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Sample records for african fossil record

  1. 004118:a0001 Fossil Record

    E-print Network

    Benton, Michael

    004118:a0001 Fossil Record Michael J Benton, University of Bristol, Bristol, UK Fossils life. 004118:s0001 Introduction 004118:p0001 Fossils are the remains of plants and animals that once lived. The common image of a fossil is an ancient shell or bone that has been turned to rock

  2. Evidence of Evolution I. Fossils and the fossil record

    E-print Network

    Dever, Jennifer A.

    radioactive elements · Generally applied to igneous & metamorphic rocks, so what about fossils & sedimentary in the rocks deposited in those Eras. #12;#12;Why is the fossil record incomplete? · fossilization - "lucky in the rock! Accurate method for determining the age of fossils and rocks - Measures the decay of certain

  3. 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.

  4. 004144:a0001 Fossil Record: Quality

    E-print Network

    Benton, Michael

    004144:a0001 Fossil Record: Quality Michael J Benton, University of Bristol, Bristol, UK There are divergent opinions about the quality of the fossil record and its ability to give a useful representation phylogenies, suggests that the fossils do tell the story relatively well. 004144:s0001 Introduction 004144:p

  5. 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.

  6. Molecules and the fossil record If the fossil record cannot provide definitive answers to

    E-print Network

    Hedges, Blair

    , sirenians and aardvarks. The group also makes geographic sense; the members are of African origin. Fossils and morphology, on the other hand,place elephants, sirenians, and hyracoids with ungulates (horses, ) 10cows, etc

  7. The Fossil Record Noel A. Heim and Dana H. Geary

    E-print Network

    Heim, Noel A.

    II.9 The Fossil Record Noel A. Heim and Dana H. Geary OUTLINE 1. Fossilization and taphonomy 2. The nature of the fossil record 3. Marine diversity in the Phanerozoic 4. The value of the fossil record The fossil record documents the history of life over the course of the past 3.5 billion years, demonstrates

  8. Biodiversity of the Fossil Record

    E-print Network

    Kammer, Thomas

    starfish #12;Echinoids: sand dollar (left) sea biscuit (below) #12;Holothurian: sea cucumber #12;Pikaia exposed in a sandstone outcrop #12;A fossil sea pen from the Ediacaran of Australia #12;Mawsonites://blogs.smithsonianmag.com/aroundthemall/index.php?s=trilobites #12;The Devonian Trilobite Phacops rana #12;Eurypterid or "Sea Scorpian", Silurian of New York #12

  9. Evolution of Tetrapod Vertebrates inferred from fossil record

    E-print Network

    Houde, Peter

    Evolution of Tetrapod Vertebrates inferred from fossil record Labyrinthodonts ­ first tetrapod reconstruction #12;Behavior of fossil species can be difficult to interpret Frogfishes (Antennarius) have limb Tiktaalik Acanthostega #12;Evolution of Reptiles from Amphibians inferred from fossil record Synapsids

  10. 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.

  11. 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, environmental disruption appears to have been a major factor in shaping the fossil record. This does not mean that continuing adaptation was not important during this interval, but it may indicate that adaptive evolution was strongest in environments other than those best represented in the paleobotanical record.

  12. RESEARCH LETTERS 161 The Fossil Record of Cretaceous

    E-print Network

    Benton, Michael

    RESEARCH LETTERS 161 The Fossil Record of Cretaceous Tetrapods EMMANUEL FARA and MICHAEL J. BENTON­165 The fossil record of the Cretaceous is critical for under- standing the evolution of modern tetrapods. Using a mea- sure of relative completeness of the fossil record--the Sim- ple Completeness Metric (SCM

  13. The quality of the fossil record Michael J. Benton

    E-print Network

    Benton, Michael

    Chapter 4 The quality of the fossil record Michael J. Benton ABSTRACT Ever since the days of Charles Darwin, palaeontologists have been concerned about the quality of the fossil record. New concerns are often twice as old as the oldest fossils, and (2) the discovery that much of the variation in diversity

  14. Neoproterozoic glaciations and the fossil record

    NASA Astrophysics Data System (ADS)

    Xiao, Shuhai

    Sedimentary, geochronological, and ?13C chemostratigraphic data require that at least three glaciations—the Sturtian, Marinoan, and Gaskiers in geochronological order—occurred in the Neoproterozoic glacial interval (NGI; ca. 750-580 Ma); at least the Gaskiers glaciation has not been demonstrated global in nature. Available radiometric and ?13C chemostratigraphic data also suggest that the fossil-rich Doushantuo Formation may have been deposited after the Marinoan but before the Gaskiers glaciation, thus representing a window between two glaciations. A review of the fossil record under this geochronological framework reveals the following patterns: 1) a broad decline in stromatolites and acritarchs occurred in the Cryogenian (ca. 750-600 Ma); 2) a taxonomically unique assemblage of large acanthomorphic acritarchs occurs between the Marinoan and Gaskiers glaciations; 3) multicellular algae diversified after the Marinoan glaciation, although they evolved earlier; 4) animals, probably in microscopic forms, evolved before the Gaskiers glaciation if not earlier; and 5) post-Gaskiers diversification of complex Ediacaran organisms/animals may have begun in deep-water slope environments and later expanded to shallow-water shelf environments where macrobilaterians and biomineralized animals first appeared. It is hypothesized that 1) the Cryogenian decline in stromatolites and acritarchs may have been causally related to glaciations; and 2) acanthomorphic acritarchs, algae, and animals may have suffered diversity loss related to the Gaskiers glaciation. The fossil record also implies that 1) at least some lineages of different algal clades survived all Neoproterozoic glaciations; and 2) some members of the animal clade survived the Gaskiers glaciation, probably in non-glaciated refiigia.

  15. 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.

  16. 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.

  17. 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. PMID:18192192

  18. 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. PMID:19210587

  19. New fossils from the Paleogene of central Libya illuminate the evolutionary history of endemic African anomaluroid rodents

    NASA Astrophysics Data System (ADS)

    Coster, Pauline; Beard, K. Christopher; Salem, Mustafa; Chaimanee, Yaowalak; Jaeger, Jean-Jacques

    2015-10-01

    Anomaluroid rodents show interesting biogeographic and macroevolutionary patterns, although their fossil record is meager and knowledge of the natural history of extant members of the clade remains inadequate. Living anomaluroids (Anomaluridae) are confined to equatorial parts of western and central Africa, but the oldest known fossil anomaluroid (Pondaungimys) comes from the late middle Eocene of Myanmar. The first appearance of anomaluroids in the African fossil record coincides with the first appearances of hystricognathous rodents and anthropoid primates there. Both of the latter taxa are widely acknowledged to have originated in Asia, suggesting that anomaluroids may show a concordant biogeographic pattern. Here we describe two new taxa of African Paleogene anomaluroids from sites in the Sirt Basin of central Libya. These include a new Eocene species of the nementchamyid genus Kabirmys, which ranks among the oldest African anomaluroids recovered to date, and a new genus and species of Anomaluridae from the early Oligocene, which appears to be closely related to extant Zenkerella, the only living non-volant anomalurid. Phylogenetic analyses incorporating the new Libyan fossils suggest that anomaluroids are not specially related to Zegdoumyidae, which are the only African rodents known to antedate the first appearance of anomaluroids there. The evolution of gliding locomotion in Anomaluridae appears to conflict with traditional assessments of relationships among living anomalurid taxa. If the historically accepted division of Anomaluridae into Anomalurinae (extant and Miocene Anomalurus and Miocene Paranomalurus) and Zenkerellinae (extant and Miocene Zenkerella and extant Idiurus) is correct, then either gliding locomotion evolved independently in Anomalurinae and Idiurus or non-volant Zenkerella evolved from a gliding ancestor. Anatomical data related to gliding in Anomaluridae are more consistent with a nontraditional systematic arrangement, whereby non-volant Zenkerella is the sister group of a clade including both Anomalurus and Idiurus.

  20. 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)

  1. 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.

  2. 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)

  3. 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. PMID:24779547

  4. 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. PMID:21680420

  5. Evidence for GRB Induced Extinctions in the Fossil Record?

    NASA Astrophysics Data System (ADS)

    Kaye, Thomas G.

    2004-09-01

    Particular problems in the fossil record are placed in context with a GRB event causing death by radiation exposure, followed by comet showers from a disruption in the Oort Cloud. The absence of pollen below the iridium layer at the KT and Triassic-Jurassic boundaries, the pattern of extinction on land and in the oceans and divergence times of molecular DNA studies may all have a common root in ionizing radiation.

  6. 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.

  7. The fossil record of early tetrapods: Worker effort and the end-Permian mass extinction

    E-print Network

    Benton, Michael

    The fossil record of early tetrapods: Worker effort and the end-Permian mass extinction EMMA L.E., and Benton, M.J. 2010. The fossil record of early tetrapods: Worker effort and the end-Permian mass of the fossil record of early tetrapods (Tetrapoda, minus Lissamphibia and Amniota) because of their key role

  8. Testing the fossil record: Sampling proxies and scaling in the British TriassicJurassic

    E-print Network

    Benton, Michael

    Testing the fossil record: Sampling proxies and scaling in the British Triassic­Jurassic Alexander March 2014 Available online 30 March 2014 Keywords: Palaeodiversity Fossil record Sampling Proxy Triassic Jurassic The quality of the fossil record varies immensely across taxa, geographic regions

  9. 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.

  10. 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.

  11. 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. PMID:25788597

  12. 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

  13. Disentangling rock record bias and common-cause from redundancy in the British fossil record

    PubMed Central

    Dunhill, Alexander M.; Hannisdal, Bjarte; Benton, Michael J.

    2014-01-01

    The fossil record documents the history of life, but the reliability of that record has often been questioned. Spatiotemporal variability in sedimentary rock volume, sampling and research effort especially frustrates global-scale diversity reconstructions. Various proposals have been made to rectify palaeodiversity estimates using proxy measures for the availability and sampling of the rock record, but the validity of these approaches remains controversial. Targeting the rich fossil record of Great Britain as a highly detailed regional exemplar, our statistical analysis shows that marine outcrop area contains a signal useful for predicting changes in diversity, collections and formations, whereas terrestrial outcrop area contains a signal useful for predicting formations. In contrast, collection and formation counts are information redundant with fossil richness, characterized by symmetric, bidirectional information flow. If this is true, the widespread use of collection and formation counts as sampling proxies to correct the raw palaeodiversity data may be unwarranted. PMID:25187994

  14. THE NATURE OF THE FOSSIL RECORD 1.1 NATURE AND SCOPE

    E-print Network

    in sedimentary rocks,and so where we find fossils is largely a matter of where we find such rocks. Over 30 yearsTHE NATURE OF THE FOSSIL RECORD 1.1 NATURE AND SCOPE OF PALEONTOLOGY · Fossils are mainly found and the number of fossil species known from a given period of geologic time (Figure 1.1).This raises the obvious

  15. Studying Function and Behavior in the Fossil Record Michael J. Benton*

    E-print Network

    Benton, Michael

    1 Primer Studying Function and Behavior in the Fossil Record Michael J. Benton* Department of Earth and fossil vertebrates and that anatomy could be reconstructed with confidence from incomplete fossil remains-interpretation, perhaps assuming that everything is an adaptation and that adaptations are all perfect [2]. Fossils can

  16. Testing the marine and continental fossil records: Comment and Reply Stephen K. Donovan*

    E-print Network

    Benton, Michael

    Testing the marine and continental fossil records: Comment and Reply COMMENT Stephen K. Donovan, D.C. 20560 Benton and Simms (1995) have presented a fascinating com- parative analysis of the fossil (1995, p. 603) that ``the surprisingly good quality of the continental vertebrate fossil record may

  17. Estimating minimum global species diversity for groups with a poor fossil record: a case study of

    E-print Network

    Herrmann, Samuel

    Estimating minimum global species diversity for groups with a poor fossil record: a case study of the fossil record and the frequent absence of stable, comprehensive phylogenetic hypotheses. In particular, fossil specimens unidentifiable at lower taxonomic levels are frequently discarded from both kinds

  18. Mesozoic echinoid diversity in Portugal: Investigating fossil record quality and environmental constraints on a regional scale

    E-print Network

    Benton, Michael

    Mesozoic echinoid diversity in Portugal: Investigating fossil record quality and environmental Diversity Sampling proxies Fossil record Portugal Several analyses of diversity through geological time use diversity patterns retrieved from raw counts of fossils through time (e.g., Raup, 1972, 1976; Sepkoski et al

  19. 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. PMID:24396267

  20. 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

  1. 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.

  2. 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 investigation are presented.

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

    E-print Network

    Grotzinger, John P.

    LETTERS Fossil steroids record the appearance of Demospongiae during the Cryogenian period Gordon D and isotopic geochemistry marked by unusual abundances of methylalkanes, steroids and triterpenoids derived

  4. 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.

  5. LET US PREY: SIMULATIONS OF GRAZING TRACES IN THE FOSSIL RECORD

    E-print Network

    Plotnick, Roy E.

    LET US PREY: SIMULATIONS OF GRAZING TRACES IN THE FOSSIL RECORD Roy E. Plotnick and Karen Koy, IL, 60607 Tel. +1 312-996-2111, E-mail: plotnick@uic.edu, kkoy@uic.edu Abstract Trace fossils basic behavior. Changes in the occurrence of trace fossil types over time, in particular during

  6. 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 Maximum (PETM). North Atlantic land bridges (NALB) seem the most plausible route for migration of Bauhinia from Asia to America; and additional aspects of the Bauhinia species distribution are explained by migration and long distance dispersal (LDD) from Eurasia to the African and American continents. PMID:25288346

  7. A new fossil thryonomyid from the Late Miocene of the United Arab Emirates and the origin of African cane rats

    NASA Astrophysics Data System (ADS)

    Kraatz, Brian P.; Bibi, Faysal; Hill, Andrew; Beech, Mark

    2013-05-01

    Cane rats (Thryonomyidae) are represented today by two species inhabiting sub-Saharan Africa. Their fossil record is predominately African, but includes several Miocene species from Arabia and continental Asia that represent dispersal events from Africa. For example, Paraulacodus indicus, known from the Miocene of Pakistan, is closely related to living Thryonomys. Here we describe a new thryonomyid, Protohummus dango, gen. et sp. nov., from the late Miocene Baynunah Formation of the United Arab Emirates. The new thryonomyid is less derived than " Thryonomys" asakomae from the latest Miocene of Ethiopia and clarifies the origin of crown Thryonomys and the evolutionary transition from Paraulacodus. A phylogenetic analysis shows Protohummus dango to be morphologically intermediate between Paraulacodus spp. and extinct and living Thryonomys spp. The morphological grade and phylogenetic position of Protohummus dango further supports previous biochronological estimates of the age of the Baynunah Formation (ca. 6-8 Ma).

  8. Testing Hypotheses About Tinkering in the Fossil Record: the Case of the Human Skull

    E-print Network

    Lieberman, Daniel E.

    -Liss, Inc. Paleontologists (e.g., Gould, '77) have long sought answers to questions about the developTesting Hypotheses About Tinkering in the Fossil Record: the Case of the Human Skull DANIEL E only be observed in the fossil record pose many challenges. Here we use the origin of modern human

  9. Testing homogeneity with the fossil record of galaxies

    E-print Network

    Alan F. Heavens; Raul Jimenez; Roy Maartens

    2011-09-15

    The standard Friedmann model of cosmology is based on the Copernican Principle, i.e. the assumption of a homogeneous background on which structure forms via perturbations. Homogeneity underpins both general relativistic and modified gravity models and is central to the way in which we interpret observations of the CMB and the galaxy distribution. It is therefore important to probe homogeneity via observations. We describe a test based on the fossil record of distant galaxies: if we can reconstruct key intrinsic properties of galaxies as functions of proper time along their worldlines, we can compare such properties at the same proper time for our galaxy and others. We achieve this by computing the lookback time using radial Baryon Acoustic Oscillations, and the time along galaxy world line using stellar physics, allowing us to probe homogeneity, in principle anywhere inside the past light cone. Agreement in the results would be an important consistency test -- although it would not in itself prove homogeneity. Any significant deviation in the results however would signal a breakdown of homogeneity.

  10. 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".

  11. Finding the tree of life: matching phylogenetic trees to the fossil record through the 20th century

    E-print Network

    Benton, Michael

    Finding the tree of life: matching phylogenetic trees to the fossil record through the 20th century in their performance. Keywords: cladistics; phylogeny; fossil record; stratigraphy; tree 1. INTRODUCTION Systematics

  12. Fossil hominin shoulders support an African ape-like last common ancestor of humans and chimpanzees.

    PubMed

    Young, Nathan M; Capellini, Terence D; Roach, Neil T; Alemseged, Zeresenay

    2015-09-22

    Reconstructing the behavioral shifts that drove hominin evolution requires knowledge of the timing, magnitude, and direction of anatomical changes over the past ?6-7 million years. These reconstructions depend on assumptions regarding the morphotype of the Homo-Pan last common ancestor (LCA). However, there is little consensus for the LCA, with proposed models ranging from African ape to orangutan or generalized Miocene ape-like. The ancestral state of the shoulder is of particular interest because it is functionally associated with important behavioral shifts in hominins, such as reduced arboreality, high-speed throwing, and tool use. However, previous morphometric analyses of both living and fossil taxa have yielded contradictory results. Here, we generated a 3D morphospace of ape and human scapular shape to plot evolutionary trajectories, predict ancestral morphologies, and directly test alternative evolutionary hypotheses using the hominin fossil evidence. We show that the most parsimonious model for the evolution of hominin shoulder shape starts with an African ape-like ancestral state. We propose that the shoulder evolved gradually along a single morphocline, achieving modern human-like configuration and function within the genus Homo. These data are consistent with a slow, progressive loss of arboreality and increased tool use throughout human evolution. PMID:26351685

  13. Evolutionary Innovations in the Fossil Record: The Intersection of Ecology, Development,

    E-print Network

    Evolutionary Innovations in the Fossil Record: The Intersection of Ecology, Development 60637 ABSTRACT The origins of evolutionary innovations have been intensively studied, but relatively appearances tend to conform to their clade-specific bathymetric diversity gradients. This discordance seems

  14. A field-based analysis of the accuracy of niche models applied to the fossil record

    E-print Network

    Walls, Bradley J.; Stigall, Alycia L.

    2012-04-11

    of ENM methods for Paleozoic brachiopod species. This study represents the first field validation analysis of ENM methods in the fossil record. Previously published species distributions models for 8 Late Ordovician brachiopod species from the Cincinnati...

  15. '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 guidebooks. The requirements for a web platform could be met by the use of the freely-available Indicia software developed by the UK Centre for Ecology and Hydrology for biodiversity recording. However, some trials with the software have found it would be suitable for recording fossil occurrences as well. The software allows users to plot collections on maps, upload and share photographs and make identifications of material. Within the UK, the British Geological Survey has made geological map data available via the iGeology smartphone app and the Geology of Britain website. Thus it is now possible for people with access to smartphones or the internet to know which geological units they are sampling from, which would previously have been difficult without access to paper copies of geological maps. Such a programme could make a significant contribution towards reviving palaeontology and geology as field-based natural history and create wider interest in basic geological and taxonomic skills and form the basis for work on geodiversity recording and exploring links between geodiversity and biodiversity.

  16. Evolutionary diversification of reef corals: a comparison of the molecular and fossil records.

    PubMed

    Simpson, Carl; Kiessling, Wolfgang; Mewis, Heike; Baron-Szabo, Rosemarie C; Müller, Johannes

    2011-11-01

    Understanding historical patterns of diversity dynamics is of paramount importance for many evolutionary questions. The fossil record has long been the only source of information on patterns of diversification, but the molecular record, derived from time-calibrated phylogenies, is becoming an important additional resource. Both fossil and molecular approaches have shortcomings and biases. These have been well studied for fossil data but much less so for molecular data and empirical comparisons between approaches are lacking. Here, we compare the patterns of diversification derived from fossil and molecular data in scleractinian reef coral species. We also assess the robustness of molecular diversification rates to poor taxon sampling. We find that the temporal pattern of molecular diversification rates is robust to incomplete sampling when rates are calculated per interval. The major obstacle of molecular methods is that rate estimates are distorted because diversification rates can never be negative, whereas the fossil record suffers from incomplete preservation and inconsistent taxonomy. Nevertheless, the molecular pattern of diversification is comparable to the pattern we observe in the fossil record, with the timing of major diversification pulses coinciding in each dataset. For example, both agree that the end-Triassic coral extinction was a catastrophic bottleneck in scleractinian evolution. PMID:22023591

  17. 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)

  18. The application of new signal analysis techniques provides increased insight into the study of the fossil record and processes of evo-

    E-print Network

    Patterson, Timothy

    into the study of the fossil record and processes of evo- lution. The fossil record of 622 planktic foraminifera transform) of the planktic foraminifera fossil record were used to discern periodic components in long behavior of the fossil record. The analyses show that stationary ~30 m.y. periodicity and complex

  19. The ``African humid period'' and the record of marine upwelling from excess 230

    E-print Network

    deMenocal, Peter B.

    The ``African humid period'' and the record of marine upwelling from excess 230 Th in Ocean end to the ``African humid period'' and a return to stronger upwelling conditions. For carbonate: Adkins, J., P. deMenocal, and G. Eshel (2006), The ``African humid period'' and the record of marine

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

    PubMed Central

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

    2015-01-01

    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. PMID:25520359

  1. 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 together to describe the relationship between time trees and a set of fossil data, which we recommend be phylogenetically vetted and referred on the basis of apomorphy. Differences from previously proposed metrics and the utility of MDI and DIG range are illustrated in three empirical case studies from angiosperms, ostracods, and birds. These case studies also illustrate the ways in which MDI and DIG range may be used to assess time trees resultant from analyses varying in calibration regime, divergence dating approach or molecular sequence data analyzed. PMID:25281846

  2. 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.

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

    PubMed

    Skawi?ski, Tomasz; Ta?anda, 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. PMID:26154335

  4. In the absence of shells or bones, the fossil record of animals can fade away to localized

    E-print Network

    Brocks, Jochen J.

    In the absence of shells or bones, the fossil record of animals can fade away to localized snapshots, such as the remarkable diversity of early animal-like fossils in the Doushantuo biotaofsouthern of fossil biomarkers -- geologically robust and taxonomically distinctive hydrocarbon molecules, derived

  5. The dawn of animal life: Evolutionary and palaeoecological patterns in the Neoproterozoic-Cambrian animal fossil record

    E-print Network

    Dornbos, Stephen Q.

    -Cambrian animal fossil record 1. Introduction The Neoproterozoic­Cambrian radiation of complex animals is arguably span this radiation, from controversial worm-like fossils preserved in early Neoproterozoic rocks skeletonized forms in the Cambrian, focusing on some of the world's most spectacular and well-known fossil

  6. Error in Estimation of Rate and Time Inferred from the Early Amniote Fossil Record and Avian Molecular Clocks

    E-print Network

    Hadly, Elizabeth

    Error in Estimation of Rate and Time Inferred from the Early Amniote Fossil Record and Avian estimates and fossil data. Errors in molecular rate estimation typically are unaccounted for and no attempts have been made to quantify this uncertainty comprehensively. Here, fo- cus is primarily on fossil

  7. Assessing the quality of the fossil record: insights from vertebrates MICHAEL J. BENTON1*, ALEXANDER M. DUNHILL1, GRAEME T. LLOYD2 &

    E-print Network

    Benton, Michael

    Assessing the quality of the fossil record: insights from vertebrates MICHAEL J. BENTON1 the quality of the fossil record is notoriously hard, and many recent attempts have used sampling proxies that depend on rock heterogeneity and fossil content (and so are not independent of the fossil record

  8. 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.

  9. Fossil earthquakes recorded by pseudotachylytes in mantle peridotite from the Alpine subduction complex of Corsica

    E-print Network

    Andersen, Torgeir Bjørge

    Fossil earthquakes recorded by pseudotachylytes in mantle peridotite from the Alpine subduction peridotite belonging to the Schistes Lustre´s of Cape Corse. Ultramafic pseudotachylyte fault- and injection veins are found within well-preserved peridotite lenses and are progressively hydrated together

  10. Patterns of biodiversity in the fossil record M. E. J. Newman and G. J. Eble

    E-print Network

    Newman, Mark

    Patterns of biodiversity in the fossil record M. E. J. Newman and G. J. Eble Santa Fe Institute a substantial increase in biodiversity interrupted by a number of extinction events which caused sharp but rela- tively brief dips in biodiversity. Modern-day biodiversity is close to the highest it has ever been

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

    E-print Network

    Assessing the fidelity of the fossil record by using marine bivalves James W. Valentine* , David, with bivalve and gastropod mollusks as dominant components. The living marine Bivalvia are particularly well for evolutionary and macroecological studies (3, 4). Nevertheless, 24% of the 1,292 living marine bivalve genera

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

    E-print Network

    Royer, Dana

    Fossil bryophytes as recorders of ancient CO2 levels: Experimental evidence and a Cretaceous case laboratory experiments, we show that the carbon isotope discrimination (D13 C) of a range of bryophyte bryophyte D13 C (White et al., 1994) is extended and calibrated using our experimental results

  13. Calibration and error in placental molecular clocks: a conservative approach using the cetartiodactyl fossil record.

    PubMed

    van Tuinen, M; Hadly, E A

    2004-01-01

    The nature of the molecular and fossil record and their limitations must be ascertained in order to gain the most precise and accurate evolutionary timescale using genetic information. Yet the majority of such timescales are based on point estimates using fossils or the molecular clock. Here we document from the primary literature minimum and maximum fossil age estimates of the divergence of whales from artiodactyls, a commonly used anchor point for calibrating both mitogenomic and nucleogenomic placental timescales. We applied these reestimates to the most recently established placental timescale based on mitochondrial rRNA and several nuclear loci, and present an attempt to account for both genetic and fossil uncertainty. Our results indicate that disregard for fossil calibration error may inflate the power of the molecular clock when testing the time of ordinal diversification in context with the K-T boundary. However, the early history of placentals, including their superordinal diversification, remained in the Cretaceous despite a conservative approach. Our conclusions need corroboration across other frequently used fossil anchor points, but also with more genetic partitions on the linear relationship between molecular substitutions and geologic time. PMID:15220386

  14. 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. PMID:26257156

  15. †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

  16. 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

  17. 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 have not yet been sampled or are difficult to identify because of the fragmentary nature of the specimens. PMID:22761723

  18. 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.

  19. 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.

  20. 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. PMID:26554038

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. Testing the marine and continental fossil records M. J. Benton Department of Geology, University of Bristol, Bristol BS8 1RJ, United Kingdom

    E-print Network

    Benton, Michael

    Testing the marine and continental fossil records M. J. Benton Department of Geology, University The fossil record of continental vertebrates is as good as that of echinoderms at the family level, as shown and vertebrates are typical of their environments, the continental fossil record is not worse than the marine

  6. 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

  7. 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.

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

    PubMed Central

    Sánchez-Villagra, Marcelo R.

    2010-01-01

    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. PMID:20071389

  9. 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.

  10. 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

  11. 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.

  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

    2009-02-01

    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). PMID:19194449

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

    PubMed

    Benton, M J

    1989-11-01

    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. PMID:2574883

  14. Distinguishing between sudden and gradual extinctions in the fossil record: Predicting the position of the Cretaceous-Tertiary iridium anomaly using the ammonite fossil record on Seymour Island, Antarctica

    NASA Astrophysics Data System (ADS)

    Marshall, Charles R.

    1995-08-01

    A simple method, employing 50% confidence intervals, may be used to distinguish sudden from gradual extinctions. In cases where the fossil record is consistent with a sudden disappearance, the expected position of the extinction horizon may als o be determined. Analysis of the fossil ammonites on Seymour Island shows that their pattern of disappearances is consistent with a sudden mass extinction at the Cretaceous-Tertiary (K-T) boundary, even though a literal reading of the fossil record shows they disappeared gradually over a stratigraphic interval 10 50 m below the boundary. It is striking that the iridium anomaly on Seymour Island falls within the stratigraphic interval determined by the 50% confidence intervals to be the most likely place for the K-T boundary (assuming there was a sudden disappearance of ammonites at the boundary). However, a computer simulation of the Seymour Island ammonite fossil record indicates a wide range of other extinction scenarios, including gradual extinctions ranging over as much as 20 m (? = 0.05), that are consistent with the ammonite fossil record; without saturation collecting near the K-T boundary it will be impossible to distinguish between gradual and sudden extinction scenarios for the Seymour Island ammonites based on the ammonite fossil record alone.

  15. Sensitivity of cool-temperate forests and their fossil pollen record to rapid temperature change

    NASA Astrophysics Data System (ADS)

    Davis, Margaret Bryan; Botkin, Daniel B.

    1985-05-01

    Simulations of cool-temperate forest growth in response to climatic change using the JABOWA computer model show that a decrease of 600 growing degree-days (equivalent to a 2°C decrease in mean annual temperature) causes red spruce ( Picea rubens) to replace sugar maple ( Acer saccharum) as the dominant tree. These changes are delayed 100-200 yr after the climatic cooling, producing gradual forest changes in response to abrupt temperature changes, and reducing the amplitude of response to brief climatic events. Soils and disturbances affect the speed and magnitude of forest response. The delayed responses are caused by the difference in sensitivity of adult trees and younger stages. The length of the delay depends on the life history characteristics of the dominant species. Delayed responses imply that fossil pollen deposits, even if they faithfully record the abundances of trees in forests, may not be able to resolve climatic changes within 100-200 yr, or to record very brief climatic events. This explains why pollen deposits do not as yet show responses to climatic changes during the past 100 yr. Only the Little Ice Age, which lasted several centuries, caused sufficient forest change to be recorded in fossil pollen, and only at certain sites.

  16. Late Pleistocene Nannofossil Assemblages and Time-Averaging in the Fossil Record [IODP Site U1419] 

    E-print Network

    Patrick, Amanda Kacy

    2014-09-21

    stream_source_info PATRICK-THESIS-2015.pdf.txt stream_content_type text/plain stream_size 28140 Content-Encoding UTF-8 stream_name PATRICK-THESIS-2015.pdf.txt Content-Type text/plain; charset=UTF-8 LATE... PLEISTOCENE NANNOFOSSIL ASSEMBLAGES AND TIME- AVERAGING IN THE FOSSIL RECORD [IODP SITE U1419] An Undergraduate Research Scholars Thesis by AMANDA KACY PATRICK Submitted to Honors and Undergraduate Research Texas A&M University in partial...

  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(?47), should closely mirror latitudinal gradients in ground temperature. Excluding results from a mummified specimen yielding T(?47) = 38 °C (that is, indistinguishable from mammalian body temperature), we find that T(?47) 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(?47). No clear correlation exists between T(?47) 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(?47) does not closely conform to maximum burial temperature, again suggesting partial recrystallization, or recrystallization during different stages of the burial and exhumation circuit. These results show that carbon, oxygen, and ‘clumped’ isotopes in fossil bone are capable of recording aspects of early diagenesis and the subsequent burial and exhumation history, but that distinguishing among different effects is challenging. However, clumped isotopes in bone can provide useful directional constraints on past temperatures. For example, T(?47) values higher than body temperature necessarily place lower limits on maximum burial temperatures, and those lower than body temperature place upper limits on minimum fossilization temperatures.

  18. 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 (?) 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

  19. 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. PMID:19730686

  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. PMID:24482295

  1. 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. PMID:25901315

  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. 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. PMID:26176667

  4. 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

  5. Stable isotope-based Plio-Pleistocene ecosystem reconstruction of some of the earliest hominid fossil sites in the East African Rift System (Chiwondo Beds, N Malawi)

    NASA Astrophysics Data System (ADS)

    Lüdecke, Tina; Thiemeyer, Heinrich; Schrenk, Friedemann; Mulch, Andreas

    2014-05-01

    The isotope geochemistry of pedogenic carbonate and fossil herbivore enamel is a powerful tool to reconstruct paleoenvironmental conditions in particular when climate change plays a key role in the evolution of ecosystems. Here, we present the first Plio-Pleistocene long-term carbon (?13C), oxygen (?18O) and clumped isotope (?47) records from pedogenic carbonate and herbivore teeth in the Malawi Rift. These data represent an important southern hemisphere record in the East African Rift System (EARS), a key region for reconstructing vegetation patterns in today's Zambezian Savanna and correlation with data on the evolution and migration of early hominids across the Inter-Tropical Convergence Zone. As our study site is situated between the well-known hominid-bearing sites of eastern and southern Africa in the Somali-Masai Endemic Zone and Highveld Grassland it fills an important geographical gap for early hominid research. 5.0 to 0.6 Ma fluviatile and lacustrine deposits of the Chiwondo Beds (NE shore of Lake Malawi) comprise abundant pedogenic carbonate and remains of a diverse fauna dominated by large terrestrial mammals. These sediments are also home to two hominid fossil remains, a mandible of Homo rudolfensis and a maxillary fragment of Paranthropus boisei, both dated around 2.4 Ma. The Chiwondo Beds therefore document early co-existence of these two species. We evaluate ?13C data from fossil enamel of different suid, bovid, and equid species and contrast these with ?13C and ?18O values of pedogenic carbonate. We complement the latter with clumped isotope soil temperature data. Results of almost 800 pedogenic carbonate samples from over 20 sections consistently average ?13C = -8.5 ‰ over the past 5 Ma with no significant short-term ?13C excursions or long-term trends. The data from molar tooth enamel of nine individual suids of the genera Metridiochoerus, Notochoerus and Nyanzachoerus support these findings with average ?13C = -10.0 ‰. The absence of long-term trends towards more positive ?13C values contrasts the increasing role of C4-grasslands in the southern EARS which is well documented for sites in Ethiopia, Kenya and Tanzania. Our data hence point to regional differences in climate and vegetation dynamics during the Plio-Pleistocene in the EARS and documents persistence of paleoenvironmental conditions in the southern branch of the EARS at times of early hominid evolution.

  6. Calcification and Silicification: Fossilization Potential of Cyanobacteria from Stromatolites of Niuafo‘ou's Caldera Lakes (Tonga) and Implications for the Early Fossil Record

    PubMed Central

    Kazmierczak, Józef; ?ukomska-Kowalczyk, Maja; Kempe, Stephan

    2012-01-01

    Abstract 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. Key Words: Stromatolites—Cyanobacteria—Calcification—Silicification—Niuafo‘ou (Tonga)—Archean. Astrobiology 12, 535–548. PMID:22794297

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

    PubMed

    Retallack, G J

    2001-05-17

    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 544 Myr), 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 300 Myr, only two intervals of low CO2 (<1,000 p.p.m.v.) are inferred, both of which coincide with known ice ages in Neogene (1-8 Myr) and early Permian (275-290 Myr) times. But for most of the Mesozoic era (65-250 Myr), CO2 levels were high (1,000-2,000 p.p.m.v.), with transient excursions to even higher CO2 (>2,000 p.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 300 Myr. PMID:11357126

  8. 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.

  9. Stable isotopes in East African precipitation record Indian Ocean zonal M. Vuille,1

    E-print Network

    Vuille, Mathias

    Stable isotopes in East African precipitation record Indian Ocean zonal mode M. Vuille,1 M. Werner ocean-atmosphere system over the Indian Ocean. During the rainy seasons d18 O is a very sensitive recorder of the Indian Ocean Zonal Mode (IOZM). The link between d18 O and the IOZM is established through

  10. Live coral cover in the fossil record: an example from Holocene reefs of the Dominican Republic

    NASA Astrophysics Data System (ADS)

    Lescinsky, H.; Titus, B.; Hubbard, D.

    2012-06-01

    Fossil reefs hold important ecological information that can provide a prehuman baseline for understanding recent anthropogenic changes in reefs systems. The most widely used proxy for reef "health," however, is live coral cover, and this has not been quantified in the fossil record because it is difficult to establish that even adjacent corals were alive at the same time. This study uses microboring and taphonomic proxies to differentiate between live and dead corals along well-defined time surfaces in Holocene reefs of the Enriquillo Valley, Dominican Republic. At Cañada Honda, live coral cover ranged from 59 to 80% along a contemporaneous surface buried by a storm layer, and the reef, as a whole had 33-80% live cover within the branching, mixed, massive and platy zones. These values equal or exceed those in the Dominican Republic and Caribbean today or reported decades ago. The values from the western Dominican Republic provide a geologic baseline against which modern anthropogenic changes in Caribbean reefs can be considered.

  11. 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

    The enhanced preservation potential of biomineralised tissues in fossil organisms is a key factor in their utility in the investigation of palaeoenvironmental change on fossil ecosystems. By contrast, the considerably lower preservation potential of entirely unmineralised organisms severely reduces the utility of their temporal and spatial distribution in such analyses. However, understanding the taphonomic processes which lead to the preservation of such soft-bodied fossils may be an under-appreciated source of information, particularly in the case of specimens preserved as moulds and casts in coarser siliciclastic sediments. This information potential is well demonstrated by fossil eldonids, a Cambrian to Devonian clade of unmineralised asymmetrical discoidal basal or stem deuterostomes, with an apparently conservative biology and no clear palaeoenvironmental or biogeographical controls on their distribution. We investigated the taphonomic processes involved in the preservation of fossil eldonids as moulds and casts on bedding surfaces and within event beds from sandstones of the Ordovician Tafilalt lagerstätte in south-eastern Morocco, and from siltstones of the Devonian West Falls Group of New York, USA. Laser Raman microspectroscopy, SEM BSE imaging and EDS elemental mapping of fossil specimens reveals that moulded biological surfaces are coated by a fossil surface veneer primarily consisting of mixed iron oxides and oxyhydroxides (including pseudomorphs after pyrite), and aluminosilicate clay minerals. Moreover, comparison to fossil eldonids preserved as carbonaceous compressions in the Burgess Shale reveals that the biological structures preserved in the Tafilalt and New York specimens - the dorsal surface and a coiled sac containing the digestive tract - represent only specific portions of the anatomy of the complete animal. We suggest that the preserved remains were the only parts of these eldonid organisms composed primarily of complex organic 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.

  12. A fossil record full of holes: The Phanerozoic history of drilling predation

    NASA Astrophysics Data System (ADS)

    Kowalewski, Michal; Dulai, Alfréd; Fürsich, Franz T.

    1998-12-01

    The evolutionary history of drilling predation, despite a long and rich fossil record (Precambrian Holocene), contains a 120 m.y. gap (Late Triassic Early Cretaceous). Drilled bivalve and brachiopod shells from Jurassic deposits of Hungary, India, and four localities documented in the literature indicate that drillers may have existed continuously throughout the Mesozoic. They may have been descendants of Paleozoic predators, unknown Mesozoic carnivores, or precursors of modern drillers. A literature database suggests three major phases in the Phanerozoic history of drilling predators: (1) the Paleozoic phase (latest Precambrian Carboniferous) dominated by rare to moderately frequent drillings in brachiopods and sessile echinoderms; (2) the Mesozoic phase (Permian Early Cretaceous) with very rare, or even facultative, drillers that had little impact on marine benthic communities, but nevertheless may have been present continuously; and (3) the Cenozoic phase (Late Cretaceous Holocene) dominated by frequent gastropod drillings in mollusks.

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

    PubMed

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

    2012-08-01

    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

  14. 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.

  15. 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.

  16. GEOL 204 Dinosaurs, Early Humans, Ancestors & Evolution: The Fossil Record of Vanished Worlds of the Prehistoric Past

    E-print Network

    Holtz Jr., Thomas R.

    1 GEOL 204 Dinosaurs, Early Humans, Ancestors & Evolution: The Fossil Record of Vanished Worlds on dinosaur paleontology! Please note that there are many words in the title of this course after "Dinosaurs dinosaurs, try my Fall semester class GEOL 104 Dinosaurs: A Natural History. (Don't worry, though: we do

  17. 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)

  18. 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.

  19. 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 phylogeographic and paleoenvironmental hypotheses inferred from a tree containing only extant taxa can be problematic without consideration of the fossil record. Incorporating the fossil record of Ruminantia is a necessary step for future analyses aiming to reconstruct the evolutionary history of this clade. PMID:23927069

  20. Modelling African aerosol using updated fossil fuel and biofuel emission inventories for 2005 and 2030

    NASA Astrophysics Data System (ADS)

    Liousse, C.; Penner, J. E.; Assamoi, E.; Xu, L.; Criqui, P.; Mima, S.; Guillaume, B.; Rosset, R.

    2010-12-01

    A regional fossil fuel and biofuel emission inventory for particulates has been developed for Africa at a resolution of 0.25° x 0.25° for the year 2005. The original database of Junker and Liousse (2008) was used after modification for updated regional fuel consumption and emission factors. Consumption data were corrected after direct inquiries conducted in Africa, including a new emitter category (i.e. two-wheel vehicles including “zemidjans”) and a new activity sector (i.e. power plants) since both were not considered in the previous emission inventory. Emission factors were measured during the 2005 AMMA campaign (Assamoi and Liousse, 2010) and combustion chamber experiments. Two prospective inventories for 2030 are derived based on this new regional inventory and two energy consumption forecasts by the Prospective Outlook on Long-term Energy Systems (POLES) model (Criqui, 2001). The first is a reference scenario, where no emission controls beyond those achieved in 2003 are taken into account, and the second is for a "clean" scenario where possible and planned policies for emission control are assumed to be effective. BC and OCp emission budgets for these new inventories will be discussed and compared to the previous global dataset. These new inventories along with the most recent open biomass burning inventory (Liousse et al., 2010) have been tested in the ORISAM-TM5 global chemistry-climate model with a focus over Africa at a 1° x 1° resolution. Global simulations for BC and primary OC for the years 2005 and 2030 are carried out and the modelled particulate concentrations for 2005 are compared to available measurements in Africa. Finally, BC and OC radiative properties (aerosol optical depths and single scattering albedo) are calculated and the direct radiative forcing is estimated using an off line model (Wang and Penner, 2009). Results of sensitivity tests driven with different emission scenarios will be presented.

  1. Fossil spiders.

    PubMed

    Selden, Paul A; Penney, David

    2010-02-01

    Over the last three decades, the fossil record of spiders has increased from being previously biased towards Tertiary ambers and a few dubious earlier records, to one which reveals a much greater diversity in the Mesozoic, with many of the modern families present in that era, and with clearer evidence of the evolutionary history of the group. We here record the history of palaeoarachnology and the major breakthroughs which form the basis of studies on fossil spiders. Understanding the preservation and taphonomic history of spider fossils is crucial to interpretation of fossil spider morphology. We also review the more recent descriptions of fossil spiders and the effect these discoveries have had on the phylogenetic tree of spiders. We discuss some features of the evolutionary history of spiders and present ideas for future work. PMID:19961468

  2. Extending the African instrumental record to the early 19th century

    SciTech Connect

    Nicholson, S.E.

    1997-11-01

    This paper describes progress toward the production of a data set that extends the African climate record back to the beginning of the 19th century. Qualitative documentary evidence, lake-level fluctuations and other proxy indicators are combined with historical rainfall records to produce regional time series. The data set has relatively high temporal and spatial resolution. The conceptualization is based on a climatic regionalization produced using modern data and an anomaly method in previous historical reconstructions. The data set provides information for some 100 regions with a 1 to 5 year resolution for most of the nineteenth century. Three to five quantitative classes of rainfall are utilized in the data set. Here, the available information to produce this record is summarized. The methodology utilized to combine proxy data and observations to produce a quantitative rainfall data set is described. This historical data set is compared with actual rainfall records for select regions where both are available. This comparison indicates the reliability of the proxy African data set. An analysis of the historical record indicates that the main characteristics of rainfall variability evident in the modern African record are also apparent in the 19th century record. 5 figs.

