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1

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

PubMed Central

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

Bibi, Faysal

2011-01-01

2

The Fossil Record  

NSDL National Science Digital Library

This lesson plan is part of the DiscoverySchool.com lesson plan library for grades 9-12. It centers around fossils found in the Burgess Shale in western Canada. Topics include body shapes of fossils found, the movement of organisms from oceans to land, and whether organisms existed that did not fossilize. This part of geologic history began in the Cambrian Sea about 540 million years ago. The resource includes objectives, materials, procedures, discussion questions, evaluation ideas, extensions, suggested readings, and vocabulary. There are videos available to order which complement this lesson, an audio-enhanced vocabulary list, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.

Wu, Lisa

3

Diagnosing Homo sapiens in the fossil record.  

PubMed

Abstract Background: Diagnosing Homo sapiens is a critical question in the study of human evolution. Although what constitutes living members of our own species is straightforward, in the fossil record this is still a matter of much debate. The issue is complicated by questions of species diagnoses and ideas about the mode by which a new species is born, by the arguments surrounding the behavioural and cognitive separateness of the species, by the increasing appreciation of variation in the early African H. sapiens record and by new DNA evidence of hybridization with extinct species. Methods and results: This study synthesizes thinking on the fossils, archaeology and underlying evolutionary models of the last several decades with recent DNA results from both H. sapiens and fossil species. Conclusion: It is concluded that, although it may not be possible or even desirable to cleanly partition out a homogenous morphological description of recent H. sapiens in the fossil record, there are key, distinguishing morphological traits in the cranium, dentition and pelvis that can be usefully employed to diagnose the H. sapiens lineage. Increasing advances in retrieving and understanding relevant genetic data provide a complementary and perhaps potentially even more fruitful means of characterizing the differences between H. sapiens and its close relatives. PMID:24932746

Stringer, Christopher Brian; Buck, Laura Tabitha

2014-07-01

4

Extinction and the fossil record  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

5

Extinction and the fossil record.  

PubMed

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. PMID:11539586

Sepkoski, J J

1994-03-01

6

Evolution and the Fossil Record  

NSDL National Science Digital Library

This publication of the American Geological Institute is a non-technical introduction to evolution and aims to help the general public gain a better understanding of one of the fundamental underlying concepts of modern science. Concepts covered include geologic time, change through time, Darwin's theory of evolution, evolution as a mechanism for change, the nature of species, the nature of theory, paleontology, and determination of age. Four case studies highlight examples of evolution from the fossil record to provide a perspective for understanding the evolution of life on Earth.

Springer, Dale; Pojeta Jr., John

2007-12-12

7

The First Fossil Record of Caecilian Amphibians  

Microsoft Academic Search

THREE groups of amphibians are living today-frogs, salamanders and caecilians. The fossil record of frogs and salamanders is relatively poor1,2, but representatives of most groups have been discovered. For the caecilians, however, no authentic fossils have been recognized, until now. We describe here a single diagnostic vertebra from the Palaeocene of Brazil.

Richard Estes; MARVALEE H. WAKE

1972-01-01

8

Species in the primate fossil record.  

PubMed

Species in the fossil record are population pools of genetic and phenetic variation at a place and time, morphologically recognizable and distinguishable from others by empirical standards. Change through time can be substantial, requiring subdivision of lineages that becomes more arbitrary as they become more complete. Evolution is about form, space, and time; it is about variation and change. Interpretation of species in the fossil record touches all of these. PMID:24591141

Gingerich, Philip D

2014-01-01

9

The fossil record of the Peronosporomycetes (Oomycota).  

PubMed

Evidence of fossil Peronosporomycetes has been slow to accumulate. In this review various fossils historically assigmed to the Peronosporomycets are dicussed briefly and an explanation is provided as to why the fossil record of this grouop has remained inconsistent. In recent year there has been several new reports of fossil peronosporomycetes based on structurally preserved oogonium-antheridium complexes from Derovonian and Carboniferous rocks that demonstrate the existence of these organisms as fossils and refute the long-standing assumption that they are too delicate to be preserved. Among these are serral tyoes characterized by oogonial surface members of the group. To date at last three groups of fossil vascular plants (i.e. lycophytes, ferns and seed ferns) are known to host peronosporomycetes aas endophytes; however only one form has been identified as a parasite. PMID:21289104

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

2011-01-01

10

Fossil pollen records of extant angiosperms  

Microsoft Academic Search

The fossil record for angiosperm pollen types which are comparable to recent taxa is evaluated, following a similar survey\\u000a published in 1970. Special attention is paid to the dating of the sediments. Evidence for 139 families is considered to be\\u000a reliable, for others the records are cited as provisional, pending the accumulation of more evidence. Some published records\\u000a are shown

Jan Muller

1981-01-01

11

Insect diversity in the fossil record.  

PubMed

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. PMID:11536548

Labandeira, C C; Sepkoski, J J

1993-07-16

12

Insect Diversity in the Fossil Record  

Microsoft Academic Search

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

Conrad C. Labandeira; J. John Sepkoski Jr.

1993-01-01

13

Adaptation, plant evolution, and the fossil record  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

14

Fossil Record Accurately Reflects Recent Flowering of Marine Biodiversity  

NSF Publications Database

... Lane (703) 292-8550 hlane@nsf.gov Fossil Record Accurately Reflects Recent Flowering of Marine ... produced by the inconsistencies of the fossil record, says a team of paleontologists led by the ...

15

Identifying and directly dating Plio-Pleistocene geomagnetic reversals and events from speleothems at South African archaeological and fossil bearing palaeocaves: implications for extending archaeomagnetic records  

NASA Astrophysics Data System (ADS)

In the last 10 years palaeomagnetic research on speleothems from archaeological and fossil bearing palaeokarst in northern South Africa has led to the identification of apparent short geomagnetic field events that were initially thought to represent one or both of the Réunion events. More recently the development of uranium-lead dating techniques for speleothem in the 5 Ma to 500 ka time range has allowed us to directly date these events for the first time, as well as date more recently discovered events and reversals. This work now indicates that the same reversals events are often found in speleothems in different caves throughout the region. An event has been directly dated at two sites to between 2.047 and 2.0005 Ma and likely represents what has been termed the 'Huckleberry Ridge' event at other localities. Another event sometime between 2.33 and 2.15 Ma likely represents the Réunion event while another between 1.111 to 1.087 Ma is thought to represent the Punaruu event. X-ray Fluorescence Microscopy work at the Australian Synchrotron has been used to map the iron distribution in the speleothems and in tandem with the demagnetisation spectra has enabled the mineralogy and mode of acquisition of remanence to be determined and the potential effects of recrystalisation on the palaeomagnetic signal to be accessed. Further work on speleothem sequences in the caves has the potential to refine the ages of geomagnetic field reversals, events and excursions over almost any time range for which speleothems exist, if certain conditions are met. Given the rapid lock-in time of the remanence and low alteration rates and effects of speleothems they provide a powerful new medium for reconstructing Plio-Pleistocene geomagnetic field variation.

Herries, A. I.; Pickering, R.; Kappen, P.

2013-05-01

16

Rates of speciation in the fossil record.  

PubMed Central

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.

Sepkoski, J J

1998-01-01

17

Rates of speciation in the fossil record  

NASA Technical Reports Server (NTRS)

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.

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

1998-01-01

18

Determinants of extinction in the fossil record.  

PubMed

The causes of mass extinctions and the nature of biological selectivity at extinction events are central questions in palaeobiology. It has long been recognized, however, that the amount of sedimentary rock available for sampling may bias perceptions of biodiversity and estimates of taxonomic rates of evolution. This problem has been particularly noted with respect to the principal mass extinctions. Here we use a new compilation of the amount of exposed marine sedimentary rock to predict how the observed fossil record of extinction would appear if the time series of true extinction rates were in fact smooth. Many features of the highly variable record of apparent extinction rates within marine animals can be predicted on the basis of temporal variation in the amount of exposed rock. Although this result is consistent with the possibility that a common geological cause determines both true extinction rates and the amount of exposed rock, it also supports the hypothesis that much of the observed short-term volatility in extinction rates is an artefact of variability in the stratigraphic record. PMID:11919629

Peters, Shanan E; Foote, Michael

2002-03-28

19

Aestivation in the fossil record: evidence from ichnology.  

PubMed

Aestivation is a physiological and behavioral response to high temperature or low moisture conditions. Therefore, it is typically not considered to be capable of being preserved in the fossil record. However, most aestivating organisms produce a burrow to protect themselves from the harmful environmental conditions that trigger aestivation. These structures can be preserved in the rock record as trace fossils. While trace fossils are abundant in the continental fossil record, few are definitively associated with aestivation. Interpreting aestivation behavior from fossil burrows requires a detailed examination and interpretation of the surrounding sedimentary rocks and comparisons with taxonomically and ecologically similar extant organisms. Currently, only four types of aestivation structures are recognized in the fossil record: Pleistocene earthworm chambers, Devonian to Cretaceous lungfish burrows, Permian lysorophid burrows, and Permian to Triassic dicynodont burrows. The trace fossil evidence suggests that aestivation evolved independently among continental organisms in several clades during the middle to late Paleozoic. PMID:20069413

Hembree, Daniel I

2010-01-01

20

First Fossil Lamprey: A Record from the Pennsylvanian of Illinois  

Microsoft Academic Search

A fossil record of lampreys has previously been unknown. A new genus demonstrates the presence of this group in the Pennsylvanian. The body outline, parts of the head skeleton, rasping tongue mechanism, gill basket, and other internal organs are preserved. The fossils are very similar in structure to modern forms. The absence of hagfish characters in the fossil supports the

David Bardack; Rainer Zangerl

1968-01-01

21

Special Creation and the Fossil Record: The Central Fallacy.  

ERIC Educational Resources Information Center

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

Miller, Kenneth R.

1982-01-01

22

Early cyanobacterial fossil record: preservation, palaeoenvironments and identification  

Microsoft Academic Search

The cyanobacterial fossil record is among the oldest for any group of organisms, possibly reaching back to 3500 Ma ago. The molecular phylogeny of cyanobacteria is complementary to the fossil findings, confirming the antiquity of the group, the role of cyanobacteria in the evolution of planetary primary production, and the symbiotic origins of plastids in algae and plants from cyanobacterial

Stjepko Golubic; Lee Seong-Joo

1999-01-01

23

Mass Extinctions in the Marine Fossil Record  

Microsoft Academic Search

A new compilation of fossil data on invertebrate and vertebrate families indicates that four mass extinctions in the marine realm are statistically distinct from background extinction levels. These four occurred late in the Ordovician, Permian, Triassic, and Cretaceous periods. A fifth extinction event in the Devonian stands out from the background but is not statistically significant in these data. Background

David M. Raup; J. John Sepkoski

1982-01-01

24

On the fossil record of the Gekkota.  

PubMed

Gekkota is often interpreted as sister to all remaining squamates, exclusive of dibamids, or as sister to Autarchoglossa. It is the only diverse lineage of primarily nocturnal lizards and includes some of the smallest amniotes. The skeleton of geckos has often been interpreted as paedomorphic and/or "primitive" but these lizards also display a wide range of structural specializations of the postcranium, including modifications associated with both scansorial locomotion and limb reduction. Although the concept of "Gekkota" has been variously applied by different authors, we here apply a rigorous apomorphy based definition, recent advances in gekkotan morphology and phylogenetics, and diverse comparative material to provide a comprehensive assessment of 28 known pre-Quaternary geckos, updating the last such review, published three decades ago. Fossils evaluated include both sedimentary fossils and amber-embedded specimens. Known Cretaceous geckos are exclusively Asian and exhibit character combinations not seen in any living forms. Cenozoic gekkotans derive from sites around the world, although Europe is especially well represented. Paleogene geckos are largely known from disarticulated remains and show similarities to Sphaerodactylidae and Diplodactylidae, although resemblances may be plesiomorphic in some cases. Many Neogene gekkotans are referable to living families or even genera, but their geographic occurrences are often extralimital to those of modern groups, as is consistent with paleoclimatic conditions. The phylogenetic placement of fossil gekkotans has important repercusions for timetree calibration, but at present only a small number of fossils can be confidently assigned to even family level groupings, limiting their utility in this regard. PMID:24482344

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

2014-03-01

25

Fossils  

NSDL National Science Digital Library

Students discover the science of paleontology and the fossilization process. Why should we study fossils? Use your KWL chart to record information you have learned and anything else you want to know about. First read about the fossils of birds and what we learn from them. Then discover the Fossilization Process. Find out if there are still new dinosaurs to be discovered. Watch paleontologists hunt for ...

Tassihj

2009-10-21

26

A review of the fossil record of monocotyledons  

Microsoft Academic Search

The fossil record of monocotyledons is reviewed in order to determine the families actually represented by fossils and their\\u000a stratigraphic ranges. In providing this information, attention is called to deficiencies and strengths in the record. Most\\u000a notable is the uneven representation of the four subclasses of monocotyledons. Three distinct phases in the history of monocots\\u000a can be delineated when the

Charles P. Daghlian

1981-01-01

27

The Fossil Record: Tracing the Roots of the Cyanobacterial Lineage  

Microsoft Academic Search

Since the mid-1960s, following a century of unrewarded search, impressive progress has been made toward deciphering the Precambrian\\u000a fossil record, evidence of life extant during the earliest seven-eighths of geologic time. Hundreds of fossiliferous units\\u000a have been discovered containing thousands of microbial fossils—dominantly but not exclusively cyanobacterial — and the documented\\u000a antiquity of life has been extended to an age

J. Schopf

28

The Paleogene fossil record of birds in Europe  

Microsoft Academic Search

The Paleogene (Paleocene-Oligocene) fossil record of birds in Europe is reviewed and recent and fossil taxa are placed into a phylogenetic framework, based on published cladistic analyses. The pre-Oligocene European avifauna is characterized by the complete absence of passeriform birds, which today are the most diverse and abundant avian taxon. Representatives of small non-passeriform perching birds thus probably had similar

Gerald Mayr

2005-01-01

29

How Good is the Fossil Record?  

ERIC Educational Resources Information Center

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)

Boucot, A. J.

1983-01-01

30

Delayed biological recovery from extinctions throughout the fossil record  

Microsoft Academic Search

How quickly does biodiversity rebound after extinctions? Palaeobiologists have examined the temporal, taxonomic and geographic patterns of recovery following individual mass extinctions in detail, but have not analysed recoveries from extinctions throughout the fossil record as a whole. Here, we measure how fast biodiversity rebounds after extinctions in general, rather than after individual mass extinctions, by calculating the cross-correlation between

James W. Kirchner; Anne Weil

2000-01-01

31

Absolute measures of the completeness of the fossil record  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

32

Epibiotic relationships in Mesoproterozoic fossil record: Gaoyuzhuang Formation, China  

Microsoft Academic Search

Epibiotic coccoid microfossils of probable cyanobacterial affinity were discovered in cherty stratiform stromatolites of the 1400 1500 Ma Gaoyuzhuang Formation, Hebei Province, northern China. Sessile coccoids with polarized growth settled on cyanobacterial sheaths and developed dense populations. These microfossils represent the earliest known occurrence of epibiosis in the fossil record with characteristics similar to those observed in modern aquatic environments.

Lee Seong Joo; Stjepko Golubic; Eric Verrecchia

1999-01-01

33

Evidence for Evolution from the Vertebrate Fossil Record.  

ERIC Educational Resources Information Center

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)

Gingerich, Philip D.

1983-01-01

34

Self-organized criticality, evolution and the fossil extinction record  

Microsoft Academic Search

Statistical analysis indicates that the fossil extinction record is\\u000acompatible with a distribution of extinction events whose frequency is related\\u000ato their size by a power law with an exponent close to two. This result is in\\u000aagreement with predictions based on self-organized critical models of\\u000aextinction, and might well be taken as evidence of critical behaviour in\\u000aterrestrial evolution.

M. E. J. Newman

1996-01-01

35

Molecular clocks and the incompleteness of the fossil record  

Microsoft Academic Search

Molecular clocks can be evaluated by comparing absolute rates of evolution and by performing relative-rate tests. Typically, calculations of absolute rates are based on earliest observed occurrences in the fossil record. Relative-rate tests, on the other hand, merely require an unambiguous outgroup. A major disadvantage of relative-rate tests is their insensitivity to concomitant and equal rate changes in all lineages.

Mark S. Springer

1995-01-01

36

Patterns of Generic Extinction in the Fossil Record  

Microsoft Academic Search

Abstract.-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 biolog- ically driven and that it is

David M. Raup; George E. Boyajian

2007-01-01

37

An overview of the dinosaur fossil record from Chile  

NASA Astrophysics Data System (ADS)

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.

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

2012-08-01

38

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

NASA Technical Reports Server (NTRS)

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.

Awramik, Stanley M.

1989-01-01

39

The hominin fossil record: taxa, grades and clades  

PubMed Central

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.

