signatures. These microbial communities appear to comprise mainly organisms that colonized the fossils recently. Our approach significantly extends the amount of useful data that can be recovered from ancient specimens using a shotgun sequencing approach. In future, it may be possible to correlate, for example, the accumulation of postmortem DNA damage with the presence and/or abundance of particular microbes.

  2. The microfossil record of early land plants.

    PubMed Central

    Wellman, C H; Gray, J

    2000-01-01

    Dispersed microfossils (spores and phytodebris) provide the earliest evidence for land plants. They are first reported from the Llanvirn (Mid-Ordovician). More or less identical assemblages occur from the Llanvirn (Mid-Ordovician) to the late Llandovery (Early Silurian), suggesting a period of relative stasis some 40 Myr in duration. Various lines of evidence suggest that these early dispersed microfossils derive from parent plants that were bryophyte-like if not in fact bryophytes. In the late Llandovery (late Early Silurian) there was a major change in the nature of dispersed spore assemblages as the separated products of dyads (hilate monads) and tetrads (trilete spores) became relatively abundant. The inception of trilete spores probably represents the appearance of vascular plants or their immediate progenitors. A little later in time, in the Wenlock (early Late Silurian), the earliest unequivocal land plant megafossils occur. They are represented by rhyniophytoids. It is only from the Late Silurian onwards that the microfossil/ megafossil record can be integrated and utilized in interpretation of the flora. Dispersed microfossils are preserved in vast numbers, in a variety of environments, and have a reasonable spatial and temporal fossil record. The fossil record of plant megafossils by comparison is poor and biased, with only a dozen or so known pre-Devonian assemblages. In this paper, the early land plant microfossil record, and its interpretation, are reviewed. New discoveries, novel techniques and fresh lines of inquiry are outlined and discussed. PMID:10905606

  3. The microfossil record of early land plants.

    PubMed

    Wellman, C H; Gray, J

    2000-06-29

    Dispersed microfossils (spores and phytodebris) provide the earliest evidence for land plants. They are first reported from the Llanvirn (Mid-Ordovician). More or less identical assemblages occur from the Llanvirn (Mid-Ordovician) to the late Llandovery (Early Silurian), suggesting a period of relative stasis some 40 Myr in duration. Various lines of evidence suggest that these early dispersed microfossils derive from parent plants that were bryophyte-like if not in fact bryophytes. In the late Llandovery (late Early Silurian) there was a major change in the nature of dispersed spore assemblages as the separated products of dyads (hilate monads) and tetrads (trilete spores) became relatively abundant. The inception of trilete spores probably represents the appearance of vascular plants or their immediate progenitors. A little later in time, in the Wenlock (early Late Silurian), the earliest unequivocal land plant megafossils occur. They are represented by rhyniophytoids. It is only from the Late Silurian onwards that the microfossil/ megafossil record can be integrated and utilized in interpretation of the flora. Dispersed microfossils are preserved in vast numbers, in a variety of environments, and have a reasonable spatial and temporal fossil record. The fossil record of plant megafossils by comparison is poor and biased, with only a dozen or so known pre-Devonian assemblages. In this paper, the early land plant microfossil record, and its interpretation, are reviewed. New discoveries, novel techniques and fresh lines of inquiry are outlined and discussed.

  4. Triassic leech cocoon from Antarctica contains fossil bell animal

    NASA Astrophysics Data System (ADS)

    Bomfleur, Benjamin; Kerp, Hans; Taylor, Thomas N.; Moestrup, Øjvind; Taylor, Edith L.

    2012-12-01

    Our understanding of the evolution of life on Earth is limited by the imperfection of the fossil record. One reason for this imperfect record is that organisms without hard parts, such as bones, shells, and wood, have a very low potential to enter the fossil record. Occasionally, however, exceptional fossil deposits that preserve soft-bodied organisms provide a rare glimpse of the true biodiversity during past periods of Earth history. We here present an extraordinary find of a fossil ciliate that is encased inside the wall layer of a more than 200 Ma leech cocoon from Antarctica. The microfossil consists of a helically contractile stalk that attaches to a main body with a peristomial feeding apparatus and a large C-shaped macronucleus. It agrees in every aspect with the living bell animals, such as Vorticella. Vorticellids and similar peritrichs are vital constituents of aquatic ecosystems worldwide, but so far have lacked any fossil record. This discovery offers a glimpse of ancient soft-bodied protozoan biotas, and also highlights the potential of clitellate cocoons as microscopic "conservation traps" comparable to amber.

  5. Triassic leech cocoon from Antarctica contains fossil bell animal.

    PubMed

    Bomfleur, Benjamin; Kerp, Hans; Taylor, Thomas N; Moestrup, Øjvind; Taylor, Edith L

    2012-12-18

    Our understanding of the evolution of life on Earth is limited by the imperfection of the fossil record. One reason for this imperfect record is that organisms without hard parts, such as bones, shells, and wood, have a very low potential to enter the fossil record. Occasionally, however, exceptional fossil deposits that preserve soft-bodied organisms provide a rare glimpse of the true biodiversity during past periods of Earth history. We here present an extraordinary find of a fossil ciliate that is encased inside the wall layer of a more than 200 Ma leech cocoon from Antarctica. The microfossil consists of a helically contractile stalk that attaches to a main body with a peristomial feeding apparatus and a large C-shaped macronucleus. It agrees in every aspect with the living bell animals, such as Vorticella. Vorticellids and similar peritrichs are vital constituents of aquatic ecosystems worldwide, but so far have lacked any fossil record. This discovery offers a glimpse of ancient soft-bodied protozoan biotas, and also highlights the potential of clitellate cocoons as microscopic "conservation traps" comparable to amber.

  6. Triassic leech cocoon from Antarctica contains fossil bell animal

    PubMed Central

    Bomfleur, Benjamin; Kerp, Hans; Taylor, Thomas N.; Moestrup, Øjvind; Taylor, Edith L.

    2012-01-01

    Our understanding of the evolution of life on Earth is limited by the imperfection of the fossil record. One reason for this imperfect record is that organisms without hard parts, such as bones, shells, and wood, have a very low potential to enter the fossil record. Occasionally, however, exceptional fossil deposits that preserve soft-bodied organisms provide a rare glimpse of the true biodiversity during past periods of Earth history. We here present an extraordinary find of a fossil ciliate that is encased inside the wall layer of a more than 200 Ma leech cocoon from Antarctica. The microfossil consists of a helically contractile stalk that attaches to a main body with a peristomial feeding apparatus and a large C-shaped macronucleus. It agrees in every aspect with the living bell animals, such as Vorticella. Vorticellids and similar peritrichs are vital constituents of aquatic ecosystems worldwide, but so far have lacked any fossil record. This discovery offers a glimpse of ancient soft-bodied protozoan biotas, and also highlights the potential of clitellate cocoons as microscopic “conservation traps” comparable to amber. PMID:23213234

  7. Correlated evolution and dietary change in fossil stickleback.

    PubMed

    Purnell, Mark A; Bell, Michael A; Baines, David C; Hart, Paul J B; Travis, Matthew P

    2007-09-28

    The importance of trophic ecology in adaptation and evolution is well known, yet direct evidence that feeding controls microevolution over extended evolutionary time scales, available only from the fossil record, is conspicuously lacking. Through quantitative analysis of tooth microwear, we show that rapid evolutionary change in Miocene stickleback was associated with shifts in feeding, providing direct evidence from the fossil record for changes in trophic niche and resource exploitation driving directional, microevolutionary change over thousands of years. These results demonstrate the potential for tooth microwear analysis to provide powerful insights into trophic ecology during aquatic adaptive radiations.

  8. Fossil fuel furnace reactor

    DOEpatents

    Parkinson, William J.

    1987-01-01

    A fossil fuel furnace reactor is provided for simulating a continuous processing plant with a batch reactor. An internal reaction vessel contains a batch of shale oil, with the vessel having a relatively thin wall thickness for a heat transfer rate effective to simulate a process temperature history in the selected continuous processing plant. A heater jacket is disposed about the reactor vessel and defines a number of independent controllable temperature zones axially spaced along the reaction vessel. Each temperature zone can be energized to simulate a time-temperature history of process material through the continuous plant. A pressure vessel contains both the heater jacket and the reaction vessel at an operating pressure functionally selected to simulate the continuous processing plant. The process yield from the oil shale may be used as feedback information to software simulating operation of the continuous plant to provide operating parameters, i.e., temperature profiles, ambient atmosphere, operating pressure, material feed rates, etc., for simulation in the batch reactor.

  9. Exploring macroevolution using modern and fossil data

    PubMed Central

    Benton, Michael J.

    2015-01-01

    Macroevolution, encompassing the deep-time patterns of the origins of modern biodiversity, has been discussed in many contexts. Non-Darwinian models such as macromutations have been proposed as a means of bridging seemingly large gaps in knowledge, or as a means to explain the origin of exquisitely adapted body plans. However, such gaps can be spanned by new fossil finds, and complex, integrated organisms can be shown to have evolved piecemeal. For example, the fossil record between dinosaurs and Archaeopteryx has now filled up with astonishing fossil intermediates that show how the unique plexus of avian adaptations emerged step by step over 60 Myr. New numerical approaches to morphometrics and phylogenetic comparative methods allow palaeontologists and biologists to work together on deep-time questions of evolution, to explore how diversity, morphology and function have changed through time. Patterns are more complex than sometimes expected, with frequent decoupling of species diversity and morphological diversity, pointing to the need for some new generalizations about the processes that lie behind such patterns. PMID:26063844

  10. Exploring macroevolution using modern and fossil data.

    PubMed

    Benton, Michael J

    2015-07-07

    Macroevolution, encompassing the deep-time patterns of the origins of modern biodiversity, has been discussed in many contexts. Non-Darwinian models such as macromutations have been proposed as a means of bridging seemingly large gaps in knowledge, or as a means to explain the origin of exquisitely adapted body plans. However, such gaps can be spanned by new fossil finds, and complex, integrated organisms can be shown to have evolved piecemeal. For example, the fossil record between dinosaurs and Archaeopteryx has now filled up with astonishing fossil intermediates that show how the unique plexus of avian adaptations emerged step by step over 60 Myr. New numerical approaches to morphometrics and phylogenetic comparative methods allow palaeontologists and biologists to work together on deep-time questions of evolution, to explore how diversity, morphology and function have changed through time. Patterns are more complex than sometimes expected, with frequent decoupling of species diversity and morphological diversity, pointing to the need for some new generalizations about the processes that lie behind such patterns.

  11. New Ediacara fossils preserved in marine limestone and their ecological implications.

    PubMed

    Chen, Zhe; Zhou, Chuanming; Xiao, Shuhai; Wang, Wei; Guan, Chengguo; Hua, Hong; Yuan, Xunlai

    2014-02-25

    Ediacara fossils are central to our understanding of animal evolution on the eve of the Cambrian explosion, because some of them likely represent stem-group marine animals. However, some of the iconic Ediacara fossils have also been interpreted as terrestrial lichens or microbial colonies. Our ability to test these hypotheses is limited by a taphonomic bias that most Ediacara fossils are preserved in sandstones and siltstones. Here we report several iconic Ediacara fossils and an annulated tubular fossil (reconstructed as an erect epibenthic organism with uniserial arranged modular units), from marine limestone of the 551-541 Ma Dengying Formation in South China. These fossils significantly expand the ecological ranges of several key Ediacara taxa and support that they are marine organisms rather than terrestrial lichens or microbial colonies. Their close association with abundant bilaterian burrows also indicates that they could tolerate and may have survived moderate levels of bioturbation.

  12. New Ediacara fossils preserved in marine limestone and their ecological implications

    NASA Astrophysics Data System (ADS)

    Chen, Zhe; Zhou, Chuanming; Xiao, Shuhai; Wang, Wei; Guan, Chengguo; Hua, Hong; Yuan, Xunlai

    2014-02-01

    Ediacara fossils are central to our understanding of animal evolution on the eve of the Cambrian explosion, because some of them likely represent stem-group marine animals. However, some of the iconic Ediacara fossils have also been interpreted as terrestrial lichens or microbial colonies. Our ability to test these hypotheses is limited by a taphonomic bias that most Ediacara fossils are preserved in sandstones and siltstones. Here we report several iconic Ediacara fossils and an annulated tubular fossil (reconstructed as an erect epibenthic organism with uniserial arranged modular units), from marine limestone of the 551-541 Ma Dengying Formation in South China. These fossils significantly expand the ecological ranges of several key Ediacara taxa and support that they are marine organisms rather than terrestrial lichens or microbial colonies. Their close association with abundant bilaterian burrows also indicates that they could tolerate and may have survived moderate levels of bioturbation.

  13. New Ediacara fossils preserved in marine limestone and their ecological implications

    PubMed Central

    Chen, Zhe; Zhou, Chuanming; Xiao, Shuhai; Wang, Wei; Guan, Chengguo; Hua, Hong; Yuan, Xunlai

    2014-01-01

    Ediacara fossils are central to our understanding of animal evolution on the eve of the Cambrian explosion, because some of them likely represent stem-group marine animals. However, some of the iconic Ediacara fossils have also been interpreted as terrestrial lichens or microbial colonies. Our ability to test these hypotheses is limited by a taphonomic bias that most Ediacara fossils are preserved in sandstones and siltstones. Here we report several iconic Ediacara fossils and an annulated tubular fossil (reconstructed as an erect epibenthic organism with uniserial arranged modular units), from marine limestone of the 551–541 Ma Dengying Formation in South China. These fossils significantly expand the ecological ranges of several key Ediacara taxa and support that they are marine organisms rather than terrestrial lichens or microbial colonies. Their close association with abundant bilaterian burrows also indicates that they could tolerate and may have survived moderate levels of bioturbation. PMID:24566959

  14. Highly skewed sex ratios and biased fossil deposition of moa: ancient DNA provides new insight on New Zealand's extinct megafauna

    NASA Astrophysics Data System (ADS)

    Allentoft, Morten E.; Bunce, Michael; Scofield, R. Paul; Hale, Marie L.; Holdaway, Richard N.

    2010-03-01

    Ancient DNA was isolated from the bones of 267 individuals of the extinct New Zealand moa (Aves: Dinornithiformes) from two late Holocene deposits [Pyramid Valley (PV) and Bell Hill Vineyard (BHV)] located 5.7 km apart in North Canterbury, South Island. The two sites' combined fossil record cover the last 3000 years of pre-human New Zealand and mitochondrial DNA confirmed that four species ( Dinornis robustus, Euryapteryx curtus, Emeus crassus, and Pachyornis elephantopus) were sympatric in the region. However, the relative species compositions in the two deposits differed significantly with D. robustus and E. crassus being most abundant at PV while E. curtus outnumbered the other three moa taxa combined at BHV. A subsample of 227 individuals had sufficient nuclear DNA preservation to warrant the use of molecular sexing techniques, and the analyses uncovered a remarkable excess of females in both deposits with an overall male to female ratio of 1:5.1. Among juveniles of E. curtus, the only species which was represented by a substantial fraction of juveniles, the sex ratio was not skewed (10 ♂, 10 ♀), suggesting that the observed imbalance arose as a result of differential mortality during maturation. Surprisingly, sex ratios proved significantly different between sites with a 1:2.2 ratio at BHV ( n = 90) and 1:14.2 at PV ( n = 137). Given the mobility of large ratites, and the proximity of the two fossil assemblages in space and time, these differences in taxonomic and gender composition indicate that moa biology and the local environment have affected the fossil representation dramatically and several possible explanations are offered. Apart from adding to our understanding of moa biology, these discoveries reinforce the need for caution when basing interpretation of the fossil record on material from a single site.

  15. Evolution in fossil lineages: paleontology and The Origin of Species.

    PubMed

    Hunt, Gene

    2010-12-01

    Of all of the sources of evidence for evolution by natural selection, perhaps the most problematic for Darwin was the geological record of organic change. In response to the absence of species-level transformations in the fossil record, Darwin argued that the fossil record was too incomplete, too biased, and too poorly known to provide strong evidence against his theory. Here, this view of the fossil record is evaluated in light of 150 years of subsequent paleontological research. Although Darwin's assessment of the completeness and resolution of fossiliferous rocks was in several ways astute, today the fossil record is much better explored, documented, and understood than it was in 1859. In particular, a reasonably large set of studies tracing evolutionary trajectories within species can now be brought to bear on Darwin's expectation of gradual change driven by natural selection. An unusually high-resolution sequence of stickleback-bearing strata records the transformation of this lineage via natural selection. This adaptive trajectory is qualitatively consistent with Darwin's prediction, but it occurred much more rapidly than he would have guessed: almost all of the directional change was completed within 1,000 generations. In most geological sequences, this change would be too rapid to resolve. The accumulated fossil record at more typical paleontological scales (10(4)-10(6) years) reveals evolutionary changes that are rarely directional and net rates of change that are perhaps surprisingly slow, two findings that are in agreement with the punctuated-equilibrium model. Finally, Darwin's view of the broader history of life is reviewed briefly, with a focus on competition-mediated extinction and recent paleontological and phylogenetic attempts to assess diversity dependence in evolutionary dynamics.

  16. Fossilized bioelectric wire – the trace fossil Trichichnus

    PubMed Central

    Kędzierski, M.; Uchman, A.; Sawlowicz, Z.; Briguglio, A.

    2015-01-01

    The trace fossil Trichichnus is proposed as an indicator of fossil bioelectric bacterial activity at the oxic–anoxic interface zone of marine sediments. This fulfils the idea that such processes, commonly found in the modern realm, should be also present in the geological past. Trichichnus is an exceptional trace fossil due to its very thin diameter (mostly less than 1 mm) and common pyritic filling. It is ubiquitous in some fine-grained sediments, where it has been interpreted as a burrow formed deeper than any other trace fossils, below the redox boundary. Trichichnus, formerly referred to as deeply burrowed invertebrates, has been found as remnant of a fossilized intrasediment bacterial mat that is pyritized. As visualized in 3-D by means of X-ray computed microtomography scanner, Trichichnus forms dense filamentous fabric, which reflects that it is produced by modern large, mat-forming, sulfide-oxidizing bacteria, belonging mostly to Thioploca-related taxa, which are able to house a complex bacterial consortium. Several stages of Trichichnus formation, including filamentous, bacterial mat and its pyritization, are proposed to explain an electron exchange between oxic and suboxic/anoxic layers in the sediment. Therefore, Trichichnus can be considered a fossilized “electric wire”. PMID:26290671

  17. Phenotypic Evolution in Fossil Species: Pattern and Process

    NASA Astrophysics Data System (ADS)

    Hunt, Gene; Rabosky, Daniel L.

    2014-05-01

    Since Darwin, scientists have looked to the fossil record with the hope of using it to document how the phenotypes of species change over substantial periods of time. How best to interpret this record has been controversial, but empirical and methodological advances have resolved at least two issues about pattern: (a) directional transformations are seldom sustained over geological timescales, and (b) net rates of morphological change in fossil species are usually quite slow. Considerable uncertainty remains, however, about the processes responsible for these patterns, but most fruitful explanations use the framework of adaptive landscapes to consider the role of natural selection and other processes. An additional, unresolved issue is the claim that most phenotypic change is associated with speciation. A variety of methods, using data from both fossil and extant species, have supported such a link, at least in some clades and traits, but its prevalence and underlying mechanism remain unresolved.