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

    PubMed Central

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

    2012-01-01

    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. PMID:22718955

  4. 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. PMID:25039238

  5. 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 (?13C) of astomatous land plants. In a series of CO2-controlled laboratory experiments, we show that the carbon isotope discrimination (?13C) 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 ?13C 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 ?13C (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 ?13C 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.

  6. 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 reveal that microbial assemblages identified from environmental DNA stemmed from a variety of sedimentary niches associated with climate-dependent factors (catchment inflows, water column conditions, productivity), but that initial assemblages underwent structural changes and selective preservation during early diagenesis to result in the final composition entombed in the sediments. We conclude that environmental DNA obtained from lacustrine sediments provides essential genetic information to complement paleoenvironmental indicators and trace climate change and post-depositional diagenetic processes over tens of millennia.

  7. A long-term association between global temperature and biodiversity, origination and extinction in the fossil record.

    PubMed

    Mayhew, Peter J; Jenkins, Gareth B; Benton, Timothy G

    2008-01-01

    The past relationship between global temperature and levels of biological diversity is of increasing concern due to anthropogenic climate warming. However, no consistent link between these variables has yet been demonstrated. We analysed the fossil record for the last 520 Myr against estimates of low latitude sea surface temperature for the same period. We found that global biodiversity (the richness of families and genera) is related to temperature and has been relatively low during warm 'greenhouse' phases, while during the same phases extinction and origination rates of taxonomic lineages have been relatively high. These findings are consistent for terrestrial and marine environments and are robust to a number of alternative assumptions and potential biases. Our results provide the first clear evidence that global climate may explain substantial variation in the fossil record in a simple and consistent manner. Our findings may have implications for extinction and biodiversity change under future climate warming. PMID:17956842

  8. Evolutionary innovations in the fossil record: the intersection of ecology, development, and macroevolution.

    PubMed

    Jablonski, David

    2005-11-15

    The origins of evolutionary innovations have been intensively studied, but relatively little is known about their large-scale ecological patterns. For post-Paleozoic benthic marine invertebrates, which have the richest and most densely sampled fossil record, order-level taxa tend to appear first in onshore, disturbed habitats, even in groups that are now exclusively deep-water (so that present-day distributions are not reliable indicators of original environments). New results presented here show that the onshore-origination pattern is robust to shifts in taxonomic methods and to new paleontological discoveries, and the few available studies suggest that this pattern can also be seen in terms of excursions in morphospace or the acquisition of derived character states, without reference to taxonomic categories. The environmental pattern at high levels contrasts significantly with the origin of low-level novelties (such as defined genera and families) in crinoids, echinoids, and bryozoans, where first appearances tend to conform to their clade-specific bathymetric diversity gradients. This discordance seems to eliminate potential driving mechanisms that simply scale up within-population genetic or ecological processes. Little is known about the factors that promote the onshore-offshore expansion of orders across the continental shelf, or that drive some clades to abandon ancestral habitats for an exclusively deep-water distribution. The origin of evolutionary innovation must ultimately reside in developmental changes, but the onshore-origination bias could emerge from two different dynamics: the pattern could be primarily genetic and developmental, i.e., innovations truly arise onshore; or primarily ecological, i.e., innovations arise randomly but preferentially survive onshore. Whatever the ultimate driving mechanisms, these macroevolutionary patterns show that theories of large-scale evolutionary novelty must include an ecological dimension. PMID:16161067

  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. PMID:26553062

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

    PubMed Central

    HYŽNÝ, MATÚŠ; GAŠPARI?, 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. The Olorgesailie Drilling Project (ODP): a high-resolution drill core record from a hominin site in the East African Rift Valley

    NASA Astrophysics Data System (ADS)

    Dommain, R.; Potts, R.; Behrensmeyer, A. K.; Deino, A. L.

    2014-12-01

    The East African rift valley contains an outstanding record of hominin fossils that document human evolution over the Plio-Pleistocene when the global and regional climate and the rift valley itself changed markedly. The sediments of fossil localities typically provide, however, only short time windows into past climatic and environmental conditions. Continuous, long-term terrestrial records are now becoming available through core drilling to help elucidate the paleoenvironmental context of human evolution. Here we present a 500,000 year long high-resolution drill core record obtained from a key fossil and archeological site - the Olorgesailie Basin in the southern Kenya Rift Valley, well known for its sequence of archeological and faunal sites for the past 1.2 million years. In 2012 two drill cores (54 and 166 m long) were collected in the Koora Plain just south of Mt. Olorgesailie as part of the Olorgesailie Drilling Project (ODP) to establish a detailed climate and ecological record associated with the last evidence of Homo erectus in Africa, the oldest transition of Acheulean to Middle Stone Age technology, and large mammal species turnover, all of which are documented in the Olorgesailie excavations. The cores were sampled at the National Lacustrine Core Facility. More than 140 samples of tephra and trachytic basement lavas have led to high-precision 40Ar/39Ar dating. The cores are being analyzed for a suite of paleoclimatic and paleoecological proxies such as diatoms, pollen, fungal spores, phytoliths, ostracodes, carbonate isotopes, leaf wax biomarkers, charcoal, and clay mineralogy. Sedimentological analyses, including lithological descriptions, microscopic smear slide analysis (242 samples), and grain-size analysis, reveal a highly variable sedimentary sequence of deep lake phases with laminated sediments, diatomites, shallow lake and near shore phases, fluvial deposits, paleosols, interspersed carbonate layers, and abundant volcanic ash deposits. Magnetic susceptibility indicates climatic variation potentially related to precessional cycles.

  12. 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.

  13. A Fish Assemblage from the Middle Eocene from Libya (Dur At-Talah) and the Earliest Record of Modern African Fish Genera

    PubMed Central

    Otero, Olga; Pinton, Aurélie; Cappetta, Henri; Adnet, Sylvain; Valentin, Xavier; Salem, Mustapha; Jaeger, Jean-Jacques

    2015-01-01

    In the early nineteen sixties, Arambourg and Magnier found some freshwater fish (i.e., Polypterus sp., Siluriformes indet. and Lates sp.) mixed with marine members in an Eocene vertebrate assemblage at Gebel Coquin, in the southern Libyan Desert. This locality, aged ca 37–39Ma and now known under the name of Dur At-Talah, has been recently excavated. A new fish assemblage, mostly composed of teeth, was collected by the Mission Paléontologique Franco-Libyenne. In this paper, we describe freshwater fish members including a dipnoan (Protopterus sp.), and several actinopterygians: bichir (Polypterus sp.), aba fish (Gymnarchus sp.), several catfishes (Chrysichthys sp. and a mochokid indet.), several characiforms (including the tiger fish Hydrocynus sp., and one or two alestin-like fish), and perciforms (including the snake-head fish Parachanna sp. and at least one cichlid). Together with the fossiliferous outcrops at Birket Qarun in Egypt, the Libyan site at Dur At-Talah reduces a 10-Ma chronological gap in the fossil record of African freshwater fish. Their fish assemblages overlap in their composition and thus constitute a rather homogenous, original and significant amount of new elements regarding the Paleogene African ichthyofauna. This supports the establishment of the modern African freshwater fish fauna during this time period because these sites mostly contain the earliest members known in modern genera. PMID:26674637

  14. 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 Phoenicopteriformes evolutionary lineage. Our results demonstrate that the nesting paleoenvironments of flamingos were closely linked to the unique ecology of this locality, which is a direct result of special climatic (high evaporitic regime) and geological (fault system) conditions. PMID:23082136

  15. 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.

  16. 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. PMID:20374486

  17. Supporting Information Comparative Field Study, the Fossil Record and Phylogenetic Analyses

    E-print Network

    Ord, Terry

    Cruces, New Mexico1 - - - Note: Rattlesnake species used are indicated by superscript numbers next squirrels and rattlesnake ancestors at approximately 15 million years ago in Texas, USA (Black 1963; Holman. wilsoni ­ was not found to co- occur with rattlesnake species. But S. shotwelli fossils co

  18. c h a p t e r t w o The Fossil Record: Biological or

    E-print Network

    Benton, Michael

    more gradual. --Charles Darwin, On the Origin of Species (1859). Darwin is referring here to Charles. Charles Darwin famously devoted two chapters in On the Origin of Species (Darwin 1859) to the fossil of the evolution of life, preserving all the intermediate forms demanded by his theory. And yet, Darwin ended

  19. Estimation of divergence times in cnidarian evolution based on mitochondrial protein-coding genes and the fossil record.

    PubMed

    Park, Eunji; Hwang, Dae-Sik; Lee, Jae-Seong; Song, Jun-Im; Seo, Tae-Kun; Won, Yong-Jin

    2012-01-01

    The phylum Cnidaria is comprised of remarkably diverse and ecologically significant taxa, such as the reef-forming corals, and occupies a basal position in metazoan evolution. The origin of this phylum and the most recent common ancestors (MRCAs) of its modern classes remain mostly unknown, although scattered fossil evidence provides some insights on this topic. Here, we investigate the molecular divergence times of the major taxonomic groups of Cnidaria (27 Hexacorallia, 16 Octocorallia, and 5 Medusozoa) on the basis of mitochondrial DNA sequences of 13 protein-coding genes. For this analysis, the complete mitochondrial genomes of seven octocoral and two scyphozoan species were newly sequenced and combined with all available mitogenomic data from GenBank. Five reliable fossil dates were used to calibrate the Bayesian estimates of divergence times. The molecular evidence suggests that cnidarians originated 741 million years ago (Ma) (95% credible region of 686-819), and the major taxa diversified prior to the Cambrian (543 Ma). The Octocorallia and Scleractinia may have originated from radiations of survivors of the Permian-Triassic mass extinction, which matches their fossil record well. PMID:22040765

  20. 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

  1. Sr isotopic composition of hydroxyapatite from recent and fossil salmon: the record of lifetime migration and diagenesis

    NASA Astrophysics Data System (ADS)

    Koch, Paul L.; Halliday, Alex N.; Walter, Lynn M.; Stearley, Ralph F.; Huston, Ted J.; Smith, Gerald R.

    1992-02-01

    By comparing the Sr isotopic composition of migratory fossil salmon, which lived in the ocean but died in continental regions, to the well established marine Sr isotopic record, the age of the continental deposit could be determined with high accuracy. This approach to marine-continental correlation and dating requires (1) that marine-resident salmon bear a marine 87Sr/ 86Sr value in their bones or teeth, and (2) that the original 87Sr/ 86Sr value of fossils is not overprinted by diagenesis. The vertebrae of modern, hatchery-reared salmon exhibit Sr isotopic variations indicative of freshwater to marine migration during bone growth. Modern marine 87Sr/ 86Sr values were preserved in growth layers formed later in life. Marine-phase growth layers in the bones and teeth of the late Miocene migratory salmon, Oncorhynchus rastrosus, were subjected to stepwise selective leaching to separate biogenic hydroxyapatite from diagenetic calcium carbonate and recrystallized hydroxyapatite. Although the procedure yielded leachates with Sr/Ca and Ca/P values characteristic of apatite, the leachates had 87Sr/ 86Sr values consistently less radiogenic than values for late Miocene seawater ( ? 0.7087. The fossils were substantially contaminated by Sr from the hosting clastic sediments. Specimens in continental deposits differed in 87Sr/ 86Sr value from host sediments by 0.0002 to 0.0200, supporting the conclusion that these salmon were migrants from marine waters. However, because the original Sr isotopic composition of fossil bones and teeth cannot be determined with confidence, archaeological, paleobiological and stratigraphic applications of this technique may be limited.

  2. Tooth counts through growth in diapsid reptiles: implications for interpreting individual and size-related variation in the fossil record.

    PubMed

    Brown, Caleb Marshall; VanBuren, Collin S; Larson, Derek W; Brink, Kirstin S; Campione, Nicolás E; Vavrek, Matthew J; Evans, David C

    2015-04-01

    Tooth counts are commonly recorded in fossil diapsid reptiles and have been used for taxonomic and phylogenetic purposes under the assumption that differences in the number of teeth are largely explained by interspecific variation. Although phylogeny is almost certainly one of the greatest factors influencing tooth count, the relative role of intraspecific variation is difficult, and often impossible, to test in the fossil record given the sample sizes available to palaeontologists and, as such, is best investigated using extant models. Intraspecific variation (largely manifested as size-related or ontogenetic variation) in tooth counts has been examined in extant squamates (lizards and snakes) but is poorly understood in archosaurs (crocodylians and dinosaurs). Here, we document tooth count variation in two species of extant crocodylians (Alligator mississippiensis and Crocodylus porosus) as well as a large varanid lizard (Varanus komodoensis). We test the hypothesis that variation in tooth count is driven primarily by growth and thus predict significant correlations between tooth count and size, as well as differences in the frequency of deviation from the modal tooth count in the premaxilla, maxilla, and dentary. In addition to tooth counts, we also document tooth allometry in each species and compare these results with tooth count change through growth. Results reveal no correlation of tooth count with size in any element of any species examined here, with the exception of the premaxilla of C. porosus, which shows the loss of one tooth position. Based on the taxa examined here, we reject the hypothesis, as it is evident that variation in tooth count is not always significantly correlated with growth. However, growth trajectories of smaller reptilian taxa show increases in tooth counts and, although current samples are small, suggest potential correlates between tooth count trajectories and adult size. Nevertheless, interspecific variation in growth patterns underscores the importance of considering and understanding growth when constructing taxonomic and phylogenetic characters, in particular for fossil taxa where ontogenetic patterns are difficult to reconstruct. PMID:25689039

  3. Lower Cretaceous Fossil Record of The Lavrasian Continental Shelf in Northwestern Turkey and Its Correlation with Surrounding Areas

    NASA Astrophysics Data System (ADS)

    Mente?, Merve; Özkar Öngen, ?zver

    2015-04-01

    This study contains Zonguldak, Amasra and K?rkalerli (??neada) area in the Northwestern Turkey. In this region, The Istanbul-Zonguldak Composite Terrane consists of two Paleozoic terranes and their Mesozoic overstep sequences around Zonguldak and Amasra. However The Istranca Terrane is characterized by a complex nappe-pile that includes metamorphic assemblages unconformably overlain by Tertiary sediments of the Thrace basin around ??neada. The original purpose of this study to analyze fossil records of Kozlu-Zonguldak, Amasra and K?rklareli (??neada) in which Lower Cretaceous of shallow nautical sedimentary stacking which is regarding to The Lavrasian continental shelf in Northwestern Turkey. After analysing about 90 thin section and 30 samples we followed and associated lito-biostratigraphical similarities and contrasts, horizontal and vertical variation in facies which includes Orbitolina, Neotrocholina, megalospheric Rudists and various benthic foraminifera fossil records. Correlation between sections with detailed paleontological analyse wasn't presented until today, however there are several geological examination in these areas. In accordance with this purpose, this study tries to determine possible paleogeographic borders, which are in Northwestern Anatolian of The Lavrasian continental shelf, with benthic foraminiferal assemblages . In this examination, the other aim is to correlate with researches of Lower Cretaceous continental shelf of Iranian in East, Bulgaria, Romania, Italy and Spain in West, to present comparisons and contrasts in Western Pontids. Keywords: Lower Cretaceous, Benthic Foraminifera, Correlation.

  4. 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. PMID:25619401

  5. 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

  6. 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, ?, 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.

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

    E-print Network

    Schöne, Bernd R.

    ) reconstructed from a 50-kyr fossil pollen record from Lake Billyakh Stefanie Müller a,*,1 , Pavel E. Tarasova,1 we present a detailed radiocarbon-dated 936 cm long pollen record from Lake Billyakh (65 170 N, 126 of the Arctic Circle. A set of 53 surface pollen samples representing tundra, cold deciduous forest and taiga

  8. 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 bivalve. Lockeia ornata exhibits distinctive, fine, parallel lines that mimic the ornamentation of Phestia, a nuculanid protobranch bivalve. Rosary and radial structures give evidence of a patterned search for food. Lockeia ornata and associated Protovirgularia record dominant horizontal locomoton and suggest the activity of deposit-feeding bivalves. Morphologic variability of Protovirgularia was controlled by substrate fluidity, which was dependent on sediment heterogeneity and tidal-cycle dynamics. This study demonstrates that detailed analysis of bivalve traces provides valuable information on bivalve ethology and paleoecology, evolutionary innovations, environmental dynamics, and substrate fluidity.

  9. www.sciencemag.org SCIENCE VOL 295 22 MARCH 2002 2193 and African fossils, and it therefore links

    E-print Network

    Gehring, William J.

    in these hominids." The idea of H. erectus as the direct ances- tor of living humans is a return to a view em, proposed that fossils found in Africa in the 1970s--including hominids that had lived as early as 1

  10. Considering the Case for Biodiversity Cycles: Reexamining the Evidence for Periodicity in the Fossil Record

    E-print Network

    Lieberman, Bruce S

    2007-01-01

    Medvedev and Melott (2007) have suggested that periodicity in fossil biodiversity may be induced by cosmic rays which vary as the Solar System oscillates normal to the galactic disk. We re-examine the evidence for a 62 million year (Myr) periodicity in biodiversity throughout the Phanerozoic history of animal life reported by Rohde & Mueller (2005), as well as related questions of periodicity in origination and extinction. We find that the signal is robust against variations in methods of analysis, and is based on fluctuations in the Paleozoic and a substantial part of the Mesozoic. Examination of origination and extinction is somewhat ambiguous, with results depending upon procedure. Origination and extinction intensity as defined by RM may be affected by an artifact at 27 Myr in the duration of stratigraphic intervals. Nevertheless, when a procedure free of this artifact is implemented, the 27 Myr periodicity appears in origination, suggesting that the artifact may ultimately be based on a signal in the...

  11. 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.

  12. Supplementary Information for: Delayed biological recovery from extinctions throughout the fossil record

    E-print Network

    Kirchner, James W.

    record James W. Kirchner Department of Geology and Geophysics, University of California, Berkeley, CA, 94720-4767 USA Anne Weil Department of Biological Anthropology and Anatomy, Duke University, Durham, NC

  13. Uncertainties in dating constrain model choice for inferring extinction time from fossil records

    NASA Astrophysics Data System (ADS)

    Saltré, Frédérik; Brook, Barry W.; Rodríguez-Rey, Marta; Cooper, Alan; Johnson, Christopher N.; Turney, Chris S. M.; Bradshaw, Corey J. A.

    2015-03-01

    Accurate estimates of the timing of extinctions (?) are critical for understanding the causes of major die-off events and for identifying evolutionary or environmental transitions. Yet many studies have demonstrated that sampling biases and underlying statistical assumptions affect the accuracy of model-based estimates of extinction times (?ˆ), and the added uncertainty contributed by inherent (laboratory) dating errors has largely been neglected. Here we provide a general guide (model-selection key) for choosing from among eight alternative ';frequentist sampling' (i.e., non-Bayesian) methods, differentiated by their treatment of both the probability of record occurrence and uncertainties in record dates, the most appropriate for a given record. We first provide a methodological framework to characterize time series of dated records as a function of the number of records, the size of the interval between successive records, and laboratory dating errors. Using both simulated data and dated Australian megafauna remains, we then assess how the characteristic of a dataset's time series dictates model performance and the probability of misclassification (false extant vs. false extinct). Among the four classic frequentist methods providing highest model performance, Marshall's (1997) and McCarthy's (1998) methods have the highest model precision. However, high model performance did not prevent misclassification errors, such that the Gaussian-resampled inverse-weighted McInerny (GRIWM) approach is the only method providing both high model accuracy and no misclassification issues, because of its unique down-weighting interval procedure and its ability to account for uncertainties in record dates. Applying the guideline to three time series of extinct Australian species, we recommend using Marshall's, McCarthy's and/or GRIWM methods to infer ? of both Thylacinus sp. and Genyornis sp., because each dataset is characterized by many sightings and a low variance of the interval between records, whereas McInerny's method better suits Diprotodon sp. due to an even lower interval variance.

  14. 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

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

    PubMed Central

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

    2015-01-01

    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. PMID:25901310

  16. 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. PMID:25901310

  17. A distal 145 ka sediment record of Nile discharge and East African monsoon variability

    NASA Astrophysics Data System (ADS)

    Ehrmann, W.; Schmiedl, G.; Seidel, M.; Krüger, S.; Schulz, H.

    2015-09-01

    Clay mineral assemblages in a sediment core from the distal Nile discharge plume off Israel have been used to reconstruct the late Quaternary Nile sediment discharge into the Eastern Mediterranean Sea (EMS). The record spans the last ca. 145 ka. Smectite abundances indicate the influence of the Blue Nile and Atbara that have their headwaters in the volcanic rocks of the Ethiopian highlands. Kaolinite abundances indicate the influence of wadis, which contribute periodically to the suspension load of the Nile. Due to the geographical position, the climate and the sedimentary framework of the EMS is controlled by two climate systems. The long-term climate regime was governed by the African monsoon that caused major humid periods with enhanced sediment discharge at 132 to < 122 ka (AHP 5), 113 to 104 ka (AHP 4), and 86 to 74 ka (AHP 3). They lasted much longer than the formation of the related sapropel layers S5, S4 and S3. During the last glacial period (MIS 4-2) the long-term changes of the monsoonal system were superimposed by millennial-scale changes of an intensified mid-latitude glacial system. This climate regime caused short but pronounced drought periods in the Nile catchment, which are linked to Heinrich Events and alternate with more humid interstadials. The clay mineral record further implies that feedback mechanisms between vegetation cover and sediment discharge of the Nile are detectable but of minor importance for the sedimentary record in the southeastern Mediterranean Sea during the investigated African Humid Periods.

  18. Quantitatively comparing morphological trends to environment in the fossil record (Cincinnatian series; Upper Ordovician).

    PubMed

    Webber, Andrew J; Hunda, Brenda R

    2007-06-01

    Determining whether morphological trends in fossil species represent evolution within a lineage or lateral shifts in morphologically variable populations through time requires a thorough examination of the details of both morphology and paleoenvironment in time and space. The purpose of this study is to explore at high resolution the relationship between morphology of the trilobite Flexicalymene granulosa and paleoenvironmental conditions in Upper Ordovician deposits of southwestern Ohio and northern Kentucky. This is achieved by using geometric morphometrics to measure high-resolution morphological changes and by using gradient analysis to capture environmental gradients underlying faunal distribution patterns. Quantitatively comparing the outcomes of these two techniques provides an assessment of whether shape changes relates to environment. Results indicate that a significant amount of shape change, seen as an anteromedial movement of the eye region over time, corresponds to ordination scores. This suggests a relationship between certain aspects of morphology and environment. The combination of these quantitative techniques has provided the foundation for determining whether morphological trends within F. granulosa represent evolution or temporal shifts in geographic variation. Future work will involve examining this relationship in greater detail both geographically and stratigraphically. PMID:17542852

  19. Considering the Case for Biodiversity Cycles: Reexamining the Evidence for Periodicity in the Fossil Record

    E-print Network

    Bruce S. Lieberman; Adrian L. Melott

    2007-08-22

    Medvedev and Melott (2007) have suggested that periodicity in fossil biodiversity may be induced by cosmic rays which vary as the Solar System oscillates normal to the galactic disk. We re-examine the evidence for a 62 million year (Myr) periodicity in biodiversity throughout the Phanerozoic history of animal life reported by Rohde & Mueller (2005), as well as related questions of periodicity in origination and extinction. We find that the signal is robust against variations in methods of analysis, and is based on fluctuations in the Paleozoic and a substantial part of the Mesozoic. Examination of origination and extinction is somewhat ambiguous, with results depending upon procedure. Origination and extinction intensity as defined by RM may be affected by an artifact at 27 Myr in the duration of stratigraphic intervals. Nevertheless, when a procedure free of this artifact is implemented, the 27 Myr periodicity appears in origination, suggesting that the artifact may ultimately be based on a signal in the data. A 62 Myr feature appears in extinction, when this same procedure is used. We conclude that evidence for a periodicity at 62 Myr is robust, and evidence for periodicity at approximately 27 Myr is also present, albeit more ambiguous.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  1. 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.

  2. Direct Comparison of the Geomagnetic Paleointensity Record and the Atmospheric Radiocarbon Content Based on Fossil Corals

    NASA Astrophysics Data System (ADS)

    Chiu, T.; Lee, T.

    2008-12-01

    The atmospheric radiocarbon content (denoted as ?14C) is thought to be controlled by the geomagnetic shielding effect, the solar variability and the Earth's carbon cycle (e.g. the changes of deep water formation and the exchange rate between carbon reservoirs). The geomagnetic shielding effect is believed to dictate the large-scale trend in the atmospheric ?14C record, and the other two factors are believed to control the smaller but rapid fluctuations. One puzzling feature of the long-term atmospheric ?14C record is the anomalously high ?14C values for the period older than 30,000 years BP. Some investigators attributed these anomalously high values to hypothetical carbon cycle conditions very different from those in the modern times. Even in the extreme carbon cycle scenarios, modeled ?14C values and measured values during the last glacial period still differ largely. Furthermore, there is little paleoceanographic evidence which supports a prolonged stagnant ocean during that time. The atmospheric ?14C values are usually being compared to the modeled ?14C values based on the calculated 14C production and an assumed carbon cycle condition. However, the coral-based atmospheric ?14C record discussed in this study seems to capture some finer structures and rapid changes observed in the paleointensity records obtained from the deep-sea sediments, despite the potential discrepancies due to differences in chronologies. This implies a more direct atmospheric response to the geomagnetism-induced 14C production change than we previously thought, and the carbon cycle change might actually play a much lesser role in controlling the atmospheric 14C variations during the last glacial period. The paleointensity may be the only dominant factor determining both the overall shape and the secondary structures of the atmospheric ?14C record for the past 50,000 years BP. Since the coral-based atmospheric ?14C record can be dated by 14C, 230Th/234U/238U and 231Pa/235U methods with high precision and accuracy, it could potentially serve as a check for deep-sea sediment-based paleointensity reconstruction.

  3. East African soil erosion recorded in a 300 year old coral colony from Dominik Fleitmann,1,2

    E-print Network

    Vuille, Mathias

    East African soil erosion recorded in a 300 year old coral colony from Kenya Dominik Fleitmann,1; published 22 February 2007. [1] Soil erosion is a key socio-economic and environmental problem in Kenya on land use. The peak in suspended sediment load and hence soil erosion occurred between 1974 and 1980

  4. A review of the fossil record of spiders (Araneae) with special reference to Africa, and description of a new specimen from the Triassic Molteno Formation of South Africa

    E-print Network

    Selden, Paul A.; Anderson, H.M.; Anderson, J.M.

    2009-06-01

    families known today. Of greater interest for phylogeny, therefore, is the fossil record of Araneae from the Mesozoic and Palaeozoic eras, and what it can tell us about the origins and longevity of major clades. Fossil spiders have been known from the late... at the moment. It is because of their great rarity that almost every new specimen of spider from the Palaeozoic and Mesozoic eras is worthy of report, and each occurrence can drastically alter our perception of spider phylogeny. For example, the identification...

  5. 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. PMID:25338197

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. The Mescal Cave Fauna (San Bernardino County, California) and testing assumptions of habitat fidelity in the Quaternary fossil record

    NASA Astrophysics Data System (ADS)

    Stegner, Mary Allison

    2015-05-01

    The late Pleistocene and Holocene vertebrate fossil record for the northern Mojave Desert (southwestern USA) is known primarily from five sites. Until now, only two of these have been radiometrically dated, and temporal placement of the others has been based on stratigraphic or biostratigraphic correlation, leading to circular interpretations of mammal extirpations in the Mojave. Here, I report a revised and complete faunal list for Mescal Cave, along with 22 AMS radiocarbon dates from 5 vertebrate taxa recovered from its deposits. The results reported here demonstrate time-averaging in Mescal Cave encompassing around ~ 34 ka, a maximum age 14 ka older and minimum age 10 ka younger than previously thought. Furthermore, radiocarbon analyses suggest local extirpation of Marmota flaviventris around 3.6 cal ka BP, considerably younger than expected based on regional patterns of warming and aridification in the Mojave. Conversely, radiocarbon dates from another presumably boreal species, Neotoma cinerea, are considerably older than expected, suggesting either that climate change at this site did not directly mirror regional patterns, that habitat requirements for these two species are not strictly boreal or cool/mesic as has often been assumed, or that local edaphic conditions and/or competitive interactions overrode the regional climatic controls on theses species' distribution.

  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 significantly higher than that of conifer fossil leaf from Ashizawa coal bed. From these results, we propose that the proportions of long chain n-alkanols released from terrigenous kerogens are applicable for paleovegetation reconstruction.

  12. Holocene Asian and African Monsoon Strength Recorded in O-18 of Atmospheric Oxygen

    NASA Astrophysics Data System (ADS)

    Severinghaus, J. P.; Beaudette, R.; Brook, E. J.

    2008-12-01

    Prior work using trapped gases in ice cores has shown that the oxygen-18/16 ratio of atmospheric molecular oxygen (?18Oatm) is sensitive to orbital-scale monsoon and ice volume variations (Bender et al., 1994) and millennial-scale monsoon variations during Marine Isotope Stage 4 (Landais et al., 2007). Here we extend these findings with a high-resolution record from the Siple Dome ice core, West Antarctica, covering the last 60 kyr. The early Holocene sample resolution is ~30 yr and precision is ±0.009‰, revealing previously unrecognized centennial-scale variations in ?18Oatm. Removal of the seawater ?18O record (Waelbroeck et al., 2002) yields a record of past changes in the Dole Effect, the difference between the ?18O of air and seawater (+23.8‰ today). A further calculation using the derivative of the ?18Oatm data and an assumed 1000-yr O2 turnover time allows a deconvolution of the implied effective value of ?18O of O2 introduced to the atmosphere by the terrestrial biosphere (?18Oland). Photosynthesis transfers the ?18O of chloroplast water (H218O/H216O) directly to the O2 that is produced (Guy et al., 1997). Strong monsoons are expected to produce low values of ?18Oland and thus a weak Dole Effect by 1) the low ?18O of heavy rainfall, 2) weak evaporative enrichment of 18O in leaf water due to the high humidity in which monsoon photosynthesis generally occurs, and 3) weak respiratory fractionation in wet tropical soils (Angert et al., 2003). In fact, our calculated ?18Oland correlates surprisingly well with Asian monsoon strength indicators such as the Dongge Cave record (Wang et al., 2005) at periods >0.2 kyr, except at 6 ka, where a prominent increase in ?18Oland coincides with the drying of the Sahara. These observations suggest that ?18Oland from ice cores may be a useful proxy of past Asian and African monsoon variations that integrates over large spatial scales (because the atmosphere is well-mixed, and photosynthesis is ubiquitous). Interestingly, ?18Oland suggests strengthening monsoons over the past ~2 kyr, probably caused by the upturn in May-June 30°N insolation, which may obviate the need to call for early anthropogenic emissions to explain rising methane in the last 2 millennia (Ruddiman, 2003).

  13. Characteristics of long recovery Early VLF signals perturbations recorded by the North African VLF network

    NASA Astrophysics Data System (ADS)

    Nait Amor, S.; Ghalila, H.

    2012-12-01

    The Early VLF signals perturbations were widely investigated and some of them were found to be in association with Transient Luminous Events (or TLEs). The Long Recovery Early signals perturbations are events that exhibit a long (more than 10mn) returning time to the pre-event signal. These events were not largely studied. In this contribution we will give a new results on these events as recorded by the North African AWESOME network where we present theirs characteristics such as the amplitude, the onset duration, the recovery times and the geographic locations. The importance of the distances frome the perturbed region to the receivers/transmitters locations was also studied. The results show that a large number of such events happened in the Mediterranean Sea or sealand. Another important result is that the perturbations proprieties depend strongly on the distance to the receiver locations: near is the event, large in amplitude and long in recovery time is the signal perturbation. The presence or absence of such perturbations was also found to be function of the scattering process and modal structure of the electromagnetic wave of the VLF signal.

  14. A comparison of death recording by health centres and civil registration in South Africans receiving antiretroviral treatment

    PubMed Central

    Johnson, Leigh F; Dorrington, Rob E; Laubscher, Ria; Hoffmann, Christopher J; Wood, Robin; Fox, Matthew P; Cornell, Morna; Schomaker, Michael; Prozesky, Hans; Tanser, Frank; Davies, Mary-Ann; Boulle, Andrew

    2015-01-01

    Introduction There is uncertainty regarding the completeness of death recording by civil registration and by health centres in South Africa. This paper aims to compare death recording by the two systems, in cohorts of South African patients receiving antiretroviral treatment (ART). Methods Completeness of death recording was estimated using a capture–recapture approach. Six ART programmes linked their patient record systems to the vital registration system using civil identity document (ID) numbers and provided data comparing the outcomes recorded in patient files and in the vital registration. Patients were excluded if they had missing/invalid IDs or had transferred to other ART programmes. Results After exclusions, 91,548 patient records were included. Of deaths recorded in patients files after 2003, 94.0% (95% CI: 93.3–94.6%) were recorded by civil registration, with completeness being significantly higher in urban areas, older adults and females. Of deaths recorded by civil registration after 2003, only 35.0% (95% CI: 34.2–35.8%) were recorded in patient files, with this proportion dropping from 60% in 2004–2005 to 30% in 2010 and subsequent years. Recording of deaths in patient files was significantly higher in children and in locations within 50 km of the health centre. When the information from the two systems was combined, an estimated 96.2% of all deaths were recorded (93.5% in children and 96.2% in adults). Conclusions South Africa's civil registration system has achieved a high level of completeness in the recording of mortality. However, the fraction of deaths recorded by health centres is low and information from patient records is insufficient by itself to evaluate levels and predictors of ART patient mortality. Previously documented improvements in ART mortality over time may be biased if based only on data from patient records. PMID:26685125

  15. African Dust Fertilizing the Amazon Rainforest: An Assessment with Seven-year Record of CALIOP Measurements

    NASA Astrophysics Data System (ADS)

    Yu, H.; Chin, M.; Yuan, T.; Bian, H.; Prospero, J. M.; Omar, A. H.; Remer, L. A.; Winker, D. M.; Yang, Y.; Zhang, Y.; Zhang, Z.

    2014-12-01

    The productivity of Amazon rainforest is constrained by the availability of nutrients, in particular phosphorus (P). Deposition of transported African dust in boreal winter and spring is considered an important nutrient input for the Amazon Basin, though its magnitude is not well qunatified. This study provides a remote sensing observation-based estimate of dust deposition in the Amazon Basin using a 7-year (2007-2013) record of three dimensional (3D) distributions of aerosol in both cloud-free and above-cloud conditions from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). It is estimated that the 7-year average of dust deposition into the Amazon Basin amounts to 15.1 ~ 32.1 Tg a-1 (Tg = 1012 g). This imported dust could provide 0.012 ~ 0.025 Tg P a-1 or equivalent to 12 ~ 26 g P ha-1 a-1 to fertilize the Amazon rainforest, which largely compensates the hydrological loss of P. The CLAIOP-based estimate agrees better with estimates from in-situ measurements and model simulations than what has been reported in literature. The closer agreement benefits from a more realistic geographic definition of the Amazon Basin and inclusion of meridional dust transport calculation in addition to the 3D nature of CALIOP aerosol measurements. The trans-Atlantic transport and deposition of dust shows strong interannual variations that are found to correlate with the North Atlantic Oscillation index in the winter season and anticorrelate with the prior-year Sahel Precipitation Index on an annual basis. Uncertainties associated with the estimate will also be discussed.

  16. Middle Holocene daily light cycle recorded in the strontium/calcium ratios of a fossil giant clam shell

    NASA Astrophysics Data System (ADS)

    Sano, Y.; Hori, M.; Takahata, N.; Shirai, K.; Watanabe, T.

    2013-12-01

    The historical record of daily light cycle in tropical and subtropical regions is short. Moreover, it remains difficult to extract this cycle in the past from natural archives such as biogenic marine carbonates. Our previous analyses of cultivated giant clam shells (Tridacna derasa) showed a diurnal variation in the Sr/Ca ratio, which is probably reflecting the daily light cycle and not the seawater temperature [1]. In order to apply the proxy method to prehistoric era, we analyzed trace elements of a fossil giant clam shell (Tridacna gigas) which was collected at the coast of the Ishigaki Island (124 09' E, 24 20' N), southern Japan. The giant clam specimen has been living in the middle Holocene, the warmest climate after the last glacial period. An inner layer part of the sample was cut and mounted in Araldite resin disk together with a carbonate standard. This species is known to form a growth line each day [2] and we found similar Sr enrichment lines to those of the cultivated clam [1] using a EPMA. The lines may facilitate age-model determination. We carried out a preliminary analysis of Sr/Ca, Mg/Ca and Ba/Ca ratios along the growth axis with a 2-micron spot at 2 micron interval using a laterally high-resolution secondary ion mass spectrometer (NanoSIMS) installed at Atmosphere and Ocean Research Institute, University of Tokyo. The Sr/Ca ratios of dark and relatively opaque area, which is probably corresponding to a cool winter [3], show striking diurnal cycle. This cycle generally consist of narrow lines of high Sr/Ca ratio and broad increments of low ratio. These variations are consistent with those of the cultivated clam [1] and pointing to the possibility of reconstructing daily light cycle at a few hour timescale in the middle Holocene. The Mg/Ca and Ba/Ca ratios also appear to indicate a diurnal cycle, but the amplitude is rather large and highly irregular, suggesting a strong biological control. Light-enhanced calcification and elemental transportation processes, in giant clam and symbiotic algae, may explain these synchronized variations [4]. [1] Sano et al. (2012) Nature Commun. 3, 761. [2] Watanabe and Oba (1999) JGR 104, 667-674. [3] Bonham (1965) Science 149, 300-302. [4] Hippler et al. (2013) PPP 373, 75-87.

  17. 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.

  18. 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 strategies appear to be more diverse than previously suggested based on new data on the osteohistology of Aenigmastropheus. PMID:24586565

  19. 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

  20. Error in estimation of rate and time inferred from the early amniote fossil record and avian molecular clocks.

    PubMed

    van Tuinen, Marcel; Hadly, Elizabeth A

    2004-08-01

    The best reconstructions of the history of life will use both molecular time estimates and fossil data. Errors in molecular rate estimation typically are unaccounted for and no attempts have been made to quantify this uncertainty comprehensively. Here, focus is primarily on fossil calibration error because this error is least well understood and nearly universally disregarded. Our quantification of errors in the synapsid-diapsid calibration illustrates that although some error can derive from geological dating of sedimentary rocks, the absence of good stem fossils makes phylogenetic error the most critical. We therefore propose the use of calibration ages that are based on the first undisputed synapsid and diapsid. This approach yields minimum age estimates and standard errors of 306.1 +/- 8.5 MYR for the divergence leading to birds and mammals. Because this upper bound overlaps with the recent use of 310 MYR, we do not support the notion that several metazoan divergence times are significantly overestimated because of serious miscalibration (sensuLee 1999). However, the propagation of relevant errors reduces the statistical significance of the pre-K-T boundary diversification of many bird lineages despite retaining similar point time estimates. Our results demand renewed investigation into suitable loci and fossil calibrations for constructing evolutionary timescales. PMID:15486700

  1. Avalonian, Ganderian and East Cadomian terranes in South Carpathians, Romania, and Pan-African events recorded in their basement

    NASA Astrophysics Data System (ADS)

    Balintoni, Ioan; Balica, Constantin

    2013-10-01

    New U-Pb geochronology is used to refine the provenance and evolution of northwest Gondwana Pan-African terranes preserved in the South Carpathians of Romania. The Dr?g?an terrane of Avalonian affinity, from the Danubian domain of the South Carpathians originated in the Panthalassa Ocean and accreted to the Amazonian part of Rodinia not much before 800 Ma, when the F?ge?el orthogneiss was intruded, at around 807-810 Ma. After this event no other Neoproterozoic magmatic pulse is known in the basement of the Dr?g?an terrane. The Ganderian type Lainici-P?iu? terrane from the same domain of the South Carpathians, recorded magmatic pulses at 782 Ma, 739 Ma, 708 Ma, 639 Ma, 600-587 Ma and 574-568 Ma. The East Cadomian Sebe?-Lotru terrane from the Getic domain of the South Carpathians recorded magmatic pulses at 817 Ma, 768 Ma, 685 Ma, 620 Ma, 584 Ma and 550 Ma. Post 630 Ma the northwestern Gondwana margin evolved as an active continental margin at least until 550 Ma, but the pre-630 Ma magmatism could be associated to some island arcs docked with different pre-Gondwanan continental fragments. Independent of the tectonic setting, the post 750 Ma orogens dated in the basement of the peri-Gondwanan terranes are discussed in the frame of the Cadomian orogens, as constituents of the Pan-African orogens in a broader sense. The detrital zircon may also record magmatic pulses from Pan-African orogens other than the Cadomian ones.

  2. The potential ocean acidification event at the Triassic-Jurassic boundary: Constraining carbonate chemistry using the presence of corals and coral reefs in the fossil record

    NASA Astrophysics Data System (ADS)

    Martindale, R. C.; Berelson, W.; Corsetti, F. A.; Bottjer, D. J.; West, A.

    2011-12-01

    Ocean acidification associated with emplacement of the Central Atlantic Magmatic Province (CAMP) has been hypothesized as a kill mechanism for the Triassic-Jurassic (T-J) mass extinction (~200Ma), but few direct proxies for ancient ocean acidity are available. Here, we suggest that the presence of fossil corals and coral reefs can constrain palaeocean acidity. Modern scleractinian corals lose the ability to biomineralize a robust skeleton below aragonite saturation states (?Arag) of 2 and modern shallow water coral reefs are only found in ?Arag > 3; we use these minima to constrain ancient ocean carbonate chemistry when corals or coral reefs are preserved in the fossil record. Atmospheric pCO2 reconstructions are combined with the coral ?Arag limitations to calculate the total dissolved inorganic carbon (TCO2) in the Late Triassic Ocean, which is a measure of the buffering capacity or ocean sensitivity to acidification. Our results suggest that Late Triassic TCO2 values were low to moderate (2000-3000 ?mol/kg) such that the pCO2 increases across the T-J boundary would have depressed saturation state to the point where coral biomineralization would have been challenging (?Arag < 2), likely resulting in the observed coral and reef gap in the fossil record. While the average pCO2 elevations recorded in stomatal and pedogenic proxies are not sufficient to cause complete carbonate undersaturation, modeled scenarios for CAMP-related T-J pCO2 increases suggest that aragonite undersaturation is plausible and in extreme cases calcite undersaturation is possible. Thus, a short but extreme acidification in an ocean with a low TCO2 concentration could occur and would satisfactorily explain the significant extinction of calcareous organisms, the coral gap, and possibly the T-J carbonate crisis.

  3. Fossil primates 1 Fossil primates

    E-print Network

    Delson, Eric

    Fossil primates 1 Fossil primates Extinct members of the order of mammals to which humans belong group of living primates. However, the chewing teeth and the locomotor anatomy of these fossil forms). These animals are also known from fossil deposits on Ellesmere Island, in Arctic Canada, which was then covered

  4. High Density GWAS for LDL Cholesterol in African Americans Using Electronic Medical Records Reveals a Strong Protective Variant in APOE

    PubMed Central

    Rasmussen-Torvik, Laura J.; Pacheco, Jennifer A.; Wilke, Russell A.; Thompson, William K.; Ritchie, Marylyn D.; Kho, Abel N.; Muthalagu, Arun; Hayes, M. Geoff; Armstrong, Loren L.; Scheftner, Douglas A.; Wilkins, John T.; Zuvich, Rebecca L.; Crosslin, David; Roden, Dan M.; Denny, Joshua C.; Jarvik, Gail P.; Carlson, Christopher S.; Kullo, Iftikhar J.; Bielinski, Suzette J.; McCarty, Catherine A.; Li, Rongling; Manolio, Teri A.; Crawford, Dana C.; Chisholm, Rex L.