Wood, Bernard; Lonergan, Nicholas

2008-01-01

40

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

NASA Astrophysics Data System (ADS)

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

Kidwell, Susan M.; Flessa, Karl W.

41

Epibiotic relationships in Mesoproterozoic fossil record: Gaoyuzhuang Formation, China  

NASA Astrophysics Data System (ADS)

Epibiotic coccoid microfossils of probable cyanobacterial affinity were discovered in cherty stratiform stromatolites of the 1400 1500 Ma Gaoyuzhuang Formation, Hebei Province, northern China. Sessile coccoids with polarized growth settled on cyanobacterial sheaths and developed dense populations. These microfossils represent the earliest known occurrence of epibiosis in the fossil record with characteristics similar to those observed in modern aquatic environments. The reported fossil epibionts are also the first known occurrence of Proterozoic cyanobacteria of chamaesiphonalean affinity. The presence of specialized epibiotic communities in Gaoyuzhuang stromatolites demonstrates that epibiosis was well established and diversified by Mesoproterozoic time, reflecting early adaptation in response to competitive pressures for microbial attachment sites in ancient, densely populated shallow-water benthos or, possibly, the onset of specialized mutualistic relationships among cooccurring microorganisms.

Joo, Lee Seong; Golubic, Stjepko; Verrecchia, Eric

1999-12-01

42

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

PubMed

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

Budd, Graham E

2013-09-01

43

At the Origin of Animals: The Revolutionary Cambrian Fossil Record  

PubMed Central

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.

Budd, Graham E

2013-01-01

44

Patterns of generic extinction in the fossil record  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

45

Delayed biological recovery from extinctions throughout the fossil record.  

PubMed

How quickly does biodiversity rebound after extinctions? Palaeobiologists have examined the temporal, taxonomic and geographic patterns of recovery following individual mass extinctions in detail, but have not analysed recoveries from extinctions throughout the fossil record as a whole. Here, we measure how fast biodiversity rebounds after extinctions in general, rather than after individual mass extinctions, by calculating the cross-correlation between extinction and origination rates across the entire Phanerozoic marine fossil record. Our results show that extinction rates are not significantly correlated with contemporaneous origination rates, but instead are correlated with origination rates roughly 10 million years later. This lagged correlation persists when we remove the 'Big Five' major mass extinctions, indicating that recovery times following mass extinctions and background extinctions are similar. Our results suggest that there are intrinsic limits to how quickly global biodiversity can recover after extinction events, regardless of their magnitude. They also imply that today's anthropogenic extinctions will diminish biodiversity for millions of years to come. PMID:10724168

Kirchner, J W; Weil, A

2000-03-01

46

Phanerozoic Marine Biodiversity Dynamics in Light of the Incompleteness of the Fossil Record  

Microsoft Academic Search

Long-term evolutionary dynamics have been approached through quantitative analysis of the fossil record, but without explicitly taking its incompleteness into account. Here we explore the temporal covariance structure of per-genus origination and extinction rates for global marine fossil genera throughout the Phanerozoic, both before and after corrections for the incompleteness of the fossil record. Using uncorrected data based on Sepkoski's

Peter J. Lu; Motohiro Yogo; Charles R. Marshall

2006-01-01

47

Phanerozoic marine biodiversity dynamics in light of the incompleteness of the fossil record  

Microsoft Academic Search

Long-term evolutionary dynamics have been approached through quantitative analysis of the fossil record, but without explicitly taking its incompleteness into account. Here we explore the temporal covariance structure of per-genus origination and extinction rates for global marine fossil genera throughout the Phanerozoic, both before and after corrections for the incompleteness of the fossil record. Using uncorrected data based on Sepkoski's

Peter J. Lu; Motohiro Yogo; Charles R. Marshall

2006-01-01

48

The Paleogene fossil record of birds in Europe.  

PubMed

The Paleogene (Paleocene-Oligocene) fossil record of birds in Europe is reviewed and recent and fossil taxa are placed into a phylogenetic framework, based on published cladistic analyses. The pre-Oligocene European avifauna is characterized by the complete absence of passeriform birds, which today are the most diverse and abundant avian taxon. Representatives of small non-passeriform perching birds thus probably had similar ecological niches before the Oligocene to those filled by modern passerines. The occurrence of passerines towards the Lower Oligocene appears to have had a major impact on these birds, and the surviving crown-group members of many small arboreal Eocene taxa show highly specialized feeding strategies not found or rare in passeriform birds. It is detailed that no crown-group members of modern 'families' are known from pre-Oligocene deposits of Europe, or anywhere else. The phylogenetic position of Paleogene birds thus indicates that diversification of the crown-groups of modern avian 'families' did not take place before the Oligocene, irrespective of their relative position within Neornithes (crown-group birds). The Paleogene fossil record of birds does not even support crown-group diversification of Galliformes, one of the most basal taxa of neognathous birds, before the Oligocene, and recent molecular studies that dated diversification of galliform crown-group taxa into the Middle Cretaceous are shown to be based on an incorrect interpretation of the fossil taxa used for molecular clock calibrations. Several taxa that occur in the Paleogene of Europe have a very different distribution than their closest extant relatives. The modern survivors of these Paleogene lineages are not evenly distributed over the continents, and especially the great number of taxa that are today restricted to South and Central America is noteworthy. The occurrence of stem-lineage representatives of many taxa that today have a restricted Southern Hemisphere distribution conflicts with recent hypotheses on a Cretaceous vicariant origin of these taxa, which were deduced from the geographical distribution of the basal crown-group members. PMID:16221327

Mayr, Gerald

2005-11-01

49

The fossil record of evolution: Data on diversification and extinction  

NASA Technical Reports Server (NTRS)

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.

Sepkoski, J. J., Jr.

1991-01-01

50

The fossil record of evolution: Data on diversification and extinction  

NASA Technical Reports Server (NTRS)

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.

Sepkoski, J. J., Jr.

1986-01-01

51

Oxygen-Collagen Priority and the Early Metazoan Fossil Record  

PubMed Central

The thesis is developed that a low oxygen level Precambrian atmosphere presented early-evolving metazoan organisms with physiological connective tissue priorities resulting from the important molecular oxygen requirements in the biosynthesis of collagen hydroxyproline. Shells, cuticles, and carapaces which are not mandatory metazoan prerequisites but which directly or indirectly demand substantial connective tissue collagen are oxygen expensive, low priority features. A marked increase in atmospheric oxygen level near the beginning of the Paleozoic would eliminate oxygen-collagen priorities simultaneously and on a world-wide basis in all metazoan stocks providing evolutionary pressure for enlarged musculatures and associated „hard parts.” This could explain the sudden presence in the fossil record of the early Cambrian of advanced and diversified metazoans, the earlier forms of which were essentially unpreservable.

Towe, Kenneth M.

1970-01-01

52

Primate evolution: Evidence from the fossil record, comparative morphology, and molecular biology  

Microsoft Academic Search

Primate evolution, Phylogeny, Stratophenetics, Cladistics, ABSTRACT Our understanding of primate evolution is ultimately based on patterns of phyletic relationship and morphological change documented in the fossil record. Stratophenetic interpretation of living and fossil primates yields an objective alternative to the arbitrary scala naturae assumed implic- itly in traditional comparative biology. Fossils provide an outline of primate history constraining comparative analyses

Philip D. Gingerich

1984-01-01

53

NGST: Exploring the Fossil Record of Galaxy Formation  

NASA Technical Reports Server (NTRS)

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".

Rich, R. Michael

1998-01-01

54

The fossil record and molecular clocks: basal radiations within the Neornithes  

Microsoft Academic Search

The fossil record of the extant clades of birds (Neornithes) is critical to understanding both the timing and pattern of the evolutionary divergences within this major verte- brate group. Interpretations of the fossil record have indicated that this radiation occurred in the aftermath of the Cretaceous-Tertiary (K-T) extinction event. However, the use of 'molecular clocks' to estimate the timing of

Gareth J. Dyke

2003-01-01

55

Applicability and resolving power of statistical tests for simultaneous extinction events in the fossil record  

Microsoft Academic Search

The recognition that past catastrophic events may have caused the simultaneous extinc- tion of many taxa has prompted the development of statistical tests to determine the compatibility of the fossil record with such scenarios. Statistical tests necessitate simplifying assumptions, the most significant of which are continuous (as opposed to discrete) data in the sampling of the fossil record and random

Jonathan L. Payne

2003-01-01

56

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

Microsoft Academic Search

Neotropical rainforests have a very poor fossil record, making hypotheses concerning their origins difficult to evaluate. Never- theless, some of their most important characteristics can be pre- served 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

S. L. Wing; Fabiany Herrera; C. A. Jaramillo; Carolina Gomez-Navarro; P. Wilf; Conrad C. Labandeira

2009-01-01

57

Micritic Peloids: Fossil Record of Biofilms Associated With Methane Seeps  

NASA Astrophysics Data System (ADS)

Biofilms of archaea and bacteria are found where reduced hydrocarbons seep upward to the seafloor. The process of oxidizing the methane coupled with the reduction of seawater sulfate increases the alkalinity in the localized area and promotes the precipitation of carbonate minerals. The biofilms and carbonate deposits are ubiquitous in the modern oceans and the geologic record of hydrocarbon seeps goes back well into the Paleozoic. However, the paleontologic record of the microbes responsible for the production of the carbonates is poorly constrained. The few examples comprise casts and molds of filaments and cocci, framboidal pyrite of assumed biological affinity, organic biomarkers (lipids, hopanoids), and microbialite. Volumetrically, these fossils are insignificant compared with the total bulk of seep carbonate. Research into Mesozoic and Cenozoic seep carbonates from California, Oregon, Colorado, and South Dakota has yielded a new recognition for ancient biofilms. Micrite—the most common lithotype of seeps globally—exists as both peloids and groundmass. Common peloids of micrite average 0.5 mm in diameter (range from 0.1 to 0.7 mm), incorporate some siliciclastic material, and have distinct margins. Opaque minerals, likely sulfides, occur throughout the peloids. The matrix surrounding the peloids is a similar micrite, though in some samples, the peloids are surrounded by cement. Diagenesis leads to blurring of the peloid margins until a homogenous micrite groundmass with scattered sulfide and siliciclastic grains results. Use of a white card helps to outline original peloids. Increased levels of diagenesis can lead to crystal coarsening and obliterate original textures. These peloids are likely fecal pellets. A second population of peloids occur that are smaller (0.05 to 0.10 mm), darker in color, and with more diffuse boundaries. There are generally no siliciclastic grains intermixed with these peloids. These peloids occur in millimeter-scale clusters and are cemented by calcite, indicating an original open porosity. The distinct pelsparite is often retained through diagenesis either as peloids or as diffuse dark micrite and is typically found at the margins of primary fabrics, where secondary crystal fans or botryoids nucleate. Where multiple generations of cement formed, the peloid area is distorted and forms a dark mantle between cements. These smaller peloids are thought to record degraded fragments of biofilms. ?13C isotopic analysis shows a depleted ratio, but indistinguishable from other primary fabrics. By differentiating micrite of fecal pellet origin from biofilm degredation, it will be feasible to quantify the amount of carbonate produced by each pathway, even with moderate diagenesis.

Shapiro, R. S.

2006-12-01

58

African-American Band Music and Recordings  

NSDL National Science Digital Library

By the late nineteenth and early twentieth century, a number of African American musicians and bandleaders had garnered the attention of the music-going public, and names such as Eubie Blake and Scott Joplin remain familiar to this very day. This rather fine online collection offered by the Library of Congress's Performing Arts division brings together a number of so-called "stock" arrangements for bands or small orchestras written by African Americans during that period. Visitors to the site should start by reading one of the four informative essays offered here, and then search through the actual music. There are over 206 pieces of music here, including "After the Cake Walk" from 1901 and the 1905 number, "Banana Man". Additionally, visitors can read any number of composer and bandleader biographies.

59

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

NASA Astrophysics Data System (ADS)

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.

McGowan, Alistair

2014-05-01

60

Using the fossil record to date splits in the primate tree  

Microsoft Academic Search

Inference about the divergence times of species has long been of interest to biol- ogists. Molecular evolutionists usually date such splits using DNA sequence data (1, 2), while paleontologists use a literal reading of the fossil record for this purpose (3). It is common that estimates derived from these approaches dier substantially, molecular estimates often being higher than the fossil

Simon Tavare; Richard Wilkinson

61

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)

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).

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

2013-05-01

62

Sedimentary records of carbonaceous particles from fossil fuel combustion  

Microsoft Academic Search

Carbonaceous particles produced by fossil fuel combustion can be found in considerable amounts in recent lake sediments. As these particles contain elemental carbon they are resistant to chemical decomposition and therefore both well preserved in sediments and possible to quantify. Sediment samples can be oxidized with H2O2 and digested with HF without the particles being destroyed. The pioneers in studying

Maria Wik; Ingemar Renberg; Judi Darley

1986-01-01

63

The fossil plant record and global climatic change  

Microsoft Academic Search

The generally sedentary character of terrestrial plants gives them a special dependence on their adaptation to the climate under which they live. As a consequence, plants normally show structural adaptations which are characteristic of their habitat, and fossil plants constitute particularly sensitive palaeoenvironmental indicators. In Quaternary pollen analysis the assumption is generally made that the species recognised as pollen had

William G. Chaloner; Jenny McElwain

1997-01-01

64

Old World Fossil Record of Modern-Type Hummingbirds  

Microsoft Academic Search

I report on tiny skeletons of stem-group hummingbirds from the early Oligocene of Germany that are of essentially modern appearance and exhibit morphological specializations toward nectarivory and hovering flight. These are the oldest fossils of modern-type hummingbirds, which had not previously been reported from the Old World. The findings demonstrate that early hummingbird evolution was not restricted to the New

Gerald Mayr

2004-01-01

65

Evolutionary Transitions in the Fossil Record of Terrestrial Hoofed Mammals  

Microsoft Academic Search

In the past few decades, many new discoveries have provided numerous transitional fossils that show the evolution of hoofed\\u000a mammals from their primitive ancestors. We can now document the origin of the odd-toed perissodactyls, their early evolution\\u000a when horses, brontotheres, rhinoceroses, and tapirs can barely be distinguished, and the subsequent evolution and radiation\\u000a of these groups into distinctive lineages with

Donald R. Prothero

2009-01-01

66

Cladistic analysis of extant and fossil African papionins using craniodental data.  

PubMed

This study examines African papionin phylogenetic history through a comprehensive cladistic analysis of extant and fossil craniodental morphology using both quantitative and qualitative characters. To account for the well-documented influence of allometry on the papionin skull, the general allometric coding method was applied to characters determined to be significantly affected by allometry. Results of the analyses suggest that Parapapio, Pliopapio, and Papio izodi are stem African papionin taxa. Crown Plio-Pleistocene African papionin taxa include Gorgopithecus, Lophocebus cf. albigena, Procercocebus, Soromandrillus (new genus defined herein) quadratirostris, and, most likely, Dinopithecus. Furthermore, S. quadratirostris is a member of a clade also containing Mandrillus, Cercocebus, and Procercocebus; ?Theropithecus baringensis is strongly supported as a primitive member of the genus Theropithecus; Gorgopithecus is closely related to Papio and Lophocebus; and Theropithecus is possibly the most primitive crown African papionin taxon. Finally, character transformation analyses identify a series of morphological transformations during the course of papionin evolution. The origin of crown African papionins is diagnosed, at least in part, by the appearance of definitive and well-developed male maxillary ridges and maxillary fossae. Among crown African papionins, Papio, Lophocebus, and Gorgopithecus are further united by the most extensive development of the maxillary fossae. The Soromandrillus/Mandrillus/Cercocebus/Procercocebus clade is diagnosed by upturned nuchal crests (especially in males), widely divergent temporal lines (especially in males), medially oriented maxillary ridges in males, medially oriented inferior petrous processes, and a tendency to enlarge the premolars as an adaptation for hard-object food processing. The adaptive origins of the genus Theropithecus appear associated with a diet requiring an increase in size of the temporalis, the optimal placement of occlusal forces onto the molar battery, and an increase in the life of the posterior dentition. This shift is associated with the evolution of distinctive morphological features such as the anterior union of the temporal lines, increased enamel infoldings on the premolars and molars, a reversed curve of Spee, and delayed molar eruption. PMID:23490264

Gilbert, Christopher C

2013-05-01

67

Fossils  

NSDL National Science Digital Library

4th Grade Science Standard 4: Students will understand how fossils are formed, where they may be found in Utah, and how they can be used to make inferences. DISCOVERING FOSSILS!!