  18. Dating Fossil Pollen: A Simulation.

    ERIC Educational Resources Information Center

    Sheridan, Philip

    1992-01-01

    Describes a hands-on simulation in which students determine the age of "fossil" pollen samples based on the pollen types present when examined microscopically. Provides instructions for the preparation of pollen slides. (MDH)

  19. Corrected placement of Mus-Rattus fossil calibration forces precision in the molecular tree of rodents.

    PubMed

    Kimura, Yuri; Hawkins, Melissa T R; McDonough, Molly M; Jacobs, Louis L; Flynn, Lawrence J

    2015-09-28

    Time calibration derived from the fossil record is essential for molecular phylogenetic and evolutionary studies. Fossil mice and rats, discovered in the Siwalik Group of Pakistan, have served as one of the best-known fossil calibration points in molecular phylogenic studies. Although these fossils have been widely used as the 12 Ma date for the Mus/Rattus split or a more basal split, conclusive paleontological evidence for the nodal assignments has been absent. This study analyzes newly recognized characters that demonstrate lineage separation in the fossil record of Siwalik murines and examines the most reasonable nodal placement of the diverging lineages in a molecular phylogenetic tree by ancestral state reconstruction. Our specimen-based approach strongly indicates that Siwalik murines of the Karnimata clade are fossil members of the Arvicanthini-Otomyini-Millardini clade, which excludes Rattus and its relatives. Combining the new interpretation with the widely accepted hypothesis that the Progonomys clade includes Mus, the lineage separation event in the Siwalik fossil record represents the Mus/Arvicanthis split. Our test analysis on Bayesian age estimates shows that this new calibration point provides more accurate estimates of murine divergence than previous applications. Thus, we define this fossil calibration point and refine two other fossil-based points for molecular dating.

  20. Fossil calibrations and molecular divergence time estimates in centrarchid fishes (Teleostei: Centrarchidae).

    PubMed

    Near, Thomas J; Bolnick, Daniel I; Wainwright, Peter C

    2005-08-01

    Molecular clock methods allow biologists to estimate divergence times, which in turn play an important role in comparative studies of many evolutionary processes. It is well known that molecular age estimates can be biased by heterogeneity in rates of molecular evolution, but less attention has been paid to the issue of potentially erroneous fossil calibrations. In this study we estimate the timing of diversification in Centrarchidae, an endemic major lineage of the diverse North American freshwater fish fauna, through a new approach to fossil calibration and molecular evolutionary model selection. Given a completely resolved multi-gene molecular phylogeny and a set of multiple fossil-inferred age estimates, we tested for potentially erroneous fossil calibrations using a recently developed fossil cross-validation. We also used fossil information to guide the selection of the optimal molecular evolutionary model with a new fossil jackknife method in a fossil-based model cross-validation. The centrarchid phylogeny resulted from a mixed-model Bayesian strategy that included 14 separate data partitions sampled from three mtDNA and four nuclear genes. Ten of the 31 interspecific nodes in the centrarchid phylogeny were assigned a minimal age estimate from the centrarchid fossil record. Our analyses identified four fossil dates that were inconsistent with the other fossils, and we removed them from the molecular dating analysis. Using fossil-based model cross-validation to determine the optimal smoothing value in penalized likelihood analysis, and six mutually consistent fossil calibrations, the age of the most recent common ancestor of Centrarchidae was 33.59 million years ago (mya). Penalized likelihood analyses of individual data partitions all converged on a very similar age estimate for this node, indicating that rate heterogeneity among data partitions is not confounding our analyses. These results place the origin of the centrarchid radiation at a time of major

  1. The legacy of fossil fuels.

    PubMed

    Armaroli, Nicola; Balzani, Vincenzo

    2011-03-01

    Currently, over 80% of the energy used by mankind comes from fossil fuels. Harnessing coal, oil and gas, the energy resources contained in the store of our spaceship, Earth, has prompted a dramatic expansion in energy use and a substantial improvement in the quality of life of billions of individuals in some regions of the world. Powering our civilization with fossil fuels has been very convenient, but now we know that it entails severe consequences. We treat fossil fuels as a resource that anyone anywhere can extract and use in any fashion, and Earth's atmosphere, soil and oceans as a dump for their waste products, including more than 30 Gt/y of carbon dioxide. At present, environmental legacy rather than consistence of exploitable reserves, is the most dramatic problem posed by the relentless increase of fossil fuel global demand. Harmful effects on the environment and human health, usually not incorporated into the pricing of fossil fuels, include immediate and short-term impacts related to their discovery, extraction, transportation, distribution, and burning as well as climate change that are spread over time to future generations or over space to the entire planet. In this essay, several aspects of the fossil fuel legacy are discussed, such as alteration of the carbon cycle, carbon dioxide rise and its measurement, greenhouse effect, anthropogenic climate change, air pollution and human health, geoengineering proposals, land and water degradation, economic problems, indirect effects on the society, and the urgent need of regulatory efforts and related actions to promote a gradual transition out of the fossil fuel era. While manufacturing sustainable solar fuels appears to be a longer-time perspective, alternatives energy sources already exist that have the potential to replace fossil fuels as feedstocks for electricity production.

  2. From Suns to Life: A Chronological Approach to the History of Life on Earth 7. Ancient Fossil Record and Early Evolution (ca. 3.8 to 0.5 Ga)

    NASA Astrophysics Data System (ADS)

    López-Garcia, Purificacón; Moreira, David; Douzery, Emmanuel; Forterre, Patrick; van Zuilen, Mark; Claeys, Philippe; Prieur, Daniel

    2006-06-01

    Once life appeared, it evolved and diversified. From primitive living entities, an evolutionary path of unknown duration, likely paralleled by the extinction of unsuccessful attempts, led to a last common ancestor that was endowed with the basic properties of all cells. From it, cellular organisms derived in a relative order, chronology and manner that are not yet completely settled. Early life evolution was accompanied by metabolic diversification, i.e. by the development of carbon and energy metabolic pathways that differed from the first, not yet clearly identified, metabolic strategies used. When did the different evolutionary transitions take place? The answer is difficult, since hot controversies have been raised in recent years concerning the reliability of the oldest life traces, regardless of their morphological, isotopic or organic nature, and there are also many competing hypotheses for the evolution of the eukaryotic cell. As a result, there is a need to delimit hypotheses from solid facts and to apply a critical analysis of contrasting data. Hopefully, methodological improvement and the increase of data, including fossil signatures and genomic information, will help reconstructing a better picture of life evolution in early times as well as to, perhaps, date some of the major evolutionary transitions. There are already some certitudes. Modern eukaryotes evolved after bacteria, since their mitochondria derived from ancient bacterial endosymbionts. Once prokaryotes and unicellular eukaryotes had colonized terrestrial ecosystems for millions of years, the first pluricellular animals appeared and radiated, thus inaugurating the Cambrian. The following sections constitute a collection of independent articles providing a general overview of these aspects.

  3. Vertebrate fossils and trace fossils in Upper Jurassic-Lower cretaceous red beds in the Atacama region, Chile

    NASA Astrophysics Data System (ADS)

    Bell, C. M.; Suárez, M.

    Pterosaur, dinosaur, and crocodile bones are recorded here for the first time in Upper Jurassic-Lower Cretaceous red beds in the Atacama region east of Copiapó, Chile. Trace fossils produced by vertebrate animals include the footprints of theropod dinosaurs and the depressions of sandstone laminae interpreted as burrows and foot impressions. The fossils occur in the 1500-meter-thick Quebrada Monardes Formation, which consists predominantly of the aeolian and alluvial deposits of a semi-arid terrestrial environment. Vertebrate fossils are very rare in Chile. Dinosaur bones and footprints have previously been recorded at only seven locations, and pterosaur remains at only one location. The newly discovered dinosaur bones are the oldest to be described in Chile.

  4. Integrating fossils with molecular phylogenies improves inference of trait evolution.

    PubMed

    Slater, Graham J; Harmon, Luke J; Alfaro, Michael E

    2012-12-01

    Comparative biologists often attempt to draw inferences about tempo and mode in evolution by comparing the fit of evolutionary models to phylogenetic comparative data consisting of a molecular phylogeny with branch lengths and trait measurements from extant taxa. These kinds of approaches ignore historical evidence for evolutionary pattern and process contained in the fossil record. In this article, we show through simulation that incorporation of fossil information dramatically improves our ability to distinguish among models of quantitative trait evolution using comparative data. We further suggest a novel Bayesian approach that allows fossil information to be integrated even when explicit phylogenetic hypotheses are lacking for extinct representatives of extant clades. By applying this approach to a comparative dataset comprising body sizes for caniform carnivorans, we show that incorporation of fossil information not only improves ancestral state estimates relative to those derived from extant taxa alone, but also results in preference of a model of evolution with trend toward large body size over alternative models such as Brownian motion or Ornstein-Uhlenbeck processes. Our approach highlights the importance of considering fossil information when making macroevolutionary inference, and provides a way to integrate the kind of sparse fossil information that is available to most evolutionary biologists.

  5. We're Going on a Fossil Hunt!

    ERIC Educational Resources Information Center

    Powell, Deborah A.; Aram, Richard B.; Aram, Roberta J.; Chase, Terry L.

    2007-01-01

    Scientists understand that scientific ideas are subject to change and improvement. Fourth- through eighth- graders develop this understanding about the nature of science as they gather and examine fossil evidence from the Paleozoic era, record their findings, and read and write about science for authentic purposes as scientists do. Students…

  6. Taxonomy and fossils: a critical appraisal.

    PubMed Central

    Forey, Peter L; Fortey, Richard A; Kenrick, Paul; Smith, Andrew B

    2004-01-01

    Many compendia at the species, genus and family levels document the fossil record, but these are not standardized, nor usually critical in content, and few are available on the World Wide Web. The sampling of the available record is good for organisms with fossilizable parts, but preservational constraints on the entire morphology, life history and geographical distribution lead to difficulties in recognizing and naming species. We recommend abandoning some of the palaeontological species concepts such as chronospecies and stratospecies, and we advocate species recognition based on unique combinations of characters. The compilation of species lists is extremely time consuming, and given the inherent problems we suggest that compilation of generic lists is a more achievable goal because genera are recognized by definitive morphological characters. In calculating taxon duration, care must be taken to distinguish between mono-, para- and polyphyletic groups, the first being the only reliable unit for use in calculating diversity curves. We support the inclusion of fossils into classifications based on Recent organisms, but we recognize some of the problems this may pose for standard Linnaean classifications. Web-based taxonomy is the way forward, having the advantages of speed and currency of information dissemination, universal access with links to primary literature and increasingly sophisticated imagery. These advantages over conventional outlets will only be realized with careful Web design and a commitment to maintenance. PMID:15253350

  7. A revised checklist of Nepticulidae fossils (Lepidoptera) indicates an Early Cretaceous origin.

    PubMed

    Doorenweerd, Camiel; Nieukerken, Erik J Van; Sohn, Jae-Cheon; Labandeira, Conrad C

    2015-05-27

    With phylogenetic knowledge of Lepidoptera rapidly increasing, catalysed by increasingly powerful molecular techniques, the demand for fossil calibration points to estimate an evolutionary timeframe for the order is becoming an increasingly pressing issue. The family Nepticulidae is a species rich, basal branch within the phylogeny of the Lepidoptera, characterized by larval leaf-mining habits, and thereby represents a potentially important lineage whose evolutionary history can be established more thoroughly with the potential use of fossil calibration points. Using our experience with extant global Nepticulidae, we discuss a list of characters that may be used to assign fossil leaf mines to Nepticulidae, and suggest useful methods for classifying relevant fossil material. We present a checklist of 79 records of Nepticulidae representing adult and leaf-mine fossils mentioned in literature, often with multiple exemplars constituting a single record. We provide our interpretation of these fossils. Two species now are included in the collective generic name Stigmellites: Stigmellites resupinata (Krassilov, 2008) comb. nov. (from Ophiheliconoma) and Stigmellites almeidae (Martins-Neto, 1989) comb. nov. (from Nepticula). Eleven records are for the first time attributed to Nepticulidae. After discarding several dubious records, including one possibly placing the family at a latest Jurassic position, we conclude that the oldest fossils likely attributable to Nepticulidae are several exemplars representing a variety of species from the Dakota Formation (USA). The relevant strata containing these earliest fossils are now dated at 102 Ma (million years ago) in age, corresponding to the latest Albian Stage of the Early Cretaceous. Integration of all records in the checklist shows that a continuous presence of nepticulid-like leaf mines preserved as compression-impression fossils and by amber entombment of adults have a fossil record extending to the latest Early Cretaceous.

  8. The "Sudden Explosion" of Animal Fossils about 600 Million Years Ago: Why?

    ERIC Educational Resources Information Center

    Kaveski, Sharon; Margulis, Lynn

    1983-01-01

    Discusses the "sudden explosion" of animal fossils during the Cambrian era, suggesting that the "explosion" is a result of organic evolution, leading to remarkably preservable calcareous skeletons. Suggests that earlier organisms were soft-bodied and consequently were poorly preserved in the fossil record. (JN)

  9. Using more than the oldest fossils: dating osmundaceae with three Bayesian clock approaches.

    PubMed

    Grimm, Guido W; Kapli, Paschalia; Bomfleur, Benjamin; McLoughlin, Stephen; Renner, Susanne S

    2015-05-01

    A major concern in molecular clock dating is how to use information from the fossil record to calibrate genetic distances from DNA sequences. Here we apply three Bayesian dating methods that differ in how calibration is achieved-"node dating" (ND) in BEAST, "total evidence" (TE) dating in MrBayes, and the "fossilized birth-death" (FBD) in FDPPDiv-to infer divergence times in the royal ferns. Osmundaceae have 16-17 species in four genera, two mainly in the Northern Hemisphere and two in South Africa and Australasia; they are the sister clade to the remaining leptosporangiate ferns. Their fossil record consists of at least 150 species in ∼17 genera. For ND, we used the five oldest fossils, whereas for TE and FBD dating, which do not require forcing fossils to nodes and thus can use more fossils, we included up to 36 rhizomes and frond compression/impression fossils, which for TE dating were scored for 33 morphological characters. We also subsampled 10%, 25%, and 50% of the 36 fossils to assess model sensitivity. FBD-derived divergence ages were generally greater than those inferred from ND; two of seven TE-derived ages agreed with FBD-obtained ages, the others were much younger or much older than ND or FBD ages. We prefer the FBD-derived ages because they best fit the Osmundales fossil record (including Triassic fossils not used in our study). Under the preferred model, the clade encompassing extant Osmundaceae (and many fossils) dates to the latest Paleozoic to Early Triassic; divergences of the extant species occurred during the Neogene. Under the assumption of constant speciation and extinction rates, the FBD approach yielded speciation and extinction rates that overlapped those obtained from just neontological data. However, FBD estimates of speciation and extinction are sensitive to violations in the assumption of continuous fossil sampling; therefore, these estimates should be treated with caution.

  10. Microbial Fossilization in Mineralizing Environments: Relevance for Mars "EXOPALEONTOLOGY"

    NASA Technical Reports Server (NTRS)

    Farmer, Jack D.; DesMarais, David J.; Morrison, David (Technical Monitor)

    1994-01-01

    The goals of post-Viking exobiology include the search for a Martian fossil record. How can we optimize future exploration efforts to search for fossils on Mars? The Precambrian fossil record indicates that key factors for the long-term preservation of microbial fossils include: 1) the rapid entombment and/or replacement of organisms and organic matter by fine-grained, stable mineral phases (e.g. silica, phosphate, and to a lesser extent, carbonate), 2) low-permeability host sediments (maintaining a closed chemical system during early diagenesis), and 3) shallow burial (maintaining post-depositional temperatures and pressures within the stability range for complex organic molecules). Modem terrestrial environments where early mineralization commonly occurs in association with microbial organisms include: subaerial thermal springs and shallow hydrothermal systems, sub-lacustrine springs and evaporites of alkaline lakes, and subsoil environments where hardpans (e.g. calcretes, silcretes) and duricrusts form. Studies of microbial fossilization in such environments provide important insights preservation patterns in Precambrian rocks, while also playing a role in the development of strategies for Mars exopaleontology. The refinement of site priorities for Mars exopaleontology is expected to benefit greatly from high resolution imaging and altimetry acquired during upcoming orbital missions, and especially infrared and gamma ray spectral data needed for determining surface composition. In anticipation of future orbital missions, constraints for identifying high priority mineral deposits on Mars are being developed through analog remote sensing studies of key mineralizing environments on Earth.

  11. The origin and paleoecologic significance of the trace fossil Asteriadtes in the Pennsylvanian of Kansas and Missouri

    USGS Publications Warehouse

    Gabriela, Mangano M.; Buatois, L.A.; West, R.R.; Maples, C.G.

    1999-01-01

    The trace fossil Asteriacites, recorded in Cambrian to Recent shallow- and deep-marine facie??s, is traditionally interpreted as the resting trace of asterozoans. Well-preserved specimens of A. lumbricalis are abundant in Pennsylvanian (Upper Carboniferous) shallow- and marginalmarine siliciclastic deposits of eastern Kansas and western Missouri. Detailed morphologic analysis of these specimens suggests that they record the activities of mobile epifaunal ophiuroids. Evidence of a brittle star (ophiuroid) producer rather than sea star (asteroid) is provided by (1) trace-fossil morphologic features reflecting the anatomy of the producer (e.g., well-differentiated central structure, slender vermiform arms) and ophiuroid burrowing technique (e.g., proximal arm expansion, arm branching), and (2) mode of occurrence (e.g., gregarious behavior, horizontal and vertical repetition). Vertical and horizontal repetition produces complex aggregates of A. lumbricalis that are interpreted either as escape structures (fugichnia) or as feeding structures, respectively. Ophiura texturata is proposed.as a modern analogue for the A. lumbricalis producer, based on inferred life habit and feeding behavior. Asteriacites lumbricalis is present in two different intertidal trace-fossil assemblages. The first assemblage is characterized by high diversity and records tidal flats developed outside of embayments under normal marine conditions. The second assemblage consists of A. lumbricalis together with a few other ichnotaxa and represents a depauperate association that developed in restricted tidal flats within an embayment or estuarine setting. This challenges the conventional view of Asteriacites as a normal-marine salinity indicator. Some echinoderms, and particularly asterozoans, penetrate and inhabit modern environments of depressed salinity. The presence of Asteriacites in Pennsylvanian marginal-marine facie??s of Kansas and Missouri provides evidence that ophiuroids had adapted to

  12. Travels with the Fossil Hunters

    NASA Astrophysics Data System (ADS)

    Whybrow, Peter J.