    2012-01-01

    Only one LDL-C GWAS has been reported in African Americans. We performed a GWAS of LDL-C in African Americans using data extracted from electronic medical records (EMR) in the eMERGE network. African Americans were genotyped on the Illumina 1M chip. All LDL-C measurements, prescriptions, and diagnoses of concomitant disease were extracted from EMR. We created two analytic datasets; one dataset having median LDL-C calculated after the exclusion of some lab values based on co-morbidities and medication (n = 618) and another dataset having median LDL-C calculated without any exclusions (n = 1249). Rs7412 in APOE was strongly associated with LDL-C at levels of GWAS significance in both datasets (p < 5 X 10?8). In the dataset with exclusions, a decrease of 20.0 mg/dl per minor allele was observed. The effect size was attenuated (12.3 mg/dl) in the dataset without any lab values excluded. Although other signals in APOE have been detected in previous GWAS, this large and important SNP association has not been well detected in large GWAS because rs7412 was not included on many genotyping arrays. Use of median LDL-C extracted from EMR after exclusions for medications and co-morbidities increased the percentage of trait variance explained by genetic variation. PMID:23067351

  5. Southeast African records reveal a coherent shift from high- to low-latitude forcing mechanisms along the east African margin across last glacial-interglacial transition

    NASA Astrophysics Data System (ADS)

    Chevalier, Manuel; Chase, Brian M.

    2015-10-01

    Late Quaternary climate variability in the southern African subtropics is still only poorly resolved, with significant complexity and apparent contradictions in the regional dataset. To more effectively interpret and synthesize key regional records, we reanalysed the data from 13 pollen sequences from the summer rainfall zone of South Africa spanning the last 45,000 years, obtaining directly comparable quantitative reconstructions of mean annual temperature and summer rainfall. Temperature reconstructions from across the region provide consistent results, with all sites reflecting trends observed in southwest Indian Ocean sea-surface temperatures in the adjacent Mozambique Channel. Precipitation reconstructions are more heterogeneous, with two distinct subregions being identified. In the northeast, long-term trends in precipitation are determined by sea-surface and continental temperature trends, revealing a positive relationship between temperature and rainfall. This long-term pattern appears to be primarily driven by high northern latitude mechanisms, with direct local insolation being subordinate. Their relative impact reversed during terminal glacial period/early Holocene, at which time direct insolation forcing became the main driver of rainfall variability. Further south, in central South Africa, precipitation variability appears also to be influenced by the latitudinal position of the Southern Hemisphere westerlies, which combine with tropical flow to create tropical-temperate trough, advecting moisture into the interior. In this region, periods of maximum precipitation coincide with periods of elevated SSTs and equatorward expansions of the westerly storm track. This study allows for a fully constrained understanding of climate dynamics along the eastern African margin for the last 45,000 years, linking dynamics to drivers and describing how the climate systems evolved across the last glacial-interglacial transition.

  6. "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)

  7. 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 coating; highly stable microstructure and low wettability. Based on their analytical properties, the carbonaceous polymorphs and the associated mineral components are shown to deriving from fossil combustible of stratospheric origin. The comparison with modern analogues (cf. Courty et al., 2012) has provided keys to explaining the organogenic microfacies from accumulation episodes of exotic stratospheric aerosols in response to serial meteor explosion at high altitude. Geogenic markers and microfacies pattern show four situations: (1) nearly intact ancient surfaces with pulverized carbonaceous composite debris that trace the local effects of meteor explosion ; (2) secondary concentrations expressing accumulation of stratospheric aerosols from the heavy rainfall events subsequent to the meteor explosions; (3) relictual concentrations resulting from selective accumulation of the most resistant components by chemical and physical erosion along to the fossilization; (4) human-controlled concentrations of the unusual debris indicating intentional collect, use and transformation of the singular fossil combustible and related materials. Ancient humans are thus suggested to have regularly exploited the local sources of the singular fossil combustible that formed during episodes of serial cosmic explosions. The direct effect of increased atmospheric dust loading on precipitation regime explains the apparent synchrony between occupation phases and local climate changes. These are simply two distinctive responses to a common cause. Courty, Benoît and Vaillant (2012). Possible interaction of meteor explosion with stratospheric aerosols on cloud nucleation based on 2011 observations. Geophysical Research Abstracts Vol. 14, EGU2012.

  8. Imprint of Climate Variability on Mesozoic Fossil Tree Rings: Evidences of Solar Activity Signals on Environmental Records Around 200 Million Years Ago?

    NASA Astrophysics Data System (ADS)

    Prestes, A.; Rigozo, N. R.; Nordemann, D. J. R.; Echer, E.; Vieira, L. E. A.; Souza Echer, M. P.; Wrasse, C. M.; Guarnieri, F. L.

    2014-08-01

    Evidence of the solar activity modulation of the Earth's climate has been observed on several parameters, from decadal to millennial time scales. Several proxies have been used to reconstruct the paleoclimate as well as the solar activity. The paleoclimate reconstructions are based on direct and/or indirect effects of global and regional climate conditions. The solar activity reconstructions are based on the production of the 14C isotope due to the interaction of cosmic ray flux and the Earth's atmosphere. Because trees respond to climate conditions and store 14C, they have been used as proxies for both for climate and solar activity reconstructions. The imprints of solar activity cycles dating back to 10,000 years ago have been observed on tree-ring samples using 14C data, and those dating back to 20 million years ago have been analyzed using fossil tree-growth rings. All this corresponds to the Cenozoic era. However, solar activity imprints on tree rings from earlier than that era have not been investigated yet. In this work, we showed that tree rings from the Mesozoic Era (of ~200 million years ago) recorded 11- and 22-year cycles, which may be related to solar activity cycles, and that were statistically significant at the 95 % confidence level. The fossil wood was collected in the southern region of Brazil. Our analysis of the fossils' tree-ring width series power spectra showed characteristics similar to the modern araucaria tree, with a noticeable decadal periodicity. Assuming that the Earth's climate responds to solar variability and that responses did not vary significantly over the last ~200 million years, we conclude that the solar-climate connection was likely present during the Mesozoic era.

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

    PubMed Central

    Petrulevi?ius, 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

  10. The Homo habitat niche: using the avian fossil record to depict ecological characteristics of Palaeolithic Eurasian hominins

    NASA Astrophysics Data System (ADS)

    Finlayson, Clive; Carrión, José; Brown, Kimberly; Finlayson, Geraldine; Sánchez-Marco, Antonio; Fa, Darren; Rodríguez-Vidal, Joaquín; Fernández, Santiago; Fierro, Elena; Bernal-Gómez, Marco; Giles-Pacheco, Francisco

    2011-06-01

    Although hardly applied to human palaeoecology, bird fossils offer a unique opportunity for quantitative studies of the hominin habitat. Here we reconstruct the Homo habitat niche across a large area of the Palaearctic, based on a database of avian fauna for Pleistocene sites. Our results reveal a striking association between Homo and habitat mosaics. A mix of open savannah-type woodland, wetlands and rocky habitats emerges as the predominant combination occupied by Homo across a wide geographical area, from the earliest populations of the Lower Palaeolithic to the latest hunter-gatherer communities of the Upper Palaeolithic. This observation is in keeping with the view that such landscapes have had long standing selective value for hominins.

  11. 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.

  12. 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. PMID:22777871

  13. 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.

  14. 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

  15. 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

  16. The Fossil RThe Fossil RThe Fossil RThe Fossil RThe Fossil Reporteporteporteporteport Oak Ridge National Laboratory Fossil Energy Program Fall 2003

    E-print Network

    Pennycook, Steve

    The Fossil RThe Fossil RThe Fossil RThe Fossil RThe Fossil Reporteporteporteporteport Oak Ridge National Laboratory Fossil Energy Program Fall 2003 Energy Technology for the Future...and for the World See NPR - page 2 The Fossil Report is published quarterly by Paul Theodore Carlson, Oak Ridge National

  17. The Fossil RThe Fossil RThe Fossil RThe Fossil RThe Fossil Reporteporteporteporteport Oak Ridge National Laboratory Fossil Energy Program Spring 2003

    E-print Network

    Pennycook, Steve

    The Fossil RThe Fossil RThe Fossil RThe Fossil RThe Fossil Reporteporteporteporteport Oak Ridge National Laboratory Fossil Energy Program Spring 2003 Energy Technology for the Future...and for the World Leasing Prctic Leasing Programogramogramogramogram The Fossil Report is published quarterly by Paul T

  18. The Fossil RThe Fossil RThe Fossil RThe Fossil RThe Fossil Reporteporteporteporteport Oak Ridge National Laboratory Fossil Energy Program Fall 2002

    E-print Network

    Pennycook, Steve

    The Fossil RThe Fossil RThe Fossil RThe Fossil RThe Fossil Reporteporteporteporteport Oak Ridge National Laboratory Fossil Energy Program Fall 2002 Energy Technology for the Future...and for the World Hermetic Seal for High-Temperature Electrochemical Application Continuing Resolutions Continuing The Fossil

  19. A dated phylogeny and collection records reveal repeated biome shifts in the African genus Coccinia (Cucurbitaceae)

    PubMed Central

    2011-01-01

    Background Conservatism in climatic tolerance may limit geographic range expansion and should enhance the effects of habitat fragmentation on population subdivision. Here we study the effects of historical climate change, and the associated habitat fragmentation, on diversification in the mostly sub-Saharan cucurbit genus Coccinia, which has 27 species in a broad range of biota from semi-arid habitats to mist forests. Species limits were inferred from morphology, and nuclear and plastid DNA sequence data, using multiple individuals for the widespread species. Climatic tolerances were assessed from the occurrences of 1189 geo-referenced collections and WorldClim variables. Results Nuclear and plastid gene trees included 35 or 65 accessions, representing up to 25 species. The data revealed four species groups, one in southern Africa, one in Central and West African rain forest, one widespread but absent from Central and West African rain forest, and one that occurs from East Africa to southern Africa. A few individuals are differently placed in the plastid and nuclear (LFY) trees or contain two ITS sequence types, indicating hybridization. A molecular clock suggests that the diversification of Coccinia began about 6.9 Ma ago, with most of the extant species diversity dating to the Pliocene. Ancestral biome reconstruction reveals six switches between semi-arid habitats, woodland, and forest, and members of several species pairs differ significantly in their tolerance of different precipitation regimes. Conclusions The most surprising findings of this study are the frequent biome shifts (in a relatively small clade) over just 6 - 7 million years and the limited diversification during and since the Pleistocene. Pleistocene climate oscillations may have been too rapid or too shallow for full reproductive barriers to develop among fragmented populations of Coccinia, which would explain the apparently still ongoing hybridization between certain species. Steeper ecological gradients in East Africa and South Africa appear to have resulted in more advanced allopatric speciation there. PMID:21269492

  20. Atmospheric Radiocarbon Record for the Past 50,000 Years via Uranium-series and Radiocarbon Dating of Pristine Fossil Corals

    NASA Astrophysics Data System (ADS)

    Chiu, T.; Fairbanks, R. G.; Cao, L.; Mortlock, R. A.; Kaplan, A.

    2005-12-01

    Changes in the earth's geomagnetic field intensity, solar variability, and the earth's carbon cycle control past changes in the atmospheric radiocarbon content. Of these three, the field intensity is the dominant factor. We present an atmospheric ?14C record for the past 50,000 years using pristine fossil corals from Kiritimati, Barbados, Araki and Santo Islands. High-precision, high-accuracy dating by 230Th/234U/238U and redundant 231Pa/235U methods anchor the timing of this ?14C record. We observe a general consistency between our ?14C record and the ?14C output from carbon cycle models based on the global 14C production estimates and fixed or modern carbon cycle parameters, but ?14C values derived from corals older than 30,000 years BP are considerably higher compared to carbon cycle-modeled ?14C values. A linear component of the long-term ?14C trend may be due to inaccuracies in the generally accepted 14C decay constant. Analysis of the published measurements of 14C half-life, combined with new measurements of the 14C beta spectrum, suggests that the commonly accepted value may be under-estimated. The uncertainty in the 14C decay constant may be large enough to shift the computed atmospheric ?14C to overlap the ?14C model estimates. We do not observe the large ?14C fluctuations computed from radiocarbon measurements made in Caricao Basin cores (Hughen et al., 2004) which we believe are artifacts attributable to inaccuracies in the GISP2 age model as applied to the Cariaco Basin sediment record. These findings serve to highlight the need for a new measurement of the radiocarbon half-life.

  1. 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…

  2. 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…

  3. A 1000-Year Carbon Isotope Rainfall Proxy Record from South African Baobab Trees (Adansonia digitata L.)

    PubMed Central

    2015-01-01

    A proxy rainfall record for northeastern South Africa based on carbon isotope analysis of four baobab (Adansonia digitata L.) trees shows centennial and decadal scale variability over the last 1,000 years. The record is in good agreement with a 200-year tree ring record from Zimbabwe, and it indicates the existence of a rainfall dipole between the summer and winter rainfall areas of South Africa. The wettest period was c. AD 1075 in the Medieval Warm Period, and the driest periods were c. AD 1635, c. AD 1695 and c. AD1805 during the Little Ice Age. Decadal-scale variability suggests that the rainfall forcing mechanisms are a complex interaction between proximal and distal factors. Periods of higher rainfall are significantly associated with lower sea-surface temperatures in the Agulhas Current core region and a negative Dipole Moment Index in the Indian Ocean. The correlation between rainfall and the El Niño/Southern Oscillation Index is non-static. Wetter conditions are associated with predominantly El Niño conditions over most of the record, but since about AD 1970 this relationship inverted and wet conditions are currently associated with la Nina conditions. The effect of both proximal and distal oceanic influences are insufficient to explain the rainfall regime shift between the Medieval Warm Period and the Little Ice Age, and the evidence suggests that this was the result of a northward shift of the subtropical westerlies rather than a southward shift of the Intertropical Convergence Zone. PMID:25970402

  4. East African soil erosion recorded in a 300 year old coral colony from Kenya

    NASA Astrophysics Data System (ADS)

    Fleitmann, Dominik; Dunbar, Robert B.; McCulloch, Malcolm; Mudelsee, Manfred; Vuille, Mathias; McClanahan, Tim R.; Cole, Julia E.; Eggins, Stephen

    2007-02-01

    Soil erosion is a key socio-economic and environmental problem in Kenya, which has been poorly documented due to the lack of long, continuous records. Here we present Ba/Ca records from Porites corals from the Malindi coral reef documenting the flux of suspended sediment from the Sabaki River with a sub-weekly resolution for the last 300 years. While sediment flux from the Sabaki River is almost constant between 1700 and 1900, a continuous rise in sediment flux is observed since 1900, first due to British settlements and afterwards due to steadily increasing demographic pressure on land use. The peak in suspended sediment load and hence soil erosion occurred between 1974 and 1980 when there is a five to tenfold increase relative to natural levels. This is attributed to the combined effects of dramatically increasing population, unregulated land use, deforestation and severe droughts in the early 1970's. We conclude that despite laudable attempts to instigate soil conservation measures, it is unlikely that there will be a sustainable reduction in soil erosion without a significant improvement in socio-economic conditions.

  5. East African Soil Erosion Recorded in a 300 Year old Coral Colony From Kenya

    NASA Astrophysics Data System (ADS)

    Dunbar, R. B.; Fleitmann, D.; McCulloch, M.; Mudelsee, M.; Vuille, M.; McClanahan, T.; Cole, J.; Eggins, S.

    2006-12-01

    Soil erosion threatens the food security of 2.6 billion people worldwide. The situation is particularly dire in East and Sub-Saharan Africa where per capita food production has declined over the past 45 years. Erosion and the resultant loss of fertile soil is a key socio-economic and ecological problem in Kenya, affecting all sectors of its economy and damaging marine and terrestrial ecosystems. The temporal pattern of soil erosion is almost unknown and currently only sparse and rather anecdotal information exists. To aid in filling this gap of knowledge, we present a 300-year long Barium record from two Kenyan coral colonies (Porites sp., 3°15'S, 40°9' E; Malindi Marine National Park) that documents a dynamic history of soil erosion in the Sabaki river drainage basin. To reconstruct Sabaki River sediment flux to the Malindi coral reef Ba/Ca ratios were measured in the skeleton of two Porites colonies (Mal 96-1 and Mal 95-3). Well-developed annual bands allow us to develop annually precise chronologies. Ba/Ca ratios were measured in core Mal 96-1 at continuous 40 ?m intervals (~400 to 500 samples yr-1) using laser-ablation inductively coupled plasma mass spectrometry (LA- ICP-MS). To test for reproducibility and accuracy of the Mal 96-1 Ba/Ca profile, coral core Mal 95-3 was analyzed at lower resolution (1 to 12 samples yr-1) using discrete micro-drill sampling and isotope dilution ICP-MS. The close similarity between both coral Ba/Ca profiles, in absolute values as well as general pattern, underscores the accuracy of the LA-ICP-MS technique and adds confidence to our interpretation of the 300 year long Mal 96-1 Ba/Ca profile. The Ba/Ca coral proxy record shows that while the sediment flux from the Sabaki River is nearly constant between 1700 and 1900, a continuous rise in sediment flux is observed since 1900, reflecting steadily increasing demographic pressure on land use. The peak in suspended sediment load and hence soil erosion recorded at the Malindi reef occurred between 1974 and 1980 where there is a five to tenfold increase relative to natural levels. This is attributed to the combined effects of dramatically increasing population, unregulated land use, deforestation and severe droughts in the early 1970s. It is concluded that despite laudable attempts to instigate soil conservation measures, it is unlikely that in Kenya there will be a sustainable reduction in soil erosion without a significant improvement in socio-economic conditions.

  6. Thermogenic or biogenic methane? Interpreting negative isotopic excursion during Oceanic Anoxic Events using atmospheric pCO2 records from fossil plant stomata.

    NASA Astrophysics Data System (ADS)

    McElwain, J. C.; Hesselbo, S. P.; Murphy, J. W.

    2005-12-01

    Oceanic anoxic events (OAE) are characterized by carbon-isotope excursions in marine and terrestrial reservoirs and mass extinction of marine faunas. Deceiphering between multiple possible causal mechanisms for these negative isotopic excursion may help to determine the triggering mechanism of OAE's - currently a subject of much debate. We have tested two leading hypotheses for an abrupt negative carbon isotopic excursion marking initiation of the Toarcian OAE (~183 myr ago) using a high-resolution atmospheric carbon dioxide (pCO2) record obtained from changes in stomatal frequency on fossil leaves preserved within nearshore sediments of the Sorthat Formation (formerly Bag) in the eastern Danish Basin. The data reveal that the negative carbon isotopic excursion was coincident with a pCO2 drawdown of 350 +/- 100 ppmV and 2.5 oC global cooling followed by an abrupt 1200 +/- 400 ppmV pCO2 increase and 6.5 +/- 1oC inferred greenhouse warming. The detected CO2 draw-down and inferred global cooling occur coincidently with a second order mass extinction of marine organisms, suggesting a possible additional extinction mechanism to marine anoxia. The pattern and magnitude of CO2 change are not consistent with catastrophic input of isotopically light methane from methane hydrates as the cause of the negative isotopic signal. Our pCO2 record better supports a magma-intrusion hypothesis and suggest that a massive injection of isotopically light carbon from release of thermogenic methane (CH4) occurred due to the intrusion of Gondwanan coals by Toarcian aged Karoo-Ferrar dolerites. We propose that CH4/CO2 generation associated with Karoo-Ferrar magmatism was an important triggering mechanism for the Toarcian OAE.

  7. 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

    2015-01-01

    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. PMID:26623859

  8. Biogeographic distribution and metric dental variation of fossil and living orangutans (Pongo spp.).

    PubMed

    Tshen, Lim Tze

    2016-01-01

    The genus Pongo has a relatively richer Quaternary fossil record than those of the African great apes. Fossil materials are patchy in terms of anatomical parts represented, limited almost exclusively to isolated teeth, jaw and bone fragments. Fossil evidence indicates that the genus Pongo had a broadly continuous distribution across the southern part of the Indomalayan biogeographic region, ranging in time from Early Pleistocene to Holocene: southern China (77 fossil sites), Vietnam (15), Laos (6), Cambodia (2), Thailand (4), Peninsular Malaysia (6), Sumatra (4), Borneo (6) and Java (4). Within this distribution range, there are major geographical gaps with no known orangutan fossils, notably central and southern Indochina, central and southern Thailand, eastern Peninsular Malaysia, northern and southern Sumatra, and Kalimantan. The geological time and place of origin of the genus remain unresolved. Fossil orangutan assemblages usually show greater extent of dental metrical variation than those of modern-day populations. Such variability shown in prehistoric populations has partially contributed to confusion regarding past taxonomic diversity and systematic relationships among extinct and living forms. To date, no fewer than 14 distinct taxa have been identified and named for Pleistocene orangutans. Clear cases suggestive of predation by prehistoric human are few in number, and limited to terminal Pleistocene-Early Holocene sites in Borneo and a Late Pleistocene site in Vietnam. PMID:26424147

  9. Records of human activity during the late-Holocene in the soils of the African dense humid forest

    NASA Astrophysics Data System (ADS)

    Morin-Rivat, Julie; Bentaleb, Ilham; Biwolé, Achille; Bourland, Nils; Bremond, Laurent; Daïnou, Kasso; Fayolle, Adeline; Gillet, Jean-François; Gorel, Anaïs; Gourlet-Fleury, Sylvie; Hardy, Olivier; Livingstone Smith, Alexandre; Oslisly, Richard; Vleminckx, Jason; Beeckman, Hans; Doucet, Jean-Louis

    2014-05-01

    Recently, several authors gathered data about the presence of past human populations in tropical regions covered by dense forest nowadays. In Central Africa, there is a growing body of evidence for past human settlements along the Atlantic coast, but very little information is available further inland. In the perspective, soil records seem to be the most appropriated so as to appraise the spatial and temporal extent of human activity in the African dense humid forest. In this paper, we thus aimed to present a synthesis of the archaeological and archaeobotanical data obtained during several fieldwork campaigns in an archaeologically unexplored area of 200,000 km² located in southern Cameroon and the northern Republic of Congo. A total of 275 test pits, among them 30 pedological pits up to 150 cm deep, were excavated in the study area. So as to get a long temporal scale as well as a fine resolution spatial scale, we quantified wood charcoal and charred endocarps in soil samples by layers of 10 cm taken for 100 pits located along transects of systematic sampling. Spatial projections were performed using statistics together with multivariate analyses. AMS radiocarbon dating allowed interpreting the temporal framework. Evidence of past human activities through either artifacts or charred botanical remains was observed in all pits, in particular with the ubiquitous presence of charcoal at each site. Main charcoal peaks were interpreted as fields (slash-and-burn agriculture) in the vicinity of ancient villages, the later marked by the presence of both potsherds and oil palm endocarps. The dichotomy of these kinds of activities may have impacted differentially the environment during the past. The set of 73 radiocarbon dates extending from 15,000 BP to the present time provided more dates in the late-Holocene showing a bimodal distribution which was interpreted as two phases of human expansion with an intermediate phase of population crash. The 2300-1300 BP phase is correlated with the migrations of supposed farming populations from northwestern Cameroon. Between 1300 and 670 BP, less material could be dated. Following that population collapse, the 670-20 BP phase corresponds to a new period of human expansion known as the Late Iron Age. The dates obtained support the established chronology reported for whole Central Africa. This study underlines the necessity of fieldwork efforts and of the usefulness of archives sealed in soil records so as to bring new, extensive and precise evidence of human activities in the Congo Basin.

  10. Evolution and the Fossil Record

    E-print Network

    Kammer, Thomas

    of evolutionary change. (The other mechanism, a destructive force, is mass extinction.) · Charles Darwin, 1859;Charles Darwin in 1837, age 28, after voyage of the HMS Beagle #12;Age 40 Age 45 #12;Darwin in 1879, age 70. #12;#12;#12;One of the most famous books of science. #12;Darwin's home, Down House, in England

  11. 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…

  12. The oldest African bat from the early Eocene of El Kohol (Algeria)

    NASA Astrophysics Data System (ADS)

    Ravel, Anthony; Marivaux, Laurent; Tabuce, Rodolphe; Adaci, Mohammed; Mahboubi, Mohammed; Mebrouk, Fateh; Bensalah, Mustapha

    2011-05-01

    The Afro-Arabian Paleogene fossil record of Chiroptera is very poor. In North Africa and Arabia, this record is limited, thus far, to a few localities mainly in Tunisia (Chambi, late early Eocene), Egypt (Fayum, late Eocene to early Oligocene), and Sultanate of Oman (Taqah, early Oligocene). It consists primarily of isolated teeth or mandible fragments. Interestingly, these African fossil bats document two modern groups (Vespertilionoidea and Rhinolophoidea) from the early Eocene, while the bat fossil record of the same epoch of North America, Eurasia, and Australia principally includes members of the "Eochiroptera." This paraphyletic group contains all primitive microbats excluding modern families. In Algeria, the region of Brezina, southeast of the Atlas Mountains, is famous for the early Eocene El Kohol Formation, which has yielded one of the earliest mammalian faunas of the African landmass. Recent fieldwork in the same area has led to the discovery of a new vertebrate locality, including isolated teeth of Chiroptera. These fossils represent the oldest occurrence of Chiroptera in Africa, thus extending back the record of the group to the middle early Eocene (Ypresian) on that continent. The material consists of an upper molar and two fragments of lower molars. The dental character association matches that of "Eochiroptera." As such, although very fragmentary, the material testifies to the first occurrence of "Eochiroptera" in Algeria, and by extension in Africa. This discovery demonstrates that this basal group of Chiroptera had a worldwide distribution during the early Paleogene.

  13. Fossil legumes from the Middle Eocene (46.0 Ma) Mahenge Flora of Singida, Tanzania.

    PubMed

    Herendeen, P S; Jacobs, B F

    2000-09-01

    Middle Eocene age caesalpinioid and mimosoid legume leaves are reported from the Mahenge site in north-central Tanzania. The Mahenge flora complements a sparse Paleogene tropical African fossil plant record, which until now consisted of a single macrobotanical assemblage, limited palynological studies in West Africa and Egypt, and fossil wood studies primarily from poorly dated deposits. Mahenge leaf macrofossils have the potential to add significantly to what is known of the evolutionary history of extant African plant groups and to expand our currently limited knowledge of African Paleogene environments. The site is associated with a kimberlite eruption and demonstrates the potential value of kimberlite-associated lake deposits as much-needed resources for African Paleogene floras. In this report we document a relatively diverse component of the flora consisting of the leaves of at least five species of Leguminosae. A new species of the extant genus Acacia (Mimosoideae), described herein, is represented by a bipinnate leaf. Another taxon is described as a new species of the extant genus Aphanocalyx (Caesalpinioideae), and a third leaf type may be related to the extant genus Cynometra (Caesalpinioideae). Two additional leaf types are less well understood: one appears to be referable to the Caesalpinioideae and subfamily affinities of the other taxon are unknown. PMID:10991905

  14. Cretaceous African life captured in amber

    PubMed Central

    Schmidt, Alexander R.; Perrichot, Vincent; Svojtka, Matthias; Anderson, Ken B.; Belete, Kebede H.; Bussert, Robert; Dörfelt, Heinrich; Jancke, Saskia; Mohr, Barbara; Mohrmann, Eva; Nascimbene, Paul C.; Nel, André; Nel, Patricia; Ragazzi, Eugenio; Roghi, Guido; Saupe, Erin E.; Schmidt, Kerstin; Schneider, Harald; Selden, Paul A.; Vávra, Norbert

    2010-01-01

    Amber is of great paleontological importance because it preserves a diverse array of organisms and associated remains from different habitats in and close to the amber-producing forests. Therefore, the discovery of amber inclusions is important not only for tracing the evolutionary history of lineages with otherwise poor fossil records, but also for elucidating the composition, diversity, and ecology of terrestrial paleoecosystems. Here, we report a unique find of African amber with inclusions, from the Cretaceous of Ethiopia. Ancient arthropods belonging to the ants, wasps, thrips, zorapterans, and spiders are the earliest African records of these ecologically important groups and constitute significant discoveries providing insight into the temporal and geographical origins of these lineages. Together with diverse microscopic inclusions, these findings reveal the interactions of plants, fungi and arthropods during an epoch of major change in terrestrial ecosystems, which was caused by the initial radiation of the angiosperms. Because of its age, paleogeographic location and the exceptional preservation of the inclusions, this fossil resin broadens our understanding of the ecology of Cretaceous woodlands. PMID:20368427

  15. First Miocene rodent from Lebanon provides the 'missing link' between Asian and African gundis (Rodentia: Ctenodactylidae)

    PubMed Central

    López-Antoñanzas, Raquel; Knoll, Fabien; Maksoud, Sibelle; Azar, Dany

    2015-01-01

    Ctenodactylinae (gundis) is a clade of rodents that experienced, in Miocene time, their greatest diversification and widest distribution. They expanded from the Far East, their area of origin, to Africa, which they entered from what would become the Arabian Peninsula. Questions concerning the origin of African Ctenodactylinae persist essentially because of a poor fossil record from the Miocene of Afro-Arabia. However, recent excavations in the Late Miocene of Lebanon have yielded a key taxon for our understanding of these issues. Proafricanomys libanensis nov. gen. nov. sp. shares a variety of dental characters with both the most primitive and derived members of the subfamily. A cladistic analysis demonstrates that this species is the sister taxon to a clade encompassing all but one of the African ctenodactylines, plus a southern European species of obvious African extraction. As such, Proafricanomys provides the 'missing link' between the Asian and African gundis. PMID:26250050

  16. Eocene primates of South America and the African origins of New World monkeys

    NASA Astrophysics Data System (ADS)

    Bond, Mariano; Tejedor, Marcelo F.; Campbell, Kenneth E.; Chornogubsky, Laura; Novo, Nelson; Goin, Francisco

    2015-04-01

    The platyrrhine primates, or New World monkeys, are immigrant mammals whose fossil record comes from Tertiary and Quaternary sediments of South America and the Caribbean Greater Antilles. The time and place of platyrrhine origins are some of the most controversial issues in primate palaeontology, although an African Palaeogene ancestry has been presumed by most primatologists. Until now, the oldest fossil records of New World monkeys have come from Salla, Bolivia, and date to approximately 26 million years ago, or the Late Oligocene epoch. Here we report the discovery of new primates from the ?Late Eocene epoch of Amazonian Peru, which extends the fossil record of primates in South America back approximately 10 million years. The new specimens are important for understanding the origin and early evolution of modern platyrrhine primates because they bear little resemblance to any extinct or living South American primate, but they do bear striking resemblances to Eocene African anthropoids, and our phylogenetic analysis suggests a relationship with African taxa. The discovery of these new primates brings the first appearance datum of caviomorph rodents and primates in South America back into close correspondence, but raises new questions about the timing and means of arrival of these two mammalian groups.

  17. Metamorphic record and Thermo-mechanical modelling of lower crust exhumation during the Palaeoproterozoic Eburnean orogeny, West African Craton

    NASA Astrophysics Data System (ADS)

    Gerbault, Muriel; Ganne, Jerome; Block, Sylvain

    2014-05-01

    A thermo-mechanical interpretation of the metamorphic evolution of moderate- to high-pressure volcano-sedimentary rocks (6-8 to >10 Kb) in the Birimian Province (2.2-2.0 Ga) of the West African Craton is explored in terms of burial and exhumation processes. Metamorphic data collected in Burkina Faso, southwest Ghana and eastern Senegal suggest that during the Eburnean orogeny (~2.1 Ga),this Palaeoproterozoic Birimian crust was dominated by moderate apparent geothermal gradients of 20-30°C/km (M2a), that produced greenschist- to amphibolite-facies metamorphic assemblages associated with regional shortening and granitoid intrusions. The M2a gradient is superimposed on a colder thermal regime (M1 : <10-15 °C/km) that produced high-P greenschist- to blueschist-facies metamorphic assemblages, and which most likely recorded the earlier formation of the protolith. The geodynamical origin of M1 is not directly addressed here. Thermo-mechanical two-dimensional numerical models were built in order to test whether late-stage compressional tectonics could generate the exhumation of meta-sediments, collected in Ca0-poor granitoids and which record elevated metamorphic pressures (P> 6-8 Kb). The poor data quality provide limited constraints on the appropriate initial setup conditions, and a number of tests have led us to conceptualize the spatial distribution of a hypothezised succession of volcanic island arcs emplaced on top of CaO rich TTG (Tonalite- Trondjhemite-Granodiorite suites) basement, tectonically paired with sedimentary basins. We postulated therefore the preexistence of wide (about 250 km) and thick flexural sedimentary basins (depth 15 km) in an orogenic mafic crust (about 20 km thick), underplated by a more felsic and lighter layer representing a TTG melange. The numerical results show that a mechanism of burial, heating and exhumation of meta-sediments can occur by simultaneous folding and gravitational instabilities within the broad extent of the basin, provided the conversion rate is slow enough, and the basin is weak and thick enough. At around 25 km depth and after about 30 Myrs of compression at a rate of 5mm/yr, the TTG layer has deepened enough to reach appropriate PT conditions for melting. The buoyant and low-viscosity partially molten material (comprising a fraction of CaO-poor melt and residual material) then ascends through the overlying sediments, and entrains upwards lower crustal material as well as the surrounding sediments up, to about 10 km depth, and over the ~200 km width of the basin. This scenario explains the important breaks in metamorphic conditions observed in the Birimian province between the thin slivers (< 2 km thick) of high-pressure rocks (P> 8 Kb) preserved in the thermal aureoles of granites, and the adjacent greenstones synforms, which consist of low-grade metasediments (P< 6 Kb; T< 450°C). This scenario is consistent with a significant recycling of the TTGs in the genesis of CaO-poor granitoid melts. Although we cannot model the subsequent evolution, we propose that further exhumation to the surface occurred by transcurrent motion. In the discussion about the implications of our results on the tectono-metamorphic and mechanical evolution of Palaeoproterozoic orogenies, the question rises as to whether an external change in far-field boundary motion or increasing internal driving forces triggered this transcurrent motion, that ended the Eburnean orogeny.

  18. Phytogeographical Implication of Bridelia Will. (Phyllanthaceae) Fossil Leaf from the Late Oligocene of India

    PubMed Central

    Srivastava, Gaurav; Mehrotra, R.C.

    2014-01-01

    Background The family Phyllanthaceae has a predominantly pantropical distribution. Of its several genera, Bridelia Willd. is of a special interest because it has disjunct equally distributed species in Africa and tropical Asia i.e. 18–20 species in Africa-Madagascar (all endemic) and 18 species in tropical Asia (some shared with Australia). On the basis of molecular phylogenetic study on Bridelia, it has been suggested that the genus evolved in Southeast Asia around 33±5 Ma, while speciation and migration to other parts of the world occurred at 10±2 Ma. Fossil records of Bridelia are equally important to support the molecular phylogenetic studies and plate tectonic models. Results We describe a new fossil leaf of Bridelia from the late Oligocene (Chattian, 28.4–23 Ma) sediments of Assam, India. The detailed venation pattern of the fossil suggests its affinities with the extant B. ovata, B. retusa and B. stipularis. Based on the present fossil evidence and the known fossil records of Bridelia from the Tertiary sediments of Nepal and India, we infer that the genus evolved in India during the late Oligocene (Chattian, 28.4–23 Ma) and speciation occurred during the Miocene. The stem lineage of the genus migrated to Africa via “Iranian route” and again speciosed in Africa-Madagascar during the late Neogene resulting in the emergence of African endemic clades. Similarly, the genus also migrated to Southeast Asia via Myanmar after the complete suturing of Indian and Eurasian plates. The emergence and speciation of the genus in Asia and Africa is the result of climate change during the Cenozoic. Conclusions On the basis of present and known fossil records of Bridelia, we have concluded that the genus evolved during the late Oligocene in northeast India. During the Neogene, the genus diversified and migrated to Southeast Asia via Myanmar and Africa via “Iranian Route”. PMID:25353345

  19. Archean Molecular Fossils and the Early Rise of Eukaryotes

    E-print Network

    Brocks, Jochen J.

    Archean Molecular Fossils and the Early Rise of Eukaryotes Jochen J. Brocks,1,2 * Graham A. Logan,2 evidence for the existence of eukaryotes 500 million to 1 billion years before the extant fossil record

  20. Earliest and first Northern Hemispheric hoatzin fossils substantiate Old World origin of a "Neotropic endemic"

    NASA Astrophysics Data System (ADS)

    Mayr, Gerald; De Pietri, Vanesa L.

    2014-02-01

    The recent identification of hoatzins (Opisthocomiformes) in the Miocene of Africa showed part of the evolution of these birds, which are now only found in South America, to have taken place outside the Neotropic region. Here, we describe a new fossil species from the late Eocene of France, which constitutes the earliest fossil record of hoatzins and the first one from the Northern Hemisphere. Protoazin parisiensis gen. et sp. nov. is more closely related to South American Opisthocomiformes than the African taxon Namibiavis and substantiates an Old World origin of hoatzins, as well as a relictual distribution of the single extant species. Although recognition of hoatzins in Europe may challenge their presumed transatlantic dispersal, there are still no North American fossils in support of an alternative, Northern Hemispheric, dispersal route. In addition to Opisthocomiformes, other avian taxa are known from the Cenozoic of Europe, the extant representatives of which are only found in South America. Recognition of hoatzins in the early Cenozoic of Europe is of particular significance because Opisthocomiformes have a fossil record in sub-Saharan Africa, which supports the hypothesis that extinction of at least some of these "South American" groups outside the Neotropic region was not primarily due to climatic factors.

  1. 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)

  2. 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.

  3. Fossil evidence of the zygomycetous fungi

    E-print Network

    Krings, Michael; Taylor, Thomas N.; Dotzler, Nora

    2013-02-18

    with the extant Rhizopus nigricans. Subsequent workers, however, have regarded the casts as indeterminable (e.g., Olsen & Baird 1990). CONCLUDING REMARKS There is an extraordinary abundance of fungal remains in the fossil record. However, systematic studies...

  4. Mid-Miocene to Pleistocene Radiolarian fossil record from IODP Expedition 346: Faunal response to the global climatic changes and local/regional tectonics

    NASA Astrophysics Data System (ADS)

    Itaki, T.; Motoyama, I.; Kamikuri, S.; Tada, R.; Murray, R. W.; Alvarez Zarikian, C. A.

    2014-12-01

    It is well known that radiolarian fossils can be used as a geological tool for the age assignment and paleoceanographic reconstruction. In this study, we analyzed radiolarian fossils for seven drilled sites of IODP Exp. 346 from the Japan, Yamato and Ulleung (JYU) basins in a marginal sea of the mid-latitude NW Pacific. Significant variations of the well-preserved fossil assemblage imply that the unique oceanic circulation changes in the basins through Mid-Miocene to Pleistocene might be controlled by global climatic changes and topographic changes with local/regional tectonics. Warm water radiolarians Dictyocoryne spp. and Tetrapyle spp. characterized in the Tsushima Current water occurred commonly since 1.7 Ma suggesting a beginning of the warm water inflow from the southern strait of the basins. It might be coincident with an opening of the Okinawa Trough in the East China Sea. On the other hand, during the Pliocene period, sporadic occurrence of the warm water species was recognized in southern part of the examined area. This implies that a minor influence of the warm water was present in the southern coastal area of the Yamato Basin. Typical deep dwelling species such as Cornutella profunda and Peripyramis circumtexta is absent in the present JYU basins, however they occurred frequently during Pliocene and Miocene. This suggests the deep-water exchange between the JYU basins and the North Pacific via the deeper strait, which might be present in the northern part of the sea. These deep-water radiolarians disappeared from the JYU basins at the early Pleistocene (~2.7 Ma to 1.7 Ma), which is almost coincident with the Northern Hemisphere Glaciation.

  5. "Small size" in the Philippine human fossil record: is it meaningful for a better understanding of the evolutionary history of the negritos?

    PubMed

    Détroit, Florent; Corny, Julien; Dizon, Eusebio Z; Mijares, Armand S

    2013-01-01

    "Pygmy populations" are recognized in several places over the world, especially in Western Africa and in Southeast Asia (Philippine "negritos," for instance). Broadly defined as "small-bodied Homo sapiens" (compared with neighboring populations), their origins and the nature of the processes involved in the maintenance of their phenotype over time are highly debated. Major results have been recently obtained from population genetics on present-day negrito populations, but their evolutionary history remains largely unresolved. We present and discuss the Upper Pleistocene human remains recovered from Tabon Cave and Callao Cave in the Philippines, which are potentially highly relevant to these research questions. Human fossils have been recovered in large numbers from Tabon Cave (Palawan Island) but mainly from reworked and mixed sediments from several archaeological layers. We review and synthesize the long and meticulous collaborative work done on the archives left from the 1960s excavations and on the field. The results demonstrate the long history of human occupations in the cave, since at least ~30,000 BP. The examination of the Tabon human remains shows a large variability: large and robust for one part of the sample, and small and gracile for the other part. The latter would fit quite comfortably within the range of variation of Philippine negritos. Farther north, on Luzon Island, the human third metatarsal recently recovered from Callao Cave and dated to ~66,000 BP is now the oldest direct evidence of human presence in the Philippines. Previous data show that, compared with H. sapiens (including Philippine negritos), this bone presents a very small size and several unusual morphological characteristics. We present a new analytical approach using three-dimensional geometric morphometrics for comparing the Callao fossil to a wide array of extant Asian mammals, including nonhuman primates and H. sapiens. The results demonstrate that the shape of the Callao metatarsal is definitely closer to humans than to any other groups. The fossil clearly belongs to the genus Homo; however, it remains at the margin of the variation range of H. sapiens. Because of its great antiquity and the presence of another diminutive species of the genus Homo in the Wallace area during this time period (H. floresiensis), we discuss here in detail the affinities and potential relatedness of the Callao fossil with negritos that are found today on Luzon Island. PMID:24297220

  6. Himalayan fossils of the oldest known pantherine establish ancient origin of big cats

    PubMed Central

    Tseng, Z. Jack; Wang, Xiaoming; Slater, Graham J.; Takeuchi, Gary T.; Li, Qiang; Liu, Juan; Xie, Guangpu

    2014-01-01

    Pantherine felids (‘big cats’) include the largest living cats, apex predators in their respective ecosystems. They are also the earliest diverging living cat lineage, and thus are important for understanding the evolution of all subsequent felid groups. Although the oldest pantherine fossils occur in Africa, molecular phylogenies point to Asia as their region of origin. This paradox cannot be reconciled using current knowledge, mainly because early big cat fossils are exceedingly rare and fragmentary. Here, we report the discovery of a fossil pantherine from the Tibetan Himalaya, with an age of Late Miocene–Early Pliocene, replacing African records as the oldest pantherine. A ‘total evidence’ phylogenetic analysis of pantherines indicates that the new cat is closely related to the snow leopard and exhibits intermediate characteristics on the evolutionary line to the largest cats. Historical biogeographic models provide robust support for the Asian origin of pantherines. The combined analyses indicate that 75% of the divergence events in the pantherine lineage extended back to the Miocene, up to 7 Myr earlier than previously estimated. The deeper evolutionary origin of big cats revealed by the new fossils and analyses indicate a close association between Tibetan Plateau uplift and diversification of the earliest living cats. PMID:24225466

  7. A Review of New and Anticipated High-Resolution Paleoclimate Records from the East African Rift System and Their Implications for Hominin Evolution and Demography

    NASA Astrophysics Data System (ADS)

    Cohen, A. S.