81

New insights into the reading of Paleozoic plant fossil record discontinuities  

Microsoft Academic Search

Studying the discontinuity patterns of Paleozoic vascular plants provides a global vision of these key events from the multivariate methods viewpoint. Non-metric multidimensional scaling, detrended correspondence analysis and cluster analysis have been employed together with a set of diversity and abundance measures and an evaluation of the geologic constraints from the plant fossil record data. The results reveal four clear

Borja Cascales-Miñana

2011-01-01

82

Toward a new synthesis: Major evolutionary trends in the angiosperm fossil record  

Microsoft Academic Search

Angiosperm paleobotany has widened its horizons, incorporated new techniques, developed new databases, and accepted new questions that can now focus on the evolution of the group. The fossil record of early flowering plants is now playing an active role in addressing questions of angiosperm phylogeny, angiosperm origins, and angiosperm radiations. Three basic nodes of angiosperm radiations are identified: (i) the

David Dilcher

2000-01-01

83

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

Microsoft Academic Search

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,

Michal Kowalewski; Alfréd Dulai; Franz T. Fürsich

1998-01-01

84

THE QUALITY OF THE FOSSIL RECORD: Populations, Species, and Communities1  

Microsoft Academic Search

Paleontologists have always been concerned about the documentary quality of the fossil record, and this has also become an important issue for biologists, who increasingly look to accumulations of bones, shells, and plant material as possible ways to extend the time-frame of observation on species and community behaviors. Quantitative data on the postmortem behavior of organic remains in modern environments

Susan M. Kidwell; Karl W. Flessa

1996-01-01

85

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

PubMed

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

Meijer, Hanneke J M

2014-01-01

86

Orbital Climate Cycles in the Fossil Record: From Semidiurnal to Million-Year Biotic Responses  

NASA Astrophysics Data System (ADS)

Understanding climate change, its effect on terrestrial and marine ecosystems, and possible ways to prevent future climate disasters is a major challenge for society, involving specialists in climate science, terrestrial and marine ecology, paleontology, and sedimentary geology. One approach is to study the deep-time record, especially when the time involved in a particular climatic change can be calibrated. Cyclostratigraphy is a useful tool for this. Throughout Earth's history, different scales of orbital cycles have had significant impacts on atmosphere-ocean dynamics; these impacts are preserved in the ecological and sedimentary record. Most characterizations of these cycles are based on the sedimentary record. But fossil records of past biota, corresponding to individual organisms and communities, have proven very useful in cyclostratigraphic research: From semidiurnal cycles mainly recorded in fossil skeletons to million-year-scale cycles involving mass extinctions, various cases illustrate their worth. This article reviews the use of the fossil record to recognize several cycles, from ecological timescales (?1.0 yr to 10 kyr cycles; calendar and solar bands) to geological timescales (>10 kyr cycles; Milankovitch and galactic bands).

Rodríguez-Tovar, Francisco J.

2014-05-01

87

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

PubMed

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

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

2012-01-01

88

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

PubMed Central

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.

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

2012-01-01

89

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

USGS Publications Warehouse

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.

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

2006-01-01

90

First reliable record of a fossil species of Anthomyiidae (Diptera), with comments on the definition of recent and fossil clades in phylogenetic classification  

Microsoft Academic Search

All previous records of fossil Anthomyiidae are shown to be unsubstantiated. A female anthomyiid of a new genus and species is hereby described from a piece of Dominican amber (Upper Eocene–Oligocene). Character analysis suggests that the fossil,Coenosopsites poinarigen. & sp. nov., belongs to a Neotropical clade with two recent genera,PhaonanthoAlbuquerque andCoenosopsiaMalloch. Evidence for a sister-group relationship betweenCoenosopsites poinariand the genusCoenosopsiais

VERNER MICHELSEN

1996-01-01

91

Optimizing the Search for a Fossil Record of Ancient Martian Life  

Microsoft Academic Search

An important focus of the decade-long Mars Surveyor Program is the search for evidence of past or present life and or prebiotic chemistry. Based on studies of terrestrial analogs, the highest-priority sites for a martian fossil record include such lithologies as fine-grained, clay-rich detrital sediments, water-lain pyroclastics and evaporite deposits of terminal paleolake basins, the deposits of mineralizing springs (including

J. D. Farmer

1998-01-01

92

An Analytical Approach for Estimating Fossil Record and Diversification Events in Sharks, Skates and Rays  

PubMed Central

Background Modern selachians and their supposed sister group (hybodont sharks) have a long and successful evolutionary history. Yet, although selachian remains are considered relatively common in the fossil record in comparison with other marine vertebrates, little is known about the quality of their fossil record. Similarly, only a few works based on specific time intervals have attempted to identify major events that marked the evolutionary history of this group. Methodology/Principal Findings Phylogenetic hypotheses concerning modern selachians’ interrelationships are numerous but differ significantly and no consensus has been found. The aim of the present study is to take advantage of the range of recent phylogenetic hypotheses in order to assess the fit of the selachian fossil record to phylogenies, according to two different branching methods. Compilation of these data allowed the inference of an estimated range of diversity through time and evolutionary events that marked this group over the past 300 Ma are identified. Results indicate that with the exception of high taxonomic ranks (orders), the selachian fossil record is by far imperfect, particularly for generic and post-Triassic data. Timing and amplitude of the various identified events that marked the selachian evolutionary history are discussed. Conclusion/Significance Some identified diversity events were mentioned in previous works using alternative methods (Early Jurassic, mid-Cretaceous, K/T boundary and late Paleogene diversity drops), thus reinforcing the efficiency of the methodology presented here in inferring evolutionary events. Other events (Permian/Triassic, Early and Late Cretaceous diversifications; Triassic/Jurassic extinction) are newly identified. Relationships between these events and paleoenvironmental characteristics and other groups’ evolutionary history are proposed.

Guinot, Guillaume; Adnet, Sylvain; Cappetta, Henri

2012-01-01

93

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

PubMed

Recent palaeogenetic studies have demonstrated the occurrence of preserved ancient DNA (aDNA) in various types of fossilised material. Environmental aDNA sequences assigned to modern species have been recovered from marine sediments dating to the Pleistocene. However, the match between the aDNA and the fossil record still needs to be evaluated for the environmental DNA approaches to be fully exploited. Here, we focus on foraminifera in sediments up to one thousand years old retrieved from the Hornsund fjord (Svalbard). We compared the diversity of foraminiferal microfossil assemblages with the diversity of aDNA sequenced from subsurface sediment samples using both cloning and high-throughput sequencing (HTS). Our study shows that 57% of the species archived in the fossil record were also detected in the aDNA data. However, the relative abundance of aDNA sequence reads and fossil specimens differed considerably. We also found a limited match between the stratigraphic occurrence of some fossil species and their aDNA sequences, especially in the case of rare taxa. The aDNA data comprised a high proportion of non-fossilised monothalamous species, which are known to dominate in modern foraminiferal communities of the Svalbard region. Our results confirm the relevance of HTS for studying past micro-eukaryotic diversity and provide insight into its ability to reflect fossil assemblages. Palaeogenetic studies including aDNA analyses of non-fossilised groups expand the range of palaeoceanographical proxies and therefore may increase the accuracy of palaeoenvironmental reconstructions. PMID:24730667

Paw?owska, J; Lejzerowicz, F; Esling, P; Szczuci?ski, W; Zaj?czkowski, M; Pawlowski, J

2014-07-01

94

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  

Microsoft Academic Search

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

Charles R. Marshall

1995-01-01

95

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

PubMed Central

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.

Sanchez-Villagra, Marcelo R.

2010-01-01

96

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

PubMed

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

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

2009-11-01

97

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

PubMed

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. PMID:19296064

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

2009-06-01

98

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

NASA Astrophysics Data System (ADS)

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.

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

2009-06-01

99

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

PubMed Central

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

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

2009-01-01

100

New records of the Elasmobranch C. Megalodon (Agassiz) and a review of the genus Carcharodon in the New Zealand fossil record  

Microsoft Academic Search

New Zealand specimens of fossil shark teeth referable to Carcharodon megalodon (Agassiz) are discussed, including the first examples from the North Island. Previously published records are reviewed and revised, and the stratigraphic distribution of this species discussed. The New Zealand records of C. megalodon, which begin in the Lower Oligocene, provide some of the earliest world records for this species.

I. W. Keyes

1972-01-01

101

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)

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.

Marshall, Charles R.

1995-08-01

102

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

NASA Astrophysics Data System (ADS)

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.

Suarez, Marina B.; Passey, Benjamin H.

2014-09-01

103

First direct evidence of a vertebrate three-level trophic chain in the fossil record.  

PubMed

We describe the first known occurrence of a Permian shark specimen preserving two temnospondyl amphibians in its digestive tract as well as the remains of an acanthodian fish, which was ingested by one of the temnospondyls. This exceptional find provides for the first time direct evidence of a vertebrate three-level food chain in the fossil record with the simultaneous preservation of three trophic levels. Our analysis shows that small-sized Lower Permian xenacanthid sharks of the genus Triodus preyed on larval piscivorous amphibians. The recorded trophic interaction can be explained by the adaptation of certain xenacanthids to fully freshwater environments and the fact that in these same environments, large temnospondyls occupied the niche of modern crocodiles. This unique faunal association has not been documented after the Permian and Triassic. Therefore, this Palaeozoic three-level food chain provides strong and independent support for changes in aquatic trophic chain structures through time. PMID:17971323

Kriwet, Jürgen; Witzmann, Florian; Klug, Stefanie; Heidtke, Ulrich H J

2008-01-22

104

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

PubMed

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

Hipsley, Christy A; Müller, Johannes

2014-03-01

105

Brief communication: possible third molar impactions in the hominid fossil record.  

PubMed

Impacted third molars affect 15%-20% of modern Americans and Western Europeans. In contrast, third molar impactions have not been reported in the early hominid fossil record. It is uncertain whether the lack of reports reflects an absence of impactions or a failure to recognize them. This communication is intended to raise awareness of the possibility of impactions by describing the appearance of impacted teeth and by noting two possible instances of impaction in early hominids. Specifically, the mandibular third molars of the Sterkfontein specimen, STS52b (Australopithecus africanus), and the left maxillary third molar of the Lake Turkana specimen, KNM-WT 17400 (Australopithecus boisei), are positioned in a manner which suggests that they would not have erupted normally. Both specimens also exhibit strong crowding of the anterior dentition, providing further support for the view that these individuals lacked sufficient space for normal eruption of the third molars. Other published reports of dental crowding in the hominid fossil record are noted, and it is suggested that more attention be paid to dental impaction and dental crowding in hominid evolution. PMID:8372939

Gibson, K R; Calcagno, J M

1993-08-01

106

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

PubMed

We tested the hypothesis that early Pliocene Australopithecus anamensis was ancestral to A. afarensis by conducting a phylogenetic analysis of four temporally successive fossil samples assigned to these species (from earliest to latest: Kanapoi, Allia Bay, Laetoli, Hadar) using polarized character-state data from 20 morphological characters of the dentition and jaws. If the hypothesis that A. anamensis is ancestral to A. afarensis is true, then character-state changes between the temporally ordered site-samples should be congruent with hypothesized polarity transformations based on outgroup (African great ape) conditions. The most parsimonious reconstruction of character-state evolution suggests that each of the hominin OTUs shares apomorphies only with geologically younger OTUs, as predicted by the hypothesis of ancestry (tree length=31; Consistency Index=0.903). This concordance of stratigraphic and character-state data supports the idea that the A. anamensis and A. afarensis samples represent parts of an anagenetically evolving lineage, or evolutionary species. Each site-sample appears to capture a different point along this evolutionary trajectory. We discuss the implications of this conclusion for the taxonomy and adaptive evolution of these early-middle Pliocene hominins. PMID:16630646

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

2006-08-01

107

Testing hypotheses about tinkering in the fossil record: the case of the human skull.  

PubMed

Efforts to test hypotheses about small-scale shifts in development (tinkering) that can only be observed in the fossil record pose many challenges. Here we use the origin of modern human craniofacial form to explore a series of analytical steps with which to propose and test evolutionary developmental hypotheses about the basic modules of evolutionary change. Using factor and geometric morphometric analyses of craniofacial variation in modern humans, fossil hominids, and chimpanzee crania, we identify several key shifts in integration (defined as patterns of covariation that result from interactions between components of a system) among units of the cranium that underlie the unique shape of the modern human cranium. The results indicate that facial retraction in modern humans is largely a product of three derived changes: a relatively longer anterior cranial base, a more flexed cranial base angle, and a relatively shorter upper face. By applying the Atchley-Hall model of morphogenesis, we show that these shifts are most likely the result of changes in epigenetic interactions between the cranial base and both the brain and the face. Changes in the size of the skeletal precursors to these regions may also have played some role. This kind of phenotype-to-genotype approach is a useful and important complement to more standard genotype-to-phenotype approaches, and may help to identify candidate genes involved in the origin of modern human craniofacial form. PMID:15211687

Lieberman, Daniel E; Krovitz, Gail E; McBratney-Owen, Brandeis

2004-05-15

108

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

NASA Astrophysics Data System (ADS)

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.

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

2012-06-01

109

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

PubMed

Plants and herbivorous insects have dominated terrestrial ecosystems for over 300 million years. Uniquely in the fossil record, foliage with well-preserved insect damage offers abundant and diverse information both about producers and about ecological and sometimes taxonomic groups of consumers. These data are ideally suited to investigate food web response to environmental perturbations, and they represent an invaluable deep-time complement to neoecological studies of global change. Correlations between feeding diversity and temperature, between herbivory and leaf traits that are modulated by climate, and between insect diversity and plant diversity can all be investigated in deep time. To illustrate, I emphasize recent work on the time interval from the latest Cretaceous through the middle Eocene (67-47 million years ago (Ma)), including two significant events that affected life: the end-Cretaceous mass extinction (65.5 Ma) and its ensuing recovery; and globally warming temperatures across the Paleocene-Eocene boundary (55.8 Ma). Climatic effects predicted from neoecology generally hold true in these deep-time settings. Rising temperature is associated with increased herbivory in multiple studies, a result with major predictive importance for current global warming. Diverse floras are usually associated with diverse insect damage; however, recovery from the end-Cretaceous extinction reveals uncorrelated plant and insect diversity as food webs rebuilt chaotically from a drastically simplified state. Calibration studies from living forests are needed to improve interpretation of the fossil data. PMID:18331425

Wilf, P

2008-01-01

110

The Hominin Sites And Paleolakes Drilling Project: Using High Resolution Paleoclimate Records From African Lake Deposits To Interpret Human Evolution  

NASA Astrophysics Data System (ADS)

For many years paleoanthropologists and earth scientists have explored and debated the potential role of climate and environmental forcing in human evolution. Although no consensus has emerged as to the importance of climate history in understanding human origins, there is broad agreement that obtaining high quality records of paleoclimate is critical for evaluating any proposed relationships. Recent workshops on the subject have converged on the central role that scientific drilling could play in obtaining such records. Records with high continuity and resolution with implications for human evolution can be retrieved from marine or lacustrine sediments, and the latter can be obtained from both extant (ancient) lakes or by drilling lake beds now exposed on land. We report here on a new initiative to obtain drill core records from on-land sites in the East African Rift Valley region. Our objective is to recover continuous cores both directly from the paleolake deposits in the depocenters of basins where important hominin fossils or artifacts have been recovered, and from basins in close proximity to fossil and artifact sites. An initial on-land drilling campaign, using off-the-shelf technology will target five of the most important basins for hominin fossil and archaeological records in East Africa, collectively spanning the last ~4Ma (N. Awash R. and the Chew Bahir Basin in Ethiopia, and W. Turkana, Tugen Hills and the Olorgesailie/L. Magadi areas in Kenya). HSPDP work to date has involved collecting subsurface geophysical data, and combining this with outcrop, prior coring and basin geometry information to identify optimal drilling targets at each area. The overall project objective is to provide detailed paleoenvironmental records across a spatial and temporal range of sites that can address hypotheses of climate/human evolution relationships at local to regional scales, through a combination of core data collection and modeling efforts. In the long term, such records could be linked to more continuous (but also more expensive) marine or ancient lake drill cores that could provide master records of regional to global scale climate change in East Africa.

Cohen, A. S.; Arrowsmith, R.; Behrensmeyer, K.; Campisano, C. J.; Feibel, C. S.; Fisseha, S.; Johnson, R. A.; Kingston, J.; Kubsa, Z.; Lamb, H.; Mbua, E.; Olago, D.; Potts, R.; Renaut, R.; Schaebitz, F.; Tiercelin, J.; Trauth, M. H.; Woldegabriel, G. W.; Umer, M.

2009-12-01

111

Toward a new synthesis: Major evolutionary trends in the angiosperm fossil record  

PubMed Central

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

Dilcher, David

2000-01-01

112

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

PubMed

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. PMID:22794297

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

2012-06-01

113

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

NASA Technical Reports Server (NTRS)

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.

Peterson, Kevin J.; Butterfield, Nicholas J.

2005-01-01

114

Origin of the Eumetazoa: Testing ecological predictions of molecular clocks against the Proterozoic fossil record  

PubMed Central

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.

Peterson, Kevin J.; Butterfield, Nicholas J.