    2000-04-01

    Whether dodging bullets in West Africa, or rabid dogs in Pakistan, surviving yak-butter tea in Tibet, or eating raw fish in China, the life of a globe-trotting fossil hunter is often hazardous and always filled with surprises. Travels with the Fossil Hunters lets readers share the wonder, joys of discovery, and excitement of these intrepid scientists. Packed with more than 100 beautiful, full-color photographs, the volume takes readers on twelve expeditions to remote parts of the world in search of diverse fossil remains, from those of dinosaurs to human ancestors. Each expedition by paleontologists from London's Natural History Museum reveals the problems and challenges of working in extreme conditions, from the deserts of the Sahara and Yemen to the frozen wastes of Antarctica, from the mountains of India to the forests of Latvia. Along the way they also describe the paleontology and geology of the countries they visit and the scientific reasons for their expeditions. With a foreword from Sir David Attenborough and an introduction from Richard Fortey, this fascinating book will appeal to amateur and professional fossil hunters alike and to readers interested in accounts of exotic locales. Peter Whybrow is a research scientist at the Natural History Museum, London. His research interests include Arabian Miocene vertebrates, paleoclimates, paleogeography, and biotic diversity. He is senior editor with A. Hill of Fossil Vertebrates of Arabia (Yale University Press, New Haven, 1999).

  13. Fossil-bearing deposits from the Bukpyeong Formation (Miocene) in the Bukpyeong Basin at Donghae city, Gangwon-do, South Korea: occurrences, taphonomy and paleoenvironmental implications

    NASA Astrophysics Data System (ADS)

    Kim, Hyun Joo; Jeong, Eun Kyoung; Uemura, Kazuhiko; Kim, Kyungsik; Paik, In Sung

    2016-04-01

    Abundant and diverse plant fossils such as land plants and subaqueous plants, freshwater mollusc fossils and invertebrate trace fossils are found in the Miocene Bukpyeong Formation at Donghae city, Gangwon-do, South Korea. Occurrences and taphofacies of the fossil-bearing deposits from the Bukpyeong Formation are described and their taphonomy and paleoenvironmental implications are interpreted. Based on fossil occurrences, lithofacies and sedimentary features of the fossil-bearing deposits, eight taphofacies are classified as the following: (1) Taphofacies 1: Gastropod fossils in massive silty mudstone; (2) Taphofacies 2: Bivalve fossils in massive silty mudstone; (3) Taphofacies 3: Plant fossils (leaf fossils) in massive silty mudstone; (4) Taphofacies 4: Gastropod and plant fossils in massive silty mudstone; (5) Taphofacies 5: Plant fossils in weakly fissile silty mudstone; (6) Taphofacies 6: Plant fossils (leaf fossils) in thin-bedded and graded silty mudstone to mudstone (claystone); (7) Taphofacies 7: Plant fragment fossils in thin-bedded and graded silty mudstone to mudstone (claystone); (8) Taphofacies 8: Plant debris in planar- to cross-laminated fine-grained sandstone. Taphonomy of taphofacies 1, 2, and 4 including freshwater mollusc fossils is interpreted to have been reworked or transported by turbidity currents after death and deposited in shallow lake to open lake. Taphonomy of taphofacies 3, 5, 6, and 7 including plant fossils is interpreted to have been transported by input of episodic flooding in the land and deposited by settling down in open lake. Taphofacies 8 including plant debris has been deposited in shallow lake by input of intensive episodic flooding from the land. The occurrences and taphofacies of the fossil-bearing deposits indicate that most of the fossils were transported by turbidity current induced by input of episodic flooding in the land and deposited in shallow lake to open lake. Moreover, plant fossils from the Bukpyeong

  14. Fossil gaps inferred from phylogenies alter the apparent nature of diversification in dragonflies and their relatives

    PubMed Central

    2011-01-01

    Background The fossil record has suggested that clade growth may differ in marine and terrestrial taxa, supporting equilibrial models in the former and expansionist models in the latter. However, incomplete sampling may bias findings based on fossil data alone. To attempt to correct for such bias, we assemble phylogenetic supertrees on one of the oldest clades of insects, the Odonatoidea (dragonflies, damselflies and their extinct relatives), using MRP and MRC. We use the trees to determine when, and in what clades, changes in taxonomic richness have occurred. We then test whether equilibrial or expansionist models are supported by fossil data alone, and whether findings differ when phylogenetic information is used to infer gaps in the fossil record. Results There is broad agreement in family-level relationships between both supertrees, though with some uncertainty along the backbone of the tree regarding dragonflies (Anisoptera). "Anisozygoptera" are shown to be paraphyletic when fossil information is taken into account. In both trees, decreases in net diversification are associated with species-poor extant families (Neopetaliidae, Hemiphlebiidae), and an upshift is associated with Calopterygidae + Polythoridae. When ghost ranges are inferred from the fossil record, many families are shown to have much earlier origination dates. In a phylogenetic context, the number of family-level lineages is shown to be up to twice as high as the fossil record alone suggests through the Cretaceous and Cenozoic, and a logistic increase in richness is detected in contrast to an exponential increase indicated by fossils alone. Conclusions Our analysis supports the notion that taxa, which appear to have diversified exponentially using fossil data, may in fact have diversified more logistically. This in turn suggests that one of the major apparent differences between the marine and terrestrial fossil record may simply be an artifact of incomplete sampling. Our results also support

  15. Fossil and genetic evidence for the polyphyletic nature of the planktonic foraminifera "Globigerinoides", and description of the new genus Trilobatus.

    PubMed

    Spezzaferri, Silvia; Kucera, Michal; Pearson, Paul Nicholas; Wade, Bridget Susan; Rappo, Sacha; Poole, Christopher Robert; Morard, Raphaël; Stalder, Claudio

    2015-01-01

    Planktonic foraminifera are one of the most abundant and diverse protists in the oceans. Their utility as paleo proxies requires rigorous taxonomy and comparison with living and genetically related counterparts. We merge genetic and fossil evidence of "Globigerinoides", characterized by supplementary apertures on spiral side, in a new approach to trace their "total evidence phylogeny" since their first appearance in the latest Paleogene. Combined fossil and molecular genetic data indicate that this genus, as traditionally understood, is polyphyletic. Both datasets indicate the existence of two distinct lineages that evolved independently. One group includes "Globigerinoides" trilobus and its descendants, the extant "Globigerinoides" sacculifer, Orbulina universa and Sphaeroidinella dehiscens. The second group includes the Globigerinoides ruber clade with the extant G. conglobatus and G. elongatus and ancestors. In molecular phylogenies, the trilobus group is not the sister taxon of the ruber group. The ruber group clusters consistently together with the modern Globoturborotalita rubescens as a sister taxon. The re-analysis of the fossil record indicates that the first "Globigerinoides" in the late Oligocene are ancestral to the trilobus group, whereas the ruber group first appeared at the base of the Miocene with representatives distinct from the trilobus group. Therefore, polyphyly of the genus "Globigerinoides" as currently defined can only be avoided either by broadening the genus concept to include G. rubescens and a large number of fossil species without supplementary apertures, or if the trilobus group is assigned to a separate genus. Since the former is not feasible due to the lack of a clear diagnosis for such a broad genus, we erect a new genus Trilobatus for the trilobus group (type species Globigerina triloba Reuss) and amend Globoturborotalita and Globigerinoides to clarify morphology and wall textures of these genera. In the new concept, Trilobatus n

  16. Fossil and Genetic Evidence for the Polyphyletic Nature of the Planktonic Foraminifera "Globigerinoides", and Description of the New Genus Trilobatus

    PubMed Central

    Spezzaferri, Silvia; Kucera, Michal; Pearson, Paul Nicholas; Wade, Bridget Susan; Rappo, Sacha; Poole, Christopher Robert; Morard, Raphaël; Stalder, Claudio

    2015-01-01

    Planktonic foraminifera are one of the most abundant and diverse protists in the oceans. Their utility as paleo proxies requires rigorous taxonomy and comparison with living and genetically related counterparts. We merge genetic and fossil evidence of “Globigerinoides”, characterized by supplementary apertures on spiral side, in a new approach to trace their “total evidence phylogeny” since their first appearance in the latest Paleogene. Combined fossil and molecular genetic data indicate that this genus, as traditionally understood, is polyphyletic. Both datasets indicate the existence of two distinct lineages that evolved independently. One group includes “Globigerinoides” trilobus and its descendants, the extant “Globigerinoides” sacculifer, Orbulina universa and Sphaeroidinella dehiscens. The second group includes the Globigerinoides ruber clade with the extant G. conglobatus and G. elongatus and ancestors. In molecular phylogenies, the trilobus group is not the sister taxon of the ruber group. The ruber group clusters consistently together with the modern Globoturborotalita rubescens as a sister taxon. The re-analysis of the fossil record indicates that the first “Globigerinoides” in the late Oligocene are ancestral to the trilobus group, whereas the ruber group first appeared at the base of the Miocene with representatives distinct from the trilobus group. Therefore, polyphyly of the genus "Globigerinoides" as currently defined can only be avoided either by broadening the genus concept to include G. rubescens and a large number of fossil species without supplementary apertures, or if the trilobus group is assigned to a separate genus. Since the former is not feasible due to the lack of a clear diagnosis for such a broad genus, we erect a new genus Trilobatus for the trilobus group (type species Globigerina triloba Reuss) and amend Globoturborotalita and Globigerinoides to clarify morphology and wall textures of these genera. In the new

  17. Palaeobiology: Argentinian unhatched pterosaur fossil.

    PubMed

    Chiappe, Luis M; Codorniú, Laura; Grellet-Tinner, Gerald; Rivarola, David

    2004-12-02

    Our knowledge of the eggs and embryos of pterosaurs, the Mesozoic flying reptiles, is sparse. Until now, the recent discovery of an ornithocheirid embryo from 121-million-year-old rocks in China constituted the only reliable evidence of an unhatched pterosaur. Here we describe an embryonic fossil of a different pterosaur from the Early Cretaceous lacustrine deposits of Loma del Pterodaustro (the Lagarcito Formation, which is about 100 million years old) in central Argentina. This new fossil provides insight into the eggshell morphology, early growth and nesting environments of pterosaurs.

  18. The oldest Mahonia (Berberidaceae) fossil from East Asia and its biogeographic implications.

    PubMed

    Huang, Jian; Su, Tao; Lebereton-Anberrée, Julie; Zhang, Shi-Tao; Zhou, Zhe-Kun

    2016-03-01

    Interpretation of the biogeography of the genus Mahonia (Berberidaceae) is limited by the lack of fossil records in East Asia. Compressed fossil foliage, described here as Mahonia mioasiatica sp. nov., were collected from the Upper Miocene Xiaolongtan Formation in Wenshan, Yunnan, southwest China. These specimens represent the oldest reliable fossil record of Mahonia in East Asia. This new fossil species shows a general similarity to Group Orientales and is most similar to the extant eastern Asian Mahonia conferta. Considering other fossil evidence of Mahonia, we propose a migration route of this genus to Asia over the North Atlantic Land Bridge rather than the Bering Land Bridge. Our results also suggest that North America, Europe and East Asia have been successive centers of diversity for the genus, as a consequence of diversification in Group Orientales potentially related to historical climate change.

  19. Silicification of trace fossils in carbonates; evidence from Permian Kaibab Formation, southwestern Utah

    SciTech Connect

    Whidden, K.J.; Bottjer, D.J.

    1989-04-01

    Silicification in carbonates, particularly silicified trace fossils, has received relatively little previous study. Chert comprises a significant percentage of the upper Fossil Mountain Member of the Kaibab Formation, a Permian epicontinental limestone. Distribution and origin of this chert were studied from outcrops in southwestern Utah. The origin of much of this chert is believed to be as silicified Thalassinoides burrows. Field evidence for trace fossil silicification includes (1) silicified cylindrical tubes with Y-shaped branching patterns as well as hollow tubes, and (2) polygonal box-work patterns of tubes. In addition, brachiopods, bryozoans, and abundant specimens of the sponge Actinocelia maendrina Finks are also silicified. Recognition of silicified trace fossils in carbonates provides a different approach to the study of early diagenetic silica precipitation. These silicified trace fossils also represent new information on bioturbation in ancient carbonates, a subject that has, until recently, been relatively unstudied.

  20. Molecular Fossils for Understanding Biodiversity During the Neoproterozoic-Cambrian Transition in China

    NASA Astrophysics Data System (ADS)

    Pi, Y.; Tuo, J.; McFadden, K.; Xiao, S.; Zhang, C. L.

    2005-12-01

    Neoproterozoic-Cambrian rocks in South China contain an extraordinary fossil record, including exceptionally well preserved animal embryos, acritarchs, and multi-cellular algae. The goal of this study was to evaluate the microbial diversity associated with these remarkably preserved fossil assemblages at the Neoproterozoic-Cambrian transition. Rock samples of 520-632 Ma in age were collected in the Yangtze Gorges area and southern Anhui Province, China. Samples were powdered and extracted for organic biomarkers. The content of bitumen A accounted for 4-16% of the rock material and most of it (49-79%) was asphaltenes. Saturated and aromatic hydrocarbons accounted for 2-6% and 1-3%, respectively. Analysis using GC-MS indicated the predominance of n-alkanes and less abundant isoprenoid alkanes in the saturated fractions. The n-alkanes were characterized by homologues dominated by C15-C17, which is consistent with the result of high thermal-evolution (Brocks et al., 2003. GCA 67:4321-4335). Hopanoids were present in less abundance and ranged from C29 to C32. A smaller amount of heavy-molecular-weight n-alkanes (C23-C39) was also detected, which indicated a source of high plants and must be contamination from younger organic matter. Still, patterns of variation can be detected among these samples. For example, the ratio of pristane to phytane was all greater than 1.0 except for one sample (JLW9.3) from Yangtze Gorges area. The results indicate that sample JLW9.3 might have been deposited in a reducing environment whereas the other samples might have been formed in relatively oxidative environments. The overall results, however, suggest that rock samples from the Neoproterozoic-Cambrian transition in China have gone through significant metamorphism; thus, understanding of microbial communities using molecular biomarkers in such altered rocks needs to be cautiously executed.

  1. Fossils, rocks, and time

    USGS Publications Warehouse

    Edwards, Lucy E.; Pojeta, John

    1999-01-01

    We study our Earth for many reasons: to find water to drink or oil to run our cars or coal to heat our homes, to know where to expect earthquakes or landslides or floods, and to try to understand our natural surroundings. Earth is constantly changing--nothing on its surface is truly permanent. Rocks that are now on top of a mountain may once have been at the bottom of the sea. Thus, to understand the world we live on, we must add the dimension of time. We must study Earth's history. When we talk about recorded history, time is measured in years, centuries, and tens of centuries. When we talk about Earth history, time is measured in millions and billions of years. Time is an everyday part of our lives. We keep track of time with a marvelous invention, the calendar, which is based on the movements of Earth in space. One spin of Earth on its axis is a day, and one trip around the Sun is a year. The modern calendar is a great achievement, developed over many thousands of years as theory and technology improved. People who study Earth's history also use a type of calendar, called the geologic time scale. It looks very different from the familiar calendar. In some ways, it is more like a book, and the rocks are its pages. Some of the pages are torn or missing, and the pages are not numbered, but geology gives us the tools to help us read this book.

  2. Fossils, rocks, and time

    USGS Publications Warehouse

    Edwards, Lucy E.; Pojeta, John

    1993-01-01

    We study out Earth for many reasons: to find water to drink or oil to run our cars or coal to heat our homes, to know where to expect earthquakes or landslides or floods, and to try to understand our natural surroundings. Earth is constantly changing--nothing on its surface is truly permanent. Rocks that are not on top of a mountain may once have been on the bottom of the sea. Thus, to understand the world we live on, we must add the dimension of time. We must study Earth's history. When we talk about recorded history, time is measured in years, centuries, and tens of centuries. When we talk about Earth history, time is measured in millions and billions of years. Time is an everyday part of our lives. We keep track of time with a marvelous invention, the calendar, which is based on the movements of the Earth in space. One spin of Earth on its axis is a day, and one trip around the sun is a year. The modern calendar is a great achievement, developed over many thousands of years as theory and technology improved. People who study Earth's history also use a type of calendar, called the geologic time scale. It looks very different from the familiar calendar. In some ways, it is more like a book, and the rocks are its pages. Some of the pages are torn or missing, and the pages are not numbered, but geology gives us the tools to help us read this book.

  3. Peaches Preceded Humans: Fossil Evidence from SW China

    PubMed Central

    Su, Tao; Wilf, Peter; Huang, Yongjiang; Zhang, Shitao; Zhou, Zhekun

    2015-01-01

    Peach (Prunus persica, Rosaceae) is an extremely popular tree fruit worldwide, with an annual production near 20 million tons. Peach is widely thought to have origins in China, but its evolutionary history is largely unknown. The oldest evidence for the peach has been Chinese archaeological records dating to 8000–7000 BP. Here, we report eight fossil peach endocarps from late Pliocene strata of Kunming City, Yunnan, southwestern China. The fossils are identical to modern peach endocarps, including size comparable to smaller modern varieties, a single seed, a deep dorsal groove, and presence of deep pits and furrows. These fossils show that China has been a critical region for peach evolution since long before human presence, much less agriculture. Peaches evolved their modern morphology under natural selection, presumably involving large, frugivorous mammals such as primates. Much later, peach size and variety increased through domestication and breeding. PMID:26610240

  4. Peaches Preceded Humans: Fossil Evidence from SW China

    NASA Astrophysics Data System (ADS)

    Su, Tao; Wilf, Peter; Huang, Yongjiang; Zhang, Shitao; Zhou, Zhekun

    2015-11-01

    Peach (Prunus persica, Rosaceae) is an extremely popular tree fruit worldwide, with an annual production near 20 million tons. Peach is widely thought to have origins in China, but its evolutionary history is largely unknown. The oldest evidence for the peach has been Chinese archaeological records dating to 8000-7000 BP. Here, we report eight fossil peach endocarps from late Pliocene strata of Kunming City, Yunnan, southwestern China. The fossils are identical to modern peach endocarps, including size comparable to smaller modern varieties, a single seed, a deep dorsal groove, and presence of deep pits and furrows. These fossils show that China has been a critical region for peach evolution since long before human presence, much less agriculture. Peaches evolved their modern morphology under natural selection, presumably involving large, frugivorous mammals such as primates. Much later, peach size and variety increased through domestication and breeding.

  5. Scratching an ancient itch: an Eocene bird louse fossil.

    PubMed Central

    Wappler, Torsten; Smith, Vincent S; Dalgleish, Robert C

    2004-01-01

    Out of the 30 extant orders of insects, all but one, the parasitic lice (Insecta: Phthiraptera), have a confirmed fossil record. Here, we report the discovery of what appears to be the first bird louse fossil: an exceptionally well-preserved specimen collected from the crater of the Eckfeld maar near Manderscheid, Germany. The 44-million-year-old specimen shows close phylogenetic affinities with modern feather louse ectoparasites of aquatic birds. Preservation of feather remnants in the specimen's foregut confirms its association as a bird ectoparasite. Based on a phylogenetic analysis of the specimen and palaeoecological data, we suggest that this louse was the parasite of a large ancestor to modern Anseriformes (swans, geese and ducks) or Charadriiformes (shorebirds). The crown group position of this fossil in the phylogeny of lice confirms the group's long coevolutionary history with birds and points to an early origin for lice, perhaps inherited from early-feathered theropod dinosaurs. PMID:15503987

  6. First records of Canis dirus and Smilodon fatalis from the late Pleistocene Tule Springs local fauna, upper Las Vegas Wash, Nevada.