    2014-12-01

    Our understanding of Late Tertiary/Quaternary climate and environmental history in East Africa has, to date, largely been based on outcrop and marine drill core records. Although these records have proven extremely valuable both in reconstructing environmental change and placing human evolution in an environmental context, their quality is limited by resolution, continuity, uncertainties about superposition and outcrop weathering. To address this problem, long drill core records from extant ancient lakes and lake beds are being collected by several research groups. Long cores (up to 100s of m.) from basin depocenters in both the western and eastern rifts are now available spanning nearly the entire latitudinal range of the East Africa Rift. This network of core records, especially when coupled with outcrop data, is providing an opportunity to compare the nature of important global climate transitions (especially glacial/interglacial events and precessional cycles) across the continent, thereby documenting regional heterogeneity in African climate history. Understanding this heterogeneity is critical for realistically evaluating competing hypotheses of environmental forcing of human evolution, and especially ideas about the dispersal of anatomically modern humans out of Africa in the early Late Pleistocene. In particular, understanding the hydrological and paleoecological history of biogeographic corridors linking eastern Africa, the Nile River Valley and the Levant is likely to be vastly improved through comparative analysis of these new drill cores over the next few years. Because we do not a priori know the primary forcing factors affecting this environmental history, it will essential to develop the best possible age models, employing multiple and novel geochronometric tools to make these comparisons.

  8. Southern African Phanerozoic marine invertebrates: Biogeography, pal?oecology, climatology and comments on adjacent regions

    NASA Astrophysics Data System (ADS)

    Boucot, A. J.

    The Palaeozoic marine invertebrate fossil record in southern Africa is characterised by extensive data for the Early and Middle Devonian but extremely limited or absent for other Palaeozoic Periods. The Mesozoic Era is lacking in marine invertebrate fossils for the Triassic, Late Jurassic, and Cretaceous. For the Cenozoic Era there is limited marine megafossil information. Overall, in benthic, cool waters, Palaeozoic, marine megafossils from southern Africa appear to represent relatively low diversity communities, when compared to ecologically comparable warm water environments elsewhere. However, the marine benthic Cretaceous and Cenozoic faunas of southwestern Africa are typically diverse warm water types, until the later Miocene when cool waters again prevailed. The Benguela Current clearly influenced lower diversity faunas. Climatically, it can be inferred from the marine megabenthic pal?ontological evidence, thatwarm conditions were present from Early Cambrian until mid-Ordovician times, followed by a much cooler climate that persisted well into the Middle Devonian. The Late Palaeozoic evidence thus indicates cool to cold conditions. In contrast, the Late Permian fossils are consistent with warmer conditions, continuing through Late Jurassic and Cretaceous times along the East African and West African coasts, until the Late Miocene. Within the Gondwanan framework, a Central African region can be envisaged that was subject to non-marine conditions during the entire Phanerozoic Eon. Peripheral to this central African region were marine environments of various ages. The geological history of these peripheral regions was fairly unique. Some features in southern Africa are similar of those found in the Paraná Basin and the Falkland Islands. Most of North Africa from central Senegal to Libya contains a Phanerozoic marine cover extending from the Early Cambrian through to the Carboniferous, characterised by warm water faunas, except for the Ordovician which yields cool-cold water faunas. The Palaeozoic of Arabia, which was an integral part of Africa until the Miocene, has yieldedwarm water fossils.

  9. The middle Holocene climatic records from Arabia: Reassessing lacustrine environments, shift of ITCZ in Arabian Sea, and impacts of the southwest Indian and African monsoons

    NASA Astrophysics Data System (ADS)

    Enzel, Yehouda; Kushnir, Yochanan; Quade, Jay

    2015-06-01

    A dramatic increase in regional summer rainfall amount has been proposed for the Arabian Peninsula during the middle Holocene (ca. 9-5 ka BP) based on lacustrine sediments, inferred lake levels, speleothems, and pollen. This rainfall increase is considered primarily the result of an intensified Indian summer monsoon as part of the insolation-driven, northward shift of the boreal summer position of the Inter-Tropical Convergence Zone (ITCZ) to over the deserts of North Africa, Arabia, and northwest India. We examine the basis for the proposed drastic climate change in Arabia and the shifts in the summer monsoon rains, by reviewing paleohydrologic lacustrine records from Arabia. We evaluate and reinterpret individual lake-basin status regarding their lacustrine-like deposits, physiography, shorelines, fauna and flora, and conclude that these basins were not occupied by lakes, but by shallow marsh environments. Rainfall increase required to support such restricted wetlands is much smaller than needed to form and maintain highly evaporating lakes and we suggest that rainfall changes occurred primarily at the elevated edges of southwestern, southern, and southeastern Arabian Peninsula. These relatively small changes in rainfall amounts and local are also supported by pollen and speleothems from the region. The changes do not require a northward shift of the Northern Hemisphere summer ITCZ and intensification of the Indian monsoon rainfall. We propose that (a) latitudinal and slight inland expansion of the North African summer monsoon rains across the Red Sea, and (b) uplifted moist air of this monsoon to southwestern Arabia highlands, rather than rains associated with intensification of Indian summer monsoon, as proposed before, increased rains in that region; these African monsoon rains produced the modest paleo-wetlands in downstream hyperarid basins. Furthermore, we postulate that as in present-day, the ITCZ in the Indian Ocean remained at or near the equator all year round, and the Indian summer monsoon, through dynamically induced air subsidence, can reduce rather than enhance summer rainfall in the Levant and neighboring deserts, including Arabia. Our summary suggests a widening to the north of the latitudinal range of the rainfall associated with the North African summer monsoon moisture crossing the Red Sea to the east. We discuss other mechanisms that could have potentially contributed to the formation and maintaining of the modest paleo-wetlands.

  10. 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.

  11. Innovative tephra studies in the East African Rift System

    NASA Astrophysics Data System (ADS)

    WoldeGabriel, Giday; Hart, William K.; Heiken, Grant

    Geosciences investigations form the foundation for paleoanthropological research in the East African Rift System. However, innovative applications of tephra studies for constraining spatial and temporal relations of diverse geological processes, biostratigraphic records, and paleoenvironmental conditions within the East African Rift System were fueled by paleoanthropological investigations into the origin and evolution of hominids and material culture. Tephra is a collective, size-independent term used for any material ejected during an explosive volcanic eruption.The East African Rift System has become a magnet for paleoanthropological research ever since the discovery of the first hominids at Olduvai Gorge, in Tanzania, in the 1950s [Leakey et al., 1961]. Currently, numerous multidisciplinary scientific teams from academic institutions in the United States and Western Europe make annual pilgrimages for a couple of months to conduct paleoanthropological field research in the fossil-rich sedimentary deposits of the East African Rift System in Ethiopia, Kenya, and Tanzania. The field expedition consists of geological, paleontological, archaeological, and paleoenvironmental investigations.

  12. History of Animals using Isotope Records (HAIR): a 6-year dietary history of one family of African elephants.

    PubMed

    Cerling, Thure E; Wittemyer, George; Ehleringer, James R; Remien, Christopher H; Douglas-Hamilton, Iain

    2009-05-19

    The dietary and movement history of individual animals can be studied using stable isotope records in animal tissues, providing insight into long-term ecological dynamics and a species niche. We provide a 6-year history of elephant diet by examining tail hair collected from 4 elephants in the same social family unit in northern Kenya. Sequential measurements of carbon, nitrogen, and hydrogen isotope rations in hair provide a weekly record of diet and water resources. Carbon isotope ratios were well correlated with satellite-based measurements of the normalized difference vegetation index (NDVI) of the region occupied by the elephants as recorded by the global positioning system (GPS) movement record; the absolute amount of C(4) grass consumption is well correlated with the maximum value of NDVI during individual wet seasons. Changes in hydrogen isotope ratios coincided very closely in time with seasonal fluctuations in rainfall and NDVI whereas diet shifts to relatively high proportions of grass lagged seasonal increases in NDVI by approximately 2 weeks. The peak probability of conception in the population occurred approximately 3 weeks after peak grazing. Spatial and temporal patterns of resource use show that the only period of pure browsing by the focal elephants was located in an over-grazed, communally managed region outside the protected area. The ability to extract time-specific longitudinal records on animal diets, and therefore the ecological history of an organism and its environment, provides an avenue for understanding the impact of climate dynamics and land-use change on animal foraging behavior and habitat relations. PMID:19365077

  13. History of Animals using Isotope Records (HAIR): A 6-year dietary history of one family of African elephants

    PubMed Central

    Cerling, Thure E.; Wittemyer, George; Ehleringer, James R.; Remien, Christopher H.; Douglas-Hamilton, Iain

    2009-01-01

    The dietary and movement history of individual animals can be studied using stable isotope records in animal tissues, providing insight into long-term ecological dynamics and a species niche. We provide a 6-year history of elephant diet by examining tail hair collected from 4 elephants in the same social family unit in northern Kenya. Sequential measurements of carbon, nitrogen, and hydrogen isotope rations in hair provide a weekly record of diet and water resources. Carbon isotope ratios were well correlated with satellite-based measurements of the normalized difference vegetation index (NDVI) of the region occupied by the elephants as recorded by the global positioning system (GPS) movement record; the absolute amount of C4 grass consumption is well correlated with the maximum value of NDVI during individual wet seasons. Changes in hydrogen isotope ratios coincided very closely in time with seasonal fluctuations in rainfall and NDVI whereas diet shifts to relatively high proportions of grass lagged seasonal increases in NDVI by ?2 weeks. The peak probability of conception in the population occurred ?3 weeks after peak grazing. Spatial and temporal patterns of resource use show that the only period of pure browsing by the focal elephants was located in an over-grazed, communally managed region outside the protected area. The ability to extract time-specific longitudinal records on animal diets, and therefore the ecological history of an organism and its environment, provides an avenue for understanding the impact of climate dynamics and land-use change on animal foraging behavior and habitat relations. PMID:19365077

  14. A comparison of antemortem tooth loss in human hunter-gatherers and non-human catarrhines: implications for the identification of behavioral evolution in the human fossil record.

    PubMed

    Gilmore, Cassandra C

    2013-06-01

    Middle and Late Pleistocene fossil hominin specimens with severe antemortem tooth loss are often regarded as evidence for the precocious evolution of human-like behaviors, such as conspecific care or cooking, in ancient hominin species. The goal of this project was to ask whether the theoretical association between antemortem tooth loss and uniquely human behaviors is supported empirically in a large skeletal sample of human hunter-gatherers, chimpanzees, orangutans, and baboons. Binomial regression modeling in a Bayesian framework allows for the investigation of the effects of tooth class, genus, age, and sex on the likelihood of tooth loss. The results strongly suggest that modern humans experience more antemortem tooth loss than non-human primates and identify age in years as an important predictor. Once age is accounted for, the difference between the humans and the closest non-human genus (chimpanzees) is less pronounced; humans are still more likely on average to experience antemortem tooth loss though 95% uncertainty envelopes around the average prediction for each genus show some overlap. These analyses support theoretical links between antemortem tooth loss and modern human characteristics; humans' significantly longer life history and a positive correlation between age and antemortem tooth loss explain, in part, the reason why humans are more likely to experience tooth loss than non-human primates, but the results do not exclude behavioral differences as a contributing factor. PMID:23640546

  15. A 25 m.y. isotopic record of paleodiet and environmental change from fossil mammals and paleosols from the NE margin

    E-print Network

    and organic matter preserve a proxy record of paleoecology and paleo- climate in terrestrial ecosystems [1 the photosynthetic path- ways associated with C3, C4 and CAM plants that are ingested by mammalian herbivores composition of local meteoric water, which in turn is related to cli- mate (e.g., [1­4]). C3 plants use the C3

  16. Dating the origin of the Orchidaceae from a fossil orchid with its pollinator

    E-print Network

    Pierce, Naomi E.

    LETTERS Dating the origin of the Orchidaceae from a fossil orchid with its pollinator Santiago R , the Orchidaceae lack a definitive fossil record and thus many aspects of their evolutionary history remain obscure both the first unambiguous fossil of Orchidaceae4 and an unpreced- ented direct fossil observation

  17. vol. 164, no. 5 the american naturalist november 2004 Maintenance of Trophic Structure in Fossil Mammal

    E-print Network

    Jernvall, Jukka

    vol. 164, no. 5 the american naturalist november 2004 Maintenance of Trophic Structure in Fossil are difficult to detect in the fossil record, we here used fossil locality coverage to approximate changes environmental change. Ecomor- phological grouping of fossils indicates that herbivore genera have low taxon

  18. The great divides: Ardipithecus ramidus reveals the postcrania of our last common ancestors with African apes.

    PubMed

    Lovejoy, C Owen; Suwa, Gen; Simpson, Scott W; Matternes, Jay H; White, Tim D

    2009-10-01

    Genomic comparisons have established the chimpanzee and bonobo as our closest living relatives. However, the intricacies of gene regulation and expression caution against the use of these extant apes in deducing the anatomical structure of the last common ancestor that we shared with them. Evidence for this structure must therefore be sought from the fossil record. Until now, that record has provided few relevant data because available fossils were too recent or too incomplete. Evidence from Ardipithecus ramidus now suggests that the last common ancestor lacked the hand, foot, pelvic, vertebral, and limb structures and proportions specialized for suspension, vertical climbing, and knuckle-walking among extant African apes. If this hypothesis is correct, each extant African ape genus must have independently acquired these specializations from more generalized ancestors who still practiced careful arboreal climbing and bridging. African apes and hominids acquired advanced orthogrady in parallel. Hominoid spinal invagination is an embryogenetic mechanism that reoriented the shoulder girdle more laterally. It was unaccompanied by substantial lumbar spine abbreviation, an adaptation restricted to vertical climbing and/or suspension. The specialized locomotor anatomies and behaviors of chimpanzees and gorillas therefore constitute poor models for the origin and evolution of human bipedality. PMID:19810199

  19. 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.

  20. Distribution of tetraether lipids in the 25-ka sedimentary record of Lake Challa: extracting reliable TEX86 and MBT/CBT palaeotemperatures from an equatorial African lake

    NASA Astrophysics Data System (ADS)

    Sinninghe Damsté, Jaap S.; Ossebaar, Jort; Schouten, Stefan; Verschuren, Dirk

    2012-09-01

    The distribution of isoprenoid and branched glycerol dialkyl glycerol tetraether (GDGT) lipids was studied in the sedimentary record of Lake Challa, a permanently stratified, partly anoxic crater lake on the southeastern slope of Mt. Kilimanjaro (Kenya/Tanzania), to examine if the GDGTs could be used to reconstruct past variation in regional temperature. The study material comprised 230 samples from a continuous sediment sequence spanning the last 25 ka with excellent age control based on high-resolution AMS 14C dating. The distribution of GDGTs showed large variation through time. In some time intervals (i.e., from 20.4 to 15.9 ka BP and during the Younger Dryas, 12.9-11.7 ka BP) crenarchaeol was the most abundant GDGT, whereas at other times (i.e., during the Early Holocene) branched GDGTs and GDGT-0 were the major GDGT constituents. In some intervals of the sequence the relative abundance of GDGT-0 and GDGT-2 was too high to be derived exclusively from lacustrine Thaumarchaeota, suggesting a sizable contribution from methanogens and other archaea. This severely complicated application of TEX86 palaeothermometry in this lake, and limited reliable reconstruction of lake water temperature to the time interval 25-13 ka BP, i.e. the Last Glacial Maximum and the period of post-glacial warming. The TEX86-inferred timing of this warming is similar to that recorded previously in two of the large African rift lakes, while its magnitude is slightly or much higher than that recorded at these other sites, depending on which lake-based TEX86 calibration is used. Application of calibration models based on distributions of branched GDGTs developed for lakes inferred temperatures of 15-18 °C for the Last Glacial Maximum and 19-22 °C for the Holocene. However, the MBT/CBT palaeothermometer reconstructs temperatures as low as 12 °C for a Lateglacial period centred on 15 ka BP. Variation in down-core values of the BIT index are mainly determined by the varying production rate of crenarchaeol relative to in-situ produced branched GDGTs. The apparent relationship of the BIT index with climatic moisture balance can be explained either by the direct influence of lake level and wind strength on nutrient recycling, or by influx of soil nutrients promoting aquatic productivity and nitrification. This study shows that GDGTs can aid in obtaining climatic information from lake records but that the obtained data should be interpreted with care.

  1. Tree-ring ?18O in African mahogany (Entandrophragma utile) records regional precipitation and can be used for climate reconstructions

    NASA Astrophysics Data System (ADS)

    van der Sleen, Peter; Groenendijk, Peter; Zuidema, Pieter A.

    2015-04-01

    The availability of instrumental climate data in West and Central Africa is very restricted, both in space and time. This limits the understanding of the regional climate system and the monitoring of climate change and causes a need for proxies that allow the reconstruction of paleoclimatic variability. Here we show that oxygen isotope values (?18O) in tree rings of Entandrophragma utile from North-western Cameroon correlate to precipitation on a regional to sub-continental scale (1930-2009). All found correlations were negative, following the proposed recording of the 'amount effect' by trees in the tropics. The capacity of E. utile to record the variability of regional precipitation is also confirmed by the significant correlation of tree-ring ?18O with river discharge data (1944-1983), outgoing longwave radiation (a proxy for cloud cover; 1974-2011) and sea surface salinity in the Gulf of Guinea (1950-2011). Furthermore, the high values in the ?18O chronology from 1970 onwards coincide with the Sahel drought period. Given that E. utile presents clear annual growth rings, has a wide-spread distribution in tropical Africa and is long lived (> 250 years), we argue that the analysis of oxygen isotopes in growth rings of this species is a promising tool for the study of paleoclimatic variability during the last centuries in West and Central Africa.

  2. Fossil-energy program

    NASA Astrophysics Data System (ADS)

    McNeese, L. E.

    1982-01-01

    The increased utilization of coal and other fossil fuel alternatives as sources of clean energy is reported. The projects reported include: coal conversion development, chemical research and development, materials technology, component development and process evaluation, technical support to major liquefaction, process analysis and engineering evaluations, fossil energy environmental analysis, environmental control technology, coal preparation waste utilization, atmospheric fluidized bed coal combustor for cogeneration, TVA FBC demonstration plant program technical support, PFBC systems analysis, FBC char utilization improvement, fossil fuel applications assessments, performance assurance system support for fossil energy projects, international energy technology, generalized equilibrium models for liquid and gaseous fuel supplies, instrumentations and controls and fossil energy information center.

  3. Note on: Considering the Case for Biodiversity Cycles: Reexamining the Evidence for Periodicity in the Fossil Record, by Lieberman and Melott, arXiv preprint 0704.2896

    E-print Network

    M. Omerbashich

    2007-06-09

    Lieberman and Melott built their recent arXiv preprint 0704.2896 on my published paper and (a preprint of) a subsequent comment by Liebermans associate Cornette. But had this group waited for the Cornette comment to actually appear in print together with the expected Reply, they would have learned that his comment exposes Cornettes confusion that likely was due to journal misprint of my figure. Thus 0704.2896 is baseless. Despite receiving the extended Reply with Errata, these authors still fail to recognize that detrending of paleontological records-which they erroneously promote as a must-is an arbitrary rather than a universal operation.

  4. Note on: Considering the Case for Biodiversity Cycles: Reexamining the Evidence for Periodicity in the Fossil Record, by Lieberman and Melott, arXiv preprint 0704.2896

    E-print Network

    Omerbashich, M

    2007-01-01

    Lieberman and Melott built their recent arXiv preprint 0704.2896 on my published paper and (a preprint of) a subsequent comment by Liebermans associate Cornette. But had this group waited for the Cornette comment to actually appear in print together with the expected Reply, they would have learned that his comment exposes Cornettes confusion that likely was due to journal misprint of my figure. Thus 0704.2896 is baseless. Despite receiving the extended Reply with Errata, these authors still fail to recognize that detrending of paleontological records-which they erroneously promote as a must-is an arbitrary rather than a universal operation.

  5. African Retentions in Blues and Jazz.

    ERIC Educational Resources Information Center

    Meadows, Eddie S.

    1979-01-01

    The perseverance of African musical characteristics among American Blacks is an historic reality. African retentions have been recorded in Black music of the antebellum period. Various African scales and rhythms permeate Black American music today as evidenced in the retentions found in blues and jazz. (RLV)

  6. New species and new records of Pterosthetops: eumadicolous water beetles of the South African Cape (Coleoptera, Hydraenidae).

    PubMed

    Bilton, David T

    2014-01-01

    Pterosthetops is one of a number of hydraenid genera endemic to the Cape of South Africa, whose minute moss beetle fauna is amongst the most diverse on earth. Here seven species are described as new: Pterosthetops baini sp. nov., Pterosthetops coriaceus sp. nov., Pterosthetops indwei sp. nov., Ptersothetops pulcherrimus sp. nov., Pterosthetops swartbergensis sp. nov., Pterosthetops tuberculatus sp. nov. and Pterosthetops uitkyki sp. nov., all from mountains in the Western Cape region. New collection records are also provided for all five previously described members of the genus, together with a revised key. Pterosthetops appear to be specialist inhabitants of seepages over rock faces (hygropetric/madicolous habitats), rarely being found outside such situations. PMID:24943181

  7. Continuous 1.3-million-year record of East African hydroclimate, and implications for patterns of evolution and biodiversity

    PubMed Central

    Lyons, Robert P.; Scholz, Christopher A.; Cohen, Andrew S.; King, John W.; Brown, Erik T.; Ivory, Sarah J.; Johnson, Thomas C.; Deino, Alan L.; Reinthal, Peter N.; McGlue, Michael M.; Blome, Margaret W.

    2015-01-01

    The transport of moisture in the tropics is a critical process for the global energy budget and on geologic timescales, has markedly influenced continental landscapes, migratory pathways, and biological evolution. Here we present a continuous, first-of-its-kind 1.3-My record of continental hydroclimate and lake-level variability derived from drill core data from Lake Malawi, East Africa (9–15° S). Over the Quaternary, we observe dramatic shifts in effective moisture, resulting in large-scale changes in one of the world’s largest lakes and most diverse freshwater ecosystems. Results show evidence for 24 lake level drops of more than 200 m during the Late Quaternary, including 15 lowstands when water levels were more than 400 m lower than modern. A dramatic shift is observed at the Mid-Pleistocene Transition (MPT), consistent with far-field climate forcing, which separates vastly different hydroclimate regimes before and after ?800,000 years ago. Before 800 ka, lake levels were lower, indicating a climate drier than today, and water levels changed frequently. Following the MPT high-amplitude lake level variations dominate the record. From 800 to 100 ka, a deep, often overfilled lake occupied the basin, indicating a wetter climate, but these highstands were interrupted by prolonged intervals of extreme drought. Periods of high lake level are observed during times of high eccentricity. The extreme hydroclimate variability exerted a profound influence on the Lake Malawi endemic cichlid fish species flock; the geographically extensive habitat reconfiguration provided novel ecological opportunities, enabling new populations to differentiate rapidly to distinct species. PMID:26644580

  8. Continuous 1.3-million-year record of East African hydroclimate, and implications for patterns of evolution and biodiversity.

    PubMed

    Lyons, Robert P; Scholz, Christopher A; Cohen, Andrew S; King, John W; Brown, Erik T; Ivory, Sarah J; Johnson, Thomas C; Deino, Alan L; Reinthal, Peter N; McGlue, Michael M; Blome, Margaret W

    2015-12-22

    The transport of moisture in the tropics is a critical process for the global energy budget and on geologic timescales, has markedly influenced continental landscapes, migratory pathways, and biological evolution. Here we present a continuous, first-of-its-kind 1.3-My record of continental hydroclimate and lake-level variability derived from drill core data from Lake Malawi, East Africa (9-15° S). Over the Quaternary, we observe dramatic shifts in effective moisture, resulting in large-scale changes in one of the world's largest lakes and most diverse freshwater ecosystems. Results show evidence for 24 lake level drops of more than 200 m during the Late Quaternary, including 15 lowstands when water levels were more than 400 m lower than modern. A dramatic shift is observed at the Mid-Pleistocene Transition (MPT), consistent with far-field climate forcing, which separates vastly different hydroclimate regimes before and after ?800,000 years ago. Before 800 ka, lake levels were lower, indicating a climate drier than today, and water levels changed frequently. Following the MPT high-amplitude lake level variations dominate the record. From 800 to 100 ka, a deep, often overfilled lake occupied the basin, indicating a wetter climate, but these highstands were interrupted by prolonged intervals of extreme drought. Periods of high lake level are observed during times of high eccentricity. The extreme hydroclimate variability exerted a profound influence on the Lake Malawi endemic cichlid fish species flock; the geographically extensive habitat reconfiguration provided novel ecological opportunities, enabling new populations to differentiate rapidly to distinct species. PMID:26644580

  9. 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.

  10. 596 SYSTEMATIC BIOLOGY VOL. 48 of randomly distributed fossil horizons. Paleobiol-

    E-print Network

    Barker, F. Keith

    596 SYSTEMATIC BIOLOGY VOL. 48 of randomly distributed fossil horizons. Paleobiol- ogy 20:459­469. MAXWELL, W. D., AND M. J. BENTON. 1990. Historical tests of the absolute completeness of the fossil record superpositional and phylogenetic patterns: Comparing cladistic patterns with fossil records. Cladistics 8

  11. Fossilized bioelectric wire - the trace fossil Trichichnus

    NASA Astrophysics Data System (ADS)

    K?dzierski, 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. Fossilized bioelectric wire - the trace fossil Trichichnus

    NASA Astrophysics Data System (ADS)

    K?dzierski, 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".

  13. Fossilized bioelectric wire – the trace fossil Trichichnus

    PubMed Central

    K?dzierski, 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

  14. Combining kimberlite (U-Th)/He dating with the mantle xenolith record to decipher elevation change in continental interiors: an example from the southern African Plateau

    NASA Astrophysics Data System (ADS)

    Stanley, J. R.; Flowers, R. M.; Bell, D. R.

    2013-12-01

    Deciphering the patterns and causes of erosion and elevation change histories in continental interiors is commonly not straightforward. Many continental shield regions are repeatedly intruded by small volume kimberlite magmas, which often contain rich xenolith records of the state of the lithosphere and the sedimentary cover at the time of eruption. Here we show that dating kimberlites with apatite (U-Th)/He thermochronometry (AHe), a tool used to constrain thermal histories within the upper 1-3 km of the crust, can tightly bracket the timing of erosion through comparison of cooling dates and eruption ages. Mantle xenoliths from kimberlites erupted at different times also record perturbations to the lithospheric mantle, indicators of changes to the mantle below. The coeval deep and shallow records of kimberlite pipes thus allow the potential to link deep earth processes with the surface response. The southern African Plateau was elevated from sea level to >1000 m elevation in post-Paleozoic time while distal from convergent plate boundaries and with little surface deformation. The timing and mechanisms of surface uplift are debated. AHe data for four kimberlites off the southwestern corner of the Kaapvaal Craton indicate a substantial Mesozoic unroofing episode that was largely completed by 90 Ma. This erosion phase is contemporaneous with significant warming, metasomatism, and thinning of the lithospheric mantle revealed in the peridotite xenoliths and garnet xenocrysts in these same pipes. We suggest that this surface signal is the erosional response to regional, mantle-induced surface uplift. These data also detect a lesser Cenozoic erosion signature in some pipes, focused around a proposed Tertiary paleo-tributary to the Orange River, suggesting that the Cenozoic signal is associated with drainage network evolution rather than long-wavelength surface uplift. Preliminary data from an E-W transect of kimberlites across the Kaapvaal Craton from Kimberley to the Lesotho highlands yields mean AHe dates ~75-85 Ma, suggesting younger Mesozoic unroofing than the off-craton group to the southwest. Together these results suggest an intriguing heterogeneity in unroofing across the plateau. This work demonstrates that combining kimberlite AHe dating with the unique geologic constraints provided by the kimberlite-borne xenoliths can help discern between erosion driven by a variety of processes, including the long wavelength response to deep-seated uplift and the more focused response to paleodrainage evolution.

  15. North African dust and its relation to paleoclimate recorded in a sediment core from Northwest Providence Channel, Bahamas

    SciTech Connect

    Eaton, M.R.; Boardman, M.R.

    1985-01-01

    Studies of the vertical distribution of insoluble residue in an 11.7 meter core recovered from 665m water depth within Northwest Providence Channel, Bahamas demonstrate cyclic fluctuations in the content and mineralogy of the insoluble residue. The insoluble residue consists of chlorite, montmorillonite, illite and kaolinite with alternating layers enriched in chlorite or montmorillonite. These fluctuations in the character of insoluble residue correspond to fluctuations of the record of oxygen isotopes and foraminiferal assemblages (paleoclimate) and of carbonate mineralogy (sea level). During glacial periods, insoluble residue concentration is high, dolomite is present and quartz, plagioclase and chlorite concentrations increase. During interglacial periods, insoluble residue concentration is low, dolomite is absent and quartz, plagioclase and chlorite concentration decreases while montmorillonite concentration increases. The source of the insoluble residue is dust derived from North Africa and transported by the Saharan Air Layer coupled with the Northeast Trades. During glacial periods, the source of the dust is the dolomite-rich southern North Africa region. This shift of the dust source suggests that the trade winds transporting the dust during glacial periods also shifted southward or expanded or both.

  16. Documenting Biogeographical Patterns of African Timber Species Using Herbarium Records: A Conservation Perspective Based on Native Trees from Angola

    PubMed Central

    Romeiras, Maria M.; Figueira, Rui; Duarte, Maria Cristina; Beja, Pedro; Darbyshire, Iain

    2014-01-01

    In many tropical regions the development of informed conservation strategies is hindered by a dearth of biodiversity information. Biological collections can help to overcome this problem, by providing baseline information to guide research and conservation efforts. This study focuses on the timber trees of Angola, combining herbarium (2670 records) and bibliographic data to identify the main timber species, document biogeographic patterns and identify conservation priorities. The study recognized 18 key species, most of which are threatened or near-threatened globally, or lack formal conservation assessments. Biogeographical analysis reveals three groups of species associated with the enclave of Cabinda and northwest Angola, which occur primarily in Guineo-Congolian rainforests, and evergreen forests and woodlands. The fourth group is widespread across the country, and is mostly associated with dry forests. There is little correspondence between the spatial pattern of species groups and the ecoregions adopted by WWF, suggesting that these may not provide an adequate basis for conservation planning for Angolan timber trees. Eight of the species evaluated should be given high conservation priority since they are of global conservation concern, they have very restricted distributions in Angola, their historical collection localities are largely outside protected areas and they may be under increasing logging pressure. High conservation priority was also attributed to another three species that have a large proportion of their global range concentrated in Angola and that occur in dry forests where deforestation rates are high. Our results suggest that timber tree species in Angola may be under increasing risk, thus calling for efforts to promote their conservation and sustainable exploitation. The study also highlights the importance of studying historic herbarium collections in poorly explored regions of the tropics, though new field surveys remain a priority to update historical information. PMID:25061858

  17. Documenting biogeographical patterns of African timber species using herbarium records: a conservation perspective based on native trees from Angola.

    PubMed

    Romeiras, Maria M; Figueira, Rui; Duarte, Maria Cristina; Beja, Pedro; Darbyshire, Iain

    2014-01-01

    In many tropical regions the development of informed conservation strategies is hindered by a dearth of biodiversity information. Biological collections can help to overcome this problem, by providing baseline information to guide research and conservation efforts. This study focuses on the timber trees of Angola, combining herbarium (2670 records) and bibliographic data to identify the main timber species, document biogeographic patterns and identify conservation priorities. The study recognized 18 key species, most of which are threatened or near-threatened globally, or lack formal conservation assessments. Biogeographical analysis reveals three groups of species associated with the enclave of Cabinda and northwest Angola, which occur primarily in Guineo-Congolian rainforests, and evergreen forests and woodlands. The fourth group is widespread across the country, and is mostly associated with dry forests. There is little correspondence between the spatial pattern of species groups and the ecoregions adopted by WWF, suggesting that these may not provide an adequate basis for conservation planning for Angolan timber trees. Eight of the species evaluated should be given high conservation priority since they are of global conservation concern, they have very restricted distributions in Angola, their historical collection localities are largely outside protected areas and they may be under increasing logging pressure. High conservation priority was also attributed to another three species that have a large proportion of their global range concentrated in Angola and that occur in dry forests where deforestation rates are high. Our results suggest that timber tree species in Angola may be under increasing risk, thus calling for efforts to promote their conservation and sustainable exploitation. The study also highlights the importance of studying historic herbarium collections in poorly explored regions of the tropics, though new field surveys remain a priority to update historical information. PMID:25061858

  18. A fossil hominoid proximal femur from Kikorongo Crater, southwestern Uganda.

    PubMed

    DeSilva, Jeremy; Shoreman, Eleanor; MacLatchy, Laura

    2006-06-01

    The external morphology of a fragmentary right proximal femur from southwestern Uganda is described here. Discovered in the Kikorongo Crater of Queen Elizabeth National Park in 1961, this specimen was informally assigned to Homo sapiens (although never described) and tentatively dated to the late Pleistocene. However, because aspects of the external morphology of the femur align the fossil with the African great apes, we suggest that the Kikorongo femur may be the first postcranial fossil of the genus Pan. Like the African apes, the Kikorongo specimen lacks both an obturator externus groove and an intertrochanteric line. It has a short femoral neck with a circular cross section, and a narrow and deep superior notch. Using resampling statistics and discriminant function analysis, the Kikorongo femur clustered with the genus Pan, as opposed to Gorilla or Homo. However, if the specimen is from Pan, it would be large for this taxon. Furthermore, features that clearly distinguish the external morphology of Plio-Pleistocene hominin proximal femora from African ape femora, such as the shape of the femoral neck in cross section and femoral neck length, have converged in Holocene humans and African apes. Unfortunately, the internal morphology of the femoral neck of the Kikorongo fossil was not discernable. Although we hypothesize that the Kikorongo femur is from the genus Pan, there is such variability in the proximal femora of modern humans that, although it would be an unusual human, it remains possible that this fossil represents H. sapiens. PMID:16620913

  19. Fossil Energy Program

    NASA Astrophysics Data System (ADS)

    McNeese, L. E.

    1981-01-01

    Increased utilization of coal and other fossil fuel alternatives as sources of clean energy is reported. The following topics are discussed: coal conversion development, chemical research and development, materials technology, component development and process evaluation studies, technical support to major liquefaction projects, process analysis and engineering evaluations, fossil energy environmental analysis, flue gas desulfurization, solid waste disposal, coal preparation waste utilization, plant control development, atmospheric fluidized bed coal combustor for cogeneration, TVA FBC demonstration plant program technical support, PFBC systems analysis, fossil fuel applications assessments, performance assurance system support for fossil energy projects, international energy technology assessment, and general equilibrium models of liquid and gaseous fuel supplies.

  20. Surface Model and Tomographic Archive of Fossil Primate and Other Mammal Holotype and Paratype Specimens of the Ditsong National Museum of Natural History, Pretoria, South Africa.

    PubMed

    Adams, Justin W; Olah, Angela; McCurry, Matthew R; Potze, Stephany

    2015-01-01

    Nearly a century of paleontological excavation and analysis from the cave deposits of the Cradle of Humankind UNESCO World Heritage Site in northeastern South Africa underlies much of our understanding of the evolutionary history of hominins, other primates and other mammal lineages in the late Pliocene and early Pleistocene of Africa. As one of few designated fossil repositories, the Plio-Pleistocene Palaeontology Section of the Ditsong National Museum of Natural History (DNMNH; the former Transvaal Museum) curates much of the mammalian faunas recovered from the fossil-rich deposits of major South African hominin-bearing localities, including the holotype and paratype specimens of many primate, carnivore, and other mammal species (Orders Primates, Carnivora, Artiodactyla, Eulipotyphla, Hyracoidea, Lagomorpha, Perissodactyla, and Proboscidea). Here we describe an open-access digital archive of high-resolution, full-color three-dimensional (3D) surface meshes of all 89 non-hominin holotype, paratype and significant mammalian specimens curated in the Plio-Pleistocene Section vault. Surface meshes were generated using a commercial surface scanner (Artec Spider, Artec Group, Luxembourg), are provided in formats that can be opened in both open-source and commercial software, and can be readily downloaded either via an online data repository (MorphoSource) or via direct request from the DNMNH. In addition to providing surface meshes for each specimen, we also provide tomographic data (both computerized tomography [CT] and microfocus [microCT]) for a subset of these fossil specimens. This archive of the DNMNH Plio-Pleistocene collections represents the first research-quality 3D datasets of African mammal fossils to be made openly available. This simultaneously provides the paleontological community with essential baseline information (e.g., updated listing and 3D record of specimens in their current state of preservation) and serves as a single resource of high-resolution digital data that improves collections accessibility, reduces unnecessary duplication of efforts by researchers, and encourages ongoing imaging-based paleobiological research across a range of South African non-hominin fossil faunas. Because the types, paratypes, and key specimens include globally-distributed mammal taxa, this digital archive not only provides 3D morphological data on taxa fundamental to Neogene and Quaternary South African palaeontology, but also lineages critical to research on African, other Old World, and New World paleocommunities. With such a broader impact of the DNMNH 3D data, we hope that establishing open access to this digital archive will encourage other researchers and institutions to provide similar resources that increase accessibility to paleontological collections and support advanced paleobiological analyses. PMID:26441324

  1. Surface Model and Tomographic Archive of Fossil Primate and Other Mammal Holotype and Paratype Specimens of the Ditsong National Museum of Natural History, Pretoria, South Africa

    PubMed Central

    Adams, Justin W.; Olah, Angela; McCurry, Matthew R.; Potze, Stephany

    2015-01-01

    Nearly a century of paleontological excavation and analysis from the cave deposits of the Cradle of Humankind UNESCO World Heritage Site in northeastern South Africa underlies much of our understanding of the evolutionary history of hominins, other primates and other mammal lineages in the late Pliocene and early Pleistocene of Africa. As one of few designated fossil repositories, the Plio-Pleistocene Palaeontology Section of the Ditsong National Museum of Natural History (DNMNH; the former Transvaal Museum) curates much of the mammalian faunas recovered from the fossil-rich deposits of major South African hominin-bearing localities, including the holotype and paratype specimens of many primate, carnivore, and other mammal species (Orders Primates, Carnivora, Artiodactyla, Eulipotyphla, Hyracoidea, Lagomorpha, Perissodactyla, and Proboscidea). Here we describe an open-access digital archive of high-resolution, full-color three-dimensional (3D) surface meshes of all 89 non-hominin holotype, paratype and significant mammalian specimens curated in the Plio-Pleistocene Section vault. Surface meshes were generated using a commercial surface scanner (Artec Spider, Artec Group, Luxembourg), are provided in formats that can be opened in both open-source and commercial software, and can be readily downloaded either via an online data repository (MorphoSource) or via direct request from the DNMNH. In addition to providing surface meshes for each specimen, we also provide tomographic data (both computerized tomography [CT] and microfocus [microCT]) for a subset of these fossil specimens. This archive of the DNMNH Plio-Pleistocene collections represents the first research-quality 3D datasets of African mammal fossils to be made openly available. This simultaneously provides the paleontological community with essential baseline information (e.g., updated listing and 3D record of specimens in their current state of preservation) and serves as a single resource of high-resolution digital data that improves collections accessibility, reduces unnecessary duplication of efforts by researchers, and encourages ongoing imaging-based paleobiological research across a range of South African non-hominin fossil faunas. Because the types, paratypes, and key specimens include globally-distributed mammal taxa, this digital archive not only provides 3D morphological data on taxa fundamental to Neogene and Quaternary South African palaeontology, but also lineages critical to research on African, other Old World, and New World paleocommunities. With such a broader impact of the DNMNH 3D data, we hope that establishing open access to this digital archive will encourage other researchers and institutions to provide similar resources that increase accessibility to paleontological collections and support advanced paleobiological analyses. PMID:26441324

  2. 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…

  3. Fossil energy program

    NASA Astrophysics Data System (ADS)

    McNeese, L. E.

    1981-12-01

    Research and development programs in support of the increased utilization of coal and other fossil fuel alternatives as sources of clean energy are reported. The following projects are reported: coal conversion development, chemical research and development, materials technology, component development and process evaluation, technical support to major liquefaction, process analysis and engineering evaluations, fossil energy environmental analysis, environmental control technology, coal preparation waste utilization, atmospheric fluidized bed coal combustor for cogeneration, TVA FBC demonstration plant program technical support, PFBC systems analysis, FBC char utilization improvement, fossil fuel applications assessments, performance assurance system support for fossil energy projects, international energy technology, generalized equilibrium models for liquid and gaseous fuel supplies, analysis of coal production, and fossil energy information center.

  4. CLANIMAE: Climatic and Anthropogenic Impacts on African Ecosystems

    NASA Astrophysics Data System (ADS)

    Verschuren, D.; André, L.; Mahy, G.; Cocquyt, C.; Plisnier, P.-D.; Gelorini, V.; Rumes, B.; Lebrun, J.; Bock, L.; Marchant, R.

    2009-04-01

    Global studies of historical land use focusing on the large-scale landscape change that can potentially affect global climate (via effects on surface albedo, aerosols, and the carbon cycle) have concluded that the impact of pre-colonial East African cultures on regional ecosystems was limited, due to very low mean population density. This contrasts with the paradigm in East African archaeology and paleoecology that the onset of anthropogenic deforestation started at least 2500 years ago, following the introduction of iron metallurgy by Bantu immigrants. This conflict highlights the present lack of real data on historical climate-environment-human interactions in East Africa, which are eminently relevant to sustainable natural resource management and biodiversity conservation in a future of continued population growth and global climate change. CLANIMAE responds to the urgent need of a correct long-term perspective to today's climate-environment-human interactions in East Africa, by reconstructing simultaneously the histories of past climate change and of vegetation and water-quality changes over the last 2500 years, through multi-disciplinary analysis of dated lake-sediment records. The climate reconstructions integrate information on biological, geochemical and sedimentological indicators of past changes in the water balance of the study lakes, which cover the climatological gradient from (sub-)humid western Uganda to semi-arid eastern Kenya. Reconstruction of past terrestrial vegetation dynamics is based on analyses of fossil plant pollen and phytoliths, plus the fossil spores of fungi associated with the excrements of large domestic animals as indicators of lake use by pastoralists. The evolution of water quality through time is reconstructed using silicon isotopes in diatom algae as proxy indicator for past phytoplankton productivity, and paleoecological analyses of fossil diatoms and aquatic macrophytes, following calibration of diatom and macrophyte species distribution against lake trophic status and turbidity in the modern-day regional lake gradient. The integrated paleoecological research method of this project addresses the question of past climate-environment-human relationships at the time scale at which the relevant processes have actually occurred. This will allow us to 1) separate the influences of natural climate variability and human activity on East African ecosystems, 2) determine the exact timing and relative magnitude of indigenous (pre-20th century) anthropogenic land clearance compared to recent landscape alteration, 3) determine the severity of lake water-quality losses due to siltation and excess nutrient input directly linked to deforestation and agriculture, compared to those associated with natural ecosystem variability, and 4) assess the resilience of African ecosystems, and prospects for the restoration of disturbed ecosystems if human pressure were to be reversed.

  5. Discovering Hominins - Application of Medical Computed Tomography (CT) to Fossil-Bearing Rocks from the Site of Malapa, South Africa.