2005-01-01

115

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

PubMed Central

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

Huntley, John Warren; Kowalewski, Michal

2007-01-01

116

Atlantic Multidecadal Oscillation recorded in fossil corals during the last Interglacial  

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

117

Earliest fossil record of bacterial–cyanobacterial mat consortia: the early Silurian Passage Creek biota (440 Ma, Virginia, USA)  

Microsoft Academic Search

Cyanobacteria in terrestrial and aquatic habitats are frequently associated with heterotrophic bacteria, and such associations are most often metabolically interactive. Functionally, the members of such bacterial-cyanobacterial consortia benefit from diverse metabolic capabilities of their associates, thus exceeding the sum of their parts. Such associations may have been just as ubiquitous in the past, but the fossil record has not produced

A. M. F. TOMESCU; R. HONEGGER; G. W. ROTHWELL

2008-01-01

118

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

ERIC Educational Resources Information Center

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)

Dodick, Jeff; Orion, Nir

2003-01-01

119

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

PubMed Central

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.

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

2012-01-01

120

Using the fossil record to estimate the age of the last common ancestor of extant primates  

Microsoft Academic Search

Divergence times estimated from molecular data often considerably predate the earliest known fossil representatives of the groups studied. For the order Primates, molecular data calibrated with various external fossil dates uniformly suggest a mid-Cretaceous divergence from other placental mammals, some 90 million years (Myr) ago, whereas the oldest known fossil primates are from the basal Eocene epoch (54-55Myr ago). The

Simon Tavaré; Charles R. Marshall; Oliver Will; Christophe Soligo; Robert D. Martin

2002-01-01

121

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)

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.

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

2014-05-01

122

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

PubMed

The increase in trace fossil diversity across the Neoproterozoic-Cambrian boundary often is presented in terms of tabulations of ichnogenera. However, a clearer picture of the increase in diversity and complexity can be reached by combining trace fossils into broad groups defined both on morphology and interpretation. This also focuses attention on looking for similarites between Neoproterozoic and Cambrian trace fossils. Siliciclastic sediments of the Neoproterozoic preserve elongate tubular organisms and structures of probable algal origin, many of which are very similar to trace fossils. Such enigmatic structures include Palaeopascichnus and Yelovichnus, previously thought to be trace fossils in the form of tight meanders.A preliminary two or tripartite terminal Neoproterozoic trace fossil zonation can be be recognized. Possibly the earliest trace fossils are short unbranched forms, probably younger than about 560 Ma. Typical Neoproterozoic trace fossils are unbranched and essentially horizontal forms found associated with diverse assemblages of Ediacaran organisms. In sections younger than about 550 Ma a modest increase in trace fossil diversity occurs, including the appearance of rare three-dimensional burrow systems (treptichnids), and traces with a three-lobed lower surfaces. PMID:21680425

Jensen, Sören

2003-02-01

123

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

PubMed

The discipline-wide effort to database the fossil record at the occurrence level has made it possible to estimate marine invertebrate extinction and origination rates with much greater accuracy. The new data show that two biotic mechanisms have hastened recoveries from mass extinctions and confined diversity to a relatively narrow range over the past 500 million years (Myr). First, a drop in diversity of any size correlates with low extinction rates immediately afterward, so much so that extinction would almost come to a halt if diversity dropped by 90%. Second, very high extinction rates are followed by equally high origination rates. The two relationships predict that the rebound from the current mass extinction will take at least 10 Myr, and perhaps 40 Myr if it rivals the Permo-Triassic catastrophe. Regardless, any large event will result in a dramatic ecological and taxonomic restructuring of the biosphere. The data also confirm that extinction and origination rates both declined through the Phanerozoic and that several extinctions in addition to the Permo-Triassic event were particularly severe. However, the trend may be driven by taxonomic biases and the rates vary in accord with a simple log normal distribution, so there is no sharp distinction between background and mass extinctions. Furthermore, the lack of any significant autocorrelation in the data is inconsistent with macroevolutionary theories of periodicity or self-organized criticality. PMID:18695240

Alroy, John

2008-08-12

124

El Niño in the Eocene greenhouse recorded by fossil bivalves and wood from Antarctica  

NASA Astrophysics Data System (ADS)

Quasi-periodic variation in sea-surface temperature, precipitation, and sea-level pressure in the equatorial Pacific known as the El Niño - Southern Oscillation (ENSO) is an important mode of interannual variability in global climate. A collapse of the tropical Pacific onto a state resembling a so-called ‘permanent El Niño’, with a preferentially warmed eastern equatorial Pacific, flatter thermocline, and reduced interannual variability, in a warmer world is predicted by prevailing ENSO theory. If correct, future warming will be accompanied by a shift toward persistent conditions resembling El Niño years today, with major implications for global hydrological cycles and consequent impacts on socioeconomic and ecological systems. However, much uncertainty remains about how interannual variability will be affected. Here, we present multi-annual records of climate derived from growth increment widths in fossil bivalves and co-occurring driftwood from the Antarctic peninsula that demonstrate significant variability in the quasi-biennial and 3-6 year bands consistent with ENSO, despite early Eocene (˜50 Mya) greenhouse conditions with global average temperature ˜10 degrees higher than today. A coupled climate model suggests an ENSO signal and teleconnections to this region during the Eocene, much like today. The presence of ENSO variation during this markedly warmer interval argues for the persistence of robust interannual variability in our future greenhouse world.

Ivany, Linda C.; Brey, Thomas; Huber, Matthew; Buick, Devin P.; Schöne, Bernd R.

2011-08-01

125

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

USGS Publications Warehouse

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

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

2005-01-01

126

A 300 kyr high-resolution aridity record of the North African continent  

NASA Astrophysics Data System (ADS)

New oxygen isotope data and a high-resolution carbonate record of a core from the northwest African margin are presented, in combination with geochemical (Zr/Rb ratio, Al, Ba, organic carbon, and biogenic opal fluxes) and sedimentological (median grain size) parameters, to show variations in African continental aridity, wind strength, and upwelling productivity. The carbonate record is diluted by the supply of aeolian dust from the arid Saharan region of north Africa and is seen to vary with a characteristic sawtooth pattern indicating rapid increases in dust flux followed by gradual declines. Spectral analysis of the carbonate profile and comparison with SPECMAP (stacked oxygen isotope) and ETP (solar radiation) profiles shows that the precessional (23 kyr) insolation-induced African climate system is decoupled from global (ice volume) climate changes operating on a 100 kyr frequency. Detailed studies of glacial terminations I, II, and III confirm the presence of rapid, short timescale climatic variations (in aridity).

Matthewson, A. P.; Shimmield, G. B.; Kroon, D.; Fallick, A. E.

1995-06-01

127

Spatio-temporal changes in forest composition inferred from fossil pollen records in the Upper Midwestern USA  

NASA Astrophysics Data System (ADS)

Understanding compositional changes in vegetation over the common era 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. To reconstruct vegetation composition, we build a Bayesian model for the Upper Midwestern USA that links vegetation composition to fossil pollen data via a dispersal model. We estimate the relationship between vegetation and pollen for the settlement era using United States Public Land Survey data and a network of pollen records. Using parameter estimates from the settlement era, we use the fossil pollen proxy records to estimate species distributions and relative abundances over the last 2500 years. Resulting composition and abundance estimates will be used to improve the forecasting capabilities of ecosystem models.

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

2013-12-01

128

Inferring ecological disturbance in the fossil record: A case study from the late Oligocene of Ethiopia  

Microsoft Academic Search

Environmental disturbances profoundly impact the structure, composition, and diversity of modern forest communities. A review of modern studies demonstrates that important characteristics used to describe fossil angiosperm assemblages, including leaf margin type, plant form, plant diversity, insect herbivore diversity and specialization, and variation in herbivory among plant species, differ between early and late successional forests. Therefore, sequences of fossil floras

Ellen D. Currano; Bonnie F. Jacobs; Aaron D. Pan; Neil J. Tabor

2011-01-01

129

A 30,000 Year Molecular Fossil Record of Ecological Change From Lake Titicaca, South America  

NASA Astrophysics Data System (ADS)

Changing downcore distributions of hydrocarbon, long-chain alkenone, and sterol lipid molecular fossils from an 8.1 m piston core taken from Lake Titicaca, South America (152 m depth, 16° S, 69° W) reveal a record of significant paleoecological change in the lake for the past ~30,000 years. Trends in lipid abundances and distributions follow previously reported changes in lake water balance and the climate of the northern Altiplano region of Bolivia and Peru over this time period. Hydrocarbon fractions are characterized by a mixture of normal alkanes and alkenes. Most samples have greatest abundances of odd-numbered C21-C25 n-alkanes and alkenes and smaller amounts of longer chain length and even numbered compounds. The ratio of C21 to C29 n-alkanes and the abundance of C25 alkenes follow similar downcore trends with highest values during periods of higher lake level (the last glacial interval and the late Holocene) and lowest values during the mid-Holocene when lake-level was lowered by as much as 90 m from the present level in response to an extended drought. Normal alkanes with chain length >C29 are consistently in low abundance and indicate little terrestrial input into Lake Titicaca throughout the record. Long-chain alkenones (C37-C40), indicators of haptophyte presence that have been used to determine paleotemperatures in marine settings are highly abundant in many mid-Holocene samples when lake-level was especially low, and nearly absent during the last glacial interval and in the late Holocene when lake-level was relatively high. Long-chain alkenones have rarely been reported in lake records, and their presence indicates the past importance of an algal species (from the phylum Chrysophyta) that is not common or absent in the modern lake. The downcore abundance of dinosterol and other 4?-methyl sterols diagnostic to dinoflagellates is also correlated with lake-level change and dinosterol is particularly abundant during the mid-Holocene. Changes in all lipid fractions indicate the algal response to salinity, temperature, and other physical and chemical changes in Lake Titicaca since the late Pleistocene. The great abundance of dinosterol and long-chain alkenones during the mid-Holocene indicate bloom conditions for a few phytoplankton species at this time.

Theissen, K. M.; Zinniker, D. A.; Moldowan, J. M.; Dunbar, R. B.

2002-12-01

130

Decay of vertebrate characters in hagfish and lamprey (Cyclostomata) and the implications for the vertebrate fossil record.  

PubMed

The timing and sequence of events underlying the origin and early evolution of vertebrates remains poorly understood. The palaeontological evidence should shed light on these issues, but difficulties in interpretation of the non-biomineralized fossil record make this problematic. Here we present an experimental analysis of decay of vertebrate characters based on the extant jawless vertebrates (Lampetra and Myxine). This provides a framework for the interpretation of the anatomy of soft-bodied fossil vertebrates and putative cyclostomes, and a context for reading the fossil record of non-biomineralized vertebrate characters. Decay results in transformation and non-random loss of characters. In both lamprey and hagfish, different types of cartilage decay at different rates, resulting in taphonomic bias towards loss of 'soft' cartilages containing vertebrate-specific Col2?1 extracellular matrix proteins; phylogenetically informative soft-tissue characters decay before more plesiomorphic characters. As such, synapomorphic decay bias, previously recognized in early chordates, is more pervasive, and needs to be taken into account when interpreting the anatomy of any non-biomineralized fossil vertebrate, such as Haikouichthys, Mayomyzon and Hardistiella. PMID:20947532

Sansom, Robert S; Gabbott, Sarah E; Purnell, Mark A

2011-04-22

131

Earliest fossil record of bacterial-cyanobacterial mat consortia: the early Silurian Passage Creek biota (440 Ma, Virginia, USA).  

PubMed

Cyanobacteria in terrestrial and aquatic habitats are frequently associated with heterotrophic bacteria, and such associations are most often metabolically interactive. Functionally, the members of such bacterial-cyanobacterial consortia benefit from diverse metabolic capabilities of their associates, thus exceeding the sum of their parts. Such associations may have been just as ubiquitous in the past, but the fossil record has not produced any direct evidence for such associations to date. In this paper, we document fossil bacteria associated with a macrophytic cyanobacterial mat in the early Silurian (Llandovery) Massanutten Sandstone of Virginia, USA. Both the bacterial and the cyanobacterial cells are preserved by mineral replacement (pyrite subsequently replaced by iron oxyhydroxides) within an amorphous carbonaceous matrix which represents the common exopolysaccharide investment of the cyanobacterial colony. The bacteria are rod-shaped, over 370 nm long and 100 nm in diameter, and occur both as isolated cells and as short filaments. This occurrence represents the oldest fossil evidence for bacterial-cyanobacterial associations, documenting that such consortia were present 440 Ma ago, and revealing the potential for them to be recognized deeper in the fossil record. PMID:18380874

Tomescu, A M F; Honegger, R; Rothwell, G W

2008-03-01

132

Faunal assemblage seriation of southern African Pliocene and Pleistocene fossil deposits.  

PubMed

Fossil assemblages from the Pliocene and Pleistocene of southern Africa were seriated in order to give a better idea of their relative chronology. Time-sensitive mammals were selected for calculation of the Faunal Resemblance Index among 17 site units. On the basis of a logistical seriation and subsequent site analysis, the following sequence of sites was deemed most probable: Makapansgat Member 3, Makapansgat Member 4, Taung Dart deposits, Sterkfontein Member 4 and Taung Hrdlicka deposits, Sterkfontein Member 5 (in part) and Kromdraai B, Kromdraai A and Swartkrans Member 1, Swartkrans Member 2, Swartkrans Member 3, Plovers Lake, Cornelia, Elandsfontein Main Site, Cave of Hearths Acheulian levels, Florisbad and Equus Cave and Klasies River Mouth. PMID:7785723

McKee, J K; Thackeray, J F; Berger, L R

1995-03-01

133

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

PubMed

Well-preserved fossils of pivotal early bird and nonavian theropod species have provided unequivocal evidence for feathers and/or downlike integuments. Recent studies have reconstructed color on the basis of melanosome structure; however, the chemistry of these proposed melanosomes has remained unknown. We applied synchrotron x-ray techniques to several fossil and extant organisms, including Confuciusornis sanctus, in order to map and characterize possible chemical residues of melanin pigments. Results show that trace metals, such as copper, are present in fossils as organometallic compounds most likely derived from original eumelanin. The distribution of these compounds provides a long-lived biomarker of melanin presence and density within a range of fossilized organisms. Metal zoning patterns may be preserved long after melanosome structures have been destroyed. PMID:21719643

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

2011-09-16

134

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

National Technical Information Service (NTIS)

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. Preliminary study of late-glacial fossil ostracodes from 'marsh deposi...

R. M. Forester A. J. Smith

1995-01-01

135

Trace Metals as Biomarkers for Eumelanin Pigment in the Fossil Record  

Microsoft Academic Search

Well-preserved fossils of pivotal early bird and nonavian theropod species have provided unequivocal evidence for feathers and\\/or downlike integuments. Recent studies have reconstructed color on the basis of melanosome structure; however, the chemistry of these proposed melanosomes has remained unknown. We applied synchrotron x-ray techniques to several fossil and extant organisms, including Confuciusornis sanctus, in order to map and characterize

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

2011-01-01

136

A canine tooth from the Siwaliks: first recorded discovery of a fossil ape?  

Microsoft Academic Search

Archival research reveals that it is highly probably that the first discovery of a fossil ape was made by Hugh Falconer and\\u000a his associates in the 1830s during surveys of Neogene deposits in the Siwalik hills of British Colonial India. However, priority\\u000a is commonly awarded to Edouard Lartet who, in 1837, brought to light a fossil primate specimen from the

Kenneth A. R. Kennedy; Russell L. Ciochon

1999-01-01

137

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

PubMed Central

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.

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

2007-01-01

138

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

Microsoft Academic Search

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 S7Sr\\/86Sr value in their bones

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

1992-01-01

139

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

140

Fossil Excavation  

NSDL National Science Digital Library

In this activity students excavate their own fossil from a teacher-prepared "rock biscuit". Students chip away the matrix with wooden stirring rods (or sharpened wooden dowels) and glue brushes. In each biscuit is a genuine fossil such as a shark's tooth. The activity is designed to be the culmination of a lesson about fossil collecting, the importance of recording data, and different preparation methods.