    PubMed

    Scott, Eric; Springer, Kathleen B

    2016-01-01

    Late Pleistocene groundwater discharge deposits (paleowetlands) in the upper Las Vegas Wash north of Las Vegas, Nevada, have yielded an abundant and diverse vertebrate fossil assemblage, the Tule Springs local fauna (TSLF). The TSLF is the largest open-site vertebrate fossil assemblage dating to the Rancholabrean North American Land Mammal Age in the southern Great Basin and Mojave Desert. Over 600 discrete body fossil localities have been recorded from the wash, including an area that now encompasses Tule Springs Fossil Beds National Monument (TUSK). Paleowetland sediments exposed in TUSK named the Las Vegas Formation span the last 250 ka, with fossiliferous sediments spanning ∼100-13 ka. The recovered fauna is dominated by remains of Camelopsand Mammuthus, and also includes relatively common remains of extinct Equusand Bisonas well as abundant vertebrate microfaunal fossils. Large carnivorans are rare, with only Puma concolor and Panthera atrox documented previously. Postcranial remains assigned to the species Canis dirus (dire wolf) and Smilodon fatalis (sabre-toothed cat) represent the first confirmed records of these species from the TSLF, as well as the first documentation of Canis dirus in Nevada and the only known occurrence of Smilodonin southern Nevada. The size of the recovered canid fossil precludes assignment to other Pleistocene species of Canis. The morphology of the felid elements differentiates them from other large predators such as Panthera, Homotherium, and Xenosmilus, and the size of the fossils prevents assignment to other species of Smilodon. The confirmed presence of S. fatalis in the TSLF is of particular interest, indicating that this species inhabited open habitats. In turn, this suggests that the presumed preference of S. fatalis for closed-habitat environments hunting requires further elucidation.

  7. First records of Canis dirus and Smilodon fatalis from the late Pleistocene Tule Springs local fauna, upper Las Vegas Wash, Nevada

    PubMed Central

    Springer, Kathleen B.

    2016-01-01

    Late Pleistocene groundwater discharge deposits (paleowetlands) in the upper Las Vegas Wash north of Las Vegas, Nevada, have yielded an abundant and diverse vertebrate fossil assemblage, the Tule Springs local fauna (TSLF). The TSLF is the largest open-site vertebrate fossil assemblage dating to the Rancholabrean North American Land Mammal Age in the southern Great Basin and Mojave Desert. Over 600 discrete body fossil localities have been recorded from the wash, including an area that now encompasses Tule Springs Fossil Beds National Monument (TUSK). Paleowetland sediments exposed in TUSK named the Las Vegas Formation span the last 250 ka, with fossiliferous sediments spanning ∼100–13 ka. The recovered fauna is dominated by remains of Camelopsand Mammuthus, and also includes relatively common remains of extinct Equusand Bisonas well as abundant vertebrate microfaunal fossils. Large carnivorans are rare, with only Puma concolor and Panthera atrox documented previously. Postcranial remains assigned to the species Canis dirus (dire wolf) and Smilodon fatalis (sabre-toothed cat) represent the first confirmed records of these species from the TSLF, as well as the first documentation of Canis dirus in Nevada and the only known occurrence of Smilodonin southern Nevada. The size of the recovered canid fossil precludes assignment to other Pleistocene species of Canis. The morphology of the felid elements differentiates them from other large predators such as Panthera, Homotherium, and Xenosmilus, and the size of the fossils prevents assignment to other species of Smilodon. The confirmed presence of S. fatalis in the TSLF is of particular interest, indicating that this species inhabited open habitats. In turn, this suggests that the presumed preference of S. fatalis for closed-habitat environments hunting requires further elucidation. PMID:27366649

  8. First records of Canis dirus and Smilodon fatalis from the late Pleistocene Tule Springs local fauna, upper Las Vegas Wash, Nevada

    USGS Publications Warehouse

    Scott, Eric; Springer, Kathleen

    2016-01-01

    Late Pleistocene groundwater discharge deposits (paleowetlands) in the upper Las Vegas Wash north of Las Vegas, Nevada, have yielded an abundant and diverse vertebrate fossil assemblage, the Tule Springs local fauna (TSLF). The TSLF is the largest open-site vertebrate fossil assemblage dating to the Rancholabrean North American Land Mammal Age in the southern Great Basin and Mojave Desert. Over 600 discrete body fossil localities have been recorded from the wash, including an area that now encompasses Tule Springs Fossil Beds National Monument (TUSK). Paleowetland sediments exposed in TUSK named the Las Vegas Formation span the last 250 ka, with fossiliferous sediments spanning ∼100–13 ka. The recovered fauna is dominated by remains of Camelopsand Mammuthus, and also includes relatively common remains of extinct Equusand Bisonas well as abundant vertebrate microfaunal fossils. Large carnivorans are rare, with only Puma concolor and Panthera atrox documented previously. Postcranial remains assigned to the species Canis dirus (dire wolf) and Smilodon fatalis(sabre-toothed cat) represent the first confirmed records of these species from the TSLF, as well as the first documentation of Canis dirus in Nevada and the only known occurrence of Smilodonin southern Nevada. The size of the recovered canid fossil precludes assignment to other Pleistocene species of Canis. The morphology of the felid elements differentiates them from other large predators such as Panthera, Homotherium, and Xenosmilus, and the size of the fossils prevents assignment to other species of Smilodon. The confirmed presence of S. fatalis in the TSLF is of particular interest, indicating that this species inhabited open habitats. In turn, this suggests that the presumed preference of S. fatalis for closed-habitat environments hunting requires further elucidation.

  9. Modulation of fossil fuel production by global temperature variations, 2

    SciTech Connect

    Rust, B.W.; Crosby, F.J.

    1994-01-01

    The report includes the inverse modulation of global fossil production by variations in Northern Hemispheric temperatures. The present study incorporates recent revisions and extensions of the fuel production record and uses a much improved temperature record. The authors show that the new data are consistent with the predictions of the original Rust-Kirk model which they then extend to allow for time lag between variations in the temperature and the corresponding responses in fuel production. The modulation enters the new model through the convolution of a lagged averaging function with the temperature time-series. The authors also include explicit terms to account for the perturbations caused by the Great Depression and World War II. The final model accounts for 99.84% of the total variance in the production record. This modulation represents a feedback which is consistent with the carbon dioxide problem; climate change; fossil fuel production; global warming Gaia hypothesis; temperature variations.

  10. Time-averaged molluscan death assemblages: Palimpsests of richness, snapshots of abundance

    NASA Astrophysics Data System (ADS)

    Kidwell, Susan M.

    2002-09-01

    Field tests that compare living communities to associated dead remains are the primary means of estimating the reliability of biological information in the fossil record; such tests also provide insights into the dynamics of skeletal accumulation. Contrary to expectations, molluscan death assemblages capture a strong signal of living species' rank-order abundances. This finding, combined with independent evidence for exponential postmortem destruction of dead cohorts, argues that, although the species richness of a death assemblage may be a time-averaged palimpsest of the habitat (molluscan death assemblages contain, on average, ˜25% more species than any single census of the local live community, after sample-size standardization), species' relative-abundance data from the same assemblage probably constitute a much higher acuity record dominated by the most recent dead cohorts (e.g., from the past few hundred years or so, rather than the several thousand years recorded by the total assemblage and usually taken as the acuity of species-richness information). The pervasive excess species richness of molluscan death assemblages requires further analysis and modeling to discriminate among possible sources. However, time averaging alone cannot be responsible unless rare species (species with low rates of dead-shell production) are collectively more durable (have longer taphonomic half-lives) than abundant species. Species richness and abundance data thus appear to present fundamentally different taphonomic qualities for paleobiological analysis. Relative- abundance information is more snapshot-like and thus taphonomically more straightforward than expected, especially compared to the complex origins of dead-species richness.

  11. Species longevity in North American fossil mammals.

    PubMed

    Prothero, Donald R

    2014-08-01

    Species longevity in the fossil record is related to many paleoecological variables and is important to macroevolutionary studies, yet there are very few reliable data on average species durations in Cenozoic fossil mammals. Many of the online databases (such as the Paleobiology Database) use only genera of North American Cenozoic mammals and there are severe problems because key groups (e.g. camels, oreodonts, pronghorns and proboscideans) have no reliable updated taxonomy, with many invalid genera and species and/or many undescribed genera and species. Most of the published datasets yield species duration estimates of approximately 2.3-4.3 Myr for larger mammals, with small mammals tending to have shorter species durations. My own compilation of all the valid species durations in families with updated taxonomy (39 families, containing 431 genera and 998 species, averaging 2.3 species per genus) yields a mean duration of 3.21 Myr for larger mammals. This breaks down to 4.10-4.39 Myr for artiodactyls, 3.14-3.31 Myr for perissodactyls and 2.63-2.95 Myr for carnivorous mammals (carnivorans plus creodonts). These averages are based on a much larger, more robust dataset than most previous estimates, so they should be more reliable for any studies that need species longevity to be accurately estimated.

  12. Rule Fossilization: A Tentative Model

    ERIC Educational Resources Information Center

    Vigil, Neddy A.; Oller, John W.

    1976-01-01

    A cybernetic model of factors involved in the fossilization of grammatical and lexical forms in learner grammars is offered. A distinction is made between affective and cognitive dimensions of a multidimensional channel of human communication; and the effect of expected and unexpected feedback on these two dimensions is discussed. (Author/POP)

  13. The colour of fossil feathers.

    PubMed

    Vinther, Jakob; Briggs, Derek E G; Prum, Richard O; Saranathan, Vinodkumar

    2008-10-23

    Feathers are complex integumentary appendages of birds and some other theropod dinosaurs. They are frequently coloured and function in camouflage and display. Previous investigations have concluded that fossil feathers are preserved as carbonized traces composed of feather-degrading bacteria. Here, an investigation of a colour-banded feather from the Lower Cretaceous Crato Formation of Brazil revealed that the dark bands are preserved as elongate, oblate carbonaceous bodies 1-2 microm long, whereas the light bands retain only relief traces on the rock matrix. Energy dispersive X-ray analysis showed that the dark bands preserve a substantial amount of carbon, whereas the light bands show no carbon residue. Comparison of these oblate fossil bodies with the structure of black feathers from a living bird indicates that they are the eumelanin-containing melanosomes. We conclude that most fossil feathers are preserved as melanosomes, and that the distribution of these structures in fossil feathers can preserve the colour pattern in the original feather. The discovery of preserved melanosomes opens up the possibility of interpreting the colour of extinct birds and other dinosaurs.

  14. Mandibular fossa morphology in the Ngandong and Sambungmacan fossil hominids.

    PubMed

    Durband, Arthur C

    2008-10-01

    There has been debate in recent years concerning the significance of the mandibular fossa morphology in the Ngandong and Sambungmacan hominids. These fossils lack a postglenoid process and their squamotympanic fissure runs along the apex of the fossa for its entire length. This configuration differs from that seen in other fossil and modern humans, which have a prominent postglenoid process and a squamotympanic fissure that takes a more posterior course that does not lie in the apex of the fossa. Some recent studies have suggested that the Ngandong and Sambungmacan hominids are not unique in their expression of these characteristics, and that they can also be found in other fossil crania from Africa and Indonesia. The present study reexamines these morphologies in an effort to better understand their distribution in the hominid fossil record. The results confirm that the lack of a prominent postglenoid process in combination with a squamotympanic fissure that lies wholly in the apex of the mandibular fossa along its entire length is indeed autapomorphic for the Ngandong and Sambungmacan fossils. This finding, in conjunction with work on other nonmetric features in these hominids, suggests that at least two hominid morphs, possibly representing separate species, were present on Java during the Pleistocene. In addition, if this apparent autapomorphy is confirmed, then it is also unlikely that the Ngandong hominids contributed to the gene pool of modern humans.

  15. Phylogeny of the Infraorder Pentatomomorpha Based on Fossil and Extant Morphology, with Description of a New Fossil Family from China

    PubMed Central

    Yao, Yunzhi; Ren, Dong; Rider, David A.; Cai, Wanzhi

    2012-01-01

    Background An extinct new family of Pentatomomorpha, Venicoridae Yao, Ren & Cai fam. nov., with 2 new genera and 2 new species (Venicoris solaris Yao, Ren & Rider gen. & sp. nov. and Clavaticoris zhengi Yao, Ren & Cai gen. & sp. nov.) are described from the Early Cretaceous Yixian Formation in Northeast China. Methodology/Principal Findings A cladistic analysis based on a combination of fossil and extant morphological characters clarified the phylogenetic status of the new family and has allowed the reconstruction of intersuperfamily and interfamily relationships within the Infraorder Pentatomomorpha. The fossil record and diversity of Pentatomomorpha during the Mesozoic is discussed. Conclusions/Significance Pentatomomorpha is a monophyletic group; Aradoidea and the Trichophora are sister groups; these fossils belong to new family, treated as the sister group of remainder of Trichophora; Pentatomoidea is a monophyletic group; Piesmatidae should be separated as a superfamily, Piesmatoidea. Origin time of Pentatomomorpha should be tracked back to the Middle or Early Triassic. PMID:22655038

  16. Trace fossil analysis of lacustrine facies and basins

    USGS Publications Warehouse

    Buatois, L.A.; Mangano, M.G.

    1998-01-01

    Two ichnofacies are typical of lacustrine depositional systems. The Scoyenia ichnofacies characterizes transitional terrestrial/nonmarine aquatic substrates, periodically inundated or desiccated, and therefore is commonly present in lake margin facies. The Mermia ichnofacies is associated with well oxygenated, permanent subaqueous, fine-grained substrates of hydrologically open, perennial lakes. Bathymetric zonations within the Mermia ichnofacies are complicated by the wide variability of lacustrine systems. Detected proximal-distal trends are useful within particular lake basins, but commonly difficult to extrapolate to other lakes. Other potential ichnofacies include the typically marine Skolithos ichnofacies for high-energy zones of lakes and substrate-controlled, still unnamed ichnofacies, associated to lake margin deposits. Trace fossils are useful for sedimentologic analysis of event beds. Lacustrine turbidites are characterized by low-diversity suites, reflecting colonization by opportunistic organisms after the turbidite event. Underflow current beds record animal activity contemporaneous with nearly continuous sedimentation. Ichnologic studies may also help to distinguish between marine and lacustrine turbidites. Deep-marine turbidites host the Nereites ichnofacies that consists of high diversity of ornate grazing traces and graphoglyptids, recording highly specialized feeding strategies developed to solve the problem of the scarcity of food in the deep sea. Deep lacustrine environments contain the Mermia ichnofacies, which is dominated by unspecialized grazing and feeding traces probably related to the abundance and accessibility of food in lacustrine systems. The lower diversity of lacustrine ichnofaunas in comparison with deep-sea assemblages more likely reflects lower species diversity as a consequence of less stable conditions. Increase of depth and extent of bioturbation through geologic time produced a clear signature in the ichnofabric record of

  17. A critical evaluation of how ancient DNA bulk bone metabarcoding complements traditional morphological analysis of fossil assemblages

    NASA Astrophysics Data System (ADS)

    Grealy, Alicia C.; McDowell, Matthew C.; Scofield, Paul; Murray, Dáithí C.; Fusco, Diana A.; Haile, James; Prideaux, Gavin J.; Bunce, Michael

    2015-11-01

    When pooled for extraction as a bulk sample, the DNA within morphologically unidentifiable fossil bones can, using next-generation sequencing, yield valuable taxonomic data. This method has been proposed as a means to rapidly and cost-effectively assess general ancient DNA preservation at a site, and to investigate temporal and spatial changes in biodiversity; however, several caveats have yet to be considered. We critically evaluated the bulk bone metabarcoding (BBM) method in terms of its: (i) repeatability, by quantifying sampling and technical variance through a nested experimental design containing sub-samples and replicates at several stages; (ii) accuracy, by comparing morphological and molecular family-level identifications; and (iii) overall utility, by applying the approach to two independent Holocene fossil deposits, Bat Cave (Kangaroo Island, Australia) and Finsch's Folly (Canterbury, New Zealand). For both sites, bone and bone powder sub-sampling were found to contribute significantly to variance in molecularly identified family assemblage, while the contribution of library preparation and sequencing was almost negligible. Nevertheless, total variance was small. Sampling over 80% fewer bones than was required to morphologically identify the taxonomic assemblages, we found that the families identified molecularly are a subset of the families identified morphologically and, for the most part, represent the most abundant families in the fossil record. In addition, we detected a range of extinct, extant and endangered taxa, including some that are rare in the fossil record. Given the relatively low sampling effort of the BBM approach compared with morphological approaches, these results suggest that BBM is largely consistent, accurate, sensitive, and therefore widely applicable. Furthermore, we assessed the overall benefits and caveats of the method, and suggest a workflow for palaeontologists, archaeologists, and geneticists that will help mitigate these

  18. Formation of the soft-sediment deformation structures and its constraints on dinosaur fossil burial of the Cretaceous in Zhucheng, Shandong province, East China

    NASA Astrophysics Data System (ADS)

    He, Bizhu; Qiao, Xiufu; Cai, Zhihui; Tian, Hongshui; Chen, Shuqing

    2013-04-01

    The triangular-shaped Zhucheng depression is located in the southwestern part of the Jiaolai basin, Jiaodong peninsula, East China. Various soft-sediment deformation structures are recognized in the southern Zhucheng depression, which have behaviour are plastic and/or brittle. Soft-sediment deformation structures mainly include undulate fold, mound and sag, diapir, convolute deformation and seismic-unconformity in the Lower Cretaceous, which are composed of fine-grained sediments in lacustrine environment, while load structure, ball and pillow structure, plunged sediment mixtures structure, fault-graded occurred in the Upper Cretaceous, which formed in a conglomeratic or coarse arenaceous alluvial fan and flood-plain setting. These soft-sediment deformation structures are proposed triggered by paleoearthquake. The deformed layers and undeformed layers developed in intervals, suggesting frequent seismic activities. In studied area, numerous giant hadrosaurid skeleton fossils have been found in the Upper Cretaceous Wangshi Group science 1958, and unusual and abundant dinosaur track fossils have been discovered in the Lower Cretaceous Yangzhuang Formation of Laiyang Group. The widespread identified soft-sediment deformation structures are proximately underlying or overlying these dinosaur fossil bearing strata. The depositional setting changed while multiple paleo-seismic events and tectonic activity happened. In the Early Cretaceous, after the occurrence of paleo-earthquakes and environmental changes, dinosaurs migrated and a lot of tracks with similar orientation on lacustrine offshore were preserved. In the Late Cretaceous, a large-scale dinosaur fossil layers and paleo-earthquake records occurred in intervals, indicating that the dinosaur fossils may be associated with large-scale debris flow and frequent earthquake events. Based on regional tectonic setting, distribution of soft-sediment deformation structures and predicted magnitude of paleo-earthquakes, the

  19. FAST FOSSIL ROTATION OF NEUTRON STAR CORES

    SciTech Connect

    Melatos, A.