    PubMed

    Smilg, Jacqueline S; Berger, Lee R

    2015-01-01

    In the South African context, computed tomography (CT) has been used applied to individually prepared fossils and small rocks containing fossils, but has not been utilized on large breccia blocks as a means of discovering fossils, and particularly fossil hominins. Previous attempts at CT imaging of rocks from other South African sites for this purpose yielded disappointing results. For this study, 109 fossil- bearing rocks from the site of Malapa, South Africa were scanned with medical CT prior to manual preparation. The resultant images were assessed for accuracy of fossil identification and characterization against the standard of manual preparation. The accurate identification of fossils, including those of early hominins, that were not visible on the surface of individual blocks, is shown to be possible. The discovery of unexpected fossils is reduced, thus lowering the potential that fossils could be damaged through accidental encounter during routine preparation, or even entirely missed. This study should significantly change the way fossil discovery, recovery and preparation is done in the South African context and has potential for application in other palaeontological situations. Medical CT imaging is shown to be reliable, readily available, cost effective and accurate in finding fossils within matrix conglomerates. Improvements in CT equipment and in CT image quality are such that medical CT is now a viable imaging modality for this palaeontological application. PMID:26684299

  6. Discovering Hominins - Application of Medical Computed Tomography (CT) to Fossil-Bearing Rocks from the Site of Malapa, South Africa

    PubMed Central

    Smilg, Jacqueline S.; Berger, Lee R.

    2015-01-01

    In the South African context, computed tomography (CT) has been used applied to individually prepared fossils and small rocks containing fossils, but has not been utilized on large breccia blocks as a means of discovering fossils, and particularly fossil hominins. Previous attempts at CT imaging of rocks from other South African sites for this purpose yielded disappointing results. For this study, 109 fossil- bearing rocks from the site of Malapa, South Africa were scanned with medical CT prior to manual preparation. The resultant images were assessed for accuracy of fossil identification and characterization against the standard of manual preparation. The accurate identification of fossils, including those of early hominins, that were not visible on the surface of individual blocks, is shown to be possible. The discovery of unexpected fossils is reduced, thus lowering the potential that fossils could be damaged through accidental encounter during routine preparation, or even entirely missed. This study should significantly change the way fossil discovery, recovery and preparation is done in the South African context and has potential for application in other palaeontological situations. Medical CT imaging is shown to be reliable, readily available, cost effective and accurate in finding fossils within matrix conglomerates. Improvements in CT equipment and in CT image quality are such that medical CT is now a viable imaging modality for this palaeontological application. PMID:26684299

  7. High-pressure whiteschists from the Ti-N-Eggoleh area (Central Hoggar, Algeria): A record of Pan-African oceanic subduction

    NASA Astrophysics Data System (ADS)

    Adjerid, Zouhir; Godard, Gaston; Ouzegane, Khadidja

    2015-06-01

    The Ti-N-Eggoleh area (Sérouènout Terrane, Central Hoggar, Algeria) comprises mainly a high-pressure Neoproterozoic metamorphic formation consisting of talc-kyanite-quartz whiteschists, chlorite schists, marbles, sulphide ores, partially serpentinized peridotites and partially amphibolitized eclogites, and reminiscent of an ophiolitic mélange that was metamorphosed and strongly deformed under eclogite-facies conditions. Major and trace elements indicate that the whiteschists underwent intense hydrothermal alteration, with Mg enrichment and leaching of alkalis and Ca, prior to high-pressure metamorphism. The main talc-kyanite-quartz paragenesis is stable within a large multivariant P-T field extending from high-P amphibolite to eclogite facies; the Tschermak substitution in talc marginally constrains peak pressure conditions to P > 11 kbar and 600 < T < ~ 800 °C. The subsequent development of cordierite ± sapphirine ± corundum symplectites and coronae at the contact between talc and kyanite was due to isochemical and almost univariant reactions (Tlc + Ky + Qtz ? Crd; Tlc + Ky ? Crd + Crn; Tlc + Ky ? Crd + Spr) which combined together to produce hybrid microstructures. These metamorphic reactions indicate a thermal overprint under granulite-facies conditions (T = 650-860 °C; P < 12 kbar). The peraluminous Mg-rich sapphirine observed in the symplectites reaches one of the highest degrees of Tschermak substitution ever reported for this mineral (with n = 3.6), intermediate between the 13:19:5 (n = 3) and 3:5:1 (n = 4) theoretical compositions. The neighbouring eclogites record a similar P-T evolution: after the eclogite-facies metamorphic peak, they underwent partial amphibolitization and a subsequent high-temperature overprint under granulite-facies conditions that led to partial dehydration. The Ti-N-Eggoleh series is interpreted as the product of the thermal alteration of oceanic rocks that were subducted prior to the continental collision that formed the West Gondwana orogenic belt during the Neoproterozoic Pan-African orogeny. The decompression associated with the early phase of exhumation was followed by an important increase in temperature towards granulite-facies conditions, possibly determined by the intrusion of abundant mafic rocks in this region due to delamination of the lithospheric mantle. The Ti-N-Eggoleh area and its high-pressure meta-ophiolitic series apparently belong to the Sérouènout Terrane, which stretches along the eastern margin of the Western Gondwana orogenic belt and consists mainly of oceanic metasediments; they are possibly markers of an ancient, yet unidentified, subduction and suture zone.

  8. 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.

  9. The Fossil Record of the Peronosporomycetes (Oomycota)

    E-print Network

    Krings, Michael; Taylor, Thomas N.; Dotzler, Nora

    2011-01-01

    that thrive in both aquatic and terrestrial environments where they are effective as saprotrophs and disease-causative agents in plants and animals including humans (Margulis and Schwartz 1998). Within the group are economically important phytopathogens....e. haustoria) suggestive of parasitism. This might suggest that most Carbonifer- ous Peronosporomycetes lived as saprotrophs. As far as is known none have been reported associated with roots or other types of below ground anchoring and absorbing organs. While...

  10. 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.

  11. Triassic Leech Cocoon From Antarctica Contains Fossil Bell Animal

    E-print Network

    Bomfleur, Benjamin; Kerp, Hans; Taylor, Thomas N.; Moestrup, Ø jvind; Taylor, Edith L.

    2012-01-01

    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...

  12. A comparative histological study of fossil and recent bone tissues 

    E-print Network

    Enlow, Donald H.

    1955-01-01

    When looking at geologically rapid climatic changes, such as glacial/interglacial cycles, the true response of organisms may be obscured in the fossil record due to time averaging. Time averaging can also impact the rates of origination...

  13. 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)

  14. Fossil energy program

    NASA Astrophysics Data System (ADS)

    McNeese, L. E.

    1981-02-01

    The projects reported include those for coal conversion development, chemical research and development, materials technology, component development and process evaluation studies, technical support to major liquefaction projects, process analysis and engineering evaluations, fossil energy environmental analysis, flue gas desulfurization, plant control development, atmospheric fluidized bed coal combustor for cogeneration, TVA, FBC demonstration plant program technical support, and PFBC systems analysis. Fossil fuel application assessments, performance assurance system support for fossil energy projects, international energy technology assessment, and general equilibrium models of liquid and gaseous fuel supplies are presented.

  15. 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.

  16. Fossil energy program

    NASA Astrophysics Data System (ADS)

    McNeese, L. E.

    1981-03-01

    A compendium of monthly progress reports for the ORNL research and development programs that are in support of the increased utilization of coal and other fossil fuel alternatives as sources of clean energy is presented. The projects reported this month include those for coal conversion development, chemical research and development, materials technology, component development and process evaluation, technical support to major liquefaction projects, process analysis; and engineering evaluations, fossil energy environmental analysis, flue gas desulfurization, solid waste disposal, coal preparation and waste utilization, plant control development, atmospheric fluidized bed coal combustor for cogeneration, Tennessee Valley Authority Fluidized Bed Combustion demonstration plant program technical support, PFBC systems analysis, fossil fuel applications assessments, performance assurance system support for fossil energy projects, international energy technology assessment, and generalized equilibrium models of liquid and gaseous fuel supplies.

  17. vol. 165, no. 2 the american naturalist february 2005 Assessing Concordance of Fossil Calibration Points in

    E-print Network

    Shaffer, H. Bradley

    vol. 165, no. 2 the american naturalist february 2005 Assessing Concordance of Fossil Calibration and accuracy of the fossil record as calibration points. Recent methodological advances have provided powerful rates among lineages. However, relatively little attention has focused on the accuracy of fossil cali

  18. 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)

  19. Fossil evidence of the zygomycetous fungi.

    PubMed

    Krings, M; Taylor, T N; Dotzler, N

    2013-06-01

    Molecular clock data indicate that the first zygomycetous fungi occurred on Earth during the Precambrian, however, fossil evidence of these organisms has been slow to accumulate. In this paper, the fossil record of the zygomycetous fungi is compiled, with a focus on structurally preserved Carboniferous and Triassic fossils interpreted as zygosporangium-gametangia complexes and resembling those of modern Endogonales. Enigmatic microfossils from the Precambrian to Cenozoic that have variously been interpreted as, or compared to, zygomycetous fungi are also discussed. Among these, the spherical structures collectively termed 'sporocarps' are especially interesting because of their complex investments and abundance in certain Carboniferous and Triassic rocks. Circumstantial evidence suggests that at least some 'sporocarp' types represent mantled zygosporangia. Zygomycetous fungi probably were an important element in terrestrial paleoecosystems at least by the Carboniferous. PMID:24027344

  20. 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. PMID:26250386

  1. Fossil Biodiversity: Red Noise Plus Signal

    E-print Network

    Adrian L. Melott; Bruce S. Lieberman

    2006-06-14

    We have examined the Fourier power spectrum as well as the Hurst exponent of extinction, origination, and total biodiversity in the marine fossil record, using a recently improved geologic timescale. We find all of them strongly inconsistent with past claims of self-similarity as well as inconsistent with random walk behavior. Instead, they are dominated by low-frequency power, with approximate f^-2 power over one decade in frequency. The spectrum turns over at about 10^8 y, lending plausibility to connections with galactic dynamics. Even in the background of this low-frequency dominance, a previously noted 62 My biodiversity cycle stands out with better than 99% confidence above the noise level, accounting for about 35% of the total variance in the fossil biodiversity record.

  2. Fossil Biodiversity: Red Noise Plus Signal

    E-print Network

    Melott, A L; Melott, Adrian L.; Lieberman, Bruce S.

    2006-01-01

    We have examined the Fourier power spectrum as well as the Hurst exponent of extinction, origination, and total biodiversity in the marine fossil record, using a recently improved geologic timescale. We find all of them strongly inconsistent with past claims of self-similarity as well as inconsistent with random walk behavior. Instead, they are dominated by low-frequency power, with approximate f^-2 power over one decade in frequency. The spectrum turns over at about 10^5 y, lending plausibility to connections with galactic dynamics. Even in the background of this low-frequency dominance, a previously noted 62 My biodiversity cycle stands out with better than 99% confidence above the noise level, accounting for about 35% of the total variance in the fossil biodiversity record.

  3. Fossil-Fired Boilers

    Energy Science and Technology Software Center (ESTSC)

    1993-09-23

    Boiler Performance Model (BPM 3.0S) is a set of computer programs developed to analyze the performance of fossil-fired utility boilers. The programs can model a wide variety of boiler designs, and can model coal, oil, or natural gas firing. The programs are intended for use by engineers performing analyses of alternative fuels, alternative operating modes, or boiler modifications.

  4. 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.

  5. Reviving the African Wolf Canis lupus lupaster in North and West Africa: A Mitochondrial Lineage Ranging More than 6,000 km Wide

    PubMed Central

    Gaubert, Philippe; Bloch, Cécile; Benyacoub, Slim; Abdelhamid, Adnan; Pagani, Paolo; Djagoun, Chabi Adéyèmi Marc Sylvestre; Couloux, Arnaud; Dufour, Sylvain

    2012-01-01

    The recent discovery of a lineage of gray wolf in North-East Africa suggests the presence of a cryptic canid on the continent, the African wolf Canis lupus lupaster. We analyzed the mtDNA diversity (cytochrome b and control region) of a series of African Canis including wolf-like animals from North and West Africa. Our objectives were to assess the actual range of C. l. lupaster, to further estimate the genetic characteristics and demographic history of its lineage, and to question its taxonomic delineation from the golden jackal C. aureus, with which it has been considered synonymous. We confirmed the existence of four distinct lineages within the gray wolf, including C. lupus/familiaris (Holarctic wolves and dogs), C. l. pallipes, C. l. chanco and C. l. lupaster. Taxonomic assignment procedures identified wolf-like individuals from Algeria, Mali and Senegal, as belonging to C. l. lupaster, expanding its known distribution c. 6,000 km to the west. We estimated that the African wolf lineage (i) had the highest level of genetic diversity within C. lupus, (ii) coalesced during the Late Pleistocene, contemporaneously with Holarctic wolves and dogs, and (iii) had an effective population size of c. 80,000 females. Our results suggest that the African wolf is a relatively ancient gray wolf lineage with a fairly large, past effective population size, as also suggested by the Pleistocene fossil record. Unique field observations in Senegal allowed us to provide a morphological and behavioral diagnosis of the African wolf that clearly distinguished it from the sympatric golden jackal. However, the detection of C. l. lupaster mtDNA haplotypes in C. aureus from Senegal brings the delineation between the African wolf and the golden jackal into question. In terms of conservation, it appears urgent to further characterize the status of the African wolf with regard to the African golden jackal. PMID:22900047

  6. Reviving the African wolf Canis lupus lupaster in North and West Africa: a mitochondrial lineage ranging more than 6,000 km wide.

    PubMed

    Gaubert, Philippe; Bloch, Cécile; Benyacoub, Slim; Abdelhamid, Adnan; Pagani, Paolo; Djagoun, Chabi Adéyèmi Marc Sylvestre; Couloux, Arnaud; Dufour, Sylvain

    2012-01-01

    The recent discovery of a lineage of gray wolf in North-East Africa suggests the presence of a cryptic canid on the continent, the African wolf Canis lupus lupaster. We analyzed the mtDNA diversity (cytochrome b and control region) of a series of African Canis including wolf-like animals from North and West Africa. Our objectives were to assess the actual range of C. l. lupaster, to further estimate the genetic characteristics and demographic history of its lineage, and to question its taxonomic delineation from the golden jackal C. aureus, with which it has been considered synonymous. We confirmed the existence of four distinct lineages within the gray wolf, including C. lupus/familiaris (Holarctic wolves and dogs), C. l. pallipes, C. l. chanco and C. l. lupaster. Taxonomic assignment procedures identified wolf-like individuals from Algeria, Mali and Senegal, as belonging to C. l. lupaster, expanding its known distribution c. 6,000 km to the west. We estimated that the African wolf lineage (i) had the highest level of genetic diversity within C. lupus, (ii) coalesced during the Late Pleistocene, contemporaneously with Holarctic wolves and dogs, and (iii) had an effective population size of c. 80,000 females. Our results suggest that the African wolf is a relatively ancient gray wolf lineage with a fairly large, past effective population size, as also suggested by the Pleistocene fossil record. Unique field observations in Senegal allowed us to provide a morphological and behavioral diagnosis of the African wolf that clearly distinguished it from the sympatric golden jackal. However, the detection of C. l. lupaster mtDNA haplotypes in C. aureus from Senegal brings the delineation between the African wolf and the golden jackal into question. In terms of conservation, it appears urgent to further characterize the status of the African wolf with regard to the African golden jackal. PMID:22900047

  7. 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. PMID:21525049

  8. A new fossil species of the genus Coptodera Dejean, 1825 (Coleoptera: Carabidae: Lebiinae) from Baltic amber.

    PubMed

    Gamboa, Sara; Ortuño, Vicente M

    2015-01-01

    In this paper a new species of fossil ground-beetle, Coptodera elektra n. sp. (Coleoptera: Carabidae) preserved in a piece of Baltic amber (Eocene) is described and the paleobiology of the species is studied. This new species represents the first known fossil record for the genus, as well as the first record of its presence in Europe. PMID:26250016

  9. 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. PMID:26597067

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

    PubMed

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

    2015-07-01

    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

  11. 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

  12. Hasiotis, S.T. and Bourke, M.C. 2006. Continental trace fossils and museum exhibits: displaying burrows as organism behaviour frozen in time. The Geological Curator, 8

    E-print Network

    Bourke, Mary C.

    -211- Hasiotis, S.T. and Bourke, M.C. 2006. Continental trace fossils and museum exhibits introduces continental trace fossils, and suggests ways in which modern and ancient traces can be used in the geologic record as continental trace fossils. Trace fossils are important because they are analogous

  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. Determining the response of African biota to climate change: using the past to model the future

    PubMed Central

    Willis, K. J.; Bennett, K. D.; Burrough, S. L.; Macias-Fauria, M.; Tovar, C.

    2013-01-01

    Prediction of biotic responses to future climate change in tropical Africa tends to be based on two modelling approaches: bioclimatic species envelope models and dynamic vegetation models. Another complementary but underused approach is to examine biotic responses to similar climatic changes in the past as evidenced in fossil and historical records. This paper reviews these records and highlights the information that they provide in terms of understanding the local- and regional-scale responses of African vegetation to future climate change. A key point that emerges is that a move to warmer and wetter conditions in the past resulted in a large increase in biomass and a range distribution of woody plants up to 400–500 km north of its present location, the so-called greening of the Sahara. By contrast, a transition to warmer and drier conditions resulted in a reduction in woody vegetation in many regions and an increase in grass/savanna-dominated landscapes. The rapid rate of climate warming coming into the current interglacial resulted in a dramatic increase in community turnover, but there is little evidence for widespread extinctions. However, huge variation in biotic response in both space and time is apparent with, in some cases, totally different responses to the same climatic driver. This highlights the importance of local features such as soils, topography and also internal biotic factors in determining responses and resilience of the African biota to climate change, information that is difficult to obtain from modelling but is abundant in palaeoecological records. PMID:23878343

  15. 21,000 years of Ethiopian African monsoon variability recorded in sediments of the western Nile deep-sea fan: impact of the Nile freshwater inflow for the Mediterranean thermo-haline circulation

    NASA Astrophysics Data System (ADS)

    Revel, Marie; Colin, Christophe; Bernasconi, Stephano; Combourieu-Nebout, Nathalie; Ducassou, Emmanuelle; Rolland, Yann; Bosch, Delphine

    2014-05-01

    The Nile delta sedimentation constitutes a continuous high resolution (1.6 mm/year) record of Ethiopian African monsoon regime intensity. Multiproxy analyses performed on core MS27PT recovered in hemipelagic Nile sediment margin (<90 km outward of the Rosetta mouth of the Nile) allow the quantification of the Saharan aeolian dust and the Blue/White Nile River suspended matter frequency fluctuations during the last 21 cal. ka BP. The radiogenic Sr and Nd isotopes, clay mineralogy, bulk elemental composition and palynological analyses reveal large changes in source components, oscillating between a dominant aeolian Saharan contribution during the LGM and the Late Holocene (~4 to 2 cal. ka BP), a dominant Blue/Atbara Nile River contribution during the early Holocene (15 to 8.4 cal. ka BP) and a probable White Nile River contribution during the Middle Holocene (8.4 to 4 cal. ka BP). The following main features are highlighted: 1. The rapid shift from the LGM arid conditions to the African Humid Period (AHP) started at about 15 cal. ka BP. AHP extends until 8.4 cal. ka BP, and we suggest that the Ethiopian African Monsoon maximum between 12 and 8 cal. ka BP is responsible for a larger Blue/Atbara Nile sediment load and freshwater input into the Eastern Mediterranean Sea. 2. The transition between the AHP and the arid Late Holocene is gradual and occurs in two main phases between 8.4 and 6.5 cal. ka BP and 6.5 to 3.2 cal. ka BP. We suggest that the main rain belt shifted southward from 8.4 to ~4 cal. ka BP and was responsible for progressively reduced sediment load and freshwater input into the eastern Mediterranean Sea. 3. The aridification along the Nile catchments occurred from ~4 to 2 cal. ka BP. A dry period, which culminates at 3.2 cal. ka BP, and seems to coincide with a re-establishment of increased oceanic primary productivity in the western Mediterranean Sea. We postulate that the decrease in thermo-haline water Mediterranean circulation could be part of a response to huge volumes of fresh-water delivered principally by the Nile River from 12 to 8.4 cal. ka BP in the eastern Mediterranean. We propose that the large hydrological change in Ethiopian latitude could be a trigger for the 8.2 ka cooling event recorded in high latitude. Revel R., Colin C., Bernasconi S., Combourieu-Nebout N., Ducassou E., Grousset F.E., Rolland Y., Migeon S., Brunet P., Zhaa Y., Bosch D., Mascle J.,. "21,000 years of Ethiopian African moonsoon variability recorded in sediments of the western Nile deep sea fan", Regional Environmental Change, in press.

  16. 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 surfaces that produce palisade and "shrub" fabrics, respectively. At finer scales, composite fabrics are seen to consist distinctive associations of microstructures formed by the encrustation of individual cells and filaments. Composite fabrics survive the diagenetic transitions from primary opaline silica to quartz and are known from subaerial thermal spring deposits as old as Lower Carboniferous. However, fossil microorganisms tend to be rare in older deposits, and are usually preserved only where cells or sheaths have been stained by iron oxides. In subaqueous mineralizing springs at lower temperatures, early infilling leads to a more rapid and complete reduction in porosity and permeability. This process, along with the slower rates of microbial degradation at lower temperatures, creates a more favorable situation for organic matter preservation. Application of this taphonomic model to the Rhynie Chert, previously interpreted as subaerial, suggest it was probably deposited in a subaqueous spring setting at lower temperatures.

  17. 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 detailed descriptions of fossil diatoms will provide the basis for making more accurate correlations and identifications, and the micromorphological detail for speculations about evolutionary relationships. ?? 1988.

  18. Phylogenetic implications of the first African Middle Miocene hominoid frontal bone from Otavi, Namibia

    NASA Astrophysics Data System (ADS)

    Pickford, Martin; Sola, Salvador Moya; Köhler, Meike

    1997-09-01

    The discovery of a hominoid frontal at Berg Aukas, Namibia, aged 13-12 Ma, permits an analysis of the phylogenetic relations between fossil and extant great apes. The Namibian specimen is closer morphologically to African apes and humans (AAH), whereas all fossil Eurasian great apes differ markedly from AAH but are closer to the Pongo clade.

  19. African Aesthetics

    ERIC Educational Resources Information Center

    Abiodun, Rowland

    2001-01-01

    No single traditional discipline can adequately supply answers to the many unresolved questions in African art history. Because of the aesthetic, cultural, historical, and, not infrequently, political biases, already built into the conception and development of Western art history, the discipline of art history as defined and practiced in the West…

  20. vol. 171, no. 1 the american naturalist january 2008 Caveats on the Use of Fossil Calibrations for Molecular Dating

    E-print Network

    Shaffer, H. Bradley

    vol. 171, no. 1 the american naturalist january 2008 Caveats on the Use of Fossil Calibrations, molecular clock, fossil record. In Parham and Irmis's (2008) commentary on our article "Assessing Concordance of Fossil Calibration Points in Molecular Clock Studies: An Example Using Turtles" (Near et al

  1. 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.

  2. The College: Arts & Sciences African & African-American Studies

    E-print Network

    Cantlon, Jessica F.

    The College: Arts & Sciences African & African-American Studies Department: African & African-American for the course description. Department: African & African-American Studies Course: AAS 122 Title: History of Jazz Description: Please see MUR 122 for the course description. Department: African & African-American Studies

  3. The college: Arts & sciences African & African-American Studies

    E-print Network

    Portman, Douglas

    The college: Arts & sciences African & African-American Studies Department: African & African-American Studies Course: AAS 110 Title: Introduction to African and African-American Studies Cross-listed: HIS 110: African & African-American Studies Course: AAS 151 Title: The Blues Cross-listed: REL 151, MUR 127

  4. Managing the Challenges of Adopting Electronic Medical Records: An Exploratory Study of the Challenges Faced by African American Health Care Professionals

    ERIC Educational Resources Information Center

    Riddick, William P.

    2013-01-01

    The implementation of technology within the health care industry is viewed as a possible solution for lowering costs and improving health care delivery to patients. Electronic medical record system(s) (EMRS) are information technology tools viewed within the health care industry as a possible solution for aiding improvements in health care…

  5. Genetics, Morphology, Advertisement Calls, and Historical Records Distinguish Six New Polyploid Species of African Clawed Frog (Xenopus, Pipidae) from West and Central Africa

    PubMed Central

    Evans, Ben J.; Carter, Timothy F.; Greenbaum, Eli; Gvoždík, Václav; Kelley, Darcy B.; McLaughlin, Patrick J.; Pauwels, Olivier S. G.; Portik, Daniel M.; Stanley, Edward L.; Tinsley, Richard C.; Tobias, Martha L.; Blackburn, David C.

    2015-01-01

    African clawed frogs, genus Xenopus, are extraordinary among vertebrates in the diversity of their polyploid species and the high number of independent polyploidization events that occurred during their diversification. Here we update current understanding of the evolutionary history of this group and describe six new species from west and central sub-Saharan Africa, including four tetraploids and two dodecaploids. We provide information on molecular variation, morphology, karyotypes, vocalizations, and estimated geographic ranges, which support the distinctiveness of these new species. We resurrect Xenopus calcaratus from synonymy of Xenopus tropicalis and refer populations from Bioko Island and coastal Cameroon (near Mt. Cameroon) to this species. To facilitate comparisons to the new species, we also provide comments on the type specimens, morphology, and distributions of X. epitropicalis, X. tropicalis, and X. fraseri. This includes significantly restricted application of the names X. fraseri and X. epitropicalis, the first of which we argue is known definitively only from type specimens and possibly one other specimen. Inferring the evolutionary histories of these new species allows refinement of species groups within Xenopus and leads to our recognition of two subgenera (Xenopus and Silurana) and three species groups within the subgenus Xenopus (amieti, laevis, and muelleri species groups). PMID:26672747

  6. 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.

  7. Plio-Pleistocene African Climate

    NASA Astrophysics Data System (ADS)

    Demenocal, Peter B.

    1995-10-01

    Marine records of African climate variability document a shift toward more arid conditions after 2.8 million years ago (Ma), evidently resulting from remote forcing by cold North Atlantic sea-surface temperatures associated with the onset of Northern Hemisphere glacial cycles. African climate before 2.8 Ma was regulated by low-latitude insolation forcing of monsoonal climate due to Earth orbital precession. Major steps in the evolution of African hominids and other vertebrates are coincident with shifts to more arid, open conditions near 2.8 Ma, 1.7 Ma, and 1.0 Ma, suggesting that some Pliocene (Plio)-Pleistocene speciation events may have been climatically mediated.

  8. Plio-pleistocene African climate

    SciTech Connect

    deMenocal, P.B.

    1995-10-06

    Marine records of African climate variability document a shift toward more arid conditions after 2.8 million years ago (Ma), evidently resulting from remote forcing by cold North Atlantic sea-surface temperatures associated with the onset of Northern Hemisphere glacial cycles. African climate before 2.8 Ma was regulated by low-latitude insolation forcing of monsoonal climate due to Earth orbital precession. Major steps in the evolution of African hominids and other vertebrates are coincident with shifts to more arid, open conditions near 2.8 Ma, 1.7 Ma, and 1.0 Ma, suggesting that some Pliocene (Plio)-Pleistocene speciation events may have been climatically mediated. 65 refs., 6 figs.

  9. Replication in plastic of three-dimensional fossils preserved in indurated clastic sedimentary rocks

    SciTech Connect

    Zapasink, H.T.; Johnston, P.A.

    1984-06-29

    A new technique for replicating in plastic the fossils preserved in clastic rocks should now make available reliable morphologic and frequency data, comparable in quality to those derived from acid-prepared silicified faunas, for a major segment of the fossil record. The technique involves 3 steps: the dissolution of carbonate in fossiliferous rocks with hydrochloric acid, impregnation of resulting voids with liquid plastic, and dissolution of the rock matrix with hydrofluoric acid, leaving a concentrate of plastic-replaced fossils.

  10. Fossil turbulence and fossil turbulence waves can be dangerous

    E-print Network

    Carl H Gibson

    2012-11-25

    Turbulence is defined as an eddy-like state of fluid motion where the inertial-vortex forces of the eddies are larger than any other forces that tend to damp the eddies out. By this definition, turbulence always cascades from small scales where vorticity is created to larger scales where turbulence fossilizes. Fossil turbulence is any perturbation in a hydrophysical field produced by turbulence that persists after the fluid is no longer turbulent at the scale of the perturbation. Fossil turbulence patterns and fossil turbulence waves preserve and propagate energy and information about previous turbulence. Ignorance of fossil turbulence properties can be dangerous. Examples include the Osama bin Laden helicopter crash and the Air France 447 Airbus crash, both unfairly blamed on the pilots. Observations support the proposed definitions, and suggest even direct numerical simulations of turbulence require caution.

  11. 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

    2015-01-01

    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. PMID:26411391

  12. Corrected placement of Mus-Rattus fossil calibration forces precision in the molecular tree of rodents

    PubMed Central

    Kimura, Yuri; Hawkins, Melissa T. R.; McDonough, Molly M.; Jacobs, Louis L.; Flynn, Lawrence J.

    2015-01-01

    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. PMID:26411391

  13. 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

  14. Exploring macroevolution using modern and fossil data.

    PubMed

    Benton, Michael J

    2015-07-01

    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

  15. 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

    2015-01-01

    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. PMID:26249403

  16. Ignoring Authentic African Literature Means Ignoring Africans

    ERIC Educational Resources Information Center

    Romano, Carlin

    2005-01-01

    Africa produces imaginative and authentic literature whose texture makes it impossible to think of Africans as statistics. African writers, however have to struggle to get recognized in America due to their culture and other racial and social differences, hence suggesting that efforts should be made to give authentic African literature its due.

  17. 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.

  18. 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…

  19. Improving paediatric tuberculosis and HIV clinical record keeping: the use of audit and a structured pro forma in a South African regional level hospital.

    PubMed

    Goenka, Anu; Annamalai, Medeshni; Dhada, Barnesh; Stephen, Cindy R; McKerrow, Neil H; Patrick, Mark E

    2014-04-01

    We report on the impact of revisions made to an existing pro forma facilitating routine assessment and the management of paediatric HIV and tuberculosis (TB) in KwaZulu-Natal, South Africa. An initial documentation audit in 2010 assessed 25 sets of case notes for the documentation of 16 select indicators based on national HIV and TB guidelines. Using the findings of this initial audit, the existing case note pro forma was revised. The introduction of the revised pro forma was accompanied by training and a similar repeat audit was undertaken in 2012. This demonstrated an overall improvement in documentation. The three indicators that improved most were documentation of maternal HIV status, child's HIV status and child's TB risk assessment (all P?record keeping in low-resource settings. PMID:24311547

  20. Shared Pattern of Endocranial Shape Asymmetries among Great Apes, Anatomically Modern Humans, and Fossil Hominins

    PubMed Central

    Balzeau, Antoine; Gilissen, Emmanuel; Grimaud-Hervé, Dominique

    2012-01-01

    Anatomical asymmetries of the human brain are a topic of major interest because of their link with handedness and cognitive functions. Their emergence and occurrence have been extensively explored in human fossil records to document the evolution of brain capacities and behaviour. We quantified for the first time antero-posterior endocranial shape asymmetries in large samples of great apes, modern humans and fossil hominins through analysis of “virtual” 3D models of skull and endocranial cavity and we statistically test for departures from symmetry. Once based on continuous variables, we show that the analysis of these brain asymmetries gives original results that build upon previous analysis based on discrete traits. In particular, it emerges that the degree of petalial asymmetries differs between great apes and hominins without modification of their pattern. We indeed demonstrate the presence of shape asymmetries in great apes, with a pattern similar to modern humans but with a lower variation and a lower degree of fluctuating asymmetry. More importantly, variations in the position of the frontal and occipital poles on the right and left hemispheres would be expected to show some degree of antisymmetry when population distribution is considered, but the observed pattern of variation among the samples is related to fluctuating asymmetry for most of the components of the petalias. Moreover, the presence of a common pattern of significant directional asymmetry for two components of the petalias in hominids implicates that the observed traits were probably inherited from the last common ancestor of extant African great apes and Homo sapiens. These results also have important implications for the possible relationships between endocranial shape asymmetries and functional capacities in hominins. It emphasizes the uncoupling between lateralized activities, some of them well probably distinctive to Homo, and large-scale cerebral lateralization itself, which is not unique to Homo. PMID:22242147

  1. 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. PMID:25503771

  2. Conversation on African Music.

    ERIC Educational Resources Information Center

    Saunders, Leslie R.

    1985-01-01

    A voice and music education teacher at the University of Lagos, Nigeria, talks about African music in this interview. Topics discussed include differences between African and Western music, African melody, rules for composing African music, the theory of counterpoint, and the popularity of classical composers in Nigeria. (RM)

  3. African American Studies Scholarships

    E-print Network

    Almor, Amit

    African American Studies Scholarships Complete Scholarship Name Application Deadline Date Contact scholarly research in African American studies. Award winner must utilize Hayes Mizell's personal papers or minor in African American studies or a graduate student in History with an emphasis on African American

  4. Fossil fuel furnace reactor

    DOEpatents

    Parkinson, William J. (Los Alamos, NM)

    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.

  5. FOSSIL2 energy policy model documentation: FOSSIL2 documentation

    SciTech Connect

    1980-10-01

    This report discusses the structure, derivations, assumptions, and mathematical formulation of the FOSSIL2 model. Each major facet of the model - supply/demand interactions, industry financing, and production - has been designed to parallel closely the actual cause/effect relationships determining the behavior of the United States energy system. The data base for the FOSSIL2 program is large, as is appropriate for a system dynamics simulation model. When possible, all data were obtained from sources well known to experts in the energy field. Cost and resource estimates are based on DOE data whenever possible. This report presents the FOSSIL2 model at several levels. Volumes II and III of this report list the equations that comprise the FOSSIL2 model, along with variable definitions and a cross-reference list of the model variables. Volume III lists the model equations and a one line definition for equations, in a short, readable format.

  6. Regional diversity patterns in African bovids, hyaenids, and felids during the past 3 million years: the role of taphonomic bias and implications for the evolution of Paranthropus

    NASA Astrophysics Data System (ADS)

    Patterson, David B.; Faith, J. Tyler; Bobe, René; Wood, Bernard

    2014-07-01

    Reconstructing patterns of Plio-Pleistocene mammalian faunal exchange between eastern and southern Africa may help us to better understand patterns of evolution within the hominin clade. However, differences in geological context, taphonomic history and collection methods, as well as a lack of a precise chronology in one of the regions, complicate attempts to compare the faunas of the two regions, but access to new comprehensive datasets encouraged us to re-examine this critical time period in the African paleontological record. In this study, we examine the biogeographic histories of three terrestrial African mammalian families whose fossil records span the past 3 million years to test hypotheses related to the evolutionary history of the hominin genus Paranthropus. We used presence/absence data for 117 species from 38 genera within the family Bovidae and 34 species from 15 genera within the families Hyaenidae and Felidae from 52 eastern African and 40 southern African fossil localities. These assemblages were placed into 500 ka time slices and compared at both the genus and species level using the Jaccard index of faunal similarity. Our findings indicate that sampling biases have more effect on the patterns of interchange between eastern and southern African Bovidae than they do the patterns of interchange seen in the Hyaenidae and Felidae. However, even when these biases are taken into account there are persistent differences in the degree of interchange within and between these families. These findings suggest that mammalian groups (including hominins) can have very different histories of exchange between eastern and southern Africa over the past 3 million years. There is no a priori reason why any of the three families we examined is a suitable proxy for the eastern and southern African hyper-megadont and megadont hominin taxa presently included in Paranthropus, but of the three we suggest that the Bovidae is likely to come closest to being an appropriate proxy. The results of this comparative study are consistent with relatively independent evolutionary trajectories in the two regions for the hominins that are presently included in the genus Paranthropus.

  7. Erosion patterns and mantle sources of topographic change across the southern African Plateau derived from the shallow and deep records of kimberlites

    NASA Astrophysics Data System (ADS)

    Stanley, Jessica R.; Flowers, Rebecca M.; Bell, David R.

    2015-09-01

    Flow in the sublithospheric mantle is increasingly invoked as a mechanism to explain both modern and past surface topography, but the importance of this phenomenon and its influence at different localities are debated. Southern Africa is an elevated continental shield proposed to represent dynamically supported topography. However, this region is also characterized by a complex lithospheric architecture variably affected by Cretaceous heating, thinning, and metasomatic alteration. We used apatite (U-Th)/He thermochronometry on 15 Cretaceous kimberlites from an ˜600 km long transect across the Kaapvaal Craton, combined with information from xenoliths in these pipes, to determine the plateau interior erosion history. The goal was to determine the relationships with lithospheric modification patterns and thereby better isolate the sublithospheric contribution to elevation. The results document a wave of erosion from west to east across the craton from ˜120 to <60 Ma, initially focused along paleorivers and then retreating as a scarp across the landscape. This spatially variable erosion event was associated with limited modification of the Archean cratonic lithospheric mantle as recorded by mantle xenoliths and xenocrysts, implying that dynamic buoyancy sources may be required to explain the elevations. In contrast, off-craton to the southwest, a more pronounced regional erosion phase at ˜110-90 Ma was coincident with significant modification of the Proterozoic lithospheric mantle. This relationship suggests that lithospheric processes were more important contributors to erosion and topographic change off-craton than on-craton. Together, these results suggest that lithospheric architecture can have an important control on the surface expression of mantle dynamics.

  8. Predicting small-mammal responses to climatic warming: autecology, geographic range, and the Holocene fossil

    E-print Network

    Hadly, Elizabeth

    , and the Holocene fossil record R E B E C C A C . T E R R Y, C H E N G ( L I LY ) L I and E L I Z A B E T H A . H use time-series data from the small-mammal fossil records of two caves in the Great Basin of an invasive annual grass (Bromus tectorum). We find that most community-level responses to climatic change

  9. An Introduction to Fossil Plants

    ERIC Educational Resources Information Center

    Thomas, B. A.

    1976-01-01

    Introduces methods of studying fossil plants and of teaching palaeobotany. Brief accounts are given of different types of preservation and where to find specimens. An annotated bibliography is provided. (Author/SL)

  10. 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)

  11. 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. PMID:21290608

  12. Molecules and fossils reveal punctuated diversification in Caribbean “faviid” corals

    PubMed Central

    2012-01-01

    Background Even with well-known sampling biases, the fossil record is key to understanding macro-evolutionary patterns. During the Miocene to Pleistocene in the Caribbean Sea, the fossil record of scleractinian corals shows a remarkable period of rapid diversification followed by massive extinction. Here we combine a time-calibrated molecular phylogeny based on three nuclear introns with an updated fossil stratigraphy to examine patterns of radiation and extinction in Caribbean corals within the traditional family Faviidae. Results Concatenated phylogenetic analysis showed most species of Caribbean faviids were monophyletic, with the exception of two Manicina species. The time-calibrated tree revealed the stem group originated around the closure of the Tethys Sea (17.0?Ma), while the genus Manicina diversified during the Late Miocene (8.20?Ma), when increased sedimentation and productivity may have favored free-living, heterotrophic species. Reef and shallow water specialists, represented by Diploria and Favia, originate at the beginning of the Pliocene (5 – 6?Ma) as the Isthmus of Panama shoaled and regional productivity declined. Conclusions Later origination of the stem group than predicted from the fossil record corroborates the hypothesis of morphological convergence in Diploria and Favia genera. Our data support the rapid evolution of morphological and life-history traits among faviid corals that can be linked to Mio-Pliocene environmental changes. PMID:22831179

  13. Ancient Ephemeroptera–Collembola Symbiosis Fossilized in Amber Predicts Contemporary Phoretic Associations

    PubMed Central

    Penney, David; McNeil, Andrew; Green, David I.; Bradley, Robert S.; Jepson, James E.; Withers, Philip J.; Preziosi, Richard F.

    2012-01-01

    X-ray computed tomography is used to identify a unique example of fossilized phoresy in 16 million-year-old Miocene Dominican amber involving a springtail being transported by a mayfly. It represents the first evidence (fossil or extant) of phoresy in adult Ephemeroptera and only the second record in Collembola (the first is also preserved in amber). This is the first record of Collembola using winged insects for dispersal. This fossil predicts the occurrence of similar behaviour in living springtails and helps explain the global distribution of Collembola today. PMID:23082186

  14. 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

    Although the age and location is disputed, the rise of the first closed-canopy forest is likely linked with the expansion of angiosperms in the late Cretacous or early Cenozoic. The carbon isotope 'canopy effect' reflects the extent of canopy closure, and is well documented in ?13C values of the leaves and leaf lipids in modern forests. To test the extent of canopy closure among the oldest documented angiosperm tropical forests, we analyzed isotopic characteristics of leaf fossils and leaf waxes from the Guaduas and Cerrejón Formations. The Guaduas Fm. (Maastrichtian) contains some of the earliest angiosperm fossils in the Neotropics, and both leaf morphology and pollen records at this site suggest an open-canopy structure. The Cerrejón Fm. (Paleocene) contains what are believed to be the first recorded fossil leaves from a closed-canopy forest. We analyzed the bulk carbon isotope content (?13Cleaf) of 199 fossil leaves, as well as the n-alkane concentration and chain-length distribution, and ?13C of alkanes (?13Clipid) of 73 fossil leaves and adjacent sediment samples. Fossil leaves are dominated by eudicots and include ten modern plant families (Apocynaceae, Bombaceae, Euphorbaceae, Fabaceae, Lauraceae, Malvaceae, Meliaceae, Menispermaceae, Moraceae, Sapotaceae). We interpreted extent of canopy coverage based on the range of ?13Cleaf values. The narrow range of ?13C values in leaves from the Guaduas Fm (2.7‰) is consistent with an open canopy. A significantly wider range in values (6.3‰) suggests a closed-canopy signature for site 0315 of the Cerrejón Fm,. In contrast, at Site 0318, a lacustrine deposit, leaves had a narrow range (3.3‰) in ?13C values, and this is not consistent with a closed-canopy, but is consistent with leaf assemblages from a forest edge. Leaves that accumulate in lake sediments tend to be biased toward plants living at the lake edge, which do not experience closed-canopy conditions, and do not express the isotopic characteristics associated with canopy effect. A biomass flux-weighted model of alkane chain-length distribution and ?13Cleaf 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 ?13Cleaf 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.

  15. 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.

  16. Packard et al. 2013 Behavioral Syndromes in African Bovids Page 1 of 17 Biodiversity Report Series No. BS13.03

    E-print Network

    Packard, Jane M.

    at Galveston, Galveston, Texas 4 Fossil Rim Wildlife Center, Glen Rose, Texas Keywords: aggression, antelope-tested this behavioral assay system on three species of African bovids (horse antelope) at two sites and report results

  17. Probing the edge of the West African Craton: A first seismic glimpse from Niger

    NASA Astrophysics Data System (ADS)

    Di Leo, Jeanette F.; Wookey, James; Kendall, J.-Michael; Selby, Neil D.

    2015-03-01

    Constraints on crustal and mantle structure of the Eastern part of the West African Craton have to date been scarce. Here we present results of P receiver function and SK(K)S wave splitting analyses of data recorded at International Monitoring System array TORD in SW Niger. Despite lacking in lateral coverage, our measurements sharply constrain crustal thickness (˜41 km), VP/VS ratio (1.69 ± 0.03), mantle transition zone (MTZ) thickness (˜247 km), and a midlithospheric discontinuity at ˜67 km depth. Splitting delay times are low with an average of 0.63 ± 0.01 s. Fast directions follow the regional surface geological trend with an average of 57 ± 1°. We suggest that splitting is due to fossil anisotropic fabrics in the crust and lithosphere, incurred during the Paleoproterozoic Eburnean Orogeny, with possible contributions from the later Pan-African Orogeny and present-day mantle flow. The MTZ appears to be unperturbed, despite the proximity of the sampled region to the deep cratonic root.