141

Fossil DNA as a Recorder of Ancient Microbial Communities and Palaeoenvironments  

Microsoft Academic Search

Fossilized organic components provide an archive of ancient aquatic microbial communities and, hence, can be used to reconstruct climate-induced environmental changes and their impacts on biodiversity. However, the interpretation of these data is complicated by the limited source specificity of some traditional biomarkers, such as lipids and pigments. The ultimate biomarkers are genes encoding for ribosomal RNA (rDNA), which sequences

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

2005-01-01

142

Recognition of vertebrate egg abnormalities in the Upper Cretaceous fossil record  

Microsoft Academic Search

In fossil vertebrate eggs, the most commonly reported abnormality consists of an unusually thick shell with one or more superimposed eggshell layers. Although rare, taxonomically referable abnormal specimens provide a more reliable basis for inferences regarding reproductive biology of extinct taxa. Eggshell abnormalities recognized in a Cretaceous turtle and three dinosaurs (hadrosaur, sauropod, theropod) are assigned to these taxa base

Frankie D. Jackson; James G. Schmitt

2008-01-01

143

Clumping behavior as a strategy against drilling predation: Implications for the fossil record  

Microsoft Academic Search

Drilling gastropod predators are of particular interest to paleontologists, because predatory drill-holes in marine invertebrates serve as one of the rare sources of data for the study of ancient predator-prey interactions. Modern laboratory studies are an important part of predation research providing valuable ecological insight and constraining fossil evidence and interpretations. Previous studies have shown that mussels use clumping behavior

Michelle M. Casey; Devapriya Chattopadhyay

2008-01-01

144

Paleoredox variations in ancient oceans recorded by rare earth elements in fossil apatite  

Microsoft Academic Search

Rare earth element concentrations in biogenic apatite of conodonts, fish debris and inarticulate brachiopods were determined in over 200 samples from Cambrian to modern sediments. Tests for experimental bias caused by the chemicals used to separate fossils from the rock matrix and for interlaboratory, interexperiment or interspecies related variations clearly show that no resolvable fractionation of REE occurs. Incorporation of

Judith Wright; Hans Schrader; William T. Holser

1987-01-01

145

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

Microsoft Academic Search

We tested the hypothesis that early Pliocene Australopithecus anamensis was ancestral to A. afarensis by conducting a phylogenetic analysis of four temporally successive fossil samples assigned to these species (from earliest to latest: Kanapoi, Allia Bay, Laetoli, Hadar) using polarized character-state data from 20 morphological characters of the dentition and jaws. If the hypothesis that A. anamensis is ancestral to

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

2006-01-01

146

Cranial shape in fruit, nectar, and exudate feeders: Implications for interpreting the fossil record  

Microsoft Academic Search

At least 29 species of fossil primates have been referred to fruit, nectar, and\\/or exudate feeding dietary niches. Many studies have detailed the morphological correlates of fruit feeding in comparison to insectivory and folivory. In contrast, few studies have sought to differentiate the morphological correlates of fruit feeding from those of nectar and exudate feeding. This study investigates the differences

Elizabeth R. Dumont

1997-01-01

147

Molecular Fossil Record of Elevated Methane Levels in Late Pleistocene Coastal Waters  

Microsoft Academic Search

Accumulating evidence suggests that methane has been released episodically from hydrates trapped in sea floor sediments during many intervals of rapid climate warming. Here we show that sediments from the Santa Barbara Basin deposited during warm intervals in the last glacial period contain molecular fossils that are diagnostic of aerobic and anaerobic methanotrophs. Sediment intervals with high abundances of these

Kai-Uwe Hinrichs; Laura R. Hmelo; Sean P. Sylva

2003-01-01

148

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

PubMed Central

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.

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

2012-01-01

149

Fossil Horses  

Microsoft Academic Search

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,

Bruce J. MacFadden

1994-01-01

150

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

PubMed

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

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

2010-05-01

151

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

Microsoft Academic Search

THEORIES that explain the extinctions characterizing the Cretaceous\\/Tertiary (K\\/T) boundary1-3 need to be tested by analyses of thoroughly sampled biotas. Palynological studies are the primary means for stratigraphic placement of the terrestrial boundary and for estimates of plant extinction4-12, but have not been combined with quantitative analyses of fossil leaves (megaflora). Megafloral studies complement palynology by representing local floras with

Kirk R. Johnson; Douglas J. Nichols; Moses Attrep; Charles J. Orth

1989-01-01

152

Basic features of gymnosperm systematics and phylogeny as evidenced by the fossil record  

Microsoft Academic Search

This paper introduces an integrated system of morphological concepts for gymnosperm fructifications, which does not lean upon\\u000a any system existing for other higher plants. Comparative analytical treatment of all available characters of the most thoroughly\\u000a studied fossil genera provided the foundation for an ordered ranking of congregations, each unit being assigned to the status\\u000a of families, orders and classes. The

Sergei V. Meyen

1984-01-01

153

Holocene records of Western Pacific Warm Pool paleoclimate using fossil long-lived giant Tridacna from Papua New Guinea  

NASA Astrophysics Data System (ADS)

The Huon Peninsula is located in the heart of the Western Pacific Warm pool (WPWP), an area which plays a key role in the dynamics of El Niño Southern Oscillation (ENSO). This region experiences exceptional tectonic uplift rates of 3 to 4 meters per 1000 years. Fossil reefs are thus subaerially exposed enabling the sampling of climatic archives such as giant long-lived Tridacna species. The Holocene reef covers the period from around 6,000 cal. BP, when it first emerged to around 9,000 cal. BP depending on the location along the coast and the local uplift rates. We collected 14 well-preserved fossil Tridacna spp. found in their growth position and one modern Tridacna gigas. Shells of Tridacna spp. reveal yearly growth bands which can be 1) subsampled to derive 20-50 years of seasonally resolved paleoclimate records and 2) bulk sampled to obtain information on the average climatic conditions. We measured the aragonite ?18O which reflects both water temperature and water ?18Ow in which they grew. ?18Ow in turn reflects changes in global sea level and local evaporation/precipitation balance at the time of deposition. The modern specimen provides a 22 year record from 2002 to 1980 and has an average ?18O values around -1.2‰ and large decadal ?18O variations of around 1‰ amplitude associated with major ENSO events. Fossil samples have an average bulk ?18O more positive -0.6 to -0.8‰. We extracted the sea level component and the residual ?18O is up to 0.5‰ more positive compared to modern ?18O values. A seasonally resolved record of a fossil shell 8,000 cal. BP shows that the decadal variability of the ?18O record is of much smaller amplitude around 0.5‰. Studies of modern climate show that temperature and precipitation increase and decrease together on seasonal and inter-annual timescales in this area, thus, our results suggest that the average state of the WPWP was colder and drier between 9 and 6,000 cal BP compared to modern conditions.

Elliot, M. M.; Welsh, K.; Yokoyama, Y.; McCulloch, M.; Chappell, J.

2006-12-01

154

Fossil Hunt  

NSDL National Science Digital Library

This activity is structured to allow students to experience one of the largest puzzles in science, the fossil record. Students will be encouraged to ask questions about the nature of science as they experience a simulated fossil hunt. They will be asked to reconstruct a book that has been literally destroyed, just as the fossil record has been changed by billions of years of geological processes. They will gain insight into the academic processes of piecing together bits and pieces of information. This site includes background information, a list of materials, introduction and description of the activity, and suggestions for evaluation.

155

Vegetation Response to Climate Change in Alaska: Examples From the Fossil Record  

USGS Publications Warehouse

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

Ager, Thomas A.

2007-01-01

156

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

NASA Astrophysics Data System (ADS)

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

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

2005-08-01

157

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

PubMed Central

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.

Boyce, C. Kevin; Zwieniecki, Maciej A.

2012-01-01

158

Abundance Is Not Enough: The Need for Multiple Lines of Evidence in Testing for Ecological Stability in the Fossil Record  

PubMed Central

The fossil record is the only source of information on the long-term dynamics of species assemblages. Here we assess the degree of ecological stability of the epifaunal pterioid bivalve assemblage (EPBA), which is part of the Middle Devonian Hamilton fauna of New York—the type example of the pattern of coordinated stasis, in which long intervals of faunal persistence are terminated by turnover events induced by environmental change. Previous studies have used changes in abundance structure within specific biofacies as evidence for a lack of ecological stability of the Hamilton fauna. By comparing data on relative abundance, body size, and predation, indexed as the frequency of unsuccessful shell-crushing attacks, of the EPBA, we show that abundance structure varied through time, but body-size structure and predation pressure remained relatively stable. We suggest that the energetic set-up of the Hamilton fauna's food web was able to accommodate changes in species attributes, such as fluctuating prey abundances. Ecological redundancy in prey resources, adaptive foraging of shell-crushing predators (arising from predator behavioral or adaptive switching in prey selection in response to changing prey abundances), and allometric scaling of predator-prey interactions are discussed as potential stabilizing factors contributing to the persistence of the Hamilton fauna's EPBA. Our study underscores the value and importance of multiple lines of evidence in tests of ecological stability in the fossil record.

Handley, John C.; Brett, Carlton E.

2013-01-01

159

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

USGS Publications Warehouse

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.

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

1998-01-01

160

Terrestrial pollen record of recent land-use changes around nine North African lakes in the CASSARINA Project  

Microsoft Academic Search

Pollen analyses and related plant macrofossil records are presented from short cores from nine North African lakes in the EU-funded CASSARINA project. Terrestrial pollen reflects human impact on the vegetation and landscape over the last 150–100 years. Pollen changes, aided by radiometric dating, could be correlated with historical developments. The chronology of the landscape changes date other biostratigraphical records reflecting

Sylvia M. Peglar; Hilary H. Birks; H. J. B. Birks; A. A. Fathi; R. J. Flower; M. M. Kraïem; S. T. Patrick; M. Ramdani

2001-01-01

161

Fossil steroids record the appearance of Demospongiae during the Cryogenian period  

Microsoft Academic Search

The Neoproterozoic era (1,000-542Myr 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 C30 sterols produced by marine demosponges, record the presence of Metazoa in the geological record before the end of the Marinoan glaciation (~635Myr ago).

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

2009-01-01

162

KZai 02 pollen record, an insight into West African monsoon fluctuations during the Last Climatic Cycle  

NASA Astrophysics Data System (ADS)

Climate of the circum-Atlantic intertropical zone is driven by the ocean/atmosphere dynamics in response to variations of yearly insolation. These latitudes correspond to the convergence of the Hadley cells expressed on earth surface by intense trade winds and in lower troposphere by the African easterly jet making the edges of the intertropical zone relatively dry, while humidity is concentrated near the Equator. This phenomenon generates a precipitation front, known as the InterTropical Convergence Zone (ITCZ), the oscillations of which regulate the latitudinal vegetation distribution. Pollen record of core KZai 02 (Guinea Gulf) allows high resolution reconstruction of variations of past ecosystems over Central Africa during the Last Climatic Cycle. Plant taxa recorded in pollen analyses have been clustered according to their ecological requirements and African phytogeography. Fluctuations of these groups inform on precipitation intensity and their distribution during the last 130 ka. During Glacials, an open vegetation made of Cyperaceae marshes developed in the central Zaire/Congo Basin, surrounded by savannah on borders and afromontane forests on reliefs. Composition and distribution of vegetation indicate a decrease in monsoon activity and the strengthening of the precipitation front in the center of the basin. Interglacial phases are characterized by rain forest expansion over Central Africa in response to a precipitation enhancement associated with a northward shift of the rainfall front. Replacement of afromontane forest and marsh ecosystems by savannah then lowland pioneering, warm-temperate and rain forests characterized glacial/interglacial transitions. This succession suggests the increasing influence of at least two climatic parameters: the water availability and temperature and/or CO2 fluctuation. Spectral analysis applied to vegetation groups evidences the forcing of insolation, mainly driven by precession, on the West African monsoon system. Sub-Milankovitch periods are also revealed and are associated to the Heinrich and Dansgaard/Oeschger events.

Dalibard, M.; Popescu, S.; Maley, J.; Suc, J.

2012-12-01

163

Biophysical constraints on the origin of leaves inferred from the fossil record  

PubMed Central

The molecular tool kit for producing flat-bladed photosynthetic structures evolved in marine and terrestrial plants during the middle Paleozoic, but it took a further 20 million years before leaves suddenly spread throughout land floras. This delay has long been difficult to explain, given the apparent advantage of leaves for photosynthetic primary production. Theory and experiments predict that exceptionally high atmospheric CO2 levels in the middle Paleozoic delayed the origin of leaves by restricting stomatal development. This would have limited evaporative cooling, leading to lethal overheating of leaves absorbing large quantities of solar energy. Here we test the central prediction of this argument with a morphometric analysis of 300 plant fossils from major European collections. We show a 25-fold enlargement of leaf blades in two phylogenetically independent clades as atmospheric CO2 levels fell during the late Paleozoic. Furthermore, preliminary data suggest that the first abrupt increase in leaf size was accompanied by an 8-fold rise in stomatal density. These evolutionary patterns support the relaxation of biophysical constraints on leaf area predicted by theory and point to a significant role for CO2 in plant evolution.

Osborne, C. P.; Beerling, D. J.; Lomax, B. H.; Chaloner, W. G.

2004-01-01

164

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

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

165

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

PubMed

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. PMID:24675482

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

2014-01-01

166

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

USGS Publications Warehouse

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

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

1989-01-01

167

An annual fossil record of production, planktivory and piscivory during whole-lake manipulations  

Microsoft Academic Search

Annual and subannual paleolimnological records of pigments and zooplankton were used to analyze three whole-lake manipulations. The relative abundance of cladoceran remains in recent seasonal laminae was significantly correlated with the relative abundance of species in the plankton (r2=0.59,PPhoxinus eos, P. neogaeus, Umbra limi) by largemouth bass (Micropterus salmoides) allowed large herbivores (Daphnia pulex) and invertebrate predators (Chaoborus punctipennis) to

Peter R. Leavitt; Patricia R. Sanford; Stephen R. Carpenter; James F. Kitchell

1994-01-01

168

The Fidelity of the Fossil Record: Using Preservational Characteristics of Fossils within an Assemblage to Interpret the Relative State of Spatial and Temporal Fidelity  

NSDL National Science Digital Library

This exercise introduces students to the concept of temporal and spatial fidelity, to the different types of fossil assemblages, and how the taphonomic characteristics of an assemblage can be used to assess the relative state of fidelity. The exercise is suitable when introducing the discipline of taphonomy, typically covered near the beginning of a course in paleontology or paleobiology. Because most universities lack appropriate collections of fossils, particularly collections from assemblages with unusual states of preservation, this exercise provides digital images of fossils from a Middle Devonian obrution deposit (or smothered assemblage) found within thin bedded limestones of the Hamilton Group of western New York State. Students are asked to make predictions concerning the relative states of preservation likely to be found in life assemblages (biocoenoses) and death assemblages (thanatocoenoses and taphocoenoses). A biocoenosis is an assemblage that contains virtually all of the species that existed when the community was alive. A thanatocoenosis is a death assemblage where all the fossils represented existed within the community, but not all community members are present as fossils (species are missing). Finally, a taphocoenosis is an assemblage where not all species present in the community are represented as fossils, and not all the fossil species within the assemblage lived in the community (i.e., there is temporal or spatial mixing). Students are then presented with a PowerPoint presentation of the Hamilton Group strata, the limestones possessing the unusual fossil assemblage, and finally images of fossils with their preservational characteristics highlighted. The slides are annotated to provide observational descriptions and not interpretations. The exercise works best with students working in small groups with each group supplied with a laptop containing the PowerPoint presentation. Finally, each group is asked to interpret the assemblage type represented (bio-, thanato-, or taphocoenosis) and present a cogent argument citing supportive preservational evidence. (Because the assemblage is created through obrution, the assemblage is correctly interpreted as a thanatocoenosis â the fossils present were found within the community with many individuals preserved in life position and with behaviors represented; not all species in the community, however, are preserved as fossils.) If time allows, students could be asked to make predictions concerning the preservational characteristics expected for each assemblage type in advance of the exercise. (A table is attached that I use to help frame their predictions.) Their interpretation and evidential argument could be written up as a short essay. I've asked students to do this individually and other times as a collaborative writing assignment for the group. Once the correct assemblage interpretation is revealed to the students, they could be asked to speculate about the mechanism leading to this style of preservation (i.e., recognizing it as an obrution deposit). A few figures are provided that are helpful in explaining obrution. The following files are uploaded as supportive teaching materials: 1. Discussion Assemblage Types.doc: Notes to guide a discussion to acquire predictions for taphonomic characteristics for each assemblage type. 2. Fossil Assemblages Exercise.ppt: PowerPoint presentation that describes the unknown fossil assemblage. 3. Exercise Assemblage Fidelity Assignment.doc: The handout provided students describing the exercise. 4. Obrution Deposits.ppt: PowerPoint presentation explaining obrution deposits.