    2012-12-10

    It is argued that the superfluid core of a neutron star super-rotates relative to the crust, because stratification prevents the core from responding to the electromagnetic braking torque, until the relevant dissipative (viscous or Eddington-Sweet) timescale, which can exceed {approx}10{sup 3} yr and is much longer than the Ekman timescale, has elapsed. Hence, in some young pulsars, the rotation of the core today is a fossil record of its rotation at birth, provided that magnetic crust-core coupling is inhibited, e.g., by buoyancy, field-line topology, or the presence of uncondensed neutral components in the superfluid. Persistent core super-rotation alters our picture of neutron stars in several ways, allowing for magnetic field generation by ongoing dynamo action and enhanced gravitational wave emission from hydrodynamic instabilities.

  20. Fast Fossil Rotation of Neutron Star Cores

    NASA Astrophysics Data System (ADS)

    Melatos, A.

    2012-12-01

    It is argued that the superfluid core of a neutron star super-rotates relative to the crust, because stratification prevents the core from responding to the electromagnetic braking torque, until the relevant dissipative (viscous or Eddington-Sweet) timescale, which can exceed ~103 yr and is much longer than the Ekman timescale, has elapsed. Hence, in some young pulsars, the rotation of the core today is a fossil record of its rotation at birth, provided that magnetic crust-core coupling is inhibited, e.g., by buoyancy, field-line topology, or the presence of uncondensed neutral components in the superfluid. Persistent core super-rotation alters our picture of neutron stars in several ways, allowing for magnetic field generation by ongoing dynamo action and enhanced gravitational wave emission from hydrodynamic instabilities.

  1. Fossil group origins. VII. Galaxy substructures in fossil systems

    NASA Astrophysics Data System (ADS)

    Zarattini, S.; Girardi, M.; Aguerri, J. A. L.; Boschin, W.; Barrena, R.; del Burgo, C.; Castro-Rodriguez, N.; Corsini, E. M.; D'Onghia, E.; Kundert, A.; Méndez-Abreu, J.; Sánchez-Janssen, R.

    2016-02-01

    Context. Fossil groups (FG) are expected to be the final product of galaxy merging within galaxy groups. In simulations, they are predicted to assemble their mass at high redshift. This early formation allows for the innermost M∗ galaxies to merge into a massive central galaxy. Then, they are expected to maintain their fossil status because of the few interactions with the large-scale structure. In this context, the magnitude gap between the two brightest galaxies of the system is considered a good indicator of its dynamical status. As a consequence, the systems with the largest gaps should be dynamically relaxed. Aims: In order to examine the dynamical status of these systems, we systematically analyze, for the first time, the presence of galaxy substructures in a sample of 12 spectroscopically-confirmed fossil systems with redshift z ≤ 0.25. Methods: We apply a number of tests to investigate the substructure in fossil systems in the two-dimensional space of projected positions out to R200. Moreover, for a subsample of five systems with at least 30 spectroscopically-confirmed members we also analyze the substructure in the velocity and in the three-dimensional velocity-position spaces. Additionally, we look for signs of recent mergers in the regions around the central galaxies. Results: We find that an important fraction of fossil systems show substructure. The fraction depends critically on the adopted test, since each test is more sensitive to a particular type of substructure. Conclusions: Our interpretation of the results is that fossil systems are not, in general, as relaxed as expected from simulations. Our sample of 12 spectroscopically-confirmed fossil systems need to be extended to compute an accurate fraction, but our conclusion is that this fraction is similar to the fraction of substructure detected in nonfossil clusters. This result points out that the magnitude gap alone is not a good indicator of the dynamical status of a system. However, the

  2. REE compositions in fossil vertebrate dental tissues indicate biomineral preservation

    NASA Astrophysics Data System (ADS)

    Žigaite, Ž.; Kear, B.; Pérez-Huerta, A.; Jeffries, T.; Blom, H.

    2012-04-01

    Rare earth element (REE) abundances have been measured in a number of Palaeozoic and Mesozoic dental tissues using Laser Ablation Inductively Coupled Plasma Mass-spectrometry (LA-ICP-MS). Fossil vertebrates analysed comprise scales and tesserae of Silurian and Devonian acanthodians, chondrichthyans, galeaspids, mongolepids, thelodonts, as well as teeth of Cretaceous lungfish and marine reptiles. The evaluation of fossil preservation level has been made by semi-quantitative spot geochemistry analyses on fine polished teeth and scale thin sections, using Energy Dispersive X-ray Spectroscopy (EDS). Fossil teeth and scales with significant structure and colour alteration have shown elevated heavy element concentrations, and the silicification of bioapatite has been common in their tissues. Stable oxygen isotope measurements (δ18O) of bulk biomineral have been conducted in parallel, and showed comparatively lower heavy oxygen values in the same fossil tissues with stronger visible alteration. Significant difference in REE concentrations has been observed between the dentine and enamel of Cretaceous plesiosaurs, suggesting the enamel to be more geochemically resistant to diagenetic overprint.

  3. Do fossil vertebrate biominerals hold the key to the Palaeozoic climate?

    NASA Astrophysics Data System (ADS)

    Žigaitė, Ž.

    2012-04-01

    Fossil vertebrate hard tissues - teeth and dermoskeleton - are considered among the most geochemically stable biominerals, and therefore are widely used for palaeoenvironmental and palaeoclimatic reconstructions. Elemental and isotopic compositions of fossil dental tissues may provide unique palaeoenvironmental information, ranging from the diet and trophic positions on a food chain, to the palaeosalinity and water temperatures of ancient seas. However, the post-mortem alteration and re-crystallisation of fossil hard tissues may hamper these interpretations. Chemical composition and isotopic equilibrium of the biomineral change readily at any time from the earliest diagenesis to the final laboratory acid treatment during the fossil preparation. This is why particular attention shall be given to the preservation of fossil tissues, evaluating carefully the level of possible alteration in the primary geochemical composition. Pre-evaluation of fossil preservation can be made by semi-quantitative spot geochemistry analyses on fine polished teeth and scale thin sections using Energy Dispersive X-ray Spectroscopy (EDS), and help to preview the chemical composition of biomineral. The Electron Backscatter Diffractometry (EBSD) is useful to examine the cristallinity and possible structural alterations. In addition, rare earth element (REE) abundances can be measured in situ within the fine fossil tissues (such as enamel) using Laser Ablation Inductively Coupled Plasma Mass-spectrometry (LA-ICP-MS), giving evidence on the selective geochemical resilience between separate vertebrate hard tissues. Therefore, in order to decipher the geochemical signal correctly, the evaluation of preservation is a necessary starting point to any further studies of fossil biomineral geochemistry.

  4. A Biological Time Capsule. Fossil Fish.

    ERIC Educational Resources Information Center

    Dolph, Gary E.; Dolph, Laura L.

    1990-01-01

    Described is an activity where students prepare high-quality fossil specimens to demonstrate the theory of evolution. The technique needed for fossil removal, the geologic and paleoclimatic setting, and the fish morphology are discussed. (KR)

  5. First report of fossil "keratose" demosponges in Phanerozoic carbonates: preservation and 3-D reconstruction.

    PubMed

    Luo, Cui; Reitner, Joachim

    2014-06-01

    Fossil record of Phanerozoic non-spicular sponges, beside of being important with respect to the lineage evolution per se, could provide valuable references for the investigation of Precambrian ancestral animal fossils. However, although modern phylogenomic studies resolve non-spicular demosponges as the sister group of the remaining spiculate demosponges, the fossil record of the former is extremely sparse or unexplored compared to that of the latter; the Middle Cambrian Vauxiidae Walcott 1920, is the only confirmed fossil taxon of non-spicular demosponges. Here, we describe carbonate materials from Devonian (Upper Givetian to Lower Frasnian) bioherms of northern France and Triassic (Anisian) microbialites of Poland that most likely represent fossil remnants of keratose demosponges. These putative fossils of keratose demosponges are preserved as automicritic clumps. They are morphologically distinguishable from microbial fabrics but similar to other spiculate sponge fossils, except that the skeletal elements consist of fibrous networks instead of assembled spicules. Consistent with the immunological behavior of sponges, these fibrous skeletons often form a rim at the edge of the automicritic aggregate, separating the inner part of the aggregate from foreign objects. To confirm the architecture of these fibrous networks, two fossil specimens and a modern thorectid sponge for comparison were processed for three-dimensional (3-D) reconstruction using serial grinding tomography. The resulting fossil reconstructions are three-dimensionally anastomosing, like modern keratose demosponges, but their irregular and nonhierarchical meshes indicate a likely verongid affinity, although a precise taxonomic conclusion cannot be made based on the skeletal architecture alone. This study is a preliminary effort, but an important start to identify fossil non-spicular demosponges in carbonates and to re-evaluate their fossilization potential.

  6. First report of fossil "keratose" demosponges in Phanerozoic carbonates: preservation and 3-D reconstruction

    NASA Astrophysics Data System (ADS)

    Luo, Cui; Reitner, Joachim

    2014-06-01

    Fossil record of Phanerozoic non-spicular sponges, beside of being important with respect to the lineage evolution per se, could provide valuable references for the investigation of Precambrian ancestral animal fossils. However, although modern phylogenomic studies resolve non-spicular demosponges as the sister group of the remaining spiculate demosponges, the fossil record of the former is extremely sparse or unexplored compared to that of the latter; the Middle Cambrian Vauxiidae Walcott 1920, is the only confirmed fossil taxon of non-spicular demosponges. Here, we describe carbonate materials from Devonian (Upper Givetian to Lower Frasnian) bioherms of northern France and Triassic (Anisian) microbialites of Poland that most likely represent fossil remnants of keratose demosponges. These putative fossils of keratose demosponges are preserved as automicritic clumps. They are morphologically distinguishable from microbial fabrics but similar to other spiculate sponge fossils, except that the skeletal elements consist of fibrous networks instead of assembled spicules. Consistent with the immunological behavior of sponges, these fibrous skeletons often form a rim at the edge of the automicritic aggregate, separating the inner part of the aggregate from foreign objects. To confirm the architecture of these fibrous networks, two fossil specimens and a modern thorectid sponge for comparison were processed for three-dimensional (3-D) reconstruction using serial grinding tomography. The resulting fossil reconstructions are three-dimensionally anastomosing, like modern keratose demosponges, but their irregular and nonhierarchical meshes indicate a likely verongid affinity, although a precise taxonomic conclusion cannot be made based on the skeletal architecture alone. This study is a preliminary effort, but an important start to identify fossil non-spicular demosponges in carbonates and to re-evaluate their fossilization potential.

  7. Determination and Radiocarbon Dating of Marine Mollusc Fossils in Ancient Sea Shelf of Central Java Indonesia

    NASA Astrophysics Data System (ADS)

    Aisyah, S.; Pringgenies, D.; Hartoko, A.; Sumantyo, J. T. S.; Matsuzaki, H.

    2017-02-01

    Mollusc phylum is one of the most adaptive animal groups on Earth. They occupy and thrive in incredibly diverse habitats. Their distribution in the fossil record is equally diverse. Indonesia is one of the country with marine mollusc fossil variety, such as in the archaeological site of Sangiran, Patiayam (Ancient Muria Strait) and Grobogan – Central Java. Radiocarbon Dating is the method for dating analysis using 14C. By measuring 14C content, we can estimate how long ago the fossils died. Radiocarbon dating is an extremely useful technique for determining the ages of geological materials (that have some organic-derived carbon in them). Field sampling had found variety of marine mollusc fossils such us 1) Sangiran: Dosinia sp., Telescopium telescopium, Anadara sp., and Dosinia insularum; 2) Patiayam (Ancient Muria Strait): Pseudodon vondenbuschianus, Elongaria orientalis, Conus (Pionoconus) sp., Ampullina bandongensis, Anadara pilula and Filopaludina javanica; 3) Grobogan: Antigona chemnitzii, Cultelus dilatatus, Plotia scabra and Tibia modesta. Mollusc fossils sample was analysed using Accelerator Mass Spectrometer (AMS) radiocarbon system. It is a good method for dating specific samples. The result showed that Sangiran as an ancient deepsea has fossils age 38710 – 31947 years, then Patiayam (Ancient Muria Strait) with fossils age 26248 – 11994. Mollusc fossils from Grobogan was the youngest area has fossils age 25692 – 6479 years.

  8. The (32)S/(33)S abundance as a function of galactocentric radius in the Milky Way

    NASA Technical Reports Server (NTRS)

    Greenhouse, M. A.; Thronson, H. A., Jr.

    1986-01-01

    Astration of heavy elements by the stars of the Milky Way forms a fossil record which may preserve spacial distribution of the mass function for the stars in the galaxy. Sulfur is among the last common element for which the relative abundance of its various isotopes have yet to be completely measured within our galaxy. Explosive oxygen burning in massive stars is thought to be the process which dominates sulfur production within stars. There models predict that the various isotopes (S-32, S-33, S-34) are formed in relative abundance which depend strongly upon the mass of the parent star. This relative abundance is thought to be unaffected by subsequent stellar procesing since all important sinks of sulfur destroy it without regard for isotopic form. Hence the spacial variation of the mass function (MF) can be studied by measuring the abundance variation of sulfur isotopes in the galaxy provided that the product yields for these isotopes are known accurately as a function of stellar mass.

  9. Looking at Fossils in New Ways

    ERIC Educational Resources Information Center

    Flannery, Maura C.

    2005-01-01

    Existing fossils could be studied from a different prospective with the use of new methods of analysis for gathering more information. The new techniques of studying fossils binds the new and the old techniques and information and provides another way to look at fossils.

  10. Cycads: Fossil evidence of late paleozoic origin

    USGS Publications Warehouse

    Mamay, S.H.

    1969-01-01

    Plant fossils from Lower Permian strata of the southwestern United States have been interpreted as cycadalean megasporophylls. They are evidently descended from spermopterid elements of the Pennsylvanian Taeniopteris complex; thus the known fossil history of the cycads is extended from the Late Triassic into the late Paleozoic. Possible implications of the Permian fossils toward evolution of the angiosperm carpel are considered.

  11. Cycads: fossil evidence of late paleozoic origin.

    PubMed

    Mamay, S H

    1969-04-18

    Plant fossils from Lower Permian strata of the southwestern United States have been interpreted as cycadalean megasporophylls. They are evidently descended from spermopterid elements of the Pennsylvanian Taeniopteris complex; thus the known fossil history of the cycads is extended from the Late Triassic into the late Paleozoic. Possible implications of the Permian fossils toward evolution of the angiosperm carpel are considered.

  12. Clustering fossils in solid inflation

    SciTech Connect

    Akhshik, Mohammad

    2015-05-01

    In solid inflation the single field non-Gaussianity consistency condition is violated. As a result, the long tenor perturbation induces observable clustering fossils in the form of quadrupole anisotropy in large scale structure power spectrum. In this work we revisit the bispectrum analysis for the scalar-scalar-scalar and tensor-scalar-scalar bispectrum for the general parameter space of solid. We consider the parameter space of the model in which the level of non-Gaussianity generated is consistent with the Planck constraints. Specializing to this allowed range of model parameter we calculate the quadrupole anisotropy induced from the long tensor perturbations on the power spectrum of the scalar perturbations. We argue that the imprints of clustering fossil from primordial gravitational waves on large scale structures can be detected from the future galaxy surveys.

  13. FOSSIL SPRINGS ROADLESS AREA, ARIZONA.

    USGS Publications Warehouse

    Beard, L.S.; Ellis, C.E.

    1984-01-01

    Based on field studies, the Fossil Springs Roadless Area in central Arizona is concluded to have little promise for the occurrence of mineral or energy resources. Rocks in the Supai Formation (Pennsylvanian-Permian) near the central part of the roadless area contain widespread but spotty copper mineralization and trace amounts of uranium. Analyses obtained during the study define geochemical anomalies in two portions of the area that remain unexplained. The suites of anomalous metals suggest the possibility of hydrothermal veins and the presence of ultramafic rocks; neither were found in the field. Although there is little promise for the occurrence of mineral resources in the Fossil Springs Roadless Area, studies to identify the source of the geochemical anomalies could have valuable implications for regional studies and mineral exploration in the surrounding area.

  14. Non-phytoseiid Mesostigmata within citrus orchards in Florida: species distribution, relative and seasonal abundance within trees, associated vines and ground cover plants and additional collection records of mites in citrus orchards.

    PubMed

    Childers, Carl C; Ueckermann, Eduard A

    2015-03-01

    Seven citrus orchards on reduced- to no-pesticide spray programs in central and south central Florida were sampled for non-phytoseiid mesostigmatid mites. Inner and outer canopy leaves, fruits, twigs and trunk scrapings were sampled monthly between August 1994 and January 1996. Open flowers were sampled in March from five of the sites. A total of 431 samples from one or more of 82 vine or ground cover plants were sampled monthly in five of the seven orchards. Two of the seven orchards (Mixon I and II) were on full herbicide programs and vines and ground cover plants were absent. A total of 2,655 mites (26 species) within the families: Ascidae, Blattisociidae, Laelapidae, Macrochelidae, Melicharidae, Pachylaelapidae and Parasitidae were identified. A total of 685 mites in the genus Asca (nine species: family Ascidae) were collected from within tree samples, 79 from vine or ground cover plants. Six species of Blattisociidae were collected: Aceodromus convolvuli, Blattisocius dentriticus, B. keegani, Cheiroseius sp. near jamaicensis, Lasioseius athiashenriotae and L. dentatus. A total of 485 Blattisociidae were collected from within tree samples compared with 167 from vine or ground cover plants. Low numbers of Laelapidae and Macrochelidae were collected from within tree samples. One Zygoseius furciger (Pachylaelapidae) was collected from Eleusine indica. Four species of Melicharidae were identified from 34 mites collected from within tree samples and 1,190 from vine or ground cover plants: Proctolaelaps lobatus was the most abundant species with 1,177 specimens collected from seven ground cover plants. One Phorytocarpais fimetorum (Parasitidae) was collected from inner leaves and four from twigs. Species of Ascidae, Blattisociidae, Melicharidae, Laelapidae and Pachylaelapidae were collected from 31 of the 82 vine or ground cover plants sampled, representing only a small fraction of the total number of Phytoseiidae collected from the same plants. Including the

  15. Fossil mammals and paleoenvironments in the Omo-Turkana Basin.

    PubMed

    Bobe, René

    2011-01-01

    Although best known for its fossil hominins, the Omo-Turkana Basin of Kenya and Ethiopia is the source of one of the best records of vertebrate evolution from the Late Cenozoic of Africa. Located near the heart of the East African Rift Valley, the basin serves as an important frame of reference for the continent. The fossil record from this region plays a key role in our efforts to understand the environmental and ecological context of human evolution in Africa. The Omo-Turkana faunal data shed light on key questions of human evolution: What kinds of environments did early humans inhabit? How did these environments change over time? What is the relationship between faunal change in East Africa and broader patterns of climatic change?

  16. Role of microbial mats in the fossilization of soft tissues

    NASA Astrophysics Data System (ADS)

    Wilby, Philip R.; Briggs, Derek E. G.; Bernier, Paul; Gaillard, Christian

    1996-09-01

    It has been speculated that microbial mats are an important agent in the fossilization of soft tissues, particularly when apatite (Ca5[CO3, PO4]3[OH, F]) is involved. This has been tested by chemical analyses of the Jurassic limestones of Cerin, France, where phosphatized soft tissues are abundant and are associated with unequivocal microbial mats. The sedimentary distribution of P, K, and Fe following deposition was controlled by the presence of the mats. P concentrations in the mats may approach 2.5 times those elsewhere in the sediment. The highest P concentrations correlate with the occurrence of phosphatized soft tissues. This is the first analytical evidence to demonstrate a fundamental role for microbial mats in the preservation of soft-bodied fossils.