  18. Peaches Preceded Humans: Fossil Evidence from SW China.

    PubMed

    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

  19. 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

  20. 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).

  1. AFRICAN AMERICAN RESOURCE GUIDE

    E-print Network

    Loudon, Catherine

    AFRICAN AMERICAN RESOURCE GUIDE #12;PACIFIC OCEAN #12;Table of Contents Message from the Chancellor ............2 Message from the Vice Chancellor ...3 Majors and Minors.............................. 4 African American Studies.................. 8 Clubs and Organizations.................... 9 Community Calendar

  2. African Americans and Glaucoma

    MedlinePLUS

    ... Involved News About Us Donate In This Section African Americans and Glaucoma email Send this article to a ... glaucoma is the leading cause of blindness in African Americans. Half of those with glaucoma don't know ...

  3. 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. PMID:25236413

  4. 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. PMID:24763744

  5. 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.

  6. African Women's History.

    ERIC Educational Resources Information Center

    Strobel, Margaret

    1982-01-01

    Examines how the historical experiences and documentation of the lives of African women differ from those of their American and European counterparts. The effect of these differences on the development of African womens' historiography is discussed. A college course on African women's history, including a list of resource materials, is described.…

  7. African American Suicide

    MedlinePLUS

    African American Suicide Fact Sheet Based on 2012 Data (2014) Overview • In 2012, 2,357 African Americans completed suicide in the U.S. Of these, 1, ... 46 per 100,000. • The suicide rate for African Americans ages 10-19 was 2.98 per 100, ...

  8. The African Connection

    ERIC Educational Resources Information Center

    Oguntoyinbo, Lekan

    2012-01-01

    From student and faculty exchanges to joint research projects, U.S. universities maintain a broad spectrum of collaborative relationships with African universities. It's unclear how many U.S. colleges and universities have partnerships with African universities. The African Studies Association, an organization of scholars, doesn't keep that kind…

  9. Explosive growth in African combustion emissions from 2005 to 2030

    NASA Astrophysics Data System (ADS)

    Liousse, C.; Assamoi, E.; Criqui, P.; Granier, C.; Rosset, R.

    2014-03-01

    Emissions of gases and particles from the combustion of fossil fuels and biofuels in Africa are expected to increase significantly in the near future due to the rapid growth of African cities and megacities. There is currently no regional emissions inventory that provides estimates of anthropogenic combustion for the African continent. This work provides a quantification of the evolution of African combustion emissions from 2005 to 2030, using a bottom-up method. This inventory predicts very large increases in black carbon, organic carbon, CO, NOx, SO2 and non-methane hydrocarbon emissions if no emission regulations are implemented. This paper discusses the effectiveness of scenarios involving certain fuels, specific to Africa in each activity sector and each region (western, eastern, northern and southern Africa), to reduce the emissions. The estimated trends in African emissions are consistent with emissions provided by global inventories, but they display a larger range of values. African combustion emissions contributed significantly to global emissions in 2005. This contribution will increase more significantly by 2030: organic carbon emissions will for example make up 50% of the global emissions in 2030. Furthermore, we show that the magnitude of African anthropogenic emissions could be similar to African biomass burning emissions around 2030.

  10. Palaeobiology: Argentinian unhatched pterosaur fossil.

    PubMed

    Chiappe, Luis M; Codorniú, Laura; Grellet-Tinner, Gerald; Rivarola, David

    2004-12-01

    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. PMID:15577899

  11. FOSSIL2 energy policy model documentation: FOSSIL2 documentation

    SciTech Connect

    1980-10-01

    This report discusses the structure, derivations, assumptions, and mathematical formulation of the FOSSIL2 model. Each major facet of the model - supply/demand interactions, industry financing, and production - has been designed to parallel closely the actual cause/effect relationships determining the behavior of the United States energy system. The data base for the FOSSIL2 program is large, as is appropriate for a system dynamics simulation model. When possible, all data were obtained from sources well known to experts in the energy field. Cost and resource estimates are based on DOE data whenever possible. This report presents the FOSSIL2 model at several levels. Volumes II and III of this report list the equations that comprise the FOSSIL2 model, along with variable definitions and a cross-reference list of the model variables. Volume II provides the model equations with each of their variables defined, while Volume III lists the equations, and a one line definition for equations, in a shorter, more readable format.

  12. Fossil Group Origins VII. Galaxy substructures in fossil systems

    E-print Network

    Zarattini, S; 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

    2015-01-01

    Fossil groups 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 $M^\\ast$ 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. 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 $z \\le 0.25$. We apply a number of tests in order to investigate the substructure in fossil systems in the two-dimensional space of projected positions out to $R_{200}$. Moreover, for a subsam...

  13. 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.

  14. Molecular and Fossil Evidence on the Origin of Angiosperms

    NASA Astrophysics Data System (ADS)

    Doyle, James A.

    2012-05-01

    Molecular data on relationships within angiosperms confirm the view that their increasing morphological diversity through the Cretaceous reflected their evolutionary radiation. Despite the early appearance of aquatics and groups with simple flowers, the record is consistent with inferences from molecular trees that the first angiosperms were woody plants with pinnately veined leaves, multiparted flowers, uniovulate ascidiate carpels, and columellar monosulcate pollen. Molecular data appear to refute the hypothesis based on morphology that angiosperms and Gnetales are closest living relatives. Morphological analyses of living and fossil seed plants that assume molecular relationships identify glossopterids, Bennettitales, and Caytonia as angiosperm relatives; these results are consistent with proposed homologies between the cupule of glossopterids and Caytonia and the angiosperm bitegmic ovule. Jurassic molecular dates for the angiosperms may be reconciled with the fossil record if the first angiosperms were restricted to wet forest understory habitats and did not radiate until the Cretaceous.

  15. 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

  16. Mitochondrial genomes as living 'fossils'.

    PubMed

    Small, Ian

    2013-01-01

    The huge variation between mitochondrial genomes makes untangling their evolutionary histories difficult. Richardson et al. report on the remarkably unaltered 'fossil' genome of the tulip tree, giving us many clues as to how the mitochondrial genomes of flowering plants have evolved over the last 150 million years, and raising questions about how such extraordinary sequence conservation can be maintained. PMID:23587103

  17. Progress of fossil fuel science

    SciTech Connect

    Demirbas, M.F.

    2007-07-01

    Coal is the most abundant and widely distributed fossil fuel. More than 45% of the world's electricity is generated from coal, and it is the major fuel for generating electricity worldwide. The known coal reserves in the world are enough for more than 215 years of consumption, while the known oil reserves are only about 39 times of the world's consumption and the known natural gas reserves are about 63 times of the world's consumption level in 1998. In recent years, there have been effective scientific investigations on Turkish fossil fuels, which are considerable focused on coal resources. Coal is a major fossil fuel source for Turkey. Turkish coal consumption has been stable over the past decade and currently accounts for about 24% of the country's total energy consumption. Lignite coal has had the biggest share in total fossil fuel production, at 43%, in Turkey. Turkish researchers may investigate ten broad pathways of coal species upgrading, such as desulfurization and oxydesulfurization, pyrolysis and hydropyrolysis, liquefaction and hydroliquefaction, extraction and supercritical fluid extraction, gasification, oxidation, briquetting, flotation, and structure identification.

  18. A Plio-Pleistocene molecular isotopic record of Turkana Basin vegetation

    NASA Astrophysics Data System (ADS)

    Uno, K. T.; Polissar, P. J.; Bonnefille, R.; Lepre, C. J.; deMenocal, P. B.

    2014-12-01

    Paleovegetation and paleontological data from East Africa suggest that over the last five million years, the evolution of mammals has been significantly influenced by the emergence and expansion of C4 grasslands. Isotopic data from soil carbonate and marine core biomarkers indicate increased C4 grasses on the landscape beginning in the late Miocene. However, most Plio-Pleistocene sediments at vertebrate fossil localities lack sufficient soil carbonates that could allow us to directly link organisms to the particular environment where they lived. Here we take advantage of the organic biomarker record of vegetation in East Africa to understand landscape variability, its long-term evolution, and the relationship to the fossil record. Biomarker isotope records from Omo Group sediments, a fluvial-lacustrine sequence in the Turkana Basin, differ from their marine core counterparts in that they provide a local vegetation signal that can be directly linked to fossil material from the same sediments; they differ from soil carbonate records in that they are not limited to the specific environmental conditions necessary for carbonate precipitation. We present carbon isotope data from n-alkane and n-alkanoic acids from Omo Group sediments that span 3.6 to 1.1 Ma. The ?13C values from nC31 alkanes and nC30 alkanoic acids indicate high landscape variability ranging from C3-dominated to pure C4 environments. In both the Shungura and Nachukui Formations, biomarker data record significantly more C4 vegetation on the landscape than existing soil carbonate data. Biomarker data from the Shungura Formation indicate a more dynamic landscape than what is shown in the soil carbonate record. Biomarker samples come from sediments initially collected for pollen or paleomagnetic analyses that generally do not contain soil carbonates. They represent a wide variety of sediment types and therefore capture a broad range of depositional environments and environmental variability. Combined ?13C records from biomarkers and soil carbonates indicate a more dynamic landscape than what is recorded by a single proxy alone. The combined paleovegetation record from these two proxies suggests that East African fauna evolved in a highly variable landscape during the Plio-Pleistocene.

  19. 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

  20. Fossil Energy: Drivers and Challenges.

    NASA Astrophysics Data System (ADS)

    Friedmann, Julio

    2007-04-01

    Concerns about rapid economic growth, energy security, and global climate change have created a new landscape for fossil energy exploration, production, and utilization. Since 85% of primary energy supply comes from fossil fuels, and 85% of greenhouse gas emissions come from fossil fuel consumption, new and difficult technical and political challenges confront commercial, governmental, and public stakeholders. As such, concerns over climate change are explicitly weighed against security of international and domestic energy supplies, with economic premiums paid for either or both. Efficiency improvements, fuel conservation, and deployment of nuclear and renewable supplies will help both concerns, but are unlikely to offset growth in the coming decades. As such, new technologies and undertakings must both provide high quality fossil energy with minimal environmental impacts. The largest and most difficult of these undertakings is carbon management, wherein CO2 emissions are sequestered indefinitely at substantial incremental cost. Geological formations provide both high confidence and high capacity for CO2 storage, but present scientific and technical challenges. Oil and gas supply can be partially sustained and replaced through exploitation of unconventional fossil fuels such as tar-sands, methane hydrates, coal-to-liquids, and oil shales. These fuels provide enormous reserves that can be exploited at current costs, but generally require substantial energy to process. In most cases, the energy return on investment (EROI) is dropping, and unconventional fuels are generally more carbon intensive than conventional, presenting additional carbon management challenges. Ultimately, a large and sustained science and technology program akin to the Apollo project will be needed to address these concerns. Unfortunately, real funding in energy research has dropped dramatically (75%) in the past three decades, and novel designs in fission and fusion are not likely to provide any substantial offset in the next 30 years when they are most needed internationally.

  1. WARFIELD CENTER FOR AFRICAN AND AFRICAN AMERICAN STUDIES

    E-print Network

    John, Lizy Kurian

    WARFIELD CENTER FOR AFRICAN AND AFRICAN AMERICAN STUDIES ON CAMPUS CARRY Statement on Pending. Accordingly, the faculty of the John L. Warfield Center for African and African American Studies stands violence against us in these often fraught settings. Moreover, African Americans are disproportionality

  2. African & African American Studies (AAS) Archaeology Technology & Historical Structures (ATHS)

    E-print Network

    Cantlon, Jessica F.

    African & African American Studies (AAS) Archaeology Technology & Historical Structures (ATHS) AAS 302, AH 302. Frederick Douglass Institute for African and African-American Studies Morey 311 - Tel of Africa, the Western Sudan, Zimbabwe, the Inland Niger Delta and the West African Rainforest. The role

  3. Morphometric analysis of chameleon fossil fragments from the Early Pliocene of South Africa: a new piece of the chamaeleonid history

    NASA Astrophysics Data System (ADS)

    Dollion, Alexis Y.; Cornette, Raphaël; Tolley, Krystal A.; Boistel, Renaud; Euriat, Adelaïde; Boller, Elodie; Fernandez, Vincent; Stynder, Deano; Herrel, Anthony

    2015-02-01

    The evolutionary history of chameleons has been predominantly studied through phylogenetic approaches as the fossil register of chameleons is limited and fragmented. The poor state of preservation of these fossils has moreover led to the origin of numerous nomen dubia, and the identification of many chameleon fossils remains uncertain. We here examine chameleon fossil fragments from the Early Pliocene Varswater formation, exposed at the locality of Langebaanweg "E" Quarry along the southwestern coast of South Africa. Our aim was to explore whether these fossil fragments could be assigned to extant genera. To do so, we used geometric morphometric approaches based on microtomographic imaging of extant chameleons as well as the fossil fragments themselves. Our study suggests that the fossils from this deposit most likely represent at least two different forms that may belong to different genera. Most fragments are phenotypically dissimilar from the South African endemic genus Bradypodion and are more similar to other chameleon genera such as Trioceros or Kinyongia. However, close phenetic similarities between some of the fragments and the Seychelles endemic Archaius or the Madagascan genus Furcifer suggest that some of these fragments may not contain enough genus-specific information to allow correct identification. Other fragments such as the parietal fragments appear to contain more genus-specific information, however. Although our data suggest that the fossil diversity of chameleons in South Africa was potentially greater than it is today, this remains to be verified based on other and more complete fragments.

  4. Morphometric analysis of chameleon fossil fragments from the Early Pliocene of South Africa: a new piece of the chamaeleonid history.

    PubMed

    Dollion, Alexis Y; Cornette, Raphaël; Tolley, Krystal A; Boistel, Renaud; Euriat, Adelaïde; Boller, Elodie; Fernandez, Vincent; Stynder, Deano; Herrel, Anthony

    2015-02-01

    The evolutionary history of chameleons has been predominantly studied through phylogenetic approaches as the fossil register of chameleons is limited and fragmented. The poor state of preservation of these fossils has moreover led to the origin of numerous nomen dubia, and the identification of many chameleon fossils remains uncertain. We here examine chameleon fossil fragments from the Early Pliocene Varswater formation, exposed at the locality of Langebaanweg "E" Quarry along the southwestern coast of South Africa. Our aim was to explore whether these fossil fragments could be assigned to extant genera. To do so, we used geometric morphometric approaches based on microtomographic imaging of extant chameleons as well as the fossil fragments themselves. Our study suggests that the fossils from this deposit most likely represent at least two different forms that may belong to different genera. Most fragments are phenotypically dissimilar from the South African endemic genus Bradypodion and are more similar to other chameleon genera such as Trioceros or Kinyongia. However, close phenetic similarities between some of the fragments and the Seychelles endemic Archaius or the Madagascan genus Furcifer suggest that some of these fragments may not contain enough genus-specific information to allow correct identification. Other fragments such as the parietal fragments appear to contain more genus-specific information, however. Although our data suggest that the fossil diversity of chameleons in South Africa was potentially greater than it is today, this remains to be verified based on other and more complete fragments. PMID:25604737

  5. 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)

  6. 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 macroevolution. PMID:16533822

  7. 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

  8. African Music in the Americas

    ERIC Educational Resources Information Center

    Goines, Leonard

    1977-01-01

    Discusses African music, how it survived slavery, why it manifests itself in specific forms, why some of these forms are almost purely African today while others are very European, the specific characteristics of African music that permeate all African-American music, and why African derived religions are flourishing in the black communities of…

  9. REPORT OF THE FOSSIL FUELS REVIEW GROUP

    E-print Network

    REPORT OF THE FOSSIL FUELS REVIEW GROUP APRIL 2015 1 #12;Table of Contents 1. Background.....................................................4 c. Evidence on Fossil Fuel Dependence, Mitigation Strategies and Relative Contributions by Fuel Divestment from All Energy Related Fossil Fuel Companies........... 13 4. Evaluating the Options

  10. Using extant morphological variation to understand fossil

    E-print Network

    Ackermann, Rebecca Rogers

    Using extant morphological variation to understand fossil relationships: a cautionary tale Rebecca of insights that are pertinent to how we evaluate relationships among our fossil human ancestors. Here I summarize four such insights. I then use a fossil hominid example to illustrate how our understanding

  11. 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.

  12. 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.

  13. Fossil: A Robust Relational Learner Johannes Furnkranz

    E-print Network

    Fürnkranz, Johannes

    Fossil: A Robust Relational Learner Johannes F¨urnkranz juffi@ai.univie.ac.at Austrian Research in this paper describes Fossil, an ILP system that uses a search heuristic based on statistical correlation, Fossil's stopping criterion depends on a search heuristic that estimates the utility of literals

  14. Constraining fossil calibrations for molecular clocks

    E-print Network

    Kumar, Sudhir

    Constraining fossil calibrations for molecular clocks Sir, In a recent paper, Mu¨ller and Reisz(1) proposed how fossil calibrations should be selected for application in molecular clock studies. The topic molecules. Nonetheless, we believe that these authors have erred both in their proposal of fossil

  15. Atmospheric Lifetime of Fossil Fuel Carbon Dioxide

    E-print Network

    Atmospheric Lifetime of Fossil Fuel Carbon Dioxide David Archer,1 Michael Eby,2 Victor Brovkin,3 released from combustion of fossil fuels equilibrates among the various carbon reservoirs of the atmosphere literature on the atmospheric lifetime of fossil fuel CO2 and its impact on climate, and we present initial

  16. The conservation and use of fossil vertebrate sites: British fossil reptile sites

    E-print Network

    Benton, Michael

    The conservation and use of fossil vertebrate sites: British fossil reptile sites Michael J. Benton and William A. Wimbledon BENTON. M. J. & W. A. WIMBLEDON. 19R5. The conservation and use of fossil vertebrate sites: British fossil reptile sites. Proc. Geol. Ass., 96 (I). 1-0. Over a thousand sites in Britain

  17. 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.

  18. 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. PMID:26674947

  19. Fossil wood from the Miocene and Oligocene epoch: chemistry and morphology.

    PubMed

    Bardet, Michel; Pournou, Anastasia

    2015-01-01

    Fossil wood is the naturally preserved remain of the secondary xylem of plants that lived before the Holocene epoch. Typically, fossil wood is preserved as coalified or petrified and rarely as mummified tissue. The process of fossilization is very complex and it is still unknown why in the same fossil record, wood can be found in different fossilisation forms. In 2007, a fossil forest was found in the Bükkábrány open-pit coal mine in Hungary. The non-petrified forest is estimated to be 7 million years old (Miocene epoch) and its trees were found standing in an upright position. This fossil assemblage is exceptionally rare because wood has been preserved as soft waterlogged tissue. This study aimed to investigate this remarkable way of fossil wood preservation, by examining its chemistry with (13)C CPMAS NMR and its morphology with light and electron microscopy. For comparison reasons, a petrified wood trunk from the Oligocene epoch (30 Myr) found in 2001 at Porrentruy region in Switzerland and two fresh wood samples of the modern equivalents of the Miocene sample were also examined. The results obtained showed that the outstanding preservation state of the Miocene fossil is not owed to petrification or coalification. Mummification is a potential mechanism that could explain Bükkábrány trunks' condition, however this fossilisation process is not well studied and therefore this hypothesis needs to be further investigated. PMID:25294390

  20. Scaling relations in fossil galaxy groups

    E-print Network

    Habib G. Khosroshahi; Trevor J. Ponman; Laurence R. Jones

    2007-02-04

    Using Chandra X-ray observations and optical imaging and spectroscopy of a flux-limited sample of 5 fossil groups, supplemented by additional systems from the literature, we provide the first detailed study of the scaling properties of fossils compared to normal groups and clusters. In general, all the fossils we study show regular and symmetric X-ray emission, indicating an absence of recent major group mergers. We confirm that, for a given optical luminosity of the group, fossils are more X-ray luminous than non-fossil groups. Fossils, however, fall comfortably on the conventional L_X-T_X relation of galaxy groups and clusters, suggesting that their X-ray luminosity and their gas temperature are both boosted, arguably, as a result of their early formation. This is supported by other scaling relations including the L_X-sigma and T_X-sigma relations in which fossils show higher X-ray luminosity and temperature for a given group velocity dispersion. We find that mass concentration in fossils is higher than in non-fossil groups and clusters. In addition, the M_X-T_X relation suggests that fossils are hotter, for a given total gravitational mass, both consistent with an early formation epoch for fossils. We show that the mass-to-light ratio in fossils is rather high but not exceptional, compared to galaxy groups and clusters. The entropy of the gas in low mass fossils appears to be systematically lower than that in normal groups, which may explain why the properties of fossils are more consistent with an extension of cluster properties. We conclude that the cuspy potential raises the luminosity and temperature of the IGM in fossils. However, this works in conjunction with lower gas entropy, which may arise from less effective preheating of the gas.

  1. Clustering Fossils in Solid Inflation

    E-print Network

    Mohammad Akhshik

    2014-09-10

    In solid inflation the single field non-Gaussianity consistency condition is violated. As a result, the long tensor perturbation induces observable clustering fossils in the form of quardupole anisotropy in large scale structure power spectrum. In this work we revisit the bispectrum analysis for the scalar-scalar-scalar and tensor-scalar-scalar 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 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 scalar perturbations. We argue that imprints of clustering fossil from primordial gravitational waves on large scale structures can be detected from the future galaxy surveys.

  2. 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.

  3. The 1 Ma Lake Bosumtwi (West Africa) Paleoclimate Record: Comparisons to Marine and Polar Records

    NASA Astrophysics Data System (ADS)

    Peck, J. A.; Shanahan, T. M.; King, J. W.; Overpeck, J. T.; Scholz, C. A.; Heil, C.; Forman, S. L.; Amoako, P. Y.

    2007-12-01

    Lake Bosumtwi is a hydrologically closed lake occupying a 1.07 Ma impact crater in Ghana, West Africa. The lake lies beneath the path of the seasonal migration of the ITCZ and therefore can provide a sedimentary record of monsoon variability in West Africa. Scientific drilling recovered a 291-m long sediment section that spans the full 1 Ma history of the lake. This long continental record is ideal for comparison to long marine and ice-core records at both glacial-interglacial and abrupt-change timescales. Oxygen-isotope stratigraphy, derived from calcareous fossils, often provides age control and a way to place individual marine sediment cores into a global stratigraphic framework. Lacking a direct tie-in to the marine oxygen-isotope stratigraphy, individual lacustrine basins can present challenges for global correlation. Through radiocarbon, optically stimulated luminescence and paleomagnetic dating, limited age control has been established for the 1 Ma Lake Bosumtwi sediment sequence. Within a Bosumtwi sediment sequence that is mostly laminated occur intervals of non-laminated sediment having increased density, decreased organic content and a high-coercivity magnetic mineral assemblage. Some of these massive layers contain slump-folding and intraformational clasts. These lithologies are interpreted to represent lake-level lowstands when a diminished West African summer monsoon resulted in decreased moisture balance and lake-level regression. Some Bosumtwi lake-level lowstands match intervals of increased sea surface salinity in the Gulf of Guinea resulting from reduced river discharge (Weldeab et al. 2007, Science, 316, 1303-1307). However, during other intervals (MIS2) there are differences between the two records. Corresponding to glacial stages and stadials, increased amounts of high-coercivity magnetic minerals are present in the Lake Bosumtwi sediment. Elevated aerosol dust export from arid Sahel sources, possibly accompanied by enhanced magnetic-mineral diagenesis during lake- level lowstands, is interpreted to have produced this magnetic signature. The Bosumtwi dust proxy record displays variability similar to that of published dust records from marine and polar settings. Comparing this continental dust record to a marine dust record off the coast of West Africa provides additional constraints on identifying glacial-interglacial variability in the 1 Ma long lacustrine sediment sequence.

  4. The African superswell

    NASA Technical Reports Server (NTRS)

    Nyblade, Andrew A.; Robinson, Scott W.

    1994-01-01

    Maps of residual bathymetry in the ocean basins around the African continent reveal a broad bathymetric swell in the southeastern Atlantic Ocean with an amplitude of about 500 m. We propose that this region of anomalously shallow bathymetry, together with the contiguous eastern and southern African plateaus, form a superswell which we refer to as the African superswell. The origin of the African superswell is uncertain. However, rifting and volcanism in eastern Africa, as well as heat flow measurements in southern Africa and the southeastern Atlantic Ocean, suggest that the superswell may be attributed, at least in part, to heating of the lithosphere.

  5. African-American women and abortion: a neglected history.

    PubMed

    Ross, L J

    1992-01-01

    The history of African-American women's efforts to control their fertility is largely unknown. From slavery to the present, the growth rate of the African-American population has been cut in half. Demographers and historians frequently attribute this change to external factors such as poverty, disease, and coerced birth control, rather than the deliberate agency of African-American women. This essay assembles a brief historical record of the ways African-American women have sought to control their fertility through the use of abortion and birth control. It also examines the activism of African-American women in the establishment of family planning clinics and in defense of abortion rights. PMID:1420666

  6. The Fossil Record of Star Formation from Galaxy Spectra 

    E-print Network

    Panter, Ben

    In this thesis I present work using the MOPED algorithm to extract in a non-parametric fashion star formation histories and galaxy masses from the spectra of galaxies in the Sloan Digital Sky Survey. The recovered ...

  7. The Future of the Fossil Record David Jablonski

    E-print Network

    , and on methodological advances ranging from high-resolution geochronology to simulation of morphological evolution. Key, magnitudes, and spatial scales of change in the physical and biotic environment will be important in all scales? The overall trend of plant and animal biodiversity--whether measured in terms of taxa, range

  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 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.

  11. 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. PMID:9310195

  12. 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.

  13. 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.

  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. PMID:9927587

  15. 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.

  16. 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:23144757

  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. Diversification of Neoaves: integration of molecular sequence data and fossils.

    PubMed

    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

    2006-12-22

    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

  19. Effectiveness of Diabetes Prevention Program translations among African Americans.

    PubMed

    Samuel-Hodge, C D; Johnson, C M; Braxton, D F; Lackey, M

    2014-10-01

    The Diabetes Prevention Program (DPP) demonstrated risk reduction for incident diabetes through weight loss among all participants, including African Americans. Several DPP translations have been conducted in less controlled settings, including primary care practices and communities; however, there is no detailed compilation of how effective these translations have been for African Americans. This systematic literature review evaluated DPP translations from 2003 to 2012. Eligible records were retrieved using a search strategy of relevant databases and gray literature. Retrieved records (n=1,272) were screened using a priori criteria, which resulted in 21 full-text studies for review. Seventeen studies were included in the full-text qualitative synthesis. Seven studies had 100% African American samples and 10 studies had mixed samples with African American subgroups. African American participants' average weight loss was roughly half of that achieved in the DPP intervention. However, with few higher-quality studies, small sample sizes and differences in intervention designs and implementation, comparisons across interventions were difficult. The suboptimal effectiveness of DPP translations among African American adults, particularly women, signals the need for enhancements to existing evidence-based interventions and more high-quality research that includes other at-risk African American subgroups such as men and younger adults of lower socioeconomic status. PMID:25196409

  20. Understanding African American Males

    ERIC Educational Resources Information Center

    Bell, Edward Earl

    2010-01-01

    The purpose of this study was to assess the socialization skills, self-esteem, and academic readiness of African American males in a school environment. Discussions with students and the School Perceptions Questionnaire provided data for this investigation. The intended targets for this investigation were African American students; however, there…

  1. 16 Extraordinary African Americans.

    ERIC Educational Resources Information Center

    Lobb, Nancy

    This collection for children tells the stories of 16 African Americans who helped make America what it is today. African Americans can take pride in the heritage of these contributors to society. Biographies are given for the following: (1) Sojourner Truth, preacher and abolitionist; (2) Frederick Douglass, abolitionist; (3) Harriet Tubman, leader…

  2. Keeping African Masks Real

    ERIC Educational Resources Information Center

    Waddington, Susan

    2012-01-01

    Art is a good place to learn about our multicultural planet, and African masks are prized throughout the world as powerfully expressive artistic images. Unfortunately, multicultural education, especially for young children, can perpetuate stereotypes. Masks taken out of context lose their meaning and the term "African masks" suggests that there is…

  3. Oldest Fossil Basidiomycete Clamp Connections

    E-print Network

    Krings, Michael; Dotzler, Nora; Galtier, Jean; Taylor, Thomas N.

    2011-01-01

    -decaying basidiomycete of the family Polyporaceae (Hibbett et al. 1994), and suggested that the fossil was a saprotroph. The biological nature of the relationship between Botryopteris antiqua and the Visean clamp-bearing hyphae is difficult to determine because... of the incompleteness of both the host plant and fungus. The fungus could have been biotrophic or saprotrophic. If the conical callosities found in several of the cortical cells (Fig. 1m,n) formed in response to invading clamp-bearing hyphae, then this host response...

  4. Direct evidence of central European forest refugia during the last glacial period based on mollusc fossils

    NASA Astrophysics Data System (ADS)

    Ju?i?ková, Lucie; Horá?ková, Jitka; Ložek, Vojen

    2014-07-01

    Although there is evidence from molecular studies for the existence of central European last glacial refugia for temperate species, there is still a great lack of direct fossil records to confirm this theory. Here we bring such evidence in the form of fossil shells from twenty strictly forest land snail species, which were recorded in radiocarbon-dated late glacial or older mollusc assemblages of nine non-interrupted mollusc successions situated in the Western Carpathians, and one in the Bohemian Massif. We proposed that molluscs survived the last glacial period in central Europe in isolated small patches of broadleaf forest, which we unequivocally demonstrate for two sites of last glacial maximum age.

  5. African bees to control African elephants

    NASA Astrophysics Data System (ADS)

    Vollrath, Fritz; Douglas-Hamilton, Iain

    2002-11-01

    Numbers of elephants have declined in Africa and Asia over the past 30 years while numbers of humans have increased, both substantially. Friction between these two keystone species is reaching levels which are worryingly high from an ecological as well as a political viewpoint. Ways and means must be found to keep the two apart, at least in areas sensitive to each species' survival. The aggressive African bee might be one such method. Here we demonstrate that African bees deter elephants from damaging the vegetation and trees which house their hives. We argue that bees can be employed profitably to protect not only selected trees, but also selected areas, from elephant damage.

  6. The Fossil Calibration Database-A New Resource for Divergence Dating.

    PubMed

    Ksepka, Daniel T; Parham, James F; Allman, James F; Benton, Michael J; Carrano, Matthew T; Cranston, Karen A; Donoghue, Philip C J; Head, Jason J; Hermsen, Elizabeth J; Irmis, Randall B; Joyce, Walter G; Kohli, Manpreet; Lamm, Kristin D; Leehr, Dan; Patané, Josés L; Polly, P David; Phillips, Matthew J; Smith, N Adam; Smith, Nathan D; Van Tuinen, Marcel; Ware, Jessica L; Warnock, Rachel C M

    2015-09-01

    Fossils provide the principal basis for temporal calibrations, which are critical to the accuracy of divergence dating analyses. Translating fossil data into minimum and maximum bounds for calibrations is the most important-often least appreciated-step of divergence dating. Properly justified calibrations require the synthesis of phylogenetic, paleontological, and geological evidence and can be difficult for nonspecialists to formulate. The dynamic nature of the fossil record (e.g., new discoveries, taxonomic revisions, updates of global or local stratigraphy) requires that calibration data be updated continually lest they become obsolete. Here, we announce the Fossil Calibration Database (http://fossilcalibrations.org), a new open-access resource providing vetted fossil calibrations to the scientific community. Calibrations accessioned into this database are based on individual fossil specimens and follow best practices for phylogenetic justification and geochronological constraint. The associated Fossil Calibration Series, a calibration-themed publication series at Palaeontologia Electronica, will serve as a key pipeline for peer-reviewed calibrations to enter the database. PMID:25922515

  7. 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.

  8. AFRICAN AMERICAN PSYCHOLOGY Sample Syllabus

    E-print Network

    Hopfinger, Joseph B.

    AFRICAN AMERICAN PSYCHOLOGY PSYC 503 Sample Syllabus Course Description and Overview: This course examines the psychology of the African American experience. We begin the course with an overview of Black/African American psychology as an evolving field of study and consider the Black/African American Psychology

  9. Fossilization causes organisms to appear erroneously primitive by distorting evolutionary trees

    PubMed Central

    Sansom, Robert S.; Wills, Matthew A.

    2013-01-01

    Fossils are vital for calibrating rates of molecular and morphological change through geological time, and are the only direct source of data documenting macroevolutionary transitions. Many evolutionary studies therefore require the robust phylogenetic placement of extinct organisms. Here, we demonstrate that the inevitable bias of the fossil record to preserve just hard, skeletal morphology systemically distorts phylogeny. Removal of soft part characters from 78 modern vertebrate and invertebrate morphological datasets resulted in significant changes to phylogenetic signal; it caused individual taxa to drift from their original position, predominately downward toward the root of their respective trees. This last bias could systematically inflate evolutionary rates inferred from molecular data because first fossil occurrences will not be recognised as such. Stem-ward slippage, whereby fundamental taphonomic biases cause fossils to be interpreted as erroneously primitive, is therefore a ubiquitous problem for all biologists attempting to infer macroevolutionary rates or sequences. PMID:23985991

  10. Black versus Black: The Relationship among African, African American, and African Caribbean Persons.

    ERIC Educational Resources Information Center

    Jackson, Jennifer V.; Cothran, Mary E.

    2003-01-01

    Surveyed people of African descent regarding relationships among African, African-American, and African-Caribbean persons, focusing on contact and friendship, travel to countries of the diaspora, cross-cultural communication, thoughts and stereotypes, and education. Most respondents had contacts with the other groups, but groups had preconceived…

  11. Fossil preservation and the stratigraphic ranges of taxa.

    PubMed

    Foote, M; Raup, D M

    1996-01-01

    The incompleteness of the fossil record hinders the inference of evolutionary rates and patterns. Here, we derive relationships among true taxonomic durations, preservation probability, and observed taxonomic ranges. We use these relationships to estimate original distributions of taxonomic durations, preservation probability, and completeness (proportion of taxa preserved), given only the observed ranges. No data on occurrences within the ranges of taxa are required. When preservation is random and the original distribution of durations is exponential, the inference of durations, preservability, and completeness is exact. However, reasonable approximations are possible given non-exponential duration distributions and temporal and taxonomic variation in preservability. Thus, the approaches we describe have great potential in studies of taphonomy, evolutionary rates and patterns, and genealogy. Analyses of Upper Cambrian-Lower Ordovician trilobite species, Paleozoic crinoid genera, Jurassic bivalve species, and Cenozoic mammal species yield the following results: (1) The preservation probability inferred from stratigraphic ranges alone agrees with that inferred from the analysis of stratigraphic gaps when data on the latter are available. (2) Whereas median durations based on simple tabulations of observed ranges are biased by stratigraphic resolution, our estimates of median duration, extinction rate, and completeness are not biased.(3) The shorter geologic ranges of mammalian species relative to those of bivalves cannot be attributed to a difference in preservation potential. However, we cannot rule out the contribution of taxonomic practice to this difference. (4) In the groups studied, completeness (proportion of species [trilobites, bivalves, mammals] or genera [crinoids] preserved) ranges from 60% to 90%. The higher estimates of completeness at smaller geographic scales support previous suggestions that the incompleteness of the fossil record reflects loss of fossiliferous rock more than failure of species to enter the fossil record in the first place. PMID:11539203

  12. Fossil preservation and the stratigraphic ranges of taxa

    NASA Technical Reports Server (NTRS)

    Foote, M.; Raup, D. M.

    1996-01-01

    The incompleteness of the fossil record hinders the inference of evolutionary rates and patterns. Here, we derive relationships among true taxonomic durations, preservation probability, and observed taxonomic ranges. We use these relationships to estimate original distributions of taxonomic durations, preservation probability, and completeness (proportion of taxa preserved), given only the observed ranges. No data on occurrences within the ranges of taxa are required. When preservation is random and the original distribution of durations is exponential, the inference of durations, preservability, and completeness is exact. However, reasonable approximations are possible given non-exponential duration distributions and temporal and taxonomic variation in preservability. Thus, the approaches we describe have great potential in studies of taphonomy, evolutionary rates and patterns, and genealogy. Analyses of Upper Cambrian-Lower Ordovician trilobite species, Paleozoic crinoid genera, Jurassic bivalve species, and Cenozoic mammal species yield the following results: (1) The preservation probability inferred from stratigraphic ranges alone agrees with that inferred from the analysis of stratigraphic gaps when data on the latter are available. (2) Whereas median durations based on simple tabulations of observed ranges are biased by stratigraphic resolution, our estimates of median duration, extinction rate, and completeness are not biased.(3) The shorter geologic ranges of mammalian species relative to those of bivalves cannot be attributed to a difference in preservation potential. However, we cannot rule out the contribution of taxonomic practice to this difference. (4) In the groups studied, completeness (proportion of species [trilobites, bivalves, mammals] or genera [crinoids] preserved) ranges from 60% to 90%. The higher estimates of completeness at smaller geographic scales support previous suggestions that the incompleteness of the fossil record reflects loss of fossiliferous rock more than failure of species to enter the fossil record in the first place.

  13. Comparable ages for the independent origins of electrogenesis in African and South American weakly electric fishes.

    PubMed

    Lavoué, Sébastien; Miya, Masaki; Arnegard, Matthew E; Sullivan, John P; Hopkins, Carl D; Nishida, Mutsumi

    2012-01-01

    One of the most remarkable examples of convergent evolution among vertebrates is illustrated by the independent origins of an active electric sense in South American and African weakly electric fishes, the Gymnotiformes and Mormyroidea, respectively. These groups independently evolved similar complex systems for object localization and communication via the generation and reception of weak electric fields. While good estimates of divergence times are critical to understanding the temporal context for the evolution and diversification of these two groups, their respective ages have been difficult to estimate due to the absence of an informative fossil record, use of strict molecular clock models in previous studies, and/or incomplete taxonomic sampling. Here, we examine the timing of the origins of the Gymnotiformes and the Mormyroidea using complete mitogenome sequences and a parametric bayesian method for divergence time reconstruction. Under two different fossil-based calibration methods, we estimated similar ages for the independent origins of the Mormyroidea and Gymnotiformes. Our absolute estimates for the origins of these groups either slightly postdate, or just predate, the final separation of Africa and South America by continental drift. The most recent common ancestor of the Mormyroidea and Gymnotiformes was found to be a non-electrogenic basal teleost living more than 85 millions years earlier. For both electric fish lineages, we also estimated similar intervals (16-19 or 22-26 million years, depending on calibration method) between the appearance of electroreception and the origin of myogenic electric organs, providing rough upper estimates for the time periods during which these complex electric organs evolved de novo from skeletal muscle precursors. The fact that the Gymnotiformes and Mormyroidea are of similar age enhances the comparative value of the weakly electric fish system for investigating pathways to evolutionary novelty, as well as the influences of key innovations in communication on the process of species radiation. PMID:22606250

  14. Comparable Ages for the Independent Origins of Electrogenesis in African and South American Weakly Electric Fishes

    PubMed Central

    Lavoué, Sébastien; Miya, Masaki; Arnegard, Matthew E.; Sullivan, John P.; Hopkins, Carl D.; Nishida, Mutsumi

    2012-01-01

    One of the most remarkable examples of convergent evolution among vertebrates is illustrated by the independent origins of an active electric sense in South American and African weakly electric fishes, the Gymnotiformes and Mormyroidea, respectively. These groups independently evolved similar complex systems for object localization and communication via the generation and reception of weak electric fields. While good estimates of divergence times are critical to understanding the temporal context for the evolution and diversification of these two groups, their respective ages have been difficult to estimate due to the absence of an informative fossil record, use of strict molecular clock models in previous studies, and/or incomplete taxonomic sampling. Here, we examine the timing of the origins of the Gymnotiformes and the Mormyroidea using complete mitogenome sequences and a parametric Bayesian method for divergence time reconstruction. Under two different fossil-based calibration methods, we estimated similar ages for the independent origins of the Mormyroidea and Gymnotiformes. Our absolute estimates for the origins of these groups either slightly postdate, or just predate, the final separation of Africa and South America by continental drift. The most recent common ancestor of the Mormyroidea and Gymnotiformes was found to be a non-electrogenic basal teleost living more than 85 millions years earlier. For both electric fish lineages, we also estimated similar intervals (16–19 or 22–26 million years, depending on calibration method) between the appearance of electroreception and the origin of myogenic electric organs, providing rough upper estimates for the time periods during which these complex electric organs evolved de novo from skeletal muscle precursors. The fact that the Gymnotiformes and Mormyroidea are of similar age enhances the comparative value of the weakly electric fish system for investigating pathways to evolutionary novelty, as well as the influences of key innovations in communication on the process of species radiation. PMID:22606250

  15. Biofilm Growth and Fossil Form

    E-print Network

    Petroff, Alexander P.

    Stromatolites can grow under the influence of microbial processes, but it is often unclear whether and how the macroscopic morphology of these rocks records biological processes. Conical stromatolites, which formed in the ...

  16. Fossil Meteorite Unearthed From Crater

    NASA Astrophysics Data System (ADS)

    Martel, L. M. V.

    2006-06-01

    A team of scientists lead by Wolf Maier (University of Quebec, Canada and University of Pretoria, South Africa and soon at University of Western Australia, Perth) and Marco Andreoli (University of the Witwatersrand and South African Nuclear Energy Corp.) and colleagues who also hail from Canada, South Africa, the United Kingdom, and the United States, have announced the discovery of a 25-centimeter-wide chondritic meteorite unearthed from the 145-million-year-old Morokweng impact crater in South Africa. Found within the crater's impact melt sheet about 770 meters (half a mile) down a drilling borehole, the hefty meteorite's existence would seem improbable given its low chance of surviving the high shock pressures and temperatures normally associated with large impact events. Its unusual composition could mean it is a sample from a previously unknown part of the LL chondrite parent body or maybe it is from an entirely different asteroid population than other known meteorites.

  17. Mineralized rods and cones suggest colour vision in a 300 Myr-old fossil fish.

    PubMed

    Tanaka, Gengo; Parker, Andrew R; Hasegawa, Yoshikazu; Siveter, David J; Yamamoto, Ryoichi; Miyashita, Kiyoshi; Takahashi, Yuichi; Ito, Shosuke; Wakamatsu, Kazumasa; Mukuda, Takao; Matsuura, Marie; Tomikawa, Ko; Furutani, Masumi; Suzuki, Kayo; Maeda, Haruyoshi

    2014-01-01

    Vision, which consists of an optical system, receptors and image-processing capacity, has existed for at least 520 Myr. Except for the optical system, as in the calcified lenses of trilobite and ostracod arthropods, other parts of the visual system are not usually preserved in the fossil record, because the soft tissue of the eye and the brain decay rapidly after death, such as within 64 days and 11 days, respectively. The Upper Carboniferous Hamilton Formation (300 Myr) in Kansas, USA, yields exceptionally well-preserved animal fossils in an estuarine depositional setting. Here we show that the original colour, shape and putative presence of eumelanin have been preserved in the acanthodii fish Acanthodes bridgei. We also report on the tissues of its eye, which provides the first record of mineralized rods and cones in a fossil and indicates that this 300 Myr-old fish likely possessed colour vision. PMID:25536302

  18. Cryptic iridescence in a fossil weevil generated by single diamond photonic crystals

    PubMed Central

    McNamara, Maria E.; Saranathan, Vinod; Locatelli, Emma R.; Noh, Heeso; Briggs, Derek E. G.; Orr, Patrick J.; Cao, Hui

    2014-01-01

    Nature's most spectacular colours originate in integumentary tissue architectures that scatter light via nanoscale modulations of the refractive index. The most intricate biophotonic nanostructures are three-dimensional crystals with opal, single diamond or single gyroid lattices. Despite intense interest in their optical and structural properties, the evolution of such nanostructures is poorly understood, due in part to a lack of data from the fossil record. Here, we report preservation of single diamond (Fd-3m) three-dimensional photonic crystals in scales of a 735 000 year old specimen of the brown Nearctic weevil Hypera diversipunctata from Gold Run, Canada, and in extant conspecifics. The preserved red to green structural colours exhibit near-field brilliancy yet are inconspicuous from afar; they most likely had cryptic functions in substrate matching. The discovery of pristine fossil examples indicates that the fossil record is likely to yield further data on the evolution of three-dimensional photonic nanostructures and their biological functions. PMID:25185581

  19. Experimental mineralization of crustacean eggs: new implications for the fossilization of Precambrian-Cambrian embryos

    NASA Astrophysics Data System (ADS)

    Hippler, D.; Hu, N.; Steiner, M.; Scholtz, G.; Franz, G.