Savarese, Michael

169

"Fossil" bright layer recorded in the low-P/T metamorphic rocks  

NASA Astrophysics Data System (ADS)

The "fossil" (geological time) bright layer was recognized in the Cretaceous low-P/T Ryoke metamorphic rocks in the Iwakuni-Yanai area, southwest Japan. Silicified pelitic schists distribute as layers or lenticular bodies several to fifteen meters in thickness, and they are restricted in the greenschist facies conditions within structurally vertical thickness about one kilometer. Silicified pelitic schist is mainly composed of fine-grained quartz and minor muscovite and biotite, and some of colored minerals are decolored by alteration more or less. The boundary between silicified layer and underlying pelitic schist is fairly distinct but that between the overlying pelitic schist is rather gradual. Quartz veins crossing high angles with schistosity were preferentially developed in the silicified rocks, while schistosity-parallel quartz veins, which underwent ductile flow, were observed in the pelitic schist. En echelon quartz vein and fishnet-like quartz veins are characteristic of silicified rocks. The mode of occurrences of quartz veins indicates that silicified rocks are competent relative to underlying pelitic schist. Fluid inclusion studies were conducted from two kinds of quartz-filled veins: crosscutting foliation in silicified pelitic schist and foliation-parallel in pelitic schist. Fluid inclusions in quartz from a vein crosscutting foliation in silicidied pelitic schist occur as isolated individual inclusions or clusters with preferred spatial arrangement. The isolated inclusions display negative crystal geometries, and are generally range in size from 5 to 10 ? m, with some inclusions up to 20 ? m across. Fluid inclusions in quartz from a foliation-parallel vein are rounded and usually small about a few ? m. Homogenization of the vapour and liquid phases to a single liquid phase occurred at temperatures (Th) between 275 and 330 ° C except in rare instances. The value is considered to be close to the condition of vein formation. Importantly, the homogenization-temperature distributions for vein quartz in silicifeid rocks and pelitic schists are similar. The Raman spectra for the vapour phase within water-rich inclusions indicate that these inclusions contain CO2 alone or CO2 and CH4, in varying molar proportions. The volatile phase is dominated by CO2 with small amount of N2. All these observations suggest that the silicification of the Ryoke pelitic rocks was a result of silica precipitation from fluids and occurred at the fore-arc region before or coincident with the low-P/T metamorphism. The subducting slab releases fluids into wedge mantle. Deeper fluids may be channelized updip. Silicification occurred in the middle crust and caused sealing process to form impermeable-competent layers. Fluids may likely concentrate just below the bright layer.

Terabayashi, M.; Yamamoto, H.; Kitajima, K.

2004-12-01

170

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

NASA Astrophysics Data System (ADS)

New Early Triassic trace fossil assemblages are documented from the Susong and Tianshengqiao areas in South China to evaluate the mode and tempo of biotic recovery of epifaunal and infaunal organisms following the end-Permian mass extinction. The Susong succession is exposed in Anhui area of the Lower Yangtze region and comprises mudstone and carbonate facies that record overall shallowing from offshore to supratidal settings. The Tianshengqiao succession crops out in the Luoping area, Yuannan Province of the Upper Yangtze region, and consists of mixed carbonate and siliciclastic facies which were deposited in shallow marine to offshore settings. Bivalve and conodont biostratigraphy helps constrain the chronostratigraphic framework of the Lower Triassic successions in these two sections. Griesbachian to Dieneria ichnological records in both successions are characterized by low ichnodiversity, low ichnofabric indices (ii=1-2) and low bedding plane bioturbation indices (bpbi=1-2). Higher ii (ii= 3 and 4) corresponding to densely populated diminutive Skolithos in the Tianshengqiao succession suggest an opportunistic strategy during earliest Triassic deposition. Ichnological data from the Susong succession show an increase in ichnodiversity during the Smithian. A total of 12 ichnogenera including Arenicolites, Chondrites, Gyrochorte, Laevicyclus, Monocraterion, Palaeophycus, Phycodes, Plaolites, Thalassinoides, Treptichnus, Trichichnus and one problematic trace are identified. Ichnofabric indices (ii) and bpbi increase to moderate to high levels (ii = 4-5, bpbi= 3-5). Although complex traces such as Rhizocorallium are in Spathian strata in this section, the low levels of ichnodiversity, ichnofabric indices and diminutive Planolites suggest a decline in recovery. In the Tianshengqiao succession, ichnofabric indices exhibit a moderate to high value (ii= 3 to 5), however, only six ichnogenera are found and Planolites burrows are consistently small (average diameter at 3.7 mm) in the Smithian strata. These stressed ichnological parameters remain unchanged during the Spathian. Complex traces such as large Rhizocorallium and Thalassinoides and large sized Planolites (average diameter is 6.9 mm) did not appear until the Anisian. Ichnological results from both successions record the response of organisms to prolonged unfavorable environmental conditions although trace fossils from the Susong succession show evidences for recovery during the Smithian followed by a decline. This maybe resulted from a recognised temperature spike at the Smithian/Spathian boundary in South China and elsewhere. Ichnological data from the Tianshengqiao succession suggests a protracted recovery throughout the Early Triassic.

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

2013-12-01

171

Terrestrial pollen record of recent land-use changes around nine North African lakes in the CASSARINA Project  

Microsoft Academic Search

? Abstract Pollen analyses and related plant macrofossil records are presented from short cores from nine North African lakes in the EU-funded CASSARINA project. Terrestrial pollen reflects human impact on the vegetation and landscape over the last 150-100 years. Pollen changes, aided by radiometric dating, could be correlated with historical developments. The chronology of the landscape changes date other biostratigraphical

Sylvia M. Peglar; Hilary H. Birks; H. J. B. Birks; P. G. Appleby; A. A. Fathi; R. J. Flower; M. M. Kraïem; S. T. Patrick; M. Ramdani

2001-01-01

172

The Lake Bosumtwi Drilling Project: A 1 Ma West African Paleoclimate Record  

NASA Astrophysics Data System (ADS)

Lake Bosumtwi occupies a 1.07 Ma impact crater located in Ghana, West Africa centered at 06*32'N and 01*25'W. This 78 m deep, hydrologically-closed lake has a water budget extremely sensitive to the precipitation/evapotranspiration balance and is located in the path of the seasonal migration of the ITCZ. Therefore, Lake Bosumtwi is ideally situated to provide a long record of change in North African monsoon strength. In addition, the stratified water column allows for the preservation of finely-laminated sediments and the potential for high-resolution (annual) paleoclimate reconstruction. Using the GLAD800 lake drilling system, five drill sites were occupied along a water-depth transect in order to facilitate the reconstruction of the lake level history. At these five sites, a total of 14 separate holes were drilled yielding a total sediment recovery of 1,833 m. The shallow water drill sites consist of alternating laminated lacustrine mud (deepwater environment), moderately-sorted sand (nearshore beach environment) and sandy gravel (fluvial or lake marginal environments). These sediment cores and seismic reflection profiles are being used to construct a basin-wide stratigraphic framework, in order to extend further back in time the present Bosumtwi lake level histories obtained from highstand terraces and short piston cores. At a deep water site, the complete 1 Ma lacustrine stratigraphic section was recovered in 294 m deep holes that ended in impact-glass bearing, accretionary lapilli fallout representing the initial days of sedimentation. The lowermost lacustrine sediment is a bioturbated, light-gray mud with abundant gastropod shells indicating that a shallow-water oxic lake environment was established in the crater. Much of the overlying 294 m of mud is laminated thus these sediment cores will provide a unique 1 million year record of tropical African climate change. Two contrasting litholgies identified in the dated, upper part of the deep water drill hole, were deposited over the last glacial cycle. Increased insolation forcing and the resulting intensified summer monsoon produce a positive moisture balance and high lake levels. Organic-rich sediment with a low-coercivity magnetic mineralogy accumulated during these wet intervals. However, at times of decreased summer insolation and the accompanying weaker summer monsoon, lake levels fell and a mineral rich sediment with lower organic content accumulated. During these dry periods aerosol dust export from North Africa increased greatly contributing to a high-coercivity magnetic mineral assemblage in Bosumtwi. On precessional time scales, the Bosumtwi profiles of organic carbon and rock magnetic parameters are readily correlated with the Vostok methane record thus reflecting an important role for equatorial African wetlands on regulating methane variability. Ongoing work will utilize the varved sediment record to address the abruptness of environmental change in West Africa as well as connections between high and low-latitude climate change.

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

2005-12-01

173

A Record of Early to Middle Holocene Hydroclimate Variability from the West African Sahel  

NASA Astrophysics Data System (ADS)

The African Humid Period (ca. 14.8 to 5.5 ka) is an interval of wet climates across northwest Africa, with evidence for widespread lake basins and savannah vegetation in areas that are now desert. There are few high-resolution continental records of hydrologic variability during the African humid period however. In particular, it remains uncertain how periods of north Atlantic climate variability were expressed in northwest Africa. We present results from a 5.4 meter sediment core from Lake Fati in northern Mali (16.29° N, 3.71° W), which represents the first lake sediment core from the western Sahel. The Lake Fati core contains a continuous record of lake mud from 10.43 to 4.66 kyr BP. Centimeter scale XRF scanning indicates strong covariation between iron, calcium, manganese and phosphorous abundance due to enrichment of these elements during periods of enhanced deposition of authigenic siderite. Preliminary oxygen isotope measurements indicate that authigenic siderite ?18O values are positively correlated with Fe counts, suggesting that siderite deposition increased during drier periods with greater evaporation of lake waters. These drying events occurred on decadal to centennial time scales, with higher-frequency variability during the early Holocene. Peaks in zirconium and titanium abundance coincide with some of the inferred dry periods, suggesting that deposition of aeolian silt coincided with periods of increased evaporation of lake water. A roughly 30 year interval of sand deposition at ~8.33 kyr BP suggests major drying and activation of aeolian sand deposition. This abrupt climate change could be related to the 8.2 ka event in the North Atlantic; further efforts to refine the sediment core age model will constrain the relationship of this rapid drying to abrupt climate change in the North Atlantic. Aluminum and silicon counts co-vary for much of the lake Fati record, and are related to input of terrigenous sediment, primarily during seasonal flooding of the Niger river. Al and Si exhibit peak abundance at approximately 9.9 ka followed by a long-term decline, suggesting a long-term decrease in seasonal flooding forced by the precession-controlled reduction in local insolation. Al and Si abundances are decoupled following a transition to deposition of 16 cm sand at 4.5 ka, with Al decreasing and Si increasing rapidly. This period of sand deposition represents the termination of the African Humid Period. The timing of this event is younger than the transition at 5.5 ka recorded in marine cores from ODP site 658 (offshore of Mauritania), possibly due to Lake Fati's location further to the south and closer to the present position of the Intertropical Convergence Zone. The transition to sand deposition in the Lake Fati core is abrupt (< 40 years), but follows increasing Fe abundance for circa 200 years that could indicate gradual drying preceding this transition. A 6 cm layer of mud at the top of the core indicates the establishment of the current lake system roughly 200 years ago.

McIntosh, R.; Douglas, P. M.; Warren, C.; Meyers, S. R.; Coutros, P.; Park, D. P.

2011-12-01

174

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

PubMed Central

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

Kano, Yasunori; Chiba, Satoshi; Kase, Tomoki

2002-01-01

175

Human species and mating systems: Neandertal-Homo sapiens reproductive isolation and the archaeological and fossil records.  

PubMed

The present paper examined the assumption of strong reproductive isolation (RI) between Homo neanderthalensis and Homo sapiens, as well as the question of what form it might have taken, using insights from the parallel case of chimpanzee–bonobo hybridization. RI from hybrid sterility or inviability was thought unlikely based on the short separation-to-introgression timeline. The forms of RI that typically develop in primates have relatively short timelines (especially for partial implementation); they generally preclude mating or influence hybrid survival and reproduction in certain contexts, and they have the potential to skew introgression directionality. These RI barriers are also consistent with some interpretations of the archaeological and fossil records, especially when behavioral, cognitive, morphological, and genetic differences between the two human species are taken into consideration. Differences potentially influencing patterns of survival and reproduction include interspecies violence, Neandertal xenophobia, provisioning behavior, and ontogenetic, morphological, and behavioral differences affecting matters such as kin and mate recognition, infanticide, and sexual selection. These factors may have skewed the occurrence of interbreeding or the survival and reproduction of hybrids in a way that might at least partially explain the pattern of introgression. PMID:24344097

Overmann, Karenleigh; Coolidge, Frederick

2013-01-01

176

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

USGS Publications Warehouse

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.

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

1996-01-01

177

Fossil Horses  

NASA Astrophysics Data System (ADS)

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.

MacFadden, Bruce J.

1994-06-01

178

Mapping Ancient Forests: Bayesian Inference for Spatio-temporal Trends in Forest Composition Using the Fossil Pollen Proxy Record  

PubMed Central

Ecologists use the relative abundance of fossil pollen in sediments to estimate how tree species abundances change over space and time. To predict historical forest composition and quantify the available information, we build a Bayesian hierarchical model of forest composition in central New England, USA, based on pollen in a network of ponds. The critical relationships between abundances of taxa in the pollen record and abundances as actual vegetation are estimated for the modern and colonial periods, for which both pollen and direct vegetation data are available, based on a latent multivariate spatial process representing forest composition. For time periods in the past with only pollen data, we use the estimated model parameters to constrain predictions about the latent spatio-temporal process conditional on the pollen data. We develop an innovative graphical assessment of feature significance to help to infer which spatial patterns are reliably estimated. The model allows us to estimate the spatial distribution and relative abundances of tree species over the last 2500 years, with an assessment of uncertainty, and to draw inference about how these patterns have changed over time. Cross-validation suggests that our feature significance approach can reliably indicate certain large-scale spatial features for many taxa, but that features on scales smaller than 50 km are difficult to distinguish, as are large-scale features for some taxa. We also use the model to quantitatively investigate ecological hypotheses, including covariate effects on taxa abundances and questions about pollen dispersal characteristics. The critical advantages of our modeling approach over current ecological analyses are the explicit spatio-temporal representation, quantification of abundance on the scale of trees rather than pollen, and uncertainty characterization.

Paciorek, Christopher J.; McLachlan, Jason S.

2008-01-01

179

Tracking changing environments using stable carbon isotopes in fossil tooth enamel: an example from the South African hominin sites.  

PubMed

The environmental contexts of the karstic hominin sites in South Africa have been established largely by means of faunal associations; taken together these data suggest a trend from relatively closed and more mesic to open, drier environments from about 3 to 1.5 Ma. Vrba argued for a major shift within this trend ca. 2.4-2.6 Ma, an influential proposal that posited links between bovid (and hominin) radiation in Africa and the intensification of Northern Hemisphere Glaciation. Yet faunal approaches often rely on habitat and feeding preferences of modern taxa that may differ from those of their extinct predecessors. Here we explore ways of extending (13)C/(12)C data from fossil mammals beyond denoting "presence" or "absence" of C(4) grasses using the evolution of open environments in South Africa as a case study. To do so we calculated the relative proportions of C(3)-, mixed-, and C(4)-feeding herbivores for all the hominin sites for which we have sufficient data based on (13)C/(12)C analyses of fossil tooth enamel. The results confirm a general trend towards more open environments since 3 Ma, but they also emphasize a marked change to open grassy habitats in the latest Pliocene/early Pleistocene. Mean (13)C/(12)C for large felids also mirrored this trend. PMID:17920103

Lee-Thorp, Julia A; Sponheimer, Matt; Luyt, Julie

2007-11-01

180

Evidence for tropical South Pacific climate change during the Younger Dryas and the Bølling–Allerød from geochemical records of fossil Tahiti corals  

Microsoft Academic Search

We present monthly resolved records of strontium\\/calcium (Sr\\/Ca) and oxygen isotope (?18O) ratios from well-preserved fossil corals drilled during the Integrated Ocean Drilling Program (IODP) Expedition 310 “Tahiti Sea Level” and reconstruct sea surface conditions in the central tropical South Pacific Ocean during two time windows of the last deglaciation. The two Tahiti corals examined here are uranium\\/thorium (U\\/Th)-dated at

Ryuji Asami; Thomas Felis; Pierre Deschamps; Kimio Hanawa; Yasufumi Iryu; Edouard Bard; Nicolas Durand; Masafumi Murayama

2009-01-01

181

Phylogenetic relationships among extant classes of echinoderms, as inferred from sequences of 18S rDNA, coincide with relationships deduced from the fossil record  

Microsoft Academic Search

In spite of the rich fossil record and multiple descriptions of morphological and embryological characteristics, the origin and subsequent evolution of echinoderms remain highly controversial issues. Using sequence data derived from 18S rDNA, we have investigated the phylogenetic relationships among five extant classes of echinoderms—namely, crinoids, asteroids, ophiuroids, echinoids, and holothurians. Almost complete sequences of 18S rDNA were determined for

Hiroshi Wada; Noriyuki Satoh

1994-01-01

182

Predicting warfarin dosage in European-Americans and African-Americans using DNA samples linked to an electronic health record  

PubMed Central

Aim Warfarin pharmacogenomic algorithms reduce dosing error, but perform poorly in non-European–Americans. Electronic health record (EHR) systems linked to biobanks may allow for pharmacogenomic analysis, but they have not yet been used for this purpose. Patients & methods We used BioVU, the Vanderbilt EHR-linked DNA repository, to identify European–Americans (n = 1022) and African–Americans (n = 145) on stable warfarin therapy and evaluated the effect of 15 pharmacogenetic variants on stable warfarin dose. Results Associations between variants in VKORC1, CYP2C9 and CYP4F2 with weekly dose were observed in European–Americans as well as additional variants in CYP2C9 and CALU in African–Americans. Compared with traditional 5 mg/day dosing, implementing the US FDA recommendations or the International Warfarin Pharmacogenomics Consortium (IWPC) algorithm reduced error in weekly dose in European–Americans (13.5–12.4 and 9.5 mg/week, respectively) but less so in African–Americans (15.2–15.0 and 13.8 mg/week, respectively). By further incorporating associated variants specific for European–Americans and African–Americans in an expanded algorithm, dose-prediction error reduced to 9.1 mg/week (95% CI: 8.4–9.6) in European–Americans and 12.4 mg/week (95% CI: 10.0–13.2) in African–Americans. The expanded algorithm explained 41 and 53% of dose variation in African–Americans and European–Americans, respectively, compared with 29 and 50%, respectively, for the IWPC algorithm. Implementing these predictions via dispensable pill regimens similarly reduced dosing error. Conclusion These results validate EHR-linked DNA biorepositories as real-world resources for pharmacogenomic validation and discovery.