  17. Estuarine trace fossil assemblages in Tournaisian Clashmelcon Formation, Kerry Head, southwest Ireland

    SciTech Connect

    Diemer, J.A.

    1987-05-01

    The Tournaisian Clashmelcon Formation comprises lateral-accretion deposits which fine upward from large-scale cross-stratified sandstone to current-dominated heterolithic beds interbedded with current- and wave-dominated heterolithic beds and desiccated cryptalgal laminites. Large-scale cross-stratification occurs in bundles with structures indicative of unsteady and reversing currents. Wave-dominated heterolithic beds and hummocky cross-stratified sandstone become more abundant upsection. A transported brachiopod-crinoid-bryozoan assemblage which is locally abundant above erosion surfaces becomes more diverse upsection. The Clashmelcon Formation is interpreted as deposits of laterally migrating and aggrading estuarine channels associated with tidal flats which gave way to estuarine embayments dominated by waves. Trace fossils are best developed in heterolithic bedding and include vertical and horizontal burrows. Low in the Clashmelcon Formation, tops of lateral-accretion deposits are locally very bioturbated by a few types of trace fossils including Skolithos, Arenicolites, Teichichnus, Cylindrichnus and, rarely, Glossifungites. Upsection, a more diverse trace fossil assemblage occurs. Wave-dominated heterolithic sediments display a moderately diverse trace fossil assemblage including Teichichnus, Monocraterion, Diplocraterion, Fucusopsis, Planolites, Paleophycus, Chondrites, Neonereites and, rarely, Curvolithus, Rhizocorallium, Bifungites, and Treptichnus. Rhizocorallium is also locally abundant immediately below the basal erosion surfaces of lateral-accretion deposits. Arenicolites, Teichichnus, Fucusopsis, Planolites, Paleophycus, and Chondrites are found in variable abundance throughout much of the succession. Chondrites is locally very abundant in wave-dominated heterolithic beds and the lower parts of channel fills.

  18. Early penguin fossils, plus mitochondrial genomes, calibrate avian evolution.

    PubMed

    Slack, Kerryn E; Jones, Craig M; Ando, Tatsuro; Harrison, G L Abby; Fordyce, R Ewan; Arnason, Ulfur; Penny, David

    2006-06-01

    Testing models of macroevolution, and especially the sufficiency of microevolutionary processes, requires good collaboration between molecular biologists and paleontologists. We report such a test for events around the Late Cretaceous by describing the earliest penguin fossils, analyzing complete mitochondrial genomes from an albatross, a petrel, and a loon, and describe the gradual decline of pterosaurs at the same time modern birds radiate. The penguin fossils comprise four naturally associated skeletons from the New Zealand Waipara Greensand, a Paleocene (early Tertiary) formation just above a well-known Cretaceous/Tertiary boundary site. The fossils, in a new genus (Waimanu), provide a lower estimate of 61-62 Ma for the divergence between penguins and other birds and thus establish a reliable calibration point for avian evolution. Combining fossil calibration points, DNA sequences, maximum likelihood, and Bayesian analysis, the penguin calibrations imply a radiation of modern (crown group) birds in the Late Cretaceous. This includes a conservative estimate that modern sea and shorebird lineages diverged at least by the Late Cretaceous about 74 +/- 3 Ma (Campanian). It is clear that modern birds from at least the latest Cretaceous lived at the same time as archaic birds including Hesperornis, Ichthyornis, and the diverse Enantiornithiformes. Pterosaurs, which also coexisted with early crown birds, show notable changes through the Late Cretaceous. There was a decrease in taxonomic diversity, and small- to medium-sized species disappeared well before the end of the Cretaceous. A simple reading of the fossil record might suggest competitive interactions with birds, but much more needs to be understood about pterosaur life histories. Additional fossils and molecular data are still required to help understand the role of biotic interactions in the evolution of Late Cretaceous birds and thus to test that the mechanisms of microevolution are sufficient to explain

  19. Protein molecular data from ancient (>1 million years old) fossil material: pitfalls, possibilities and grand challenges.

    PubMed

    Schweitzer, Mary Higby; Schroeter, Elena R; Goshe, Michael B

    2014-07-15

    Advances in resolution and sensitivity of analytical techniques have provided novel applications, including the analyses of fossil material. However, the recovery of original proteinaceous components from very old fossil samples (defined as >1 million years (1 Ma) from previously named limits in the literature) is far from trivial. Here, we discuss the challenges to recovery of proteinaceous components from fossils, and the need for new sample preparation techniques, analytical methods, and bioinformatics to optimize and fully utilize the great potential of information locked in the fossil record. We present evidence for survival of original components across geological time, and discuss the potential benefits of recovery, analyses, and interpretation of fossil materials older than 1 Ma, both within and outside of the fields of evolutionary biology.

  20. The First Report on the Medicinal Use of Fossils in Latin America

    PubMed Central

    Moura, Geraldo Jorge Barbosa; Albuquerque, Ulysses Paulino

    2012-01-01

    There have been very few ethnopharmacological studies performed on the traditional use of fossil species, although a few records have been conducted in Asia, Africa, and Europe. This study is the first ever to be performed on the use of Testudine (turtle) fossils for folk medicine in Latin America. An investigation was conducted in the Araripe Basin, which is one of the most important fossil-bearing reserves in the world due to the diversity, endemism, and quality of preservation of its fossils. We propose the formalization of a new discipline called ethnopaleontology, which will involve the study of the dynamic relationship between humans and fossils, from human perception to direct use. PMID:21969843

  1. Influence of Past Changes in Atmospheric CO2 on Boron/Calcium of Planktic Fossil Foraminifera

    NASA Astrophysics Data System (ADS)

    Domeyko, R. A.; Allen, K. A.; deMenocal, P. B.

    2014-12-01

    Culture experiments have revealed that B/Ca of shells grown by the foraminiferal species Globigerinoides ruber increase with increasing seawater pH. Specifically, B/Ca responds to changes in the relative abundance of pH-sensitive dissolved carbon and boron species (Allen et al. 2011, 2012). Here, we present a high-resolution study on fossilized G. ruber from two sites in North Atlantic subtropical gyres (VM25-21 and ODP 1055B) through 20 ka BP to evaluate how B/Ca responds to past changes in atmospheric CO2. Forams were picked and crushed gently, then cleaned and dissolved using a variation of the Boyle and Keigwin (1985) and Barker et al. (2003) cleaning protocols prior to analysis. ODP 1055B (from Carolina Slope, West Atlantic) produced a high-resolution record with lower B/Ca values during the glacial period followed by a rapid shift to higher B/Ca values in the early deglaciation, with values remaining high through the Holocene. These results were not predicted by culture calibrations, but they are consistent with B/Ca records from the Caribbean (ODP 999, Foster et al. 2008), suggesting this pattern is characteristic of surface waters in the greater North Atlantic region.

  2. An Extraordinary Gobioid Fish Fossil from Southern France

    PubMed Central

    Gierl, Christoph; Reichenbacher, Bettina; Gaudant, Jean; Erpenbeck, Dirk; Pharisat, André

    2013-01-01

    Background The classification of gobioid fishes is still under discussion. Several lineages, including the Eleotridae and Butidae, remain difficult to characterize because synapomorphies are rare (Eleotridae) or have not yet been determined (Butidae). Moreover, the fossil record of these groups is scarce. Results Exceptionally well-preserved fish fossils with otoliths in situ from uppermost Oligocene sediments (≈23–24 Mio. y. ago) in Southern France provide the most in-depth description of a fossil gobioid to date. The species was initially described as Cottus aries Agassiz, then transferred to †Lepidocottus Sauvage, and subsequently assigned to Gobius. Based on a comparative analysis of meristic, osteological and otolith data, this species most likely is a member of the family Butidae. This discovery is important because it represents the first record of a fossil butid fish based on articulated skeletons from Europe. Significance The Butidae and Eleotridae are currently distributed in W-Africa, Madagascar, Asia and Australia, but they do not appear in Europe and also not in the Mediterranean Sea. The new results indicate that several species of the Butidae thrived in Europe during the Oligocene and Early Miocene. Similar to the recent Butidae and Eleotridae, these fishes were adapted to a wide range of salinities and thrived in freshwater, brackish and marginal marine habitats. The fossil Butidae disappeared from Europe and the Mediterranean and Paratethys areas during the Early Miocene, due probably to their lack of competitiveness compared to other Gobioidei that radiated during this period of time. In addition, this study documents the great value of otoliths for gobioid systematics. PMID:23691158

  3. Quaternary tectonic stability of the Bahamian archipelago: evidence from fossil coral reefs and flank margin caves

    NASA Astrophysics Data System (ADS)

    Carew, James L.; Mylroie, John E.

    Throughout the islands of the Bahamian archipelago fossil coral reefs are found from current sea level up to a maximum elevation of +4 m. {234U}/{230Th} radiometric dates obtained from in situ corals from these reefs, by both alpha-count and mass-spectrometric techniques, indicates that they were all formed during Oxygen Isotope Substage 5e (ca. 125,000 years ago). Those data are consistent with a maximum sea-level highstand of +6 m during Substage 5e, and either no vertical motion of the Bahamas, or possible isostatic subsidence of up to 2 m during the past 120,000 years. No older in situ fossil corals, or other subtidal deposits, have been found subaerially exposed anywhere in the Bahamas. That finding suggests that late Quaternary (at least the past 300,000 years) isostatic subsidence has occurred at a rate of 1-2 m per hundred thousand years, and/or no pre-5e highstands were above modern sea level. An independent corroboration of the conclusions drawn about sea level amplitude and tectonic stability of the Bahamas from the coral reef data is available from examination of abundant flank margin caves (horizontal, phreatic dissolution caves) found above modern sea level throughout the Bahamas. These horizontally extensive air-filled caves have dissolutional ceilings with elevations that are restricted to +1 to +7 m, which is consistent with formation at the margin of a thin freshwater lens elevated by a past +6 m sea-level highstand. The restricted cave elevations, and the lack of stalagmites in these caves that are older than 100,000 years, are also consistent with cave formation during Substage 5e, and possible subsequent isostatic subsidence of a few metres. The subsurface geology of the southeastern Bahamas contains a long-term record (millions of years) that has been attributed to past tectonic activity along the North American/Caribbean plate boundary. While that record suggests differential subsidence across the Bahamas in the Tertiary Period, the data from

  4. THE NATURE OF FOSSIL GALAXY GROUPS: ARE THEY REALLY FOSSILS?

    SciTech Connect

    La Barbera, F.; Sorrentino, G.; De Carvalho, R. R.; De la Rosa, I. G.; Gal, R. R.; Kohl-Moreira, J. L.

    2009-04-15

    We use SDSS-DR4 photometric and spectroscopic data out to redshift z {approx} 0.1 combined with ROSAT All Sky Survey X-ray data to produce a sample of 25 fossil groups (FGs), defined as bound systems dominated by a single, luminous elliptical galaxy with extended X-ray emission. We examine possible biases introduced by varying the parameters used to define the sample, and the main pitfalls are also discussed. The spatial density of FGs, estimated via the V/V {sub MAX} test, is 2.83 x 10{sup -6} h {sup 3} {sub 75} Mpc{sup -3} for L{sub X} > 0.89 x 10{sup 42} h {sup -2} {sub 75} erg s{sup -1} consistent with Vikhlinin et al., who examined an X-ray overluminous elliptical galaxy sample (OLEG). We compare the general properties of FGs identified here with a sample of bright field ellipticals generated from the same data set. These two samples show no differences in the distribution of neighboring faint galaxy density excess, distance from the red sequence in the color-magnitude diagram, and structural parameters such as a {sub 4} and internal color gradients. Furthermore, examination of stellar populations shows that our 25 FGs have similar ages, metallicities, and {alpha}-enhancement as the bright field ellipticals, undermining the idea that these systems represent fossils of a physical mechanism that occurred at high redshift. Our study reveals no difference between FGs and field ellipticals, suggesting that FGs might not be a distinct family of true fossils, but rather the final stage of mass assembly in the universe.

  5. Experimental and Temporal Observations on the Occurrence and Abundance of Pyrogenic PAH Relative to Atmospheric Oxygen Levels

    NASA Astrophysics Data System (ADS)

    Schuneman, P. J.; Uhle, M. E.

    2004-12-01

    The Phanerozoic record of atmospheric O2 is based on a global mass balance of several dynamic geochemical cycles, with error margins reflecting such complexity. The potential for accurately determining the record of atmospheric O2 may significantly improve with the proposed method, which relies on a direct relationship between atmospheric oxygen, fuels, and fire products. The interaction between combustion and atmospheric-oxygen level during biomass burning events is investigated by comparing the occurrence and abundance of pyrogenic polycyclic aromatic hydrocarbons (PAH) from experimentally-produced, modern, Triassic, and Carboniferous chars. The combustion process consumes O2 directly from the atmosphere and thermally alters organic matter to produce chars. PAH that develop through combustion, and are preserved within chars, are expected to be more abundant at times of elevated atmospheric O2, which facilitates biomass burning efficiency. To investigate the hypothesized relationship in the geologic record, PAH have been extracted from chars of three periods - modern, Triassic, and Carboniferous - relating to 21%, 15%, and 35% atmospheric O2, respectively (Berner and Canfield, 1989). Surface samples of modern chars that developed in controlled burns set by National Park Service personnel in a mixed conifer-deciduous forest were collected at Zion National Park, Utah. Triassic fusain from Petrified Forest National Park, AZ, and Carboniferous fusain from Joggins Fossil Cliffs, Nova Scotia, were collected from floodplain- and coastal plain-deposited mudstone and sandstone. Target PAH shown to be uniquely pyrogenic include: phenanthrene, anthracene, fluoranthene, pyrene, benz(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene, and benzo(ghi)perylene. The abundance of PAH from modern chars at Zion National Park, Triassic fusain from Petrified Forest National Park, and Carboniferous fusain from Joggins Fossil Cliffs

  6. Assessing the role of cladogenesis in macroevolution by integrating fossil and molecular evidence

    PubMed Central

    Strotz, Luke C.; Allen, Andrew P.

    2013-01-01

    Assessing the extent to which population subdivision during cladogenesis is necessary for long-term phenotypic evolution is of fundamental importance in a broad range of biological disciplines. Differentiating cladogenesis from anagenesis, defined as evolution within a species, has generally been hampered by dating precision, insufficient fossil data, and difficulties in establishing a direct link between morphological changes detectable in the fossil record and biological species. Here we quantify the relative frequencies of cladogenesis and anagenesis for macroperforate planktic Foraminifera, which arguably have the most complete fossil record currently available, to address this question. Analyzing this record in light of molecular evidence, while taking into account the precision of fossil dating techniques, we estimate that the fraction of speciation events attributable to anagenesis is <19% during the Cenozoic era (last 65 Myr) and <10% during the Neogene period (last 23 Myr). Our central conclusion—that cladogenesis is the predominant mode by which new planktic Foraminifera taxa become established at macroevolutionary time scales—differs markedly from the conclusion reached in a recent study based solely on fossil data. These disparate findings demonstrate that interpretations of macroevolutionary dynamics in the fossil record can be fundamentally altered in light of genetic evidence. PMID:23378632

  7. DNA and Morphology Unite Two Species and 10 Million Year Old Fossils

    PubMed Central

    Hills, Simon F. K.; Crampton, James S.; Trewick, Steven A.; Morgan-Richards, Mary

    2012-01-01

    Species definition and delimitation is a non-trivial problem in evolutionary biology that is particularly problematic for fossil organisms. This is especially true when considering the continuity of past and present species, because species defined in the fossil record are not necessarily equivalent to species defined in the living fauna. Correctly assigned fossil species are critical for sensitive downstream analysis (e.g., diversification studies and molecular-clock calibration). The marine snail genus Alcithoe exemplifies many of the problems with species identification. The paucity of objective diagnostic characters, prevalence of morphological convergence between species and considerable variability within species that are observed in Alcithoe are typical of a broad range of fossilised organisms. Using a synthesis of molecular and morphometric approaches we show that two taxa currently recognised as distinct are morphological variants of a single species. Furthermore, we validate the fossil record for one of these morphotypes by finding a concordance between the palaeontological record and divergence time of the lineage inferred using molecular-clock analysis. This work demonstrates the utility of living species represented in the fossil record as candidates for molecular-clock calibration, as the veracity of fossil species assignment can be more rigorously tested. PMID:23284880

  8. Climatic influences on species: Evidence from the fossil record

    USGS Publications Warehouse

    Cronin, T. M.; Schneider, C.E.

    1990-01-01

    The detailed Neogene and Quaternary paleoclimatic reconstructions now available provide a means to test how species respond to environmental change. Paleontologic studies of marine organisms show that climatic change causes evolution (via cladogenesis and anagenesis), ecophenotypic variation, migration, morphologic stasis and extinction. Evolution during climatic change is a rare event relative to the number of climatic cycles that have occurred, but climate-related environmental barriers, usually temperature, may play an important role in the isolation of populations during allopatric speciation.

  9. Cell symbiosis theory - Status and implications for the fossil record

    NASA Technical Reports Server (NTRS)

    Margulis, L.; Stolz, J. F.

    1984-01-01

    Smith (1981) has presented three alternative models of the origin of eukaryotes. In the present investigation, alternative theories are discussed along with the status of serial endosymbiotic theory. It is pointed out that the usefulness of the serial endosymbiotic theory is attested by the great flourishing of productive scientific studies it has generated. Attention is given to the origin of mitochondria and plastids from free-living bacteria, the polyphyly of mitochondria, the origin of the nuclear membrane, the origin of undulipodia (cilia and other 9 + 2 organelles), the sequence of acquisition of organelles, large ribosomes, genome organization, animals and plants, and systematics and axonomy of the microorganisms.

  10. The Fossil Record of Plant-Insect Dynamics

    NASA Astrophysics Data System (ADS)

    Labandeira, Conrad C.; Currano, Ellen D.

    2013-05-01

    Progress toward understanding the dynamics of ancient plant-insect associations has addressed major patterns in the ecology and evolution of herbivory and pollination. This advancement involves development of more analytical ways of describing plant-insect associational patterns in time and space and an assessment of the role that the environment and internal biological processes have in their control. Current issues include the deep origins of terrestrial herbivory, the spread of herbivory across late Paleozoic landscapes, recoveries from sudden major crises, reaction to and accommodation of protracted environmental perturbations, and the nature of herbivory and pollination before the appearance of angiosperms during the mid-Mesozoic. These and other exploratory research themes provide a more complete account of a great nexus of ecological activity that has been wedged between the two most diverse organismic groups on land for the past 410 million years.

  11. The fossil record of evolution: Data on diversification and extinction

    NASA Technical Reports Server (NTRS)

    Sepkoski, J. John, Jr.

    1990-01-01

    The two principle efforts include: (1) a compilation of a synoptic, mesoscale data base on times of origination and extinction of animal genera in the oceans over the last 600 million years of geologic time; and (2) an analysis of statistical patterns in these data that relate to the diversification of complex life and to the occurrence of mass extinctions, especially those that might be associated with extraterrestrial phenomena. The data base is unique in its taxonomic scope and detail and in its temporal resolution. It is a valuable resource for investigating evolutionary expansions and extinctions of complex life.