    2012-05-01

    Phosphatized globular microfossils from the Ediacaran and lower Cambrian of South China represent an impressive record of early animal evolution and development. However, their phylogenetic affinity is strongly debated. Understanding key processes and conditions that cause exceptional egg and embryo preservation and fossilization are crucial for a reliable interpretation of their phylogenetic position. We conducted phosphatization experiments on eggs of the marbled crayfish Procambarus that indicate a close link between early mineralization and rapid anaerobic decay of the endochorional envelope. Our experiments replicated the different preservational stages of degradation observed in the fossil record. Stabilization of the spherical morphology was achieved by pre-heating of the eggs. Complete surface mineralization occurred under reduced conditions within one to two weeks, with fine-grained brushite (CaHPO4 · 2H2O) and calcite. The mechanisms of decay, preservation of surface structures, and mineral replacement in the experiment were likely similar during fossilization of Cambrian embryos.

  20. The original colours of fossil beetles.

    PubMed

    McNamara, Maria E; Briggs, Derek E G; Orr, Patrick J; Noh, Heeso; Cao, Hui

    2012-03-22

    Structural colours, the most intense, reflective and pure colours in nature, are generated when light is scattered by complex nanostructures. Metallic structural colours are widespread among modern insects and can be preserved in their fossil counterparts, but it is unclear whether the colours have been altered during fossilization, and whether the absence of colours is always real. To resolve these issues, we investigated fossil beetles from five Cenozoic biotas. Metallic colours in these specimens are generated by an epicuticular multi-layer reflector; the fidelity of its preservation correlates with that of other key cuticular ultrastructures. Where these other ultrastructures are well preserved in non-metallic fossil specimens, we can infer that the original cuticle lacked a multi-layer reflector; its absence in the fossil is not a preservational artefact. Reconstructions of the original colours of the fossils based on the structure of the multi-layer reflector show that the preserved colours are offset systematically to longer wavelengths; this probably reflects alteration of the refractive index of the epicuticle during fossilization. These findings will allow the former presence, and original hue, of metallic structural colours to be identified in diverse fossil insects, thus providing critical evidence of the evolution of structural colour in this group. PMID:21957131

  1. Ediacaran Fossils: Metazoan Origins in the

    E-print Network

    Kammer, Thomas

    , relatives of corals #12;Mawsonites, a fossil jellyfish? #12;A variety of Ediacaran fossils #12;Dickinsonia) preceded the Ediacaran. How did this affect animal evolution? #12;#12;Equatorial Marinoan diamictites What role did it play in the evolution of metazoans? · The Cryogenian (Greek: cryos "cold" and genesis

  2. The original colours of fossil beetles

    PubMed Central

    McNamara, Maria E.; Briggs, Derek E. G.; Orr, Patrick J.; Noh, Heeso; Cao, Hui

    2012-01-01

    Structural colours, the most intense, reflective and pure colours in nature, are generated when light is scattered by complex nanostructures. Metallic structural colours are widespread among modern insects and can be preserved in their fossil counterparts, but it is unclear whether the colours have been altered during fossilization, and whether the absence of colours is always real. To resolve these issues, we investigated fossil beetles from five Cenozoic biotas. Metallic colours in these specimens are generated by an epicuticular multi-layer reflector; the fidelity of its preservation correlates with that of other key cuticular ultrastructures. Where these other ultrastructures are well preserved in non-metallic fossil specimens, we can infer that the original cuticle lacked a multi-layer reflector; its absence in the fossil is not a preservational artefact. Reconstructions of the original colours of the fossils based on the structure of the multi-layer reflector show that the preserved colours are offset systematically to longer wavelengths; this probably reflects alteration of the refractive index of the epicuticle during fossilization. These findings will allow the former presence, and original hue, of metallic structural colours to be identified in diverse fossil insects, thus providing critical evidence of the evolution of structural colour in this group. PMID:21957131

  3. Forty Years Later: Updating the Fossilization Hypothesis

    ERIC Educational Resources Information Center

    Han, ZhaoHong

    2013-01-01

    A founding concept in second language acquisition (SLA) research, fossilization has been fundamental to understanding second language (L2) development. The Fossilization Hypothesis, introduced in Selinker's seminal text (1972), has thus been one of the most influential theories, guiding a significant bulk of SLA research for four decades; 2012…

  4. African American Child 

    E-print Network

    Unknown

    2011-09-05

    This study investigated the perceptions of African American undergraduate males who attend a predominately White institution in the southwest as they concern leadership after participation in a leadership development program and the influence...

  5. The Oldest Gibbon Fossil (Hylobatidae) from Insular Southeast Asia: Evidence from Trinil, (East Java, Indonesia), Lower/Middle Pleistocene

    PubMed Central

    Ingicco, Thomas; de Vos, John; Huffman, O. Frank

    2014-01-01

    A fossil femur excavated by Eugène Dubois between 1891–1900 in the Lower/Middle Pleistocene bonebed of the Trinil site (Java, Indonesia) was recognised by us as that of a Hylobatidae. The specimen, Trinil 5703 of the Dubois Collection (Leiden, The Netherlands), has the same distinctive form of fossilization that is seen in many of the bonebed fossils from Trinil in the collection. Anatomical comparison of Trinil 5703 to a sample of carnivore and primate femora, supported by morphometric analyses, lead to the attribution of the fossil to gibbon. Trinil 5703 therefore provides the oldest insular record of this clade, one of the oldest known Hylobatidae fossils from Southeast Asia. Because living Hylobatidae only inhabit evergreen rain forests, the paleoenvironment within the river drainage in the greater Trinil area evidently included forests of this kind during the Lower/Middle Pleistocene as revealed here. PMID:24914951

  6. A new species of the genus Orchesia Latreille (Coleoptera: Melandryidae) from Baltic amber with a key to species described from fossil resins.

    PubMed

    Alekseev, Vitalii I; Bukejs, Andris

    2015-01-01

    Orchesia (Orchestera) canaliculata sp. nov. is described and illustrated from Eocene Baltic amber (Kaliningrad Region, Russia). New fossil records on O. turkini Alekseev & Bukejs and O. rasnitzyni Nikitsky are presented. A key to species of Orchesia Latreille, described from fossil resins, is provided. PMID:25947758

  7. Altered states: Effects of diagenesis on fossil tooth chemistry

    SciTech Connect

    Kohn, M.J.; Schoeninger, M.J.; Barker, W.W.

    1999-09-01

    Investigation of modern and fossil teeth from northern and central Kenya, using the ion microprobe, electron microprobe, and transmission electron microscope, confirms that fossil tooth chemistry is controlled not only by the diagenetic precipitation of secondary minerals but also by the chemical alteration of the biogenic apatite. Increases in the concentrations of Fe, Mn, Si, Al, Ba, and possibly Cu in fossil vs. modern teeth reflect mixtures of apatite and secondary minerals. These secondary minerals occur in concentrations ranging from {approximately}0.3% in enamel to {approximately}5% in dentine and include sub-{micro}m, interstitial Fe-bearing manganite [(Fe{sup 3+}, Mn{sup 3+})O(OH)], and smectite. The pervasive distribution and fine grain size of the secondary minerals indicate that mixed analyses of primary and secondary material are unavoidable in in situ methods, even in ion microprobe spots only 10 {micro}m in diameter, and that bulk chemical analyses are severely biased. Increases in other elements, including the rare earth elements, U, F, and possibly Sr apparently reflect additional alteration of apatite in both dentine and enamel. Extreme care will be required to separate secondary minerals from original biogenic apatite for paleobiological or paleoclimate studies, and nonetheless bulk analyses of purified apatite may be suspect. Although the PO{sub 4} component of teeth seems resistant to chemical alteration, the OH component is extensively altered. This OH alteration implies that bulk analyses of fossil tooth enamel for oxygen isotope composition may be systematically biased by {+-}1%, and seasonal records of oxygen isotope composition may be spuriously shifted, enhanced, or diminished.

  8. Health Conditions Common in African American Women

    MedlinePLUS

    ... Minority Women's Health > African-Americans Minority Women's Health African-Americans Health conditions common in African-American women Of ... health. Return to top Health conditions common in African-American women Asthma Breast cancer Cancer Cervical cancer Diabetes ...

  9. Relationships of new world phlebotomine sand flies (Diptera: Psychodidae) based on fossil evidence.

    PubMed

    Filho, José Dilermando Andrade; Brazil, Reginaldo Peçanha

    2003-01-01

    The fossil record and systematics of phlebotomid sand flies, vectors of leishmaniasis and arbovirus in several regions of the world, strongly support that living genera existed long before the Oligocene (38 million years, myr). A common Phlebotominae ancestor was present in the Triassic period before the separations of continents (248 myr). PMID:12687775

  10. On the evolutionary history of Ephedra: Cretaceous fossils and extant molecules

    PubMed Central

    Rydin, Catarina; Pedersen, Kaj Raunsgaard; Friis, Else Marie

    2004-01-01

    Gnetales comprise three unusual genera of seed plants, Ephedra, Gnetum, and Welwitschia. Their extraordinary morphological diversity suggests that they are survivors of an ancient, more diverse group. Gnetalean antiquity is also supported by fossil data. Dispersed “ephedroid” (polyplicate) pollen first appeared in the Permian >250 million years ago (Myr), and a few megafossils document the presence of gnetalean features in the early Cretaceous. The Cretaceous welwitschioid seedling Cratonia cotyledon dates the split between Gnetum and Welwitschia to before 110 Myr. Ages and character evolution of modern diversity are, however, controversial, and, based on molecular data, it has recently been suggested that Ephedra is very young, only 8–32 Myr. Here, we present data on the evolutionary history of Ephedra. Fossil seeds from Buarcos, Portugal, unequivocally link one type of Cretaceous polyplicate pollen to Ephedra and document that plants with unique characters, including the peculiar naked male gametophyte, were established already in the Early Cretaceous. Clades in our molecular phylogeny of extant species correspond to geographical regions, with African species in a basal grade/clade. The study demonstrates extremely low divergence in both molecular and morphological characters in Ephedra. Features observed in the fossils are present in all major extant clades, showing that modern species have retained unique reproductive characters for >110 million years. A recent origin of modern species of Ephedra would imply that the Cretaceous Ephedra fossils discussed here were members of widespread, now extinct sister lineage(s), and that no morphological innovations characterized the second diversification. PMID:15545612

  11. Discovery of fossil lamprey larva from the Lower Cretaceous reveals its three-phased life cycle

    PubMed Central

    Chang, Mee-mann; Wu, Feixiang; Miao, Desui; Zhang, Jiangyong

    2014-01-01

    Lampreys are one of the two surviving jawless vertebrate groups and one of a few vertebrate groups with the best exemplified metamorphosis during their life cycle, which consists of a long-lasting larval stage, a peculiar metamorphosis, and a relatively short adulthood with a markedly different anatomy. Although the fossil records have revealed that many general features of extant lamprey adults were already formed by the Late Devonian (ca. 360 Ma), little is known about the life cycle of the fossil lampreys because of the lack of fossilized lamprey larvae or transformers. Here we report the first to our knowledge discovery of exceptionally preserved premetamorphic and metamorphosing larvae of the fossil lamprey Mesomyzon mengae from the Lower Cretaceous of Inner Mongolia, China. These fossil ammocoetes look surprisingly modern in having an eel-like body with tiny eyes, oral hood and lower lip, anteriorly positioned branchial region, and a continuous dorsal skin fin fold and in sharing a similar feeding habit, as judged from the detritus left in the gut. In contrast, the larger metamorphosing individuals have slightly enlarged eyes relative to large otic capsules, thickened oral hood or pointed snout, and discernable radials but still anteriorly extended branchial area and lack a suctorial oral disk, which characterize the early stages of the metamorphosis of extant lampreys. Our discovery not only documents the larval conditions of fossil lampreys but also indicates the three-phased life cycle in lampreys emerged essentially in their present mode no later than the Early Cretaceous. PMID:25313060

  12. Multiple global radiations in tadpole shrimps challenge the concept of 'living fossils'.

    PubMed

    Mathers, Thomas C; Hammond, Robert L; Jenner, Ronald A; Hänfling, Bernd; Gómez, Africa

    2013-01-01

    'Living fossils', a phrase first coined by Darwin, are defined as species with limited recent diversification and high morphological stasis over long periods of evolutionary time. Morphological stasis, however, can potentially lead to diversification rates being underestimated. Notostraca, or tadpole shrimps, is an ancient, globally distributed order of branchiopod crustaceans regarded as 'living fossils' because their rich fossil record dates back to the early Devonian and their morphology is highly conserved. Recent phylogenetic reconstructions have shown a strong biogeographic signal, suggesting diversification due to continental breakup, and widespread cryptic speciation. However, morphological conservatism makes it difficult to place fossil taxa in a phylogenetic context. Here we reveal for the first time the timing and tempo of tadpole shrimp diversification by inferring a robust multilocus phylogeny of Branchiopoda and applying Bayesian divergence dating techniques using reliable fossil calibrations external to Notostraca. Our results suggest at least two bouts of global radiation in Notostraca, one of them recent, so questioning the validity of the 'living fossils' concept in groups where cryptic speciation is widespread. PMID:23638400

  13. Multiple global radiations in tadpole shrimps challenge the concept of ‘living fossils

    PubMed Central

    Mathers, Thomas C.; Hammond, Robert L.; Jenner, Ronald A.; Hänfling, Bernd

    2013-01-01

    ‘Living fossils’, a phrase first coined by Darwin, are defined as species with limited recent diversification and high morphological stasis over long periods of evolutionary time. Morphological stasis, however, can potentially lead to diversification rates being underestimated. Notostraca, or tadpole shrimps, is an ancient, globally distributed order of branchiopod crustaceans regarded as ‘living fossils’ because their rich fossil record dates back to the early Devonian and their morphology is highly conserved. Recent phylogenetic reconstructions have shown a strong biogeographic signal, suggesting diversification due to continental breakup, and widespread cryptic speciation. However, morphological conservatism makes it difficult to place fossil taxa in a phylogenetic context. Here we reveal for the first time the timing and tempo of tadpole shrimp diversification by inferring a robust multilocus phylogeny of Branchiopoda and applying Bayesian divergence dating techniques using reliable fossil calibrations external to Notostraca. Our results suggest at least two bouts of global radiation in Notostraca, one of them recent, so questioning the validity of the ‘living fossils’ concept in groups where cryptic speciation is widespread. PMID:23638400

  14. The fossilized birth–death process for coherent calibration of divergence-time estimates

    PubMed Central

    Heath, Tracy A.; Huelsenbeck, John P.; Stadler, Tanja

    2014-01-01

    Time-calibrated species phylogenies are critical for addressing a wide range of questions in evolutionary biology, such as those that elucidate historical biogeography or uncover patterns of coevolution and diversification. Because molecular sequence data are not informative on absolute time, external data—most commonly, fossil age estimates—are required to calibrate estimates of species divergence dates. For Bayesian divergence time methods, the common practice for calibration using fossil information involves placing arbitrarily chosen parametric distributions on internal nodes, often disregarding most of the information in the fossil record. We introduce the “fossilized birth–death” (FBD) process—a model for calibrating divergence time estimates in a Bayesian framework, explicitly acknowledging that extant species and fossils are part of the same macroevolutionary process. Under this model, absolute node age estimates are calibrated by a single diversification model and arbitrary calibration densities are not necessary. Moreover, the FBD model allows for inclusion of all available fossils. We performed analyses of simulated data and show that node age estimation under the FBD model results in robust and accurate estimates of species divergence times with realistic measures of statistical uncertainty, overcoming major limitations of standard divergence time estimation methods. We used this model to estimate the speciation times for a dataset composed of all living bears, indicating that the genus Ursus diversified in the Late Miocene to Middle Pliocene. PMID:25009181

  15. 22 CFR 1507.6 - Access to records.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Relations AFRICAN DEVELOPMENT FOUNDATION RULES SAFEGUARDING PERSONAL INFORMATION § 1507.6 Access to records... and Finance, African Development Foundation, 1625 Massachusetts Avenue NW., Suite 600, Washington, DC 20036. Personal contacts should normally be made during the regular duty hours of the officer...

  16. 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.

  17. A dating success story: genomes and fossils converge on placental mammal origins.

    PubMed

    Goswami, Anjali

    2012-01-01

    The timing of the placental mammal radiation has been a source of contention for decades. The fossil record of mammals extends over 200 million years, but no confirmed placental mammal fossils are known prior to 64 million years ago, which is approximately 1.5 million years after the Cretaceous-Paleogene (K-Pg) mass extinction that saw the end of non-avian dinosaurs. Thus, it came as a great surprise when the first published molecular clock studies suggested that placental mammals originated instead far back in the Cretaceous, in some cases doubling divergence estimates based on fossils. In the last few decades, more than a hundred new genera of Mesozoic mammals have been discovered, and molecular divergence studies have grown from simple clock-like models applied to a few genes to sophisticated analyses of entire genomes. Yet, molecular and fossil-based divergence estimates for placental mammal origins have remained remote, with knock-on effects for macro-scale reconstructions of mammal evolution. A few recent molecular studies have begun to converge with fossil-based estimates, and a new phylogenomic study in particular shows that the palaeontological record was mostly correct; most placental mammal orders diversified after the K-Pg mass extinction. While a small gap still remains for Late Cretaceous supraordinal divergences, this study has significantly improved the congruence between molecular and palaeontological data and heralds a broader integration of these fields of evolutionary science. PMID:22883371

  18. A second Eocene species of death-watch beetle belonging to the genus
    Microbregma Seidlitz (Coleoptera: Bostrichoidea) with a checklist of fossil Ptinidae.

    PubMed

    Bukejs, Andris; Alekseev, Vitalii I

    2015-01-01

    Based on a well-preserved specimen from Upper Eocene Baltic amber (Kaliningrad region, Russia), Microbregma waldwico sp. nov., the second fossil species of this genus, is described. The new species is similar to the extant Holarctic M. emarginatum (Duftschmid), 1825, and fossil M. sucinoemarginatum (Ku?ka), 1992, but differs in its shorter abdominal ventrite 1 (about 0.43 length of ventrite 2) and larger body (5.1 mm). A key to species of the genus Microbregma is given, and a check-list of described fossil Ptinidae is provided. The fossil record of Ptinidae now includes 48 species in 27 genera and 8 subfamilies. PMID:25947754

  19. Cycling operation of fossil plants

    SciTech Connect

    Bhatnagar, U.S.; Weiss, M.D.; White, W.H. ); Buchanan, T.L.; Harvey, L.E.; Shewchuk, P.K.; Weinstein, R.E. )

    1991-05-01

    This report presents a methodology for examining the economic feasibility of converting fossil power plants from baseload to cycling service. It employs this approach to examine a proposed change of Pepco's Potomac River units 3, 4, and 5 from baseload operation of two-shift cycling. The project team first reviewed all components and listed potential cycling effects involved in the conversion of Potomac River units 3, 4, and 5. They developed general cycling plant screening criteria including the number of hot, warm, or cold restart per year and desired load ramp rates. In addition, they evaluated specific limitations on the boiler, turbine, and the balance of plant. They estimated the remaining life of the facility through component evaluation and boiler testing and also identified and prioritized potential component deficiencies by their impact on key operational factors: safety, heat rate, turn down, startup/shutdown time, and plant availability. They developed solutions to these problems; and, since many solutions mitigate more than one problem, they combined and reprioritized these synergistic solutions. Economic assessments were performed on all solutions. 13 figs., 20 tabs.

  20. Correlations in fossil extinction and origination rates through geological time.

    PubMed Central

    Kirchner, J W; Weil, A

    2000-01-01

    Recent analyses have suggested that extinction and origination rates exhibit long-range correlations, implying that the fossil record may be controlled by self-organized criticality or other scale-free internal dynamics of the biosphere. Here we directly test for correlations in the fossil record by calculating the autocorrelation of extinction [corrected] and origination rates through time. Our results show that extinction rates are uncorrelated beyond the average duration of a stratigraphic interval. Thus, they lack the long-range correlations predicted by the self-organized criticality hypothesis. In contrast, origination rates show strong autocorrelations due to long-term trends. After detrending, origination rates generally show weak positive correlations at lags of 5-10 million years (Myr) and weak negative correlations at lags of 10-30 Myr, consistent with aperiodic oscillations around their long-term trends. We hypothesize that origination rates are more correlated than extinction rates because originations of new taxa create new ecological niches and new evolutionary pathways for reaching them, thus creating conditions that favour further diversification. PMID:10972124

  1. AFRICAN AND AFRICAN AMERICAN STUDIES CRN Course Course # Section Course Title Days Time Instructor Room

    E-print Network

    AFRICAN AND AFRICAN AMERICAN STUDIES CRN Course Course # Section Course Title Days Time Instructor Room AFRICAN AND AFRICAN AMERICAN STUDIES 25768 AFAM 200 1 Introduction To African And African American R 7:05 pm-9:45 pm Springer LWH 2044 25547 SOC 344 1 African American Women: Feminism, Race

  2. ETHNIC STUDIES (AFRICAN & AFRICAN AMERICAN STUDIES) 2008-2010 DEGREE PLAN (expires 08/2016)

    E-print Network

    Pillow, Jonathan

    ETHNIC STUDIES (AFRICAN & AFRICAN AMERICAN STUDIES) 2008-2010 DEGREE PLAN (expires 08 REQUIREMENTS MAJOR: AFRICAN AND AFRICAN AMERICAN STUDIES (33 HOURS, INCLUDING 18 UPPER-DIVISION & 18 IN RESIDENCE) 9 hours specified African & African American Studies: AFR 301 African American Culture AFR 375

  3. Testing the impact of seasonal phytodetritus deposition on ?13C of epibenthic foraminifer Cibicidoides wuellerstorfi: A 31,000 year high-resolution record from the northwest African continental slope

    NASA Astrophysics Data System (ADS)

    Zarriess, Michelle; Mackensen, Andreas

    2011-06-01

    Studies of temporal changes of ocean circulation and deepwater ventilation often rely on ?13C records of epibenthic foraminifer Cibicidoides wuellerstorfi. However, primary productivity-related overprints may distort the signal and simulate a chemical age of ambient water mass that is too old and simulates poorly ventilated ambient bottom waters. To further constrain the use of C. wuellerstorfi ?13C records from high-productivity areas, we analyzed a 14CAMS-dated gravity core from the upwelling regime off northwest Africa at 12°N. We compare this new record with 37 radiocarbon dated ?13C records from the eastern Atlantic Ocean between 45°N and 25°S that are bathed by the same water mass. Only during Heinrich events 1 and 2, when the investigated core site off northwest Africa experienced year-round, sustained deposition of organic matter, the ?13C values at this site faithfully record deepwater ventilation states. During times of predominantly seasonal deposition of fresh phytodetritus, however, ?13C values were significantly lower than at the reference sites. This underscores that reconstruction of paleocirculation and deep ocean ventilation using C. wuellerstorfi ?13C from regions that experienced seasonal phytodetritus deposition needs to be validated by additional proxies that are not affected by local productivity.

  4. African Americans and Multiple Sclerosis

    MedlinePLUS

    ... financial challenges n Find support when MS progresses African American Council The National MS Society mobilizes people and ... support this mission, the Society established the National African American Advisory Council — which advises on the best approaches ...

  5. Precedents in African American architecture

    E-print Network

    Sass, Lawrence

    1994-01-01

    As a sub-sets of American culture, African Americans have not been able to offer culturally specific architectural elements to the design process because the history of African American form and space has not been recognized ...

  6. Fossils, feet and the evolution of human bipedal locomotion.

    PubMed

    Harcourt-Smith, W E H; Aiello, L C

    2004-05-01

    We review the evolution of human bipedal locomotion with a particular emphasis on the evolution of the foot. We begin in the early twentieth century and focus particularly on hypotheses of an ape-like ancestor for humans and human bipedal locomotion put forward by a succession of Gregory, Keith, Morton and Schultz. We give consideration to Morton's (1935) synthesis of foot evolution, in which he argues that the foot of the common ancestor of modern humans and the African apes would be intermediate between the foot of Pan and Hylobates whereas the foot of a hypothetical early hominin would be intermediate between that of a gorilla and a modern human. From this base rooted in comparative anatomy of living primates we trace changing ideas about the evolution of human bipedalism as increasing amounts of postcranial fossil material were discovered. Attention is given to the work of John Napier and John Robinson who were pioneers in the interpretation of Plio-Pleistocene hominin skeletons in the 1960s. This is the period when the wealth of evidence from the southern African australopithecine sites was beginning to be appreciated and Olduvai Gorge was revealing its first evidence for Homo habilis. In more recent years, the discovery of the Laetoli footprint trail, the AL 288-1 (A. afarensis) skeleton, the wealth of postcranial material from Koobi Fora, the Nariokotome Homo ergaster skeleton, Little Foot (Stw 573) from Sterkfontein in South Africa, and more recently tantalizing material assigned to the new and very early taxa Orrorin tugenensis, Ardipithecus ramidus and Sahelanthropus tchadensis has fuelled debate and speculation. The varying interpretations based on this material, together with changing theoretical insights and analytical approaches, is discussed and assessed in the context of new three-dimensional morphometric analyses of australopithecine and Homo foot bones, suggesting that there may have been greater diversity in human bipedalism in the earlier phases of our evolutionary history than previously suspected. PMID:15198703

  7. Fossils, feet and the evolution of human bipedal locomotion

    PubMed Central

    Harcourt-Smith, W E H; Aiello, L C

    2004-01-01

    We review the evolution of human bipedal locomotion with a particular emphasis on the evolution of the foot. We begin in the early twentieth century and focus particularly on hypotheses of an ape-like ancestor for humans and human bipedal locomotion put forward by a succession of Gregory, Keith, Morton and Schultz. We give consideration to Morton's (1935) synthesis of foot evolution, in which he argues that the foot of the common ancestor of modern humans and the African apes would be intermediate between the foot of Pan and Hylobates whereas the foot of a hypothetical early hominin would be intermediate between that of a gorilla and a modern human. From this base rooted in comparative anatomy of living primates we trace changing ideas about the evolution of human bipedalism as increasing amounts of postcranial fossil material were discovered. Attention is given to the work of John Napier and John Robinson who were pioneers in the interpretation of Plio-Pleistocene hominin skeletons in the 1960s. This is the period when the wealth of evidence from the southern African australopithecine sites was beginning to be appreciated and Olduvai Gorge was revealing its first evidence for Homo habilis. In more recent years, the discovery of the Laetoli footprint trail, the AL 288-1 (A. afarensis) skeleton, the wealth of postcranial material from Koobi Fora, the Nariokotome Homo ergaster skeleton, Little Foot (Stw 573) from Sterkfontein in South Africa, and more recently tantalizing material assigned to the new and very early taxa Orrorin tugenensis, Ardipithecus ramidus and Sahelanthropus tchadensis has fuelled debate and speculation. The varying interpretations based on this material, together with changing theoretical insights and analytical approaches, is discussed and assessed in the context of new three-dimensional morphometric analyses of australopithecine and Homo foot bones, suggesting that there may have been greater diversity in human bipedalism in the earlier phases of our evolutionary history than previously suspected. PMID:15198703

  8. Environment, Health and Climate: Impact of African aerosols

    NASA Astrophysics Data System (ADS)

    Liousse, C.; Doumbia, T.; Assamoi, E.; Galy-Lacaux, C.; Baeza, A.; Penner, J. E.; Val, S.; Cachier, H.; Xu, L.; Criqui, P.

    2012-12-01

    Fossil fuel and biofuel emissions of particles in Africa are expected to significantly increase in the near future, particularly due to rapid growth of African cities. In addition to biomass burning emissions prevailing in these areas, air quality degradation is then expected with important consequences on population health and climatic/radiative impact. In our group, we are constructing a new integrated methodology to study the relations between emissions, air quality and their impacts. This approach includes: (1) African combustion emission characterizations; (2) joint experimental determination of aerosol chemistry from ultrafine to coarse fractions and health issues (toxicology and epidemiology). (3) integrated environmental, health and radiative modeling. In this work, we show some results illustrating our first estimates of African anthropogenic emission impacts: - a new African anthropogenic emission inventory adapted to regional specificities on traffic, biofuel and industrial emissions has been constructed for the years 2005 and 2030. Biomass burning inventories were also improved in the frame of AMMA (African Monsoon) program. - carbonaceous aerosol radiative impact in Africa has been modeled with TM5 model and Penner et al. (2011) radiative code for these inventories for 2005 and 2030 and for two scenarios of emissions : a reference scenario, with no further emission controls beyond those achieved in 2003 and a ccc* scenario including planned policies in Kyoto protocol and regulations as applied to African emission specificities. In this study we will show that enhanced heating is expected with the ccc* scenarios emissions in which the OC fraction is relatively lower than in the reference scenario. - results of short term POLCA intensive campaigns in Bamako and Dakar in terms of aerosol chemical characterization linked to specific emissions sources and their inflammatory impacts on the respiratory tract through in vitro studies. In this study, organic carbon particles have appeared quite biologically active. Quite importantly, air quality improvement obtained through regulations in the ccc* scenario are accompanied by stronger heating impact.

  9. Hybrid solar-fossil fuel power generation

    E-print Network

    Sheu, Elysia J. (Elysia Ja-Zeng)

    2012-01-01

    In this thesis, a literature review of hybrid solar-fossil fuel power generation is first given with an emphasis on system integration and evaluation. Hybrid systems are defined as those which use solar energy and fuel ...

  10. Fossil Finds Expand Early Hominid Anatomy.

    ERIC Educational Resources Information Center

    Bower, B.

    1991-01-01

    Hominid fossils found in late 1990 in Ethiopia are reported. A controversy surrounding these remains and those of earlier expeditions, including Lucy, over whether more than one species of hominid are represented is discussed. (CW)

  11. Environmental Analysis Team Capabilities in Fossil Energy

    E-print Network

    Pennycook, Steve

    Environmental Analysis Team Capabilities in Fossil Energy ORNL EA Team Background Provides comprehensive, integrated analyses and assessments to Federal decision makers about the potential environmental for assisting Federal agencies in conducting environmental reviews under the National Environmental Policy Act

  12. Fossil energy program. Progress report, July 1980

    SciTech Connect

    McNeese, L. E.

    1980-10-01

    This report - the seventy-second of a series - is a compendium of monthly progress reports for the ORNL research and development programs that are in support of the increased utilization of coal and other fossil fuel alternatives to oil and gas as sources of clean energy. The projects reported this month include those for coal conversion development, chemical research and development, materials technology, component development and process evaluation, technical support to major liquefaction projects, process and program analysis, fossil energy environmental analysis, coal preparation and waste utilization, coal preparation plant automation, atmospheric fluidized bed coal combustor for cogeneration, technical support to the TVA fluidized bed combustion demonstration plant program, fossil energy applications assessments, performance assurance system support for fossil energy projects, international assessment of atmospheric fluidized bed combustion technology, and PFBC systems analysis.

  13. Development incentives for fossil fuel subsidy reform

    NASA Astrophysics Data System (ADS)

    Jakob, Michael; Chen, Claudine; Fuss, Sabine; Marxen, Annika; Edenhofer, Ottmar

    2015-08-01

    Reforming fossil fuel subsidies could free up enough funds to finance universal access to water, sanitation, and electricity in many countries, as well as helping to cut global greenhouse-gas emissions.

  14. Spitzer Digs Up Galactic Fossil

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site] Figure 1

    [figure removed for brevity, see original site] Figure 2

    This false-color image taken by NASA's Spitzer Space Telescope shows a globular cluster previously hidden in the dusty plane of our Milky Way galaxy. Globular clusters are compact bundles of old stars that date back to the birth of our galaxy, 13 or so billion years ago. Astronomers use these galactic 'fossils' as tools for studying the age and formation of the Milky Way.

    Most clusters orbit around the center of the galaxy well above its dust-enshrouded disc, or plane, while making brief, repeated passes through the plane that each last about a million years. Spitzer, with infrared eyes that can see into the dusty galactic plane, first spotted the newfound cluster during its current pass. A visible-light image (inset of Figure 1) shows only a dark patch of sky.

    The red streak behind the core of the cluster is a dust cloud, which may indicate the cluster's interaction with the Milky Way. Alternatively, this cloud may lie coincidentally along Spitzer's line of sight.

    Follow-up observations with the University of Wyoming Infrared Observatory helped set the distance of the new cluster at about 9,000 light-years from Earth - closer than most clusters - and set the mass at the equivalent of 300,000 Suns. The cluster's apparent size, as viewed from Earth, is comparable to a grain of rice held at arm's length. It is located in the constellation Aquila.

    Astronomers believe that this cluster may be one of the last in our galaxy to be uncovered.

    This image composite was taken on April 21, 2004, by Spitzer's infrared array camera. It is composed of images obtained at four wavelengths: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red).

    Galactic Fossil Found Behind Curtain of Dust In Figure 2, the image mosaic shows the same patch of sky in various wavelengths of light. While the visible-light image (left) shows a dark sky speckled with stars, infrared images (middle and right), reveal a never-before-seen bundle of stars, called a globular cluster. The left panel is from the California Institute of Technology's Digitized Sky Survey; the middle panel includes images from the NASA-funded Two Micron All-Sky Survey and the University of Wyoming Infrared Observatory (circle inset); and the right panel is from NASA's Spitzer Space Telescope.

    The Two Micron All-Sky Survey false-color image was obtained using near-infrared wavelengths ranging from 1.3 to 2.2 microns. The University of Wyoming Observatory false-color image was captured on July 31, 2004, at wavelengths ranging from 1.2 to 2.2 microns. The Spitzer false-color image composite was taken on April 21, 2004, by its infrared array camera. It is composed of images obtained at four mid-infrared wavelengths: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red).

  15. Land - Ocean Climate Linkages and the Human Evolution - New ICDP and IODP Drilling Initiatives in the East African Rift Valley and SW Indian Ocean

    NASA Astrophysics Data System (ADS)

    Zahn, R.; Feibel, C.; Co-Pis, Icdp/Iodp

    2009-04-01

    The past 5 Ma were marked by systematic shifts towards colder climates and concomitant reorganizations in ocean circulation and marine heat transports. Some of the changes involved plate-tectonic shifts such as the closure of the Panamanian Isthmus and restructuring of the Indonesian archipelago that affected inter-ocean communications and altered the world ocean circulation. These changes induced ocean-atmosphere feedbacks with consequences for climates globally and locally. Two new ICDP and IODP drilling initiatives target these developments from the perspectives of marine and terrestrial palaeoclimatology and the human evolution. The ICDP drilling initiative HSPDP ("Hominid Sites and Paleolakes Drilling Project"; ICDP ref. no. 10/07) targets lacustrine depocentres in Ethiopia (Hadar) and Kenya (West Turkana, Olorgesailie, Magadi) to retrieve sedimentary sequences close to the places and times where various species of hominins lived over currently available outcrop records. The records will provide a spatially resolved record of the East African environmental history in conjunction with climate variability at orbital (Milankovitch) and sub-orbital (ENSO decadal) time scales. HSPDP specifically aims at (1) compiling master chronologies for outcrops around each of the depocentres; (2) assessing which aspects of the paleoenvironmental records are a function of local origin (hydrology, hydrogeology) and which are linked with regional or larger-scale signals; (3) correlating broad-scale patterns of hominin phylogeny with the global beat of climate variability and (4) correlating regional shifts in the hominin fossil and archaeological record with more local patterns of paleoenvironmental change. Ultimately the aim is to test hypotheses that link physical and cultural adaptations in the course of the hominin evolution to local environmental change and variability. The IODP initiative SAFARI ("Southern African Climates, Agulhas Warm Water Transports and Retroflection, and Interocean Exchanges"; IODP ref. no. 702-full) aims at deciphering the late Neogene ocean history of the SW Indian Ocean. SAFARI specifically targets the Agulhas Current in the SW Indian Ocean that constitutes the strongest western boundary current in the southern hemisphere oceans. The Current transports warm and saline surface waters from the tropical Indian Ocean to the southern tip of Africa. Exchanges with the atmosphere influence eastern and southern African climates including individual weather systems such as extra-tropical cyclone formation in the region and rainfall patterns. Ocean models further suggest the "leakage" of Agulhas water around South Africa into the Atlantic potentially modulates the Atlantic meridional overturning circulation (MOC) with consequences for climate globally. The SAFARI drilling initiative aims to retrieve a suite of long drill cores along the southeast African margin and in the Indian-Atlantic ocean gateway. SAFARI will shed light on the history of Agulhas Current warm water transports along the southeast African margin during the late Neogene and its linking with ocean-climate developments. Specific objectives of SAFARI are to test (1) the sensitivity of the Agulhas Current to changing climates of the Plio/Pleistocene, including upstream forcing linked with equatorial Indian Ocean changes and Indonesian Throughflow; (2) the Current's influence on eastern and southern Africa climates, including rain fall patterns and vegetation changes; (3) buoyancy transfer to the Atlantic by Agulhas leakage around southern Africa, and (4) the contribution of variable Agulhas Leakage to shifts of the Atlantic MOC during episodes of major ocean and climate reorganizations of the past 5 Ma. These studies will provide insight into the Current's influence on eastern and southern African terrestrial climates, including its possible impact on the late Neogene evolution of large mammals including hominids. The ICDP and IODP drilling campaigns will enable us to establish the linkages between the ocean climatology o

  16. Microbial trace-fossil formation, biogenous, and abiotic weathering in the Antarctic cold desert

    NASA Technical Reports Server (NTRS)

    Friedmann, E. Imre; Weed, Rebecca

    1987-01-01

    In the Antarctic cold desert (Ross Desert), the survival of the cryptoendolithic microorganisms that colonize the near-surface layer of porous sandstone rocks depends on a precarious equilibrium of biological and geological factors. An unfavorable shift of this equilibrium results in death, and this may be followed by formation of trace fossils that preserve the characteristic iron-leaching pattern caused by microbial activity. Similar microbial trace fossils may exist in the geological record. If life ever arose on early Mars, similar processes may have occurred there and left recognizable traces.

  17. Fossil facies of the Greater Caspian region

    NASA Astrophysics Data System (ADS)

    Svitoch, A. A.

    2015-05-01

    The Pliocene-Pleistocene marine sediments of the Great Caspian region host various lithological fossil facies, which reflect specific sedimentation conditions caused by different structural-geomorphologic settings, tectonic regimes, climates, and hydrologies. The facies of shelf, epicontinental basins, ingression gulfs and estuaries, intermontane and mountainous basins, and deep-sea depressions form a hierarchy of geological bodies from types to subtypes. Paragenetic associations of fossil facies, which form various series in space and along the section, are typical of marine sediments.

  18. 22 CFR 1507.7 - Contents of records systems.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Contents of records systems. 1507.7 Section 1507.7 Foreign Relations AFRICAN DEVELOPMENT FOUNDATION RULES SAFEGUARDING PERSONAL INFORMATION § 1507.7..., development, operation, or maintenance of any system of records, or in maintaining any record. Each...

  19. 22 CFR 1507.5 - Accounting for disclosure of records.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Accounting for disclosure of records. 1507.5 Section 1507.5 Foreign Relations AFRICAN DEVELOPMENT FOUNDATION RULES SAFEGUARDING PERSONAL INFORMATION § 1507.5 Accounting for disclosure of records. (a) With respect to each system of records under...

  20. Knowledge and Attitudes about Colon Cancer Screening among African Americans

    ERIC Educational Resources Information Center

    James, Aimee S.; Daley, Christine M.; Greiner, K. Allen

    2011-01-01

    Objectives: To explore knowledge and attitudes about colorectal cancer (CRC) screening among African American patients age 45 and older at a community health center serving low-income and uninsured patients. Methods: We conducted 7 focus groups and 17 additional semistructured interviews. Sessions were audio-recorded, transcribed, and analyzed…

  1. Fossil group origins - VI. Global X-ray scaling relations of fossil galaxy clusters

    NASA Astrophysics Data System (ADS)

    Kundert, A.; Gastaldello, F.; D'Onghia, E.; Girardi, M.; Aguerri, J. A. L.; Barrena, R.; Corsini, E. M.; De Grandi, S.; Jiménez-Bailón, E.; Lozada-Muñoz, M.; Méndez-Abreu, J.; Sánchez-Janssen, R.; Wilcots, E.; Zarattini, S.

    2015-11-01

    We present the first pointed X-ray observations of 10 candidate fossil galaxy groups and clusters. With these Suzaku observations, we determine global temperatures and bolometric X-ray luminosities of the intracluster medium (ICM) out to r500 for six systems in our sample. The remaining four systems show signs of significant contamination from non-ICM sources. For the six objects with successfully determined r500 properties, we measure global temperatures in the range 2.8 ? TX ? 5.3 keV, bolometric X-ray luminosities of 0.8 × 1044 ? LX, bol ? 7.7 × 1044 erg s-1, and estimate masses, as derived from TX, of M500 ? 1014 M?. Fossil cluster scaling relations are constructed for a sample that combines our Suzaku observed fossils with fossils in the literature. Using measurements of global X-ray luminosity, temperature, optical luminosity, and velocity dispersion, scaling relations for the fossil sample are then compared with a control sample of non-fossil systems. We find the fits of our fossil cluster scaling relations are consistent with the relations for normal groups and clusters, indicating fossil clusters have global ICM X-ray properties similar to those of comparable mass non-fossil systems.

  2. Fossil group origins. IV. Characterization of the sample and observational properties of fossil systems

    NASA Astrophysics Data System (ADS)

    Zarattini, S.; Barrena, R.; Girardi, M.; Castro-Rodriguez, N.; Boschin, W.; Aguerri, J. A. L.; Méndez-Abreu, J.; Sánchez-Janssen, R.; Catalán-Torrecilla, C.; Corsini, E. M.; del Burgo, C.; D'Onghia, E.; Herrera-Ruiz, N.; Iglesias-Páramo, J.; Jimenez Bailon, E.; Lozada Muoz, M.; Napolitano, N.; Vilchez, J. M.