Ramirez, Andrea H; Shi, Yaping; Schildcrout, Jonathan S; Delaney, Jessica T; Xu, Hua; Oetjens, Matthew T; Zuvich, Rebecca L; Basford, Melissa A; Bowton, Erica; Jiang, Min; Speltz, Peter; Zink, Raquel; Cowan, James; Pulley, Jill M; Ritchie, Marylyn D; Masys, Daniel R; Roden, Dan M; Crawford, Dana C; Denny, Joshua C

2012-01-01

183

Cenozoic denudation rates of the West African marginal upwarp recorded by lateritic paleotopographies  

NASA Astrophysics Data System (ADS)

Quantifying long-term erosion of tropical shields is crucial to constraining the role of lateritic regolith covers as prominent sinks and sources of CO2 and sediments in the context of long-term Cenozoic climate change. It is also a key to understanding long-term landform evolution processes operating over most of the continental surface, particularly passive margins, and their control onto the sediment routing system. We study the surface evolution of West Africa over three erosion periods (~ 45-24, ~ 24-11 and ~ 11-0 Ma) recorded by relicts of 3 sub-continental scale lateritic paleolandsurfaces whose age is bracketed by 39Ar/40Ar dating of lateritic K-Mn oxides [1]. Denudation depths and rates compiled from 380 field stations show that despite heterogeneities confined to early-inherited reliefs, the sub-region underwent low and homogeneous denudation (~ 2-20 m Ma-1) over most of its surface whatever the considered time interval. This homogeneity is further documented by a worldwide compilation of cratonic denudation rates, over long-term, intermediate and modern Cenozoic time scales (100 - 107 yr). These results allow defining a steady-state cratonic denudation regime that is weathering-limited i.e. controlled by the thickness of the (lateritic) regolith available for stripping. Steady-state cratonic denudation regimes are enabled by maintained compartmentalization of the base levels between river knick points controlled by relief inheritance. Under such regimes, lowering of base levels and their fossilization are primarily imposed by long-term eustatic sea level fall and climate rather than by epeirogeny. The results suggest that Cenozoic post-rift vertical mobility of marginal upwarps in the tropical belt was unable to modify slow, weathering-controlled, steady state denudation regimes. The potentially complex expression of steady-state cratonic denudation regimes in clastic sedimentary fluxes remains to be investigated. [1] Beauvais et al., Journal of Geophysical Research, 113, F04007, 2008.

Beauvais, Anicet; Chardon, Dominique

2013-04-01

184

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

Microsoft Academic Search

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,

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

2011-01-01

185

The fossil record and estimating divergence times between lineages: Maximum divergene times and the importance of reliable phylogenies  

Microsoft Academic Search

Summary Bounded estimates on divergence times between lineaes are crucial to the calculation of absolute rates of molecular evolution. Upper (minimum) bounds on divergence times are easily estimated based on earliest fossil finds. Lower (maximum) bounds are more difficult to estimate; the age of putative ancestors may be used, though in practice it is virtually impossible to distinguish ancestors from

Charles R. Marshall

1990-01-01

186

The origin and early evolution of Sauria: reassessing the permian Saurian fossil record and the timing of the crocodile-lizard divergence.  

PubMed

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

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

2014-01-01

187

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

NASA Astrophysics Data System (ADS)

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

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

188

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

PubMed Central

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.

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

189

Tectonic evolution of the northern African margin in Tunisia from paleostress data and sedimentary record  

Microsoft Academic Search

A reconstruction of the tectonic evolution of the northern African margin in Tunisia since the Late Permian combining paleostress, tectonic stratigraphic and sedimentary approaches allows the characterization of several major periods corresponding to consistent stress patterns. The extension lasting from the Late Permian to the Middle Triassic is contemporaneous of the rifting related to the break up of Pangea. During

Samir Bouaziz; Eric Barrier; Mohamed Soussi; Mohamed M. Turki; Hédi Zouari

2002-01-01

190

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

PubMed

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

Srivastava, Gaurav; Mehrotra, Rakesh C

2013-01-01

191

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

PubMed Central

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

Srivastava, Gaurav; Mehrotra, Rakesh C.

2013-01-01

192

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

NASA Astrophysics Data System (ADS)

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

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

2005-10-01

193

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

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

194

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

NASA Astrophysics Data System (ADS)

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.

Wake, Thomas A.; Roeder, Mark A.

2009-11-01

195

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

PubMed

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

Petrulevi?ius, Julián F; Popov, Yuri A

2014-01-01

196

East African mid-Holocene wet-dry transition recorded in palaeo-shorelines of Lake Turkana, northern Kenya Rift  

NASA Astrophysics Data System (ADS)

The 'wet' early to mid-Holocene of tropical Africa, with its enhanced monsoon, ended with an abrupt shift toward drier conditions and was ultimately replaced by a drier climate that has persisted until the present day. The forcing mechanisms, the timing, and the spatial extent of this major climatic transition are not well understood and remain the subject of ongoing research. We have used a detailed palaeo-shoreline record from Lake Turkana (Kenya) to decipher and characterise this marked climatic transition in East Africa. We present a high-precision survey of well-preserved palaeo-shorelines, new radiocarbon ages from shoreline deposits, and oxygen-isotope measurements on freshwater mollusk shells to elucidate the Holocene moisture history from former lake water-levels in this climatically sensitive region. In combination with previously published data our study shows that during the early Holocene the water-level in Lake Turkana was high and the lake overflowed temporarily into the White Nile drainage system. During the mid-Holocene (~ 5270 ± 300 cal. yr BP), however, the lake water-level fell by ~ 50 m, coeval with major episodes of aridity on the African continent. A comparison between palaeo-hydrological and archaeological data from the Turkana Basin suggests that the mid-Holocene climatic transition was associated with fundamental changes in prehistoric cultures, highlighting the significance of natural climate variability and associated periods of protracted drought as major environmental stress factors affecting human occupation in the East African Rift System.

Garcin, Yannick; Melnick, Daniel; Strecker, Manfred R.; Olago, Daniel; Tiercelin, Jean-Jacques

2012-05-01

197

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

NASA Astrophysics Data System (ADS)

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

Wierzchos, Jacek; Ascaso, Carmen

2002-01-01

198

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

NASA Astrophysics Data System (ADS)

Bioclimatic Envelope Models (BEMs) for a set of socio-economically important tree species in Europe were independently validated using a hindcasting approach and fossil pollen records spanning the last 1000 years, including the Medieval Warm Period (MWP), the Little Ice Age (LIA) and the 20th Century warming (PRES). The aim was to determine the accuracy of combining BEMs and palaeoecological data to predict continental-scale changes in distribution, and the availability of fossil data to hindcast economically important species. Eight types of BEMs were implemented in this study, covering most state-of-the-art modelling techniques. Present and palaeoclimatic data were obtained from the Atmosphere-Ocean Global Circulation Model ECHO-G. Last millenium was divided into three climatically distinct periods: MWP (AD 900-1300), LIA (AD 1600-1850) and PRES (AD 1900-2000). Models were calibrated for each period and validated with climatic and pollen data from the remaining periods. Successfully validated models were projected onto a 1-degree European grid, allowing the reconstruction of past modelled species distributions. BEMs were successfully validated with independent data. Strong model performance suggested high potential for BEMs to be used to model future species distributions, and highlighted the importance of palaeoecological data to independently validate these models, taking into account the scales at which this data operates. Although valid, BEMs showed poorer performance with species heavily managed and/or growing in heterogeneous terrain or with discontinuous distributions. Last millennium in Europe was characterized by an increase of crop woody species and a decline of forest species, suggesting an increasing land use by humans. The same approach was then implemented to a set of sub-Saharan plant species of high importance as a source of food, wood, and other ecosystem services such as carbon storage or erosion protection. The African study covered most of the Holocene, including the sharp transition from wet to dry climate about 5000 yr. B.P., of crucial importance to understand the response of the savannah/desert system to large climatic shifts over a region especially sensitive to these oscillations. Validated models were projected onto ensemble climate projections for the late 21st century, providing robust predictions of the future distribution of these key plant species.

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

2011-12-01

199

Biomass burning in Indonesia and Papua New Guinea: natural and human induced fire events in the fossil record  

Microsoft Academic Search

Microscopic charcoal preserved in sediments from ten wetlands in the Indonesian and Papua New Guinea region provide a proxy record of regional fire events during the last 20,000years. Two periods of high regional charcoal frequency are encountered during the last glacial transition (17,000–9000years B.P.) and the middle to late Holocene (5000years B.P. to the present). Despite the presence of humans

Simon G Haberle; Geoff S Hope; Sander van der Kaars

2001-01-01

200

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

PubMed

Carbon particle analysis was performed on a dated sediment core from Lake Erie in order to explore the inputs of pollution from incomplete combustion of coal, oil, and wood. Carbon particles were isolated from the sediment by chemical digestion, and elemental carbon content was determined by CHN analysis. The type of carbon particle (from burning coal, oil, and wood) and particle size and relative abundance were determined using scanning electron microscopy on 100 particles from each core section. The elemental carbon content in the Lake Erie core ranges from 2.5 to 7.4 mg of carbon/g of sediment (1850-1998), and the maximum carbon content in the sediment occurs in the late 1960s to early 1970s. It is shown that particle mass is a better predictor than particle number of historical energy consumption records. This is especially clear for wood where variable particle volumes play a significant role in determining the record of elemental carbon mass from wood burning. Lake Erie core's content of total carbon and carbon particle type is in agreement with U.S. energy consumption records, except that a wood maximum occurs during 1905-1917, about 36 yr after the U.S. consumption maximum from 1870 to 1880. PMID:11999043

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

2002-04-01

201

"Fossil" Forecasting.  

ERIC Educational Resources Information Center

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)

Brody, Michael J.; deOnis, Ann

2001-01-01

202

Fossil fuels  

Microsoft Academic Search

The recovery, handling and combustion of fossil fuels is damaging the environment. This damage may ultimately cause many plant and animal species to become extinct. If we continue to increase our use of fossil fuels for energy production, humanity may ultimately become one of the species that perish. This is an overwhelming reason to stop the use of fossil fuels

Herman Daly

1994-01-01

203

Pollen dispersal over complex terrain: How does anisotropic airborne pollen transport affect interpretation of fossil pollen records? A case study in Northern Patagonia.  

NASA Astrophysics Data System (ADS)

Accumulated pollen in stratified fossil reservoirs is used to infer temporal changes in vegetation composition. Transport and dispersal by winds are known to introduce large biases in the interpretation of polynic records. In order to calibrate the models used to infer information about past species distributions, human activities and climate, contemporary time series of polynic records are assessed and modelled. In this study we analyse measurements collected hourly in Bariloche, Argentina (41° 10' S, 71° 15' W, 850 masl) of the species Weinmannia trichosperma, a characteristic forest tree which grows only the western (Chilean) slopes of the Andes, but not on the eastern (Argentinian) slopes where the measurements were collected. Instead of the simplistic Gaussian plume mixing model that is usually employed by the palynological community, we apply a full 3D Lagrangian dispersion model to interpret the observations and assess the impact of long-range transport over the Andean mountain range. The Lagrangian calculation of the origins of the air masses (the "backward footprint") is consistent not only with the Chilean Weinmania pollen measurements but also with a set of species only found on the dryer steppe located to the east of the measurement site in Argentina. The agreement of the modelling results indicates that significant interpretation mistakes may arise from inconsistent transport treatment. We also discuss the further application of inverse trajectory modelling to the estimation of source intensity.

Pérez, Claudio; Bianchi, María Martha; Gassmann, Marisa; Pisso, Ignacio

2014-05-01

204

"It's Alive!" Fossil Activity  

NSDL National Science Digital Library

The first lab activity for the course is called "PaleontologyâPast, Present, and Future". In addition to discussing several documents related to present and future research directions in the field, students review a brief timeline of the historical development of paleontology as a science. Then they get their first opportunity to work directly with fossils. Students are presented with a set of fossil specimens in boxes (with no identifying labels). Each student selects one fossil of their own. They are asked to make and record very close, detailed observations of the specimen, and to sketch the fossil. Then they are told to "think like it's 1600." Someone has brought this object, taken out of the local rocks, for the student to investigate. The student must write a "proof" that this fossil was obviously once alive, and is not just an interesting mineral or rock formation. They can use their observations, compare the specimen to other objects with which they're familiar, resort to pure logic, or apply any other avenue of argumentation they think will help make their case. Note: In the next lab, on fossil preservation and taphonomy, the students revisit their fossil specimen, and determine its mode of preservation. Indeed, the student's "pet fossil" could be used throughout the course to illustrate various components of the course content.

Yacobucci, Peg

205

Cosmic-Ray Production of 6Li by Structure Formation Shocks in the Early Milky Way: A Fossil Record of Dissipative Processes during Galaxy Formation  

NASA Astrophysics Data System (ADS)

While the abundances of Be and B observed in metal-poor halo stars are well explained as resulting from spallation of CNO-enriched cosmic rays (CRs) accelerated by supernova shocks, accounting for the observed 6Li in such stars with supernova CRs is more problematic. Here we propose that gravitational shocks induced by infalling and merging subgalactic clumps during hierarchical structure formation of the Galaxy should dissipate enough energy at early epochs so that the CRs accelerated by such shocks can provide a natural explanation of the observed 6Li. In clear contrast to supernovae, structure formation shocks do not eject freshly synthesized CNO nor Fe, so that ?-? fusion, which is the only effective production channel at low metallicity, is capable of generating sufficient 6Li with no accompanying Be or B and no direct correspondence with Fe. Correlations between the 6Li abundance and the kinematic properties of the halo stars may also be expected in this scenario. Further, more extensive observations of 6Li in metal-poor halo stars, e.g., by the Subaru High Dispersion Spectrograph or the Very Large Telescope UV-Visual Echelle Spectrograph, may offer us an invaluable fossil record of dissipative dynamical processes that occurred during the formation of our Galaxy.

Suzuki, Takeru Ken; Inoue, Susumu

2002-07-01

206

Fossil formation  

NSDL National Science Digital Library

The National Science Education Standards Life Science Content Standard mentions that fossils indicate extinct species and contribute to an understanding of evolution and diversity. The Earth and Space Sciences Content Standard tells us they provide clues about past environments. But what is a fossil? How does it form? The processes can be complex. An understanding of fossil formation will enable accurate student conceptions of related science concepts including methods of science in geology, paleontology, and evolution.

University, Staff A.

2008-03-07

207

Finding Fossils  

NSDL National Science Digital Library

This activity (located on page 4 of the PDF) is a full inquiry investigation to determine the age of fossils based on where they are discovered. Groups of learners will dig for fossils embedded in a cake of multiple layers, carefully excavating each stratum and eventually preparing a chart from their notes for discussion with the group. The two main lessons from this exercise are that fossils from different layers come from different eras and that multiple interpretations of incomplete fossil evidence are possible. Relates to linked video, DragonflyTV GPS: Baby Dinosaurs.

Twin Cities Public Television, Inc.

2007-01-01

208

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

Microsoft Academic Search

We use the carbon and oxygen isotopic compositions of fossil tooth enamel and paleosols to reconstruct the late Cenozoic history of vegetation and environmental change in the Linxia Basin at the northeastern margin of the Tibetan Plateau. The ?13C values of fossil enamel from a diverse group of herbivores and of paleosol carbonate and organic matter indicate that C4 grasses

Yang Wang; Tao Deng

2005-01-01

209

Fossil Records of Mendelian Mutants  

Microsoft Academic Search

WITH the help of Prof. A. E. Boycott and others, I have been engaged for the past ten years in collecting data for the study of the distribution of variations in natural populations. The species selected for study were the two common and very variable British landsnails, Helix (Cepæa) nemoralis L. and H. (Cepæa) hertensis, Müll. These snails normally occur

C. Diver

1929-01-01

210

Fossil Fuels.  

ERIC Educational Resources Information Center

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…

Crank, Ron

211

Ediacara Fossils  

ERIC Educational Resources Information Center

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…

Science Teacher, 2005

2005-01-01

212

Recordings  

Microsoft Academic Search

Akom: the art of possession. Village Pulse VPU?1009, 1999. 72 mins. Recordings and booklet (24pp.) by Scott Kiehl in English.Soungalo Coulibaly: Dengo. Ethnomad ARN 64544, 2001 (recorded in 1995). 51 mins. Booklet (16pp.) in French, English.Serbie: antholagie de la musique populaire serbe \\/ Serbia: an anthology of Serbian folk musk. VDE?GALLO, CP 945\\/ AIMP LX, 1999. 72.22 mins. Recordings (1975–96)

Trevor Wiggins; Jelena Jovanovi?; Razia Sultanova; Neil Sorrell; Jan Fairley

2001-01-01

213

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

NASA Astrophysics Data System (ADS)

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.