  12. Replaying evolutionary transitions from the dental fossil record

    PubMed Central

    Harjunmaa, Enni; Seidel, Kerstin; Häkkinen, Teemu; Renvoisé, Elodie; Corfe, Ian J.; Kallonen, Aki; Zhang, Zhao-Qun; Evans, Alistair R.; Mikkola, Marja L.; Salazar-Ciudad, Isaac; Klein, Ophir D.; Jernvall, Jukka

    2014-01-01

    The evolutionary relationships of extinct species are ascertained primarily through the analysis of morphological characters. Character inter-dependencies can have a substantial effect on evolutionary interpretations, but the developmental underpinnings of character inter-dependence remain obscure because experiments frequently do not provide detailed resolution of morphological characters. Here we show experimentally and computationally how gradual modification of development differentially affects characters in the mouse dentition. We found that intermediate phenotypes could be produced by gradually adding ectodysplasin A (EDA) protein in culture to tooth explants carrying a null mutation in the tooth-patterning gene Eda. By identifying development-based character interdependencies, we show how to predict morphological patterns of teeth among mammalian species. Finally, in vivo inhibition of sonic hedgehog signalling in Eda null teeth enabled us to reproduce characters deep in the rodent ancestry. Taken together, evolutionarily informative transitions can be experimentally reproduced, thereby providing development-based expectations for character state transitions used in evolutionary studies. PMID:25079326

  13. The evolution of tetrapod ears and the fossil record.

    PubMed

    Clack, J A

    1997-01-01

    In the earliest tetrapods, the fenestra vestibuli was a large hole in the braincase wall bounded by bones of different embryological origins: the otic capsule and occipital arch components, and also, in all except the Devonian Acanthostega, the dermal parasphenoid. This means that the hole lay along the line of the embryonic metotic fissure. Early tetrapod braincases were poorly ossified internally, and no specialized opening for a perilymphatic duct is evident. It is arguable that the earliest tetrapods had neither a perilympllatic duct crossing the otic capsule nor a specialized auditory receptor in a separate lagenar pouch. The primitive tetrapod condition is found in the earliest amniotes, and the separate development of (1) a fenestra vestibuli confined to the limits of the otic capsule, (2) a specialized pressure relief window also derived from components on the line of the metolic fissure, (3) a nonstructural, vibratory stapes and (4) increased internal ossification of the internal walls of the otic capsule, can be traced separately in synapsids, lepidosauromorph diapsids, archosauromorph diapsids, probably turtles, and amphibians. This suggests separate development of true tympanic ears in each of these groups. Developments indicating the existence of a true tympanic ear in amniotes are first found in animals from the Triassic period, and a correlation with the evolution of insect sound production is suggested.

  14. Profound 62 Myr Cycle in Fossil Diversity

    NASA Astrophysics Data System (ADS)

    Muller, R. A.; Rohde, R. A.

    2004-12-01

    By combining the Sepkoski Compendium of Marine Fossil Genera with the new ICS 2004 geologic time scale, we have shown that the fossil record contains a 62 +/- 3 Myr cycle in the diversity of genera. This cycle has a very high statistical significance and while the associated changes in diversity are frequently gradual, all of the sharp drops known as major mass extinctions have occurred during declining phases of this cycle. This suggests that the timing or magnitude of these extinctions has been influenced by this periodic process; however, it remains unclear whether extinction events actually cause the cycle. While, we cannot explain the origin of the 62 Myr cycle, we believe it indicates a profound influence of some periodic physical process on Earth's environment throughout at least the last 540 Myr. In addition, the diversity data contain a statistically ambiguous 140 +/- 15 Myr cycle which could be due to changes of the same frequency reported in climate and cosmic rays. While all major mass extinctions seem to bear some relation to this cycle, we also find that the Permian-Triassic extinction was qualitatively unique. This extinction, the most severe in Earth's history, had substantial impact on classes of organisms that were historically resistant to the 62 Myr changes. This suggests that the processes leading to the P-T extinction may have included factors that were unique to that point in the Phanerozoic. It should be noted that the 62 Myr hypothesis is originally due to Thomson (Thomson KS, Nature 261, 578-580 (1976); Devs. in Palaeo. and Strat. 5, 377-404 (1977)) and Ager (Ager DV, Proc. Geologists' Assoc. 87, 131-159 (1977)), though their work has largely been forgotten. At the time of this submission, our revival of the 62 Myr hypothesis and related analysis is currently undergoing peer review at Nature.

  15. An application of synchrotron based x-ray tomography in palaeontology: Investigating small, three-dimensional, exceptionally preserved fossil arthropods

    NASA Astrophysics Data System (ADS)

    Braiden, A. K.; Orr, P. J.; Tafforeau, P.; Kearns, S. L.

    2009-04-01

    The fossil record is biased towards biomineralised elements (for example bones, shells and teeth) that usually retain their original three-dimensional shape. Non-biomineralised arthropods, often comprising only exoskeletal tissues such as cuticle, are comparatively rare and are usually preserved in two-dimensions (including examples inside early diagenetic concretions). Rarer still are exceptionally preserved fossils that contain replicated soft tissues; although tissues that are replicated during the initial stages of decay are usually three- dimensional and often preserved in detail, the fossil as a whole is almost invariably two dimensional. Fossil shrimp recovered from Upper Triassic (Rhaetian) unconsolidated clays at Frome, Somerset, England represent a low diversity, three-dimensionally preserved fauna, in which certain labile tissues and organs are routinely preserved in three dimensions in life position. Initial SEM analysis of exposed, internal structures in unprepared specimens confirmed the presence of musculature (replicated in calcium phosphate) and a clay infilled gut. Due to the rarity of the material, and small size of the specimens (maximum length 12mm), non-destructive synchrotron radiation, x-ray microtomography was used to determine the extent, and fidelity, of preservation of the internal anatomy. Medium resolution (voxel size of 5.3μm) and high resolution (voxel size 0.7μm) imaging was carried out on selected specimens. This confirmed high fidelity replication of the following: limited volumes of abdominal, and more rarely, cephalothoracic musculature; the hepatopancreas; gonads and, in rare cases, blood vessels and antennal glands. Notably, these are all preserved in situ enveloped by structureless, fine-grained, authigenic carbonate. This carbonate precipitated inside the cuticle, but only at the periphery of the carcass and after, or during, the initial stages of decay; it infills voids created by the initial shrinkage of abdominal

  16. Estimating past precipitation and temperature from fossil ostracodes

    SciTech Connect

    Smith, A.J.; Forester, R.M.

    1994-12-31

    The fossil records of certain aquatic organisms provide a way of obtaining meaningful estimates of past temperature and precipitation. These estimates of past environmental conditions are derived from multivariate statistical methods that are in turn based on the modern biogeographic distributions and environmental tolerances of the biota of interest. These estimates are helpful in conducting slimate studies as part of the Yucca Mountain site characterization. Ostracodes are microscopic crustaceans that produce bivalved calcite shells which are easily fossilized in the sediments of the lakes and wetlands in which the animals lived. The modern biogeographic distribution and environmental conditions of living ostracodes are the basis for the interpretation of the past environmental conditions of the fossil ostracodes. The major assumption in this method of interpretation is that the environmental tolerances of ostracodes have not changed substantially over thousands of years. Two methods using these modern analogs to determine past environmental conditions are the modern analog method and the range method. The range method also considers the information provided by fossil ostracode assemblages that have no modern analog in today`s world.

  17. New Miocene Fossils and the History of Penguins in Australia.

    PubMed

    Park, Travis; Fitzgerald, Erich M G; Gallagher, Stephen J; Tomkins, Ellyn; Allan, Tony

    2016-01-01

    Australia has a fossil record of penguins reaching back to the Eocene, yet today is inhabited by just one breeding species, the little penguin Eudyptula minor. The description of recently collected penguin fossils from the re-dated upper Miocene Port Campbell Limestone of Portland (Victoria), in addition to reanalysis of previously described material, has allowed the Cenozoic history of penguins in Australia to be placed into a global context for the first time. Australian pre-Quaternary fossil penguins represent stem taxa phylogenetically disparate from each other and E. minor, implying multiple dispersals and extinctions. Late Eocene penguins from Australia are closest to contemporaneous taxa in Antarctica, New Zealand and South America. Given current material, the Miocene Australian fossil penguin fauna is apparently unique in harbouring 'giant penguins' after they went extinct elsewhere; and including stem taxa until at least 6 Ma, by which time crown penguins dominated elsewhere in the southern hemisphere. Separation of Australia from Antarctica during the Palaeogene, and its subsequent drift north, appears to have been a major event in Australian penguin biogeography. Increasing isolation through the Cenozoic may have limited penguin dispersal to Australia from outside the Australasian region, until intensification of the eastwards-flowing Antarctic Circumpolar Current in the mid-Miocene established a potential new dispersal vector to Australia.

  18. New Miocene Fossils and the History of Penguins in Australia

    PubMed Central

    Park, Travis; Fitzgerald, Erich M. G.; Gallagher, Stephen J.; Tomkins, Ellyn; Allan, Tony

    2016-01-01

    Australia has a fossil record of penguins reaching back to the Eocene, yet today is inhabited by just one breeding species, the little penguin Eudyptula minor. The description of recently collected penguin fossils from the re-dated upper Miocene Port Campbell Limestone of Portland (Victoria), in addition to reanalysis of previously described material, has allowed the Cenozoic history of penguins in Australia to be placed into a global context for the first time. Australian pre-Quaternary fossil penguins represent stem taxa phylogenetically disparate from each other and E. minor, implying multiple dispersals and extinctions. Late Eocene penguins from Australia are closest to contemporaneous taxa in Antarctica, New Zealand and South America. Given current material, the Miocene Australian fossil penguin fauna is apparently unique in harbouring ‘giant penguins’ after they went extinct elsewhere; and including stem taxa until at least 6 Ma, by which time crown penguins dominated elsewhere in the southern hemisphere. Separation of Australia from Antarctica during the Palaeogene, and its subsequent drift north, appears to have been a major event in Australian penguin biogeography. Increasing isolation through the Cenozoic may have limited penguin dispersal to Australia from outside the Australasian region, until intensification of the eastwards-flowing Antarctic Circumpolar Current in the mid-Miocene established a potential new dispersal vector to Australia. PMID:27115739

  19. Kinneyia: a flow-induced anisotropic fossil pattern from ancient microbial mats

    NASA Astrophysics Data System (ADS)

    Herminghaus, Stephan; Thomas, Katherine; Aliaskarisohi, Saeedeh; Porada, Hubertus; Goehring, Lucas

    2016-07-01

    Kinneyia is the commonly-used term to describe a class of trace fossil that is strongly associated with microbial mats. The appearance of Kinneyia (or wrinkle-structures) in the fossil record has recently led to a number of possible mechanisms being proposed to explain its formation. Here we outline, and critically compare, three of these models, involving formation of the characteristic ripple-structures (i) in mats over liquefied sediment, (ii) by oscillatory flow of microbial aggregates, and (iii) by a Kelvin-Helmholtz instability of the mat surface. Of these models, our study shows that the hydrodynamic instability compares most favorably with the corresponding structures in the fossil record. Implications for the conditions under which the fossils formed are then further discussed.

  20. Fossils and living taxa agree on patterns of body mass evolution: a case study with Afrotheria

    PubMed Central

    Puttick, Mark N.; Thomas, Gavin H.

    2015-01-01

    Most of life is extinct, so incorporating some fossil evidence into analyses of macroevolution is typically seen as necessary to understand the diversification of life and patterns of morphological evolution. Here we test the effects of inclusion of fossils in a study of the body size evolution of afrotherian mammals, a clade that includes the elephants, sea cows and elephant shrews. We find that the inclusion of fossil tips has little impact on analyses of body mass evolution; from a small ancestral size (approx. 100 g), there is a shift in rate and an increase in mass leading to the larger-bodied Paenungulata and Tubulidentata, regardless of whether fossils are included or excluded from analyses. For Afrotheria, the inclusion of fossils and morphological character data affect phylogenetic topology, but these differences have little impact upon patterns of body mass evolution and these body mass evolutionary patterns are consistent with the fossil record. The largest differences between our analyses result from the evolutionary model, not the addition of fossils. For some clades, extant-only analyses may be reliable to reconstruct body mass evolution, but the addition of fossils and careful model selection is likely to increase confidence and accuracy of reconstructed macroevolutionary patterns. PMID:26674947

  1. Fossils and living taxa agree on patterns of body mass evolution: a case study with Afrotheria.

    PubMed

    Puttick, Mark N; Thomas, Gavin H

    2015-12-22

    Most of life is extinct, so incorporating some fossil evidence into analyses of macroevolution is typically seen as necessary to understand the diversification of life and patterns of morphological evolution. Here we test the effects of inclusion of fossils in a study of the body size evolution of afrotherian mammals, a clade that includes the elephants, sea cows and elephant shrews. We find that the inclusion of fossil tips has little impact on analyses of body mass evolution; from a small ancestral size (approx. 100 g), there is a shift in rate and an increase in mass leading to the larger-bodied Paenungulata and Tubulidentata, regardless of whether fossils are included or excluded from analyses. For Afrotheria, the inclusion of fossils and morphological character data affect phylogenetic topology, but these differences have little impact upon patterns of body mass evolution and these body mass evolutionary patterns are consistent with the fossil record. The largest differences between our analyses result from the evolutionary model, not the addition of fossils. For some clades, extant-only analyses may be reliable to reconstruct body mass evolution, but the addition of fossils and careful model selection is likely to increase confidence and accuracy of reconstructed macroevolutionary patterns.

  2. Identification of Preferential Paths of Fossil Carbon within Water Resource Recovery Facilities via Radiocarbon Analysis.

    PubMed

    Tseng, Linda Y; Robinson, Alice K; Zhang, Xiaying; Xu, Xiaomei; Southon, John; Hamilton, Andrew J; Sobhani, Reza; Stenstrom, Michael K; Rosso, Diego

    2016-11-15

    The Intergovernmental Panel on Climate Change (IPCC) reported that all carbon dioxide (CO2) emissions generated by water resource recovery facilities (WRRFs) during treatment are modern, based on available literature. Therefore, such emissions were omitted from IPCC's greenhouse gas (GHG) accounting procedures. However, a fraction of wastewater's carbon is fossil in origin. We hypothesized that since the fossil carbon entering municipal WRRFs is mostly from soaps and detergents as dissolved organic matter, its fate can be selectively determined during the universally applied separation treatment processes. Analyzing radiocarbon at different treatment points within municipal WRRFs, we verified that the fossil content could amount to 28% in primary influent and showed varying distribution leaving different unit operations. We recorded the highest proportion of fossil carbon leaving the secondary treatment as off-gas and as solid sludge (averaged 2.08 kg fossil-CO2-emission-potential m(-3) wastewater treated). By including fossil CO2, total GHG emission in municipal WRRFs increased 13%, and 23% if an on-site energy recovery system exists although much of the postdigestion fossil carbon remained in biosolids rather than in biogas, offering yet another carbon sequestration opportunity during biosolids handling. In comparison, fossil carbon contribution to GHG emission can span from negligible to substantial in different types of industrial WRRFs. With such a considerable impact, CO2 should be analyzed for each WRRF and not omitted from GHG accounting.

  3. The age for the fossil-bearing Tabbowa beds in Sri Lanka

    NASA Astrophysics Data System (ADS)

    Chang, S. C.; Dassanayake, S.; Wang, J.

    2014-12-01

    Well-preserved terrestrial fossils, mainly including conifers, cycads and ferns, were discovered from the Tabbowa beds in northwestern Sri Lanka. The high diversity and abundance of plants and insects from these Jurassic sediments provide a unique window to understand floral evolution and plant-insect co-evolution in the Mesozoic. For example, unearthed fossils from the Tabbowa beds indicate that leaf feeding and dwelling insects played a significant role in the Jurassic ecosystem. For another example, feeding and chewing marks on leaves allow studying insect behavior and paleo-ecology. Additionally, the recent discoveries of Otozamites latiphyllus and Otozamites tabbowensis from these sediments provide evidence that Bennettitales, an extinct order of seed plants, widely spread in the Gondwana during the Jurassic period. Although most fossils are yet to be well studied, and only few of the fossil occurrences have been published in western journals, plant fossils from the Tabbowa beds have great potential for substantially increasing our knowledge of Jurassic terrestrial ecosystems. The fossil-bearing Tabbowa beds are mainly composed of sandstone, siltstone, and mudstone with occasional thin bands of nodular limestone. Until now, radio-isotopic age determinations for the fossil-rich Tabbowa beds are lacking. In this study, we investigate the geological and geochronological setting of this area by dating detrital zircons from the Tabbowa beds. The age data will allow testing several hypotheses regarding the plant evolution, the basin development of this region.

  4. Benefits of solar/fossil hybrid gas turbine systems

    NASA Technical Reports Server (NTRS)

    Bloomfield, H. S.

    1978-01-01

    The potential benefits of solar/fossil hybrid gas turbine power systems were assessed. Both retrofit and new systems were considered from the aspects of; cost of electricity, fuel conservation, operational mode, technology requirements, and fuels flexibility. Hybrid retrofit (repowering) of existing combustion (simple Brayton cycle) turbines can provide near-term fuel savings and solar experience, while new and advanced recuperated or combined cycle systems may be an attractive fuel saving and economically competitive vehicle to transition from today's gas and oil-fired powerplants to other more abundant fuels.

  5. Benefits of solar/fossil hybrid gas turbine systems

    NASA Technical Reports Server (NTRS)

    Bloomfield, H. S.

    1979-01-01

    The potential benefits of solar/fossil hybrid gas turbine power systems were assessed. Both retrofit and new systems were considered from the aspects of cost of electricity, fuel conservation, operational mode, technology requirements, and fuels flexibility. Hybrid retrofit (repowering) of existing combustion (simple Brayton cycle) turbines can provide near-term fuel savings and solar experience, while new and advanced recuperated or combined cycle systems may be an attractive fuel saving and economically competitive vehicle to transition from today's gas and oil-fired powerplants to other more abundant fuels.

  6. Middle Cambrian fossils from the Doonerak anticlinorium, central Brooks Range, Alaska.

    USGS Publications Warehouse

    Dutro, J.T.; Palmer, A.R.; Repetski, J.E.; Brosge, W.P.

    1984-01-01

    Middle Cambrian fossils collected near Wolf Creek in the Wiseman quadrangle, northern Alaska, include trilobites and paraconodonts. Trilobites date the strata as early Middle Cambrian, correlative with the Amgan Stage of Siberia. The assemblage includes: Kootenia cf. K. anabarensis Lermontova, cf. 'Parehmania' lata Chernysheva and Pagetia sp. Specimens of the paracondont genus Westergaardodina, from the same sample as the megafossils, record the earliest known occurrence of this taxon. These fossils, the first to establish an age for part of the sedimentary sequence in the Doonerak Anticlinorium, are the oldest fossils yet taken from the central and western Brooks Range.-Authors

  7. Fossils of hydrothermal vent worms from Cretaceous sulfide ores of the Samail ophiolite, Oman

    USGS Publications Warehouse

    Haymon, R.M.; Koski, R.A.; Sinclair, C.