    2014-05-01

    Context. Virialized halos grow by the accretion of smaller ones in the cold dark matter scenario. The rate of accretion depends on the different properties of the host halo. Those halos for which this accretion rate was very fast and efficient resulted in systems dominated by a central galaxy surrounded by smaller galaxies that were at least two magnitudes fainter. These galaxy systems are called fossil systems, and they can be the fossil relics of ancient galaxy structures. Aims: We started an extensive observational program to characterize a sample of 34 fossil group candidates spanning a broad range of physical properties. Methods: Deep r-band images were obtained with the 2.5-m Isaac Newton Telescope and Nordic Optic Telescope. Optical spectroscopic observations were performed at the 3.5-m Telescopio Nazionale Galileo for ~1200 galaxies. This new dataset was completed with Sloan Digital Sky Survey Data Release 7 archival data to obtain robust cluster membership and global properties of each fossil group candidate. For each system, we recomputed the magnitude gaps between the two brightest galaxies (?m12) and the first and fourth ranked galaxies (?m14) within 0.5 R200. We consider fossil systems to be those with ?m12 ? 2 mag or ?m14 ? 2.5 mag within the errors. Results: We find that 15 candidates turned out to be fossil systems. Their observational properties agree with those of non-fossil systems. Both follow the same correlations, but the fossil systems are always extreme cases. In particular, they host the brightest central galaxies, and the fraction of total galaxy light enclosed in the brightest group galaxy is larger in fossil than in non-fossil systems. Finally, we confirm the existence of genuine fossil clusters. Conclusions: Combining our results with others in the literature, we favor the merging scenario in which fossil systems formed from mergers of L? galaxies. The large magnitude gap is a consequence of the extreme merger ratio within fossil systems and therefore it is an evolutionary effect. Moreover, we suggest that at least one fossil group candidate in our sample could represent a transitional fossil stage. This system could have been a fossil in the past, but not now owing to the recent accretion of another group of galaxies.

  3. Paleoenvironmental context of the Middle Stone Age record from Karungu, Lake Victoria Basin, Kenya, and its implications for human and faunal dispersals in East Africa.

    PubMed

    Faith, J Tyler; Tryon, Christian A; Peppe, Daniel J; Beverly, Emily J; Blegen, Nick; Blumenthal, Scott; Chritz, Kendra L; Driese, Steven G; Patterson, David

    2015-06-01

    The opening and closing of the equatorial East African forest belt during the Quaternary is thought to have influenced the biogeographic histories of early modern humans and fauna, although precise details are scarce due to a lack of archaeological and paleontological records associated with paleoenvironmental data. With this in mind, we provide a description and paleoenvironmental reconstruction of the Late Pleistocene Middle Stone Age (MSA) artifact- and fossil-bearing sediments from Karungu, located along the shores of Lake Victoria in western Kenya. Artifacts recovered from surveys and controlled excavations are typologically MSA and include points, blades, and Levallois flakes and cores, as well as obsidian flakes similar in geochemical composition to documented sources near Lake Naivasha (250 km east). A combination of sedimentological, paleontological, and stable isotopic evidence indicates a semi-arid environment characterized by seasonal precipitation and the dominance of C4 grasslands, likely associated with a substantial reduction in Lake Victoria. The well-preserved fossil assemblage indicates that these conditions are associated with the convergence of historically allopatric ungulates from north and south of the equator, in agreement with predictions from genetic observations. Analysis of the East African MSA record reveals previously unrecognized north-south variation in assemblage composition that is consistent with episodes of population fragmentation during phases of limited dispersal potential. The grassland-associated MSA assemblages from Karungu and nearby Rusinga Island are characterized by a combination of artifact types that is more typical of northern sites. This may reflect the dispersal of behavioral repertoires-and perhaps human populations-during a paleoenvironmental phase dominated by grasslands. PMID:25883052

  4. 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 (?13C) 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 ?13C values were measured for both fossil leaves and their living relatives. Both the saw-tooth pattern of ?13C values between odd and even chain lengths and the general decrease in ?13C values with increasing chain length are consistent with modern plant data. These results suggest that n-alkanes extracted directly from a fossil leaf provide a true signature of an individual leaf fossil rather than a mixture from the entire plant community. Therefore, comparisons between fossil morphotypes and between fossil and related modern taxa should be robust. Furthermore, by placing fossil leaf data within the context of the chemostratigraphy of Bighorn Basin sediments across the P-E boundary, fossil leaf n-alkanes can be used to bridge the gap between our understanding of modern plant lipids and bulk lipid data from sediments across the PETM. It has been hypothesized that changes in the both the molecular distribution and carbon isotope composition of n-alkanes across the PETM were due to changes in the local plant community, which included a large proportion of deciduous gymnosperms before and after-but not during-the PETM. Analysis of fossils such as Ginkgo and angiosperms provides the opportunity to compare and distinguish the molecular and isotopic signatures of gymnosperms and angiosperms. These comparisons shed light on the dynamics of climate and ecosystem changes as they are recorded in the signatures of lipid biomarkers.

  5. Elective: African Literature.

    ERIC Educational Resources Information Center

    Jenkins, Kenneth V.

    The make-up of a course in African literature for high school students is discussed. It is pointed out that the course can be constructed on already familiar lines. High school students will be able to describe clearly, for example, the relationship between environment and character or the dilemma of characters caught between traditional values…

  6. Chimpanzee fauna isotopes provide new interpretations of fossil ape and hominin ecologies

    PubMed Central

    Nelson, Sherry V.

    2013-01-01

    Carbon and oxygen stable isotopes within modern and fossil tooth enamel record the aspects of an animal's diet and habitat use. This investigation reports the first isotopic analyses of enamel from a large chimpanzee community and associated fauna, thus providing a means of comparing fossil ape and early hominin palaeoecologies with those of a modern ape. Within Kibale National Park forest, oxygen isotopes differentiate primate niches, allowing for the first isotopic reconstructions of degree of frugivory versus folivory as well as use of arboreal versus terrestrial resources. In a comparison of modern and fossil community isotopic profiles, results indicate that Sivapithecus, a Miocene ape from Pakistan, fed in the forest canopy, as do chimpanzees, but inhabited a forest with less continuous canopy or fed more on leaves. Ardipithecus, an early hominin from Ethiopia, fed both arboreally and terrestrially in a more open habitat than inhabited by chimpanzees. PMID:24197413

  7. RUNNING HEAD: THE FOSSIL CALIBRATION DATABASE Title: The Fossil Calibration Database, A New Resource for Divergence Dating

    E-print Network

    Benton, Michael

    1 RUNNING HEAD: THE FOSSIL CALIBRATION DATABASE Title: The Fossil Calibration Database, A New://sysbio.oxfordjournals.org/Downloadedfrom #12;3 Abstract.-- Fossils provide the principal basis for temporal calibrations, which are critical to the accuracy of divergence dating analyses. Translating fossil data into minimum and maximum bounds

  8. The GB/3D Type Fossils Online Web Portal

    NASA Astrophysics Data System (ADS)

    McCormick, T.; Howe, M. P.

    2013-12-01

    Fossils are the remains of once-living organisms that existed and played out their lives in 3-dimensional environments. The information content provided by a 3d representation of a fossil is much greater than that provided by a traditional photograph, and can grab the attention and imagination of the younger and older general public alike. The British Geological Survey has been leading a consortium of UK natural history museums including the Oxford University Museum of Natural History, the Sedgwick Museum Cambridge, the National Museum of Wales Cardiff, and a number of smaller regional British museums to construct a web portal giving access to metadata, high resolution images and interactive 3d models of type fossils from the UK. The web portal at www.3d-fossils.ac.uk was officially launched in August 2013. It can be used to discover metadata describing the provenance, taxonomy, and stratigraphy of the specimens. Zoom-able high resolution digital photographs are available, including for many specimens ';anaglyph' stereo images that can be viewed in 3d using red-cyan stereo spectacles. For many of the specimens interactive 3d models were generated by scanning with portable ';NextEngine 3D HD' 3d scanners. These models can be downloaded in zipped .OBJ and .PLY format from the web portal, or may be viewed and manipulated directly in certain web browsers. The images and scans may be freely downloaded subject to a Creative Commons Attribution ShareAlike Non-Commercial license. There is a simple application programming interface (API) allowing metadata to be downloaded, with links to the images and models, in a standardised format for use in data mash-ups and third party applications. The web portal also hosts ';open educational resources' explaining the process of fossilization and the importance of type specimens in taxonomy, as well as providing introductions to the most important fossil groups. We have experimented with using a 3d printer to create replicas of the fossils which can be used in education and public outreach. The audience for the web portal includes both professional paleontologists and the general public. The professional paleontologist can use the portal to discover the whereabouts of the type material for a taxon they are studying, and can use the pictures and 3d models to assess the completeness and preservation quality of the material. This may reduce or negate the need to send specimens (which are often fragile and always irreplaceable) to researchers through the post, or for researchers to make possibly long, expensive and environmentally damaging journeys to visit far-off collections. We hope that the pictures and 3d models will help to stimulate public interest in paleontology and natural history. The ability to digitally image and scan specimens in 3d enables institutions to have an archive record in case specimens are lost or destroyed by accident or warfare. Recent events in Cairo and Baghdad remind us that museum collections are vulnerable to civil and military strife.

  9. Earliest Phanerozoic or latest Proterozoic fossils from the Arabian Shield

    USGS Publications Warehouse

    Cloud, P.; Awramik, S.M.; Morrison, K.; Hadley, D.G.

    1979-01-01

    We report here the first biologically definable fossils from pre-Saq (pre-Middle Cambrian) rocks of the Arabian Shield. They include the distinctive helically coiled tubular filaments of the oscillatorialean blue-green alga Obruchevella parva as well as two size classes of spheroidal unicells of uncertain affinity. Also present is the conical stromatolite Conophyton and unidentified stromatolites. All occur in cherty limestones of the Jubaylah Group, northern Saudi Arabia, a nonmarine to locally marine taphrogeosynclinal sequence that fills depressions along the northwest-trending Najd faults. Conophyton has heretofore been found only in strata older than about 680 Ma (except for puzzling records in modern hot springs) while Obruchevella is so far known only from rocks between about 680 and 470 Ma old. Thus it appears that the Jubaylah Group is close to the Proterozoic-Phanerozoic transition. The simple spheroidal nanno-fossils are not diagnostic as to age. Their relationships within what appears to be early diagenetic chert suggest a classical algal-mat association. The brecciated and microchanneled appearance of much of the fossiliferous rock, its locally dolomitic nature, and the prevalence of cryptalgalaminate favors a very shallow, locally turbulent, and perhaps episodically exposed marine or marginal marine setting. The Jubaylah Group lies unconformably beneath the Siq Sandstone (basal member of the Saq Sandstone) of medial Cambrian age, rests nonconformably on crystalline basement, and has yielded a K-Ar whole-rock age (on andesitic basalt) of ???540 Ma. To judge from the fossils, however, that age may be as much as 100 Ma or more too young. ?? 1979.

  10. Nd and Sr isotope compositions in modern and fossil bones - Proxies for vertebrate provenance and taphonomy

    NASA Astrophysics Data System (ADS)

    Tütken, Thomas; Vennemann, Torsten W.; Pfretzschner, Hans-U.

    2011-10-01

    Rare earth elements (REE), while not essential for the physiologic functions of animals, are ingested and incorporated in ppb concentrations in bones and teeth. Nd isotope compositions of modern bones of animals from isotopically distinct habitats demonstrate that the 143Nd/ 144Nd of the apatite can be used as a fingerprint for bedrock geology or ambient water mass. This potentially allows the provenance and migration of extant vertebrates to be traced, similar to the use of Sr isotopes. Although REE may be enriched by up to 5 orders of magnitude during diagenesis and recrystallization of bone apatite, in vivo143Nd/ 144Nd may be preserved in the inner cortex of fossil bones or enamel. However, tracking the provenance of ancient or extinct vertebrates is possible only for well-preserved archeological and paleontological skeletal remains with in vivo-like Nd contents at the ppb-level. Intra-bone and -tooth REE analysis can be used to screen for appropriate areas. Large intra-bone Nd concentration gradients of 10 1-10 3 are often measured. Nd concentrations in the inner bone cortex increase over timescales of millions of years, while bone rims may be enriched over millenial timescales. Nevertheless, ? Nd values are often similar within one ? Nd unit within a single bone. Larger intra-bone differences in specimens may either reflect a partial preservation of in vivo values or changing ? Nd values of the diagenetic fluid during fossilization. However, most fossil specimens and the outer rims of bones will record taphonomic 143Nd/ 144Nd incorporated post mortem during diagenesis. Unlike REE patterns, 143Nd/ 144Nd are not biased by fractionation processes during REE-uptake into the apatite crystal lattice, hence the ? Nd value is an important tracer for taphonomy and reworking. Bones and teeth from autochthonous fossil assemblages have small variations of ±1 ? Nd unit only. In contrast, fossil bones and teeth from over 20 different marine and terrestrial fossil sites have a total range of ? Nd values from -13.0 to 4.9 ( n = 80), often matching the composition of the embedding sediment. This implies that the surrounding sediment is the source of Nd in the fossil bones and that the specimens of this study seem not to have been reworked. Differences in ? Nd values between skeletal remains and embedding sediment may either indicate reworking of fossils and/or a REE-uptake from a diagenetic fluid with non-sediment derived ? Nd values. The latter often applies to fossil shark teeth, which may preserve paleo-seawater values. Complementary to ? Nd values, 87Sr/ 86Sr can help to further constrain the fossil provenance and reworking.

  11. Fossil fuels in a trillion tonne world

    NASA Astrophysics Data System (ADS)

    Scott, Vivian; Haszeldine, R. Stuart; Tett, Simon F. B.; Oschlies, Andreas

    2015-05-01

    The useful energy services and energy density value of fossil carbon fuels could be retained for longer timescales into the future if their combustion is balanced by CO2 recapture and storage. We assess the global balance between fossil carbon supply and the sufficiency (size) and capability (technology, security) of candidate carbon stores. A hierarchy of value for extraction-to-storage pairings is proposed, which is augmented by classification of CO2 containment as temporary (<1,000 yr) or permanent (>100,000 yr). Using temporary stores is inefficient and defers an intergenerational problem. Permanent storage capacity is adequate to technically match current fossil fuel reserves. However, rates of storage creation cannot balance current and expected rates of fossil fuel extraction and CO2 consequences. Extraction of conventional natural gas is uniquely holistic because it creates the capacity to re-inject an equivalent tonnage of carbon for storage into the same reservoir and can re-use gas-extraction infrastructure for storage. By contrast, balancing the extraction of coal, oil, biomass and unconventional fossil fuels requires the engineering and validation of additional carbon storage. Such storage is, so far, unproven in sufficiency.

  12. AFRICAN AND AFRICAN AMERICAN STUDIES CRN Course Course Section Course Title Days Time Instructor Room

    E-print Network

    AFRICAN AND AFRICAN AMERICAN STUDIES CRN Course Course Section Course Title Days Time Instructor AND AFRICAN AMERICAN STUDIES 10008 AFAM 200 1 Intro. To African And African American Studies TR 12:15 - 1 Intro to African American English T 4:15 - 6:55 pm Hallett LWH 3105 PHILOSOPHY 11003 PHIL 364 1 Critical

  13. Reciprocal evolution of the cerebellum and neocortex in fossil humans

    PubMed Central

    Weaver, Anne H.

    2005-01-01

    Human brain evolution involved both neurological reorganization and an increase in overall brain volume relative to body mass. It is generally difficult to draw functional inferences about the timing and nature of brain reorganization, given that superficial brain morphology recorded on fossil endocasts is functionally ambiguous. However, the cerebellum, housed in the clearly delineated posterior cranial fossa, is functionally and ontologically discrete. The cerebellum is reciprocally connected to each of 14 neocortical regions important to human cognitive evolution. Cerebellar volume varies significantly relative to overall brain volume among mammalian orders, as well as within the primate order. There is also significant diachronic variation among fossil human taxa. In the australopithecines and early members of the genus Homo, the cerebral hemispheres were large in proportion to the cerebellum, compared with other hominoids. This trend continued in Middle and Late Pleistocene humans, including Neandertals and Cro-Magnon 1, who have the largest cerebral hemispheres relative to cerebellum volume of any primates, including earlier and Holocene humans. In recent humans, however, the pattern is reversed; the cerebellum is larger with respect to the rest of the brain (and, conversely, the cerebral hemispheres are smaller with respect to the cerebellum) than in Late Pleistocene humans. The cerebellum and cerebral hemispheres appear to have evolved reciprocally. Cerebellar development in Holocene humans may have provided greater computational efficiency for coping with an increasingly complex cultural and conceptual environment. PMID:15731345

  14. Reciprocal evolution of the cerebellum and neocortex in fossil humans.

    PubMed

    Weaver, Anne H

    2005-03-01

    Human brain evolution involved both neurological reorganization and an increase in overall brain volume relative to body mass. It is generally difficult to draw functional inferences about the timing and nature of brain reorganization, given that superficial brain morphology recorded on fossil endocasts is functionally ambiguous. However, the cerebellum, housed in the clearly delineated posterior cranial fossa, is functionally and ontologically discrete. The cerebellum is reciprocally connected to each of 14 neocortical regions important to human cognitive evolution. Cerebellar volume varies significantly relative to overall brain volume among mammalian orders, as well as within the primate order. There is also significant diachronic variation among fossil human taxa. In the australopithecines and early members of the genus Homo, the cerebral hemispheres were large in proportion to the cerebellum, compared with other hominoids. This trend continued in Middle and Late Pleistocene humans, including Neandertals and Cro-Magnon 1, who have the largest cerebral hemispheres relative to cerebellum volume of any primates, including earlier and Holocene humans. In recent humans, however, the pattern is reversed; the cerebellum is larger with respect to the rest of the brain (and, conversely, the cerebral hemispheres are smaller with respect to the cerebellum) than in Late Pleistocene humans. The cerebellum and cerebral hemispheres appear to have evolved reciprocally. Cerebellar development in Holocene humans may have provided greater computational efficiency for coping with an increasingly complex cultural and conceptual environment. PMID:15731345

  15. Miocene Fossils Reveal Ancient Roots for New Zealand's Endemic Mystacina (Chiroptera) and Its Rainforest Habitat.

    PubMed

    Hand, Suzanne J; Lee, Daphne E; Worthy, Trevor H; Archer, Michael; Worthy, Jennifer P; Tennyson, Alan J D; Salisbury, Steven W; Scofield, R Paul; Mildenhall, Dallas C; Kennedy, Elizabeth M; Lindqvist, Jon K

    2015-01-01

    The New Zealand endemic bat family Mystacinidae comprises just two Recent species referred to a single genus, Mystacina. The family was once more diverse and widespread, with an additional six extinct taxa recorded from Australia and New Zealand. Here, a new mystacinid is described from the early Miocene (19-16 Ma) St Bathans Fauna of Central Otago, South Island, New Zealand. It is the first pre-Pleistocene record of the modern genus and it extends the evolutionary history of Mystacina back at least 16 million years. Extant Mystacina species occupy old-growth rainforest and are semi-terrestrial with an exceptionally broad omnivorous diet. The majority of the plants inhabited, pollinated, dispersed or eaten by modern Mystacina were well-established in southern New Zealand in the early Miocene, based on the fossil record from sites at or near where the bat fossils are found. Similarly, many of the arthropod prey of living Mystacina are recorded as fossils in the same area. Although none of the Miocene plant and arthropod species is extant, most are closely related to modern taxa, demonstrating potentially long-standing ecological associations with Mystacina. PMID:26083758

  16. A Phenomenological Study of Undergraduate African American College Students' Decision to Participate in Study Abroad

    ERIC Educational Resources Information Center

    Cheppel, Alena

    2012-01-01

    The purpose of this phenomenological qualitative study was to explore African American undergraduate college students' intentions and reasons for participation in study abroad programs. The study involved gathering data from recorded and transcribed semi-structured interviews with 20 African American volunteer participants. Data analysis…

  17. 2007 The Outcrop 45http://www.geology.wisc.edu Book SalesBushels of FossilsBushels of FossilsBushels of FossilsBushels of FossilsBushels of Fossils

    E-print Network

    Johnson, Clark M.

    2007 The Outcrop 45http://www.geology.wisc.edu Book SalesBushels of FossilsBushels of Fossils.95 plus shipping. Profits are donated to the Department of Geology and Geophysics and the University Kansas. An order form is on the web at http://www.geology.wisc.edu/alumni/LRLaudon/index.html Roadside

  18. Recent synchronous radiation of a living fossil.

    PubMed

    Nagalingum, N S; Marshall, C R; Quental, T B; Rai, H S; Little, D P; Mathews, S

    2011-11-11

    Modern survivors of previously more diverse lineages are regarded as living fossils, particularly when characterized by morphological stasis. Cycads are often cited as a classic example, reaching their greatest diversity during the Jurassic-Cretaceous (199.6 to 65.5 million years ago) then dwindling to their present diversity of ~300 species as flowering plants rose to dominance. Using fossil-calibrated molecular phylogenies, we show that cycads underwent a near synchronous global rediversification beginning in the late Miocene, followed by a slowdown toward the Recent. Although the cycad lineage is ancient, our timetrees indicate that living cycad species are not much older than ~12 million years. These data reject the hypothesized role of dinosaurs in generating extant diversity and the designation of today's cycad species as living fossils. PMID:22021670

  19. Cerium anomaly at microscale in fossils.

    PubMed

    Gueriau, Pierre; Mocuta, Cristian; Bertrand, Loïc

    2015-09-01

    Patterns in rare earth element (REE) concentrations are essential instruments to assess geochemical processes in Earth and environmental sciences. Excursions in the "cerium anomaly" are widely used to inform on past redox conditions in sediments. This proxy resources to the specificity of cerium to adopt both the +III and +IV oxidation states, while most rare earths are purely trivalent and share very similar reactivity and transport properties. In practical terms, the level of cerium anomaly is established through elemental point quantification and profiling. All these models rely on a supposed homogeneity of the cerium oxidation state within the samples. However, this has never been demonstrated, whereas the cerium concentration can significantly vary within a sample, as shown for fossils, which would vastly complicate interpretation of REE patterns. Here, we report direct micrometric mapping of Ce speciation through synchrotron X-ray absorption spectroscopy and production of local rare earth patterns in paleontological fossil tissues through X-ray fluorescence mapping. The sensitivity of the approach is demonstrated on well-preserved fishes and crustaceans from the Late Cretaceous (ca. 95 million years (Myr) old). The presence of Ce under the +IV form within the fossil tissues is attributed to slightly oxidative local conditions of burial and agrees well with the limited negative cerium anomaly observed in REE patterns. The [Ce(IV)]/[Ce(tot)] ratio appears remarkably stable at the microscale within each fossil and is similar between fossils from the locality. Speciation maps were obtained from an original combination of synchrotron microbeam X-ray fluorescence, absorption spectroscopy, and diffraction, together with light and electron microscopy. This work also highlights the need for more systematic studies of cerium geochemistry at the microscale in paleontological contexts, in particular across fossil histologies. PMID:26239283

  20. Shallow and marginal marine Triassic trace fossils and ichnofabric from northwest Australia (ocean drilling program leg 122)

    SciTech Connect

    Droser, M.L. ); O'Connell, S. )

    1990-05-01

    The ichnofabric index method of ranking amount of bioturbation was used for the first time in conjunction with discrete trace fossils to examine shallow-water marine cores. Previous ichnological studies on cores have focused primarily on outer shelf and deep-sea discrete trace fossils. Upper Triassic cores examined in this study were recovered off northwest Australia during ODP Leg 122. These sediments were deposited in a shallow-water and continental shelf setting, which included swamp and prodelta environments. The most common lithology is siltstone with interbedded mudstone and sandstone. Sediments deposited in a swamp setting have rootlets and coal beds with an ichnological record consisting primarily of mottled bedding rather than discrete trace fossils. Ichnofabric indices 1 through 5 were recorded. Marginal marine/lagoonal facies have a low trace fossil diversity with common Chondrites, Planolites, and Teichichnus. Recorded ichnofabric indices include 1, 2, and 3. Laminated mudstones and siltstones (ii1) are most common. Fully marine open shelf strata are thoroughly bioturbated (ii5 and ii6) with Thalassinoides, Zoophycos, Teichichnus, and Planolites. Wackestone and packstone occur in discrete uppermost Triassic intervals and have ii1 through ii6 represented. In part due to the drilling process, sandstones and reefal limestones were poorly recovered and ichnofabric is not well preserved. Physical sedimentary structures and lateral facies relationships can be difficult to discern in core. In shallow marine deposits, the distribution of ichnofabric indices and discrete trace fossils within these strata provide an additional important data base to evaluate depositional environments.

  1. Fossil generation restructuring in the Ukraine

    SciTech Connect

    Galambas, J.W.

    1996-12-31

    This paper describes the Ukrainian electrical system as it was in 1991, defines the need for restructuring, outlines the restructuring process, identifies a number of major obstacles that are hindering the implementation of the fossil generation, restructuring process, and points out major problems in the coal procurement system. It describes the visits to several Ukrainian power plants, defines restructuring success to date, makes suggestions for improved restructuring progress, highlights lessons learned, and enlightens the audience on the opportunities of investing in the Ukrainian power generation industry. The primary focus is on the Fossil Generator Advisor task, which was carried out under the direction of Hagler Bailly Consulting, Inc. (Hagler Bailly).

  2. Fossils, Genes and The Origin of Organs

    SciTech Connect

    Shubin, Neil

    2011-04-20

    A toolkit of experimental and comparative biology can be applied to understand the great transformations in the history of life. Expeditionary paleontology can be used to target key nodes of the tree of life for which new fossils can provide insights into major morphological transformations. These fossils often have intermediate conditions that allow extant creatures to be compared in new ways. The tools of developmental genetics can then be used to explore these new comparisons to understand the genetic basis for macroevolutionary change. These different approaches can be used to predict new discoveries and this is only possible because of the empirical content of the tree of life.

  3. Fossils as candidate material for orthopedic applications.

    PubMed

    Pesenti, Hector; Leoni, Matteo; Motta, Antonella; Scardi, Paolo

    2011-01-01

    Ceramic powders from fossil deposits were thoroughly characterized from the material point of view and sintered to produce massive components. The raw material, a mixture of apatite minerals, feldspars, and quartz, seems ideally suitable to obtain a biologically compatible glass ceramic. Preliminary in vitro tests of proliferation and adhesion of MG63 human osteoblast-like cell line on a selected sample are encouraging. Results are correlated with sintering conditions and phase composition: the fossil can be sintered to almost full density at temperatures as low as 900 °C and seems to quickly promote cell activation with respect to hydroxylapatite. PMID:20089607

  4. Aquatic ape theory and fossil hominids.

    PubMed

    Verhaegen, M J

    1991-06-01

    While most older palaeo-anthropological studies emphasise the similarities of the fossil hominids with modern man, recent studies often stress the unique and the apelike features of the australopithecine dentitions, skulls and postcranial bones. It is worth reconsidering the features of Australopithecus, Homo erectus and Homo neanderthalensis in the light of the so-called Aquatic Ape Theory (AAT) of Hardy and Morgan, and to compare the skeletal parts of our fossil relatives with those of (semi)aquatic animals. Possible convergences are observed with proboscis monkeys, beavers, sea-otters, hippopotamuses, seals, sea-lions, walruses, sea-cows, whales, dolphins, porpoises, penguins and crocodiles. PMID:1909768

  5. Microbial Fossils Detected in Desert Varnish

    NASA Technical Reports Server (NTRS)

    Flood, B. E.; Allen, C.; Longazo, T.

    2003-01-01

    Mars Global Surveyor Thermal Emission Spectrometer data indicate regions with significant levels of hematite (_Fe2O3). Fe-oxides, like hematite, can form as aqueous mineral precipitates and as such may preserve microscopic fossils or other biosignatures. Several potential terrestrial analogues to martian hematite like hydrothermal vents have preserved microfossils. Microbial fossilization in Fe-oxides is often a function of biomineralization. For example, goethite (FeO2H) encrustation of fungal mycelia from the mid-Tertiary preserved fungal morphologies such that their genera could be determined.

  6. The oldest human fossil in Europe, from Orce (Spain).

    PubMed

    Toro-Moyano, Isidro; Martínez-Navarro, Bienvenido; Agustí, Jordi; Souday, Caroline; Bermúdez de Castro, José María; Martinón-Torres, María; Fajardo, Beatriz; Duval, Mathieu; Falguères, Christophe; Oms, Oriol; Parés, Josep Maria; Anadón, Pere; Julià, Ramón; García-Aguilar, José Manuel; Moigne, Anne-Marie; Espigares, María Patrocinio; Ros-Montoya, Sergio; Palmqvist, Paul

    2013-07-01

    The Orce region has one of the best late Pliocene and early Pleistocene continental paleobiological records of Europe. It is situated in the northeastern sector of the intramontane Guadix-Baza Basin (Granada, Andalusia, southern Spain). Here we describe a new fossil hominin tooth from the site of Barranco León, dated between 1.02 and 1.73 Ma (millions of years ago) by Electron Spin Resonance (ESR), which, in combination with paleomagnetic and biochronologic data, is estimated to be close to 1.4 Ma. While the range of dates obtained from these various methods overlaps with those published for the Sima del Elefante hominin locality (1.2 Ma), the overwhelming majority of evidence points to an older age. Thus, at the moment, the Barranco León hominin is the oldest from Western Europe. PMID:23481345

  7. A compendium of fossil marine animal families, 2nd edition

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    A comprehensive listing of 4075 taxonomic families of marine animals known from the fossil record is presented. This listing covers invertebrates, vertebrates, and animal-like protists, gives time intervals of apparent origination and extinction, and provides literature sources for these data. The time intervals are mostly 81 internationally recognized stratigraphic stages; more than half of the data are resolved to one of 145 substage divisions, providing more highly resolved data for studies of taxic macroevolution. Families are classified by order, class, and phylum, reflecting current classifications in the published literature. This compendium is a new edition of the 1982 publication, correcting errors and presenting greater stratigraphic resolution and more current ideas about acceptable families and their classification.

  8. Molecular fossils in Cretaceous condensate from western India

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Sharmila; Dutta, Suryendu; Dutta, Ratul

    2014-06-01

    The present study reports the biomarker distribution of condensate belonging to the early Cretaceous time frame using gas chromatography-mass spectrometry (GC-MS). The early Cretaceous palaeoenvironment was inscribed into these molecular fossils which reflected the source and conditions of deposition of the condensate. The saturate fraction of the condensate is characterized by normal alkanes ranging from n-C9 to n-C29 (CPI-1.13), cycloalkanes and C14 and C15 sesquiterpanes. The aromatic fraction comprises of naphthalene, phenanthrene, their methylated derivatives and cyclohexylbenzenes. Isohexylalkylnaphthalenes, a product of rearrangement process of terpenoids, is detected in the condensate. Several aromatic sesquiterpenoids and diterpenoids have been recorded. Dihydro- ar-curcumene, cadalene and ionene form the assemblage of sesquiterpenoids which are indicative of higher plant input. Aromatic diterpenoid fraction comprises of simonellite and retene. These compounds are also indicative of higher plants, particularly conifer source which had been a predominant flora during the Cretaceous time.

  9. Understanding traditional African healing

    PubMed Central

    MOKGOBI, M.G.

    2015-01-01

    Traditional African healing has been in existence for many centuries yet many people still seem not to understand how it relates to God and religion/spirituality. Some people seem to believe that traditional healers worship the ancestors and not God. It is therefore the aim of this paper to clarify this relationship by discussing a chain of communication between the worshipers and the Almighty God. Other aspects of traditional healing namely types of traditional healers, training of traditional healers as well as the role of traditional healers in their communities are discussed. In conclusion, the services of traditional healers go far beyond the uses of herbs for physical illnesses. Traditional healers serve many roles which include but not limited to custodians of the traditional African religion and customs, educators about culture, counselors, social workers and psychologists.

  10. Climatic Effects on Mammalian Body Size During the African Plio-Pleistocene

    NASA Astrophysics Data System (ADS)

    Reynolds, S. C.

    2004-12-01

    Climatic and environmental differences cause geographic patterns of larger versus smaller body sizes (size clines) in certain extant mammals, such as the spotted hyaena (Crocuta crocuta) and the Plains zebra (Equus burchellii). Likewise, body size changes seen in fossil specimens of these taxa from East and southern African Plio-Pleistocene sites are presumed to have climatic and environmental causes. This paper examines body size changes in these two taxa from key fossil sites in East Africa (Olduvai Beds I-IV, East Turkana and Olorgesailie) and southern Africa (Swartkrans, Sterkfontein and Kromdraai) to assess the nature and extent of body size changes. The differences between modern size variation and fossil size variation will be discussed. Results indicate that body sizes of fossil conspecifics in the focal taxa do not follow the pattern of geographic variation seen in modern conspecifics. Climatic and environmental changes may explain these differences, in particular that shifts in the East African region during the Plio-Pleistocene were greater than contemporaneous changes in southern Africa.

  11. Kidney Disease Risks among African-Americans

    MedlinePLUS

    ... Partners Search This Site Kidney Disease Risks Among African-Americans African-Americans are more at risk for kidney ... Fund doing to help? More Information Why are African-Americans more at risk? Although we are not exactly ...

  12. 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.

  13. East African Rift Valley, Kenya

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This rare, cloud free view of the East African Rift Valley, Kenya (1.5N, 35.5E) shows a clear view of the Turkwell River Valley, an offshoot of the African REift System. The East African Rift is part of a vast plate fracture which extends from southern Turkey, through the Red Sea, East Africa and into Mozambique. Dark green patches of forests are seen along the rift margin and tea plantations occupy the cooler higher ground.

  14. Diversity among African Pygmies

    PubMed Central

    Ramírez Rozzi, Fernando V.; Sardi, Marina L.

    2010-01-01

    Although dissimilarities in cranial and post-cranial morphology among African pygmies groups have been recognized, comparative studies on skull morphology usually pull all pygmies together assuming that morphological characters are similar among them and different with respect to other populations. The main aim of this study is to compare cranial morphology between African pygmies and non-pygmies populations from Equatorial Africa derived from both the Eastern and the Western regions in order to test if the greatest morphological difference is obtained in the comparison between pygmies and non-pygmies. Thirty three-dimensional (3D) landmarks registered with Microscribe in four cranial samples (Western and Eastern pygmies and non-pygmies) were obtained. Multivariate analysis (generalized Procrustes analysis, Mahalanobis distances, multivariate regression) and complementary dimensions of size were evaluated with ANOVA and post hoc LSD. Results suggest that important cranial shape differentiation does occur between pygmies and non-pygmies but also between Eastern and Western populations and that size changes and allometries do not affect similarly Eastern and Western pygmies. Therefore, our findings raise serious doubt about the fact to consider African pygmies as a homogenous group in studies on skull morphology. Differences in cranial morphology among pygmies would suggest differentiation after divergence. Although not directly related to skull differentiation, the diversity among pygmies would probably suggest that the process responsible for reduced stature occurred after the split of the ancestors of modern Eastern and Western pygmies. PMID:21049030

  15. Genomic Fossils Calibrate the Long-Term Evolution of Hepadnaviruses

    PubMed Central

    Gilbert, Clément; Feschotte, Cédric

    2010-01-01

    Because most extant viruses mutate rapidly and lack a true fossil record, their deep evolution and long-term substitution rates remain poorly understood. In addition to retroviruses, which rely on chromosomal integration for their replication, many other viruses replicate in the nucleus of their host's cells and are therefore prone to endogenization, a process that involves integration of viral DNA into the host's germline genome followed by long-term vertical inheritance. Such endogenous viruses are highly valuable as they provide a molecular fossil record of past viral invasions, which may be used to decipher the origins and long-term evolutionary characteristics of modern pathogenic viruses. Hepadnaviruses (Hepadnaviridae) are a family of small, partially double-stranded DNA viruses that include hepatitis B viruses. Here we report the discovery of endogenous hepadnaviruses in the genome of the zebra finch. We used a combination of cross-species analysis of orthologous insertions, molecular dating, and phylogenetic analyses to demonstrate that hepadnaviruses infiltrated repeatedly the germline genome of passerine birds. We provide evidence that some of the avian hepadnavirus integration events are at least 19 My old, which reveals a much deeper ancestry of Hepadnaviridae than could be inferred based on the coalescence times of modern hepadnaviruses. Furthermore, the remarkable sequence similarity between endogenous and extant avian hepadnaviruses (up to 75% identity) suggests that long-term substitution rates for these viruses are on the order of 10?8 substitutions per site per year, which is a 1,000-fold slower than short-term rates estimated based on the sequences of circulating hepadnaviruses. Together, these results imply a drastic shift in our understanding of the time scale of hepadnavirus evolution, and suggest that the rapid evolutionary dynamics characterizing modern avian hepadnaviruses do not reflect their mode of evolution on a deep time scale. PMID:20927357

  16. Fossil struthionid eggshells from Laetoli, Tanzania: Taxonomic and biostratigraphic significance

    NASA Astrophysics Data System (ADS)

    Harrison, Terry; Msuya, Charles P.

    2005-04-01

    Recent paleontological investigations at Laetoli and neighboring localities in northern Tanzania have produced a large collection of fossil ostrich eggshells from the Pliocene-aged Laetolil Beds (˜3.5-4.5 Ma) and Ndolanya Beds (˜2.6-2.7 Ma). A detailed analysis of the morphology of the eggshells and their taxonomic affinities indicates that two different species of Struthio are represented. In the Lower Laetolil Beds and in the Upper Laetolil Beds below Tuff 3 a new species is recognized— Struthio kakesiensis. This is replaced in the Upper Laetolil Beds by Struthio camelus, the modern species of ostrich. Since radiometric age determinations are available for the stratigraphic sequence at Laetoli, it is possible to precisely date the first appearance of S. camelus at ˜3.6-3.8 Ma. Comparisons of the Laetoli material with specimens from the well-dated sequences at Lothagam and Kanapoi in northern Kenya, allow the taxonomic and biochronological analysis to be extended back in time to the late Miocene. At about 6.5 Ma, Diamantornis and elephant birds were replaced in East Africa by ostriches belonging to the genus Struthio. Three time-successive species of ostriches are identified in the fossil record of East Africa, beginning with Struthio. cf. karingarabensis (˜6.5-4.2 Ma), followed by S. kakesiensis (˜4.5-3.6 Ma) and then S. camelus (˜3.8 Ma onwards). A similar sequence of taxa has previously been recorded from localities in Namibia, but at these sites there is no possibility to precisely calibrate the ages of the different species using radiometric dating. Nevertheless, the broadly similar evolutionary sequence and the close correspondence in inferred ages for the succession of species in East Africa and Namibia suggest that ostrich eggshells are a very useful tool for biochronological correlation of paleontological sites in sub-Saharan Africa.

  17. An integrated study of the Homo-bearing Aalat stratigraphic section (Eritrea): An expanded continental record at the Early-Middle Pleistocene transition

    NASA Astrophysics Data System (ADS)

    Ghinassi, Massimiliano; Oms, Oriol; Papini, Mauro; Scarciglia, Fabio; Carnevale, Giorgio; Sani, Federico; Rook, Lorenzo; Delfino, Massimo; Pavia, Marco; Libsekal, Yosief; Bondioli, Luca; Coppa, Alfredo; Frayer, David W.; Macchiarelli, Roberto

    2015-12-01

    The Early to Middle Pleistocene continental transition in East Africa is widely documented from lacustrine and deep-sea records, although significant insights are also provided by fluvio-lacustrine successions of the central and southern African Rift Valley, such as the at Olduvai Gorge succession (Tanzania), the Bouri Formation (Ethiopia) and the Olorgesailie Formation (Kenya). The Early to Middle Pleistocene Dandiero Basin fill (Eritrean Danakil) represents the only continental succession in the northernmost sector of the African Rift Valley that provided abundant fossil vertebrates, including human remains. The present study integrates already available data with new sedimentological, pedological, magnetostratigraphic, paleontological and paleoanthropological investigations of the 300 m thick Aalat section (North Dandiero Basin). This sedimentary succession records repeated shifts from fluvial to lacustrine depositional settings, which occurred under the tight interaction between local tectonics and Pleistocene climate changes. Accumulation was associated with axial sedimentation in a NS-trending extensional basin, with an overall tectono-sedimentary setting comparable with that of the coeval Bouri Formation (Ethiopia). Because of the high rates of sedimentation, a poor to moderate degree of soil development characterizes the whole succession. Sporadic soil horizons testify to carbonate dissolution, leaching and accumulation in calcic and petrocalcic horizons (indicating an overall dry climate). The alternate with local to extensive iron-oxide/hydroxide segregation, promoted by water infiltration under varying drainage conditions and/or seasonal contrast, that record more humid conditions. Magnetostratigraphic dating and correlation indicates that this section is among the world's thickest record embracing the Early-Middle Pleistocene transition, spanning from the Jaramillo to the base of Brunhes chron. The terrestrial vertebrate fauna includes a typical Early to Middle Pleistocene East African mammalian assemblage for this age and is dominated by taxa characterized by strong water dependence. The ichthyofauna, with its abundant Clariidae, is also consistent with the shallow water, fluvio-lacustrine paleobiotopes. The cranial, dental and postcranial human remains from the lower part of the Aalat succession add valuable evidence about the patterns of variation and evolutionary dynamics in African Homo erectus/ergaster near the end of the Early Pleistocene.

  18. Major African contributions to Palaeozoic and Mesozoic vertebrate palaeontology

    NASA Astrophysics Data System (ADS)

    Durand, J. F.

    2005-10-01

    Over more than two centuries, Africa has been an important source of knowledge with regard to the origins, evolution and distribution of important animal taxa. Not only did Africa south of the Sahara contain a second zoogeographical region virtually unknown four centuries ago, but also gave the world the first insight into the palaeontological wealth and the existence of Gondwana. The section on Agnatha includes a discussion on conodonts from South Africa, considered to be the some of the oldest and best-preserved vertebrate fossils in the world. The section on the Gnathostomata includes a very brief overview of the most important fish taxa from the Palaeozoic to Mesozoic of Africa. The section on the Tetrapoda includes an overview of the major taxa found in the fossil record of the Palaeozoic and Mesozoic of Africa. The Permian and Triassic tetrapod fossils that indicate the evolution and radiation of the parareptiles, eureptiles and synapsids are highlighted. The most important vertebrate fossils from Africa that contributed to our understanding of the radiation of evolutionary important groups such as the fish, tetrapods, tortoises, snakes, crocodiles, dinosaurs and mammals are discussed. The Jurassic and Cretaceous assemblages containing dinosaur and mammal remains, deposited after the break up of Gondwana, are discussed. Finally a perspective on the importance of Africa as fossil repository and the limitations of palaeontological endeavour in Africa is given.

  19. Exceptionally preserved insect fossils in the Late Jurassic lagoon of Orbagnoux (Rhône Valley, France)

    PubMed Central

    Nel, Patricia; Krieg-Jacquier, Régis; Pouillon, Jean-Marc

    2014-01-01

    The Late Kimmeridgian marine limestones of the area around Orbagnoux (Rhône, France) are well known for their fish fauna and terrestrial flora. Here we record the first insects and their activities (mines on leaves and trails in sediments) from these layers, including the oldest record of the gerromorphan bugs, as a new genus and species Gallomesovelia grioti, attributed to the most basal family Mesoveliidae and subfamily Madeoveliinae. These new fossils suggest the presence of a complex terrestrial palaeoecosystem on emerged lands near the lagoon where the limestones were deposited. The exquisite state of preservation of these fossils also suggests that these outcrops can potentially become an important Konservat-Lagerstätte for the Late Jurassic of Western Europe. PMID:25210652

  20. Education no longer deferred: the possibilities of educating urban african american males in a single gender school. 

    E-print Network

    James, Marlon C.

    2009-05-15

    teacher interviews, and reviewed student academic and behavioral records. This exploratory analysis consisted of two separate; but interrelated, qualitative studies relevant to educating urban African American males. The first inquiry featured a case study...