    1984-01-01

    Fossil worm tubes of Cretaceous age preserved in the Bayda massive sulfide deposit of the Samail ophiolite, Oman, are apparently the first documented examples of fossils embedded in massive sulfide deposits from the geologic record. The geologic setting of the Bayda deposit and the distinctive mineralogic and textural features of the fossiliferous samples suggest that the Bayda sulfide deposit and fossil fauna are remnants of a Cretaceous sea-floor hydrothermal vent similar to modern hot springs on the East Pacific Rise and the Juan de Fuca Ridge.

  8. Cyanobacteria and the Great Oxidation Event: evidence from genes and fossils.

    PubMed

    Schirrmeister, Bettina E; Gugger, Muriel; Donoghue, Philip C J

    2015-09-01

    Cyanobacteria are among the most ancient of evolutionary lineages, oxygenic photosynthesizers that may have originated before 3.0 Ga, as evidenced by free oxygen levels. Throughout the Precambrian, cyanobacteria were one of the most important drivers of biological innovations, strongly impacting early Earth's environments. At the end of the Archean Eon, they were responsible for the rapid oxygenation of Earth's atmosphere during an episode referred to as the Great Oxidation Event (GOE). However, little is known about the origin and diversity of early cyanobacterial taxa, due to: (1) the scarceness of Precambrian fossil deposits; (2) limited characteristics for the identification of taxa; and (3) the poor preservation of ancient microfossils. Previous studies based on 16S rRNA have suggested that the origin of multicellularity within cyanobacteria might have been associated with the GOE. However, single-gene analyses have limitations, particularly for deep branches. We reconstructed the evolutionary history of cyanobacteria using genome scale data and re-evaluated the Precambrian fossil record to get more precise calibrations for a relaxed clock analysis. For the phylogenomic reconstructions, we identified 756 conserved gene sequences in 65 cyanobacterial taxa, of which eight genomes have been sequenced in this study. Character state reconstructions based on maximum likelihood and Bayesian phylogenetic inference confirm previous findings, of an ancient multicellular cyanobacterial lineage ancestral to the majority of modern cyanobacteria. Relaxed clock analyses provide firm support for an origin of cyanobacteria in the Archean and a transition to multicellularity before the GOE. It is likely that multicellularity had a greater impact on cyanobacterial fitness and thus abundance, than previously assumed. Multicellularity, as a major evolutionary innovation, forming a novel unit for selection to act upon, may have served to overcome evolutionary constraints and

  9. Fossil energy program. Summary document

    SciTech Connect

    1980-05-01

    This program summary document presents a comprehensive overview of the research, development, and demonstration (RD and D) activities that will be performed in FY 1981 by the Assistant Secretary for Fossil Energy (ASFE), US Department of Energy (DOE). The ASFE technology programs for the fossil resources of coal, petroleum (including oil shale) and gas have been established with the goal of making substantive contributions to the nation's future supply and efficienty use of energy. On April 29, 1977, the Administration submitted to Congress the National Energy Plan (NEP) and accompanying legislative proposals designed to establish a coherent energy policy structure for the United States. Congress passed the National Energy Act (NEA) on October 15, 1978, which allows implementation of the vital parts of the NEP. The NEP was supplemented by additional energy policy statements culminating in the President's address on July 15, 1979, presenting a program to further reduce dependence on imported petroleum. The passage of the NEA-related energy programs represent specific steps by the Administration and Congress to reorganize, redirect, and clarify the role of the Federal Government in the formulation and execution of national energy policy and programs. The energy technology RD and D prog4rams carried out by ASFE are an important part of the Federal Government's effort to provide the combination and amounts of energy resources needed to ensure national security and continued economic growth.

  10. A comprehensive database of quality-rated fossil ages for Sahul's Quaternary vertebrates.

    PubMed

    Rodríguez-Rey, Marta; Herrando-Pérez, Salvador; Brook, Barry W; Saltré, Frédérik; Alroy, John; Beeton, Nicholas; Bird, Michael I; Cooper, Alan; Gillespie, Richard; Jacobs, Zenobia; Johnson, Christopher N; Miller, Gifford H; Prideaux, Gavin J; Roberts, Richard G; Turney, Chris S M; Bradshaw, Corey J A

    2016-07-19

    The study of palaeo-chronologies using fossil data provides evidence for past ecological and evolutionary processes, and is therefore useful for predicting patterns and impacts of future environmental change. However, the robustness of inferences made from fossil ages relies heavily on both the quantity and quality of available data. We compiled Quaternary non-human vertebrate fossil ages from Sahul published up to 2013. This, the FosSahul database, includes 9,302 fossil records from 363 deposits, for a total of 478 species within 215 genera, of which 27 are from extinct and extant megafaunal species (2,559 records). We also provide a rating of reliability of individual absolute age based on the dating protocols and association between the dated materials and the fossil remains. Our proposed rating system identified 2,422 records with high-quality ages (i.e., a reduction of 74%). There are many applications of the database, including disentangling the confounding influences of hypothetical extinction drivers, better spatial distribution estimates of species relative to palaeo-climates, and potentially identifying new areas for fossil discovery.

  11. A comprehensive database of quality-rated fossil ages for Sahul’s Quaternary vertebrates

    NASA Astrophysics Data System (ADS)

    Rodríguez-Rey, Marta; Herrando-Pérez, Salvador; Brook, Barry W.; Saltré, Frédérik; Alroy, John; Beeton, Nicholas; Bird, Michael I.; Cooper, Alan; Gillespie, Richard; Jacobs, Zenobia; Johnson, Christopher N.; Miller, Gifford H.; Prideaux, Gavin J.; Roberts, Richard G.; Turney, Chris S. M.; Bradshaw, Corey J. A.

    2016-07-01

    The study of palaeo-chronologies using fossil data provides evidence for past ecological and evolutionary processes, and is therefore useful for predicting patterns and impacts of future environmental change. However, the robustness of inferences made from fossil ages relies heavily on both the quantity and quality of available data. We compiled Quaternary non-human vertebrate fossil ages from Sahul published up to 2013. This, the FosSahul database, includes 9,302 fossil records from 363 deposits, for a total of 478 species within 215 genera, of which 27 are from extinct and extant megafaunal species (2,559 records). We also provide a rating of reliability of individual absolute age based on the dating protocols and association between the dated materials and the fossil remains. Our proposed rating system identified 2,422 records with high-quality ages (i.e., a reduction of 74%). There are many applications of the database, including disentangling the confounding influences of hypothetical extinction drivers, better spatial distribution estimates of species relative to palaeo-climates, and potentially identifying new areas for fossil discovery.

  12. A comprehensive database of quality-rated fossil ages for Sahul’s Quaternary vertebrates

    PubMed Central

    Rodríguez-Rey, Marta; Herrando-Pérez, Salvador; Brook, Barry W.; Saltré, Frédérik; Alroy, John; Beeton, Nicholas; Bird, Michael I.; Cooper, Alan; Gillespie, Richard; Jacobs, Zenobia; Johnson, Christopher N.; Miller, Gifford H.; Prideaux, Gavin J.; Roberts, Richard G.; Turney, Chris S.M.; Bradshaw, Corey J.A.

    2016-01-01

    The study of palaeo-chronologies using fossil data provides evidence for past ecological and evolutionary processes, and is therefore useful for predicting patterns and impacts of future environmental change. However, the robustness of inferences made from fossil ages relies heavily on both the quantity and quality of available data. We compiled Quaternary non-human vertebrate fossil ages from Sahul published up to 2013. This, the FosSahul database, includes 9,302 fossil records from 363 deposits, for a total of 478 species within 215 genera, of which 27 are from extinct and extant megafaunal species (2,559 records). We also provide a rating of reliability of individual absolute age based on the dating protocols and association between the dated materials and the fossil remains. Our proposed rating system identified 2,422 records with high-quality ages (i.e., a reduction of 74%). There are many applications of the database, including disentangling the confounding influences of hypothetical extinction drivers, better spatial distribution estimates of species relative to palaeo-climates, and potentially identifying new areas for fossil discovery. PMID:27434208

  13. Fossils, molecules and embryos: new perspectives on the Cambrian explosion

    NASA Technical Reports Server (NTRS)

    Valentine, J. W.; Jablonski, D.; Erwin, D. H.

    1999-01-01

    The Cambrian explosion is named for the geologically sudden appearance of numerous metazoan body plans (many of living phyla) between about 530 and 520 million years ago, only 1.7% of the duration of the fossil record of animals. Earlier indications of metazoans are found in the Neoproterozic; minute trails suggesting bilaterian activity date from about 600 million years ago. Larger and more elaborate fossil burrows appear near 543 million years ago, the beginning of the Cambrian Period. Evidence of metazoan activity in both trace and body fossils then increased during the 13 million years leading to the explosion. All living phyla may have originated by the end of the explosion. Molecular divergences among lineages leading to phyla record speciation events that have been earlier than the origins of the new body plans, which can arise many tens of millions of years after an initial branching. Various attempts to date those branchings by using molecular clocks have disagreed widely. While the timing of the evolution of the developmental systems of living metazoan body plans is still uncertain, the distribution of Hox and other developmental control genes among metazoans indicates that an extensive patterning system was in place prior to the Cambrian. However, it is likely that much genomic repatterning occurred during the Early Cambrian, involving both key control genes and regulators within their downstream cascades, as novel body plans evolved.

  14. Fossils, molecules and embryos: new perspectives on the Cambrian explosion.

    PubMed

    Valentine, J W; Jablonski, D; Erwin, D H

    1999-02-01

    The Cambrian explosion is named for the geologically sudden appearance of numerous metazoan body plans (many of living phyla) between about 530 and 520 million years ago, only 1.7% of the duration of the fossil record of animals. Earlier indications of metazoans are found in the Neoproterozic; minute trails suggesting bilaterian activity date from about 600 million years ago. Larger and more elaborate fossil burrows appear near 543 million years ago, the beginning of the Cambrian Period. Evidence of metazoan activity in both trace and body fossils then increased during the 13 million years leading to the explosion. All living phyla may have originated by the end of the explosion. Molecular divergences among lineages leading to phyla record speciation events that have been earlier than the origins of the new body plans, which can arise many tens of millions of years after an initial branching. Various attempts to date those branchings by using molecular clocks have disagreed widely. While the timing of the evolution of the developmental systems of living metazoan body plans is still uncertain, the distribution of Hox and other developmental control genes among metazoans indicates that an extensive patterning system was in place prior to the Cambrian. However, it is likely that much genomic repatterning occurred during the Early Cambrian, involving both key control genes and regulators within their downstream cascades, as novel body plans evolved.

  15. Fossil land snails of East Africa and their palaeoecological significance

    NASA Astrophysics Data System (ADS)

    Pickford, Martin

    1995-04-01

    This study deals with the Neogene and extant land snails of tropical East Africa and their implications for interpreting the paleoenvironments of the numerous localities at which they have been found. Of major significance to the study is the intimate association between the terrestrial molluscs and the rich mammalian faunas, hominoids included, of East Africa. Thus, palaeoecological reconstructions based on land snails are directly applicable to the mammalian faunas. Palaeoecological reconstructions are proposed for most of the Lower and Middle Miocene hominoids, including Proconsul, Rangwapithecus, Limnopithecus, Micropithecus, Nyanzapithecus, Kenyapithecus and others, and for the mid-Pliocene Australopithecus from Laetoli, Tanzania. The departure point for the palaeoecological reconstructions is a comprehensive study of extant terrestrial molluscs of East Africa, the habitat preferences of which are well documented. All the fossil gastropods studied comprise extant genera and even species, so the usual problems regarding the application of actualism to fossil assemblages is avoided. Furthermore, the fossil gastropod assemblages resemble extant ones, confirming their utility for such reconstructions. Among the parameters examined are rainfall, altitude, vegetation cover and type and zoogeography. A further point of interest is that the samples are more than adequate for the purposes of the study, many of the fossil localities having yielded several thousand specimens. Finally, more than 40% of the extant genera of East Africa have now been recognized in the fossil state. The molluscs are thus, by far, the best represented biological group known in the fossil record of Africa and as such hold great potential for understanding the past. This study ends with reconstructions of the palaeoecology of numerous fossiliferous localities in East Africa which have yielded molluscs and mammals. Changes through the geological column are documented and the habitat preferences

  16. Inferring modern extinction risk from fossil occupancy trajectories

    NASA Astrophysics Data System (ADS)

    Kiessling, Wolfgang; Kocsis, Adam

    2016-04-01

    Besides providing information on ancient mass extinctions and intrinsic extinction risk, the fossil record may also provide useful data for assessing the extinction risk of extant species. Here we analyse the palaeontological trajectories of geographical occupancy in extant marine species to identify species that have been declining over geological time scales and may thus be more prone to extinction than expanding species. The slopes of these occupancy trajectories are used to categorize evolutionary extinction risk. Mapping the risk at global scale we find that low to mid latitude regions are at significantly higher risk than high latitude regions. We also find a moderate correspondence between high extinction risk on geological time scales and modern extinction risk for reef corals and propose to add fossil data to the assessment of current extinction risk, especially for the notoriously data deficient marine taxa.

  17. Diversification of Neoaves: integration of molecular sequence data and fossils

    PubMed Central

    Ericson, Per G.P; Anderson, Cajsa L; Britton, Tom; Elzanowski, Andrzej; Johansson, Ulf S; Källersjö, Mari; Ohlson, Jan I; Parsons, Thomas J; Zuccon, Dario; Mayr, Gerald

    2006-01-01

    Patterns of diversification and timing of evolution within Neoaves, which includes almost 95% of all bird species, are virtually unknown. On the other hand, molecular data consistently indicate a Cretaceous origin of many neoavian lineages and the fossil record seems to support an Early Tertiary diversification. Here, we present the first well-resolved molecular phylogeny for Neoaves, together with divergence time estimates calibrated with a large number of stratigraphically and phylogenetically well-documented fossils. Our study defines several well-supported clades within Neoaves. The calibration results suggest that Neoaves, after an initial split from Galloanseres in Mid-Cretaceous, diversified around or soon after the K/T boundary. Our results thus do not contradict palaeontological data and show that there is no solid molecular evidence for an extensive pre-Tertiary radiation of Neoaves. PMID:17148284

  18. Using extant taxa to inform studies of fossil footprints

    NASA Astrophysics Data System (ADS)

    Falkingham, Peter; Gatesy, Stephen

    2016-04-01

    Attempting to use the fossilized footprints of extinct animals to study their palaeobiology and palaeoecology is notoriously difficult. The inconvenient extinction of the trackmaker makes direct correlation between footprints and foot far from straightforward. However, footprints are the only direct evidence of vertebrate motion recorded in the fossil record, and are potentially a source of data on palaeobiology that cannot be obtained from osteological remains alone. Our interests lie in recovering information about the movements of dinosaurs from their tracks. In particular, the Hitchcock collection of early Jurassic tracks held at the Beneski Museum of Natural History, Amherst, provide a rare look into the 3D form of tracks at and below the surface the animal walked on. Breaking naturally along laminations into 'track books', the specimens present sediment deformation at multiple levels, and in doing so record more of the foot's motion than a single surface might. In order to utilize this rich information source to study the now extinct trackmakers, the process of track formation must be understood at a fundamental level; the interaction of the moving foot and compliant substrate. We used bi-planar X-ray techniques (X-ray Reconstruction of Moving Morphology) to record the limb and foot motions of a Guineafowl traversing both granular and cohesive substrates. This data was supplemented with photogrammetric records of the resultant track surfaces, as well as the motion of metal beads within the sediment, to provide a full experimental dataset of foot and footprint formation. The physical experimental data was used to generate computer simulations of the process using high performance computing and the Discrete Element Method. The resultant simulations showed excellent congruence with reality, and enabled visualization within the sediment volume, and throughout the track-forming process. This physical and virtual experimental set-up has provided major insight into

  19. Double fossilization in eukaryotic microorganisms from Lower Cretaceous amber

    PubMed Central

    Martín-González, Ana; Wierzchos, Jacek; Gutiérrez, Juan-Carlos; Alonso, Jesús; Ascaso, Carmen

    2009-01-01

    Background Microfossils are not only useful for elucidating biological macro- and microevolution but also the biogeochemical history of our planet. Pyritization is the most important and extensive mode of preservation of animals and especially of plants. Entrapping in amber, a fossilized resin, is considered an alternative mode of biological preservation. For the first time, the internal organization of 114-million-year-old microfossils entrapped in Lower Cretaceous amber is described and analyzed, using adapted scanning electron microscopy in backscattered electron mode in association with energy dispersive X-ray spectroscopy microanalysis. Double fossilization of several protists included in diverse taxonomical groups and some vegetal debris is described and analyzed. Results In protists without an exoskeleton or shell (ciliates, naked amoebae, flagellates), determinate structures, including the nuclei, surface envelopes (cortex or cytoplasmic membrane) and hyaloplasm are the main sites of pyritization. In protists with a biomineralized skeleton (diatoms), silicon was replaced by pyrite. Permineralization was the main mode of pyritization. Framboidal, subhedral and microcrystalline are the predominant pyrite textures detected in the cells. Abundant pyritized vegetal debris have also been found inside the amber nuggets and the surrounding sediments. This vegetal debris usually contained numerous pyrite framboids and very densely packed polycrystalline pyrite formations infilled with different elements of the secondary xylem. Conclusion Embedding in amber and pyritization are not always alternative modes of biological preservation during geological times, but double fossilization is possible under certain environmental conditions. Pyritization in protists shows a quite different pattern with regard to plants, due to the different composition and cellular architecture in these microorganisms and organisms. Anaerobic sulphate-reducing bacteria could play a crucial

  20. Revisiting global fossil fuel and biofuel emissions of ethane

    NASA Astrophysics Data System (ADS)

    Tzompa-Sosa, Z. A.; Mahieu, E.; Franco, B.; Keller, C. A.; Turner, A. J.; Helmig, D.; Fried, A.; Richter, D.; Weibring, P.; Walega, J.; Yacovitch, T. I.; Herndon, S. C.; Blake, D. R.; Hase, F.; Hannigan, J. W.; Conway, S.; Strong, K.; Schneider, M.; Fischer, E. V.

    2017-02-01

    Recent measurements over the Northern Hemisphere indicate that the long-term decline in the atmospheric burden of ethane (C2H6) has ended and the abundance increased dramatically between 2010 and 2014. The rise in C2H6 atmospheric abundances has been attributed to oil and natural gas extraction in North America. Existing global C2H6 emission inventories are based on outdated activity maps that do not account for current oil and natural gas exploitation regions. We present an updated global C2H6 emission inventory based on 2010 satellite-derived CH4 fluxes with adjusted C2H6 emissions over the U.S. from the National Emission Inventory (NEI 2011). We contrast our global 2010 C2H6 emission inventory with one developed for 2001. The C2H6 difference between global anthropogenic emissions is subtle (7.9 versus 7.2 Tg yr-1), but the spatial distribution of the emissions is distinct. In the 2010 C2H6 inventory, fossil fuel sources in the Northern Hemisphere represent half of global C2H6 emissions and