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

214

Restoring Fossil Creek  

NSDL National Science Digital Library

As part of an ongoing environmental project and partnership with a local university, high school students monitor changes to Fossil Creek in Arizona. Components of the project include fish behavior studies, responses to fishing, water chemistry measurements, aquatic invertebrate studies, photographic recording, riparian habitat transects, and small mammal trapping transects. The data collected will ultimately provide an invaluable annual record for students, working scientists, and the wider community as changes are monitored over time.

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

2004-07-01

215

Fossil Halls  

NSDL National Science Digital Library

The American Museum of Natural History is home to the world's largest collection of vertebrate fossils, totaling nearly one million specimens. This Web site offers visitors a virtual visit to the Museum's famed Fossil Halls. It features sections on Cladistics, Vertebrate Evolution, Exhibit Specimens, a collection of 19 biographies of important people in paleontology and Virtual Tours of four of the halls. There is also an elementary school teacher guide to the museum exhibit.

216

Pronounced occurrence of long-chain alkenones and dinosterol in a 25,000-year lipid molecular fossil record from Lake Titicaca, South America  

NASA Astrophysics Data System (ADS)

Our analysis of lipid molecular fossils from a Lake Titicaca (16° S, 69° W) sediment core reveals distinct changes in the ecology of the lake over an ˜25,000-yr period spanning latest Pleistocene to late Holocene time. Previous investigations have shown that over this time period Lake Titicaca was subject to large changes in lake level in response to regional climatic variability. Our results indicate that lake algal populations were greatly affected by the changing physical and chemical conditions in Lake Titicaca. Hydrocarbons are characterized by a combination of odd-numbered, mid- to long-chain (C 21-C 31) normal alkanes and alkenes. During periods when lake level was higher (latest Pleistocene, early Holocene, and late Holocene), the C 21n-alkane, and the C 25 and C 27 alkenes dominate hydrocarbon distributions and indicate contribution from an algal source, potentially the freshwater alga Botryococcus braunii. The C 30 4 ?-methyl sterol (dinosterol) increases sharply during the mid-Holocene, suggesting a greatly increased dinoflagellate presence at that time. Long-chain alkenones (LCAs) become significant during the early Holocene and are highly abundant in mid-Holocene samples. There are relatively few published records of LCA detection in lake sediments but their occurrence is geographically widespread (Antarctica, Asia, Europe, North America). Lake Titicaca represents the first South American lake and the first low-latitude lake in which LCAs have been reported. LCA abundance and distribution may be related to the temperature-dependent response of an unidentified algal precursor. Although the LCA unsaturation indices cannot be used to determine absolute Lake Titicaca temperatures, we suspect that the published LCA U37K unsaturation calibrations can be applied to infer relative temperatures for early to mid-Holocene time when LCA concentrations are high. Using these criteria, the U37K unsaturation indices suggest relatively warmer temperatures in the mid-Holocene. In contrast to previous speculation, lipid analysis provides little evidence of a greatly increased presence of aquatic plants during the mid-Holocene. Instead, it appears that a few algal species were dominant in the lake. Based on the dramatic rise in abundances of LCAs and dinosterol during the early to mid-Holocene, we suspect that the algal producers of these compounds rose in response to a combination of physical and chemical changes in the lake. These include temperature, salinity, and alkalinity changes that occurred as lake level dropped sharply during a multi-millennial drought affecting the Central Andean Altiplano.

Theissen, Kevin M.; Zinniker, David A.; Moldowan, J. Michael; Dunbar, Robert B.; Rowe, Harold D.

2005-02-01

217

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

NASA Astrophysics Data System (ADS)

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.

Gerbault, Muriel; Ganne, Jerome; Block, Sylvain

2014-05-01

218

Pronounced occurrence of long-chain alkenones and dinosterol in a 25,000-year lipid molecular fossil record from Lake Titicaca, South America  

Microsoft Academic Search

Our analysis of lipid molecular fossils from a Lake Titicaca (16° S, 69° W) sediment core reveals distinct changes in the ecology of the lake over an ?25,000-yr period spanning latest Pleistocene to late Holocene time. Previous investigations have shown that over this time period Lake Titicaca was subject to large changes in lake level in response to regional climatic

Kevin M. Theissen; David A. Zinniker; J. Michael Moldowan; Robert B. Dunbar; Harold D. Rowe

2005-01-01

219

Fossil Algæ  

Microsoft Academic Search

IN a review of Saporta's work on ``Fossil Algæ'' in NATURE (vol. xxvii. p. 514) there are certain opinions brought forward which ought not to be passed by without some remarks. At first it should be stated that Saporta, while still insisting upon the vegetable nature of his so-called ``algæ,'' does not only defend his views about those doubtful bodies

A. G. Nathorst

1883-01-01

220

Hominid mandibular corpus shape variation and its utility for recognizing species diversity within fossil Homo.  

PubMed

Mandibular corpora are well represented in the hominin fossil record, yet few studies have rigorously assessed the utility of mandibular corpus morphology for species recognition, particularly with respect to the linear dimensions that are most commonly available. In this study, we explored the extent to which commonly preserved mandibular corpus morphology can be used to: (i) discriminate among extant hominid taxa and (ii) support species designations among fossil specimens assigned to the genus Homo. In the first part of the study, discriminant analysis was used to test for significant differences in mandibular corpus shape at different taxonomic levels (genus, species and subspecies) among extant hominid taxa (i.e. Homo, Pan, Gorilla, Pongo). In the second part of the study, we examined shape variation among fossil mandibles assigned to Homo (including H. habilis sensu stricto, H. rudolfensis, early African H. erectus/H. ergaster, late African H. erectus, Asian H. erectus, H. heidelbergensis, H. neanderthalensis and H. sapiens). A novel randomization procedure designed for small samples (and using group 'distinctness values') was used to determine whether shape variation among the fossils is consistent with conventional taxonomy (or alternatively, whether a priori taxonomic groupings are completely random with respect to mandibular morphology). The randomization of 'distinctness values' was also used on the extant samples to assess the ability of the test to recognize known taxa. The discriminant analysis results demonstrated that, even for a relatively modest set of traditional mandibular corpus measurements, we can detect significant differences among extant hominids at the genus and species levels, and, in some cases, also at the subspecies level. Although the randomization of 'distinctness values' test is more conservative than discriminant analysis (based on comparisons with extant specimens), we were able to detect at least four distinct groups among the fossil specimens (i.e. H. sapiens, H. heidelbergensis, Asian H. erectus and a combined 'African Homo' group consisting of H. habilis sensu stricto, H. rudolfensis, early African H. erectus/H. ergaster and late African H. erectus). These four groups appear to be distinct at a level similar to, or greater than, that of modern hominid species. In addition, the mandibular corpora of H. neanderthalensis could be distinguished from those of 'African Homo', although not from those of H. sapiens, H. heidelbergensis, or the Asian H. erectus group. The results suggest that the features most commonly preserved on the hominin mandibular corpus have some taxonomic utility, although they are unlikely to be useful in generating a reliable alpha taxonomy for early African members of the genus Homo. PMID:19094183

Lague, Michael R; Collard, Nicole J; Richmond, Brian G; Wood, Bernard A

2008-12-01

221

Hominid mandibular corpus shape variation and its utility for recognizing species diversity within fossil Homo  

PubMed Central

Mandibular corpora are well represented in the hominin fossil record, yet few studies have rigorously assessed the utility of mandibular corpus morphology for species recognition, particularly with respect to the linear dimensions that are most commonly available. In this study, we explored the extent to which commonly preserved mandibular corpus morphology can be used to: (i) discriminate among extant hominid taxa and (ii) support species designations among fossil specimens assigned to the genus Homo. In the first part of the study, discriminant analysis was used to test for significant differences in mandibular corpus shape at different taxonomic levels (genus, species and subspecies) among extant hominid taxa (i.e. Homo, Pan, Gorilla, Pongo). In the second part of the study, we examined shape variation among fossil mandibles assigned to Homo(including H. habilis sensu stricto, H. rudolfensis, early African H. erectus/H. ergaster, late African H. erectus, Asian H. erectus, H. heidelbergensis, H. neanderthalensis and H. sapiens). A novel randomization procedure designed for small samples (and using group ‘distinctness values’) was used to determine whether shape variation among the fossils is consistent with conventional taxonomy (or alternatively, whether a priori taxonomic groupings are completely random with respect to mandibular morphology). The randomization of ‘distinctness values’ was also used on the extant samples to assess the ability of the test to recognize known taxa. The discriminant analysis results demonstrated that, even for a relatively modest set of traditional mandibular corpus measurements, we can detect significant differences among extant hominids at the genus and species levels, and, in some cases, also at the subspecies level. Although the randomization of ‘distinctness values’ test is more conservative than discriminant analysis (based on comparisons with extant specimens), we were able to detect at least four distinct groups among the fossil specimens (i.e. H. sapiens, H. heidelbergensis, Asian H. erectus and a combined ‘African Homo’ group consisting of H. habilis sensu stricto, H. rudolfensis, early African H. erectus/H. ergaster and late African H. erectus). These four groups appear to be distinct at a level similar to, or greater than, that of modern hominid species. In addition, the mandibular corpora of H. neanderthalensis could be distinguished from those of ‘African Homo’, although not from those of H. sapiens, H. heidelbergensis, or the Asian H. erectus group. The results suggest that the features most commonly preserved on the hominin mandibular corpus have some taxonomic utility, although they are unlikely to be useful in generating a reliable alpha taxonomy for early African members of the genus Homo.

Lague, Michael R; Collard, Nicole J; Richmond, Brian G; Wood, Bernard A

2008-01-01

222

The Link Between continental weathering, strength of the African Monsoon and Middle Miocene Cooling: A Central Mediterranean Record.  

NASA Astrophysics Data System (ADS)

During the Plio-Pleistocene, the strength of the African monsoon is known to have played a major role in determining sedimentation pattern in the Mediterranean by triggering sapropels deposition through increased meteoric water input. Here we present a mixed siliciclastic-carbonate section outcropping on the Maltese Islands that suggests that sapropels deposits already existed in the Middle Miocene, and thus that an enhanced monsoonal climate was likely active at that time. Organic matter analysis at this location indeed reflects mixing of terrigenous and marine sources. Moreover, runoff proxies coupled with oxygen isotopes indicate that a direct link existed between strength of the Monsoon and Miocene global climate. Our astronomically calibrated age model shows that the African monsoon has probably initiated around 16.7 Ma and underwent a major strengthening around 13.8 Ma. We argue based on other studies results and on the teleconnection existing nowadays between the two monsoons that this is also true for the Asian monsoon.

John, C. M.; Mutti, M.; Adatte, T.; Laskar, J.

2002-12-01

223

Cretaceous African life captured in amber.  

PubMed

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

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

2010-04-20

224

First fossil record of Discocephalinae (Insecta, Pentatomidae): a new genus from the middle Eocene of R?o Pichileuf?, Patagonia, Argentina  

PubMed Central

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.

Petrulevicius, Julian F.; Popov, Yuri A.

2014-01-01

225

Alkenone and coccolith records of the mid-Pleistocene in the south-east Atlantic: Implications for the U index and South African climate  

NASA Astrophysics Data System (ADS)

Successful application of the alkenone palaeothermometer, the U index, relies upon the assumption that fossil alkenone synthesisers responded to growth-temperature changes in a similar manner to the modern producers, chiefly the coccolithophores Emiliania huxleyi and Gephyrocapsa oceanica. We compare coccolith and U data from ODP Site 1087 in the south-east Atlantic between 1500 and 500 ka, and show that evolutionary events and changes in species dominance within the coccolithophore populations had little impact on the U record. The relative abundances of the C 37 and C 38 alkenones also closely resembled those found in modern populations, and suggest a similar temperature sensitivity of U during the early and mid-Pleistocene to that found at present. These results support the application of the U index to reconstruct sea-surface temperatures (SSTs) throughout the Quaternary. The U record at ODP Site 1087 contains an SST signal that documents the emergence of the 100-kyr cycles that characterise the late Quaternary ice volume records. This is preceded by significant cooling at ODP Site 1087, marked by a negative shift in SSTs and a positive shift in the planktonic ? 18O some 250-kyr earlier, at ca 1150-1000 ka. This results in a permanent fall in average SSTs of around 1.5 °C. The predicted increase in aridity onshore as a result of this cooling can be identified in a number of published records from southern Africa, and may have played a role in some important evolutionary events of the mid-Pleistocene.

McClymont, Erin L.; Rosell-Melé, Antoni; Giraudeau, Jacques; Pierre, Catherine; Lloyd, Jerry M.

2005-08-01

226

A Fossil Thermometer  

NSDL National Science Digital Library

In this activity, students calculate temperatures during a time in the geologic record when rapid warming occurred using a well known method called 'leaf-margin analysis.' Students determine the percentage of the species that have leaves with smooth edges, as opposed to toothed, or jagged, edges. Facsimiles of fossil leaves from two collection sites are examined, categorized, and the data is plugged into an equation to provide an estimate of paleotemperature for two sites in the Bighorn Basin. It also introduces students to a Smithsonian scientist who worked on the excavation sites and did the analysis.

Institution, Smithsonian; Institute, Smithsonian

227

Fossil and molecular evidence constrain scenarios for the early evolutionary and biogeographic history of hystricognathous rodents.  

PubMed

The early evolutionary and paleobiogeographic history of the diverse rodent clade Hystricognathi, which contains Hystricidae (Old World porcupines), Caviomorpha (the endemic South American rodents), and African Phiomorpha (cane rats, dassie rats, and blesmols) is of great interest to students of mammalian evolution, but remains poorly understood because of a poor early fossil record. Here we describe the oldest well-dated hystricognathous rodents from an earliest late Eocene (approximately 37 Ma) fossil locality in the Fayum Depression of northern Egypt. These taxa exhibit a combination of primitive and derived features, the former shared with Asian "baluchimyine" rodents, and the latter shared with Oligocene phiomorphs and caviomorphs. Phylogenetic analysis incorporating morphological, temporal, geographic, and molecular information places the new taxa as successive sister groups of crown Hystricognathi, and supports an Asian origin for stem Hystricognathi and an Afro-Arabian origin for crown Hystricognathi, stem Hystricidae, and stem Caviomorpha. Molecular dating of early divergences within Hystricognathi, using a Bayesian "relaxed clock" approach and multiple fossil calibrations, suggests that the split between Hystricidae and the phiomorph-caviomorph clade occurred approximately 39 Ma, and that phiomorphs and caviomorphs diverged approximately 36 Ma. These results are remarkably congruent with our phylogenetic results and the fossil record of hystricognathous rodent evolution in Afro-Arabia and South America. PMID:19805363

Sallam, Hesham M; Seiffert, Erik R; Steiper, Michael E; Simons, Elwyn L

2009-09-29

228

Fossil and molecular evidence constrain scenarios for the early evolutionary and biogeographic history of hystricognathous rodents  

PubMed Central

The early evolutionary and paleobiogeographic history of the diverse rodent clade Hystricognathi, which contains Hystricidae (Old World porcupines), Caviomorpha (the endemic South American rodents), and African Phiomorpha (cane rats, dassie rats, and blesmols) is of great interest to students of mammalian evolution, but remains poorly understood because of a poor early fossil record. Here we describe the oldest well-dated hystricognathous rodents from an earliest late Eocene (?37 Ma) fossil locality in the Fayum Depression of northern Egypt. These taxa exhibit a combination of primitive and derived features, the former shared with Asian “baluchimyine” rodents, and the latter shared with Oligocene phiomorphs and caviomorphs. Phylogenetic analysis incorporating morphological, temporal, geographic, and molecular information places the new taxa as successive sister groups of crown Hystricognathi, and supports an Asian origin for stem Hystricognathi and an Afro-Arabian origin for crown Hystricognathi, stem Hystricidae, and stem Caviomorpha. Molecular dating of early divergences within Hystricognathi, using a Bayesian “relaxed clock” approach and multiple fossil calibrations, suggests that the split between Hystricidae and the phiomorph-caviomorph clade occurred ?39 Ma, and that phiomorphs and caviomorphs diverged ?36 Ma. These results are remarkably congruent with our phylogenetic results and the fossil record of hystricognathous rodent evolution in Afro-Arabia and South America.

Sallam, Hesham M.; Seiffert, Erik R.; Steiper, Michael E.; Simons, Elwyn L.

2009-01-01

229

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

PubMed

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. PMID:24441712

Mayr, Gerald; De Pietri, Vanesa L

2014-02-01

230

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

NASA Astrophysics Data System (ADS)

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.

Mayr, Gerald; De Pietri, Vanesa L.

2014-02-01

231

Fossil energy review  

SciTech Connect

The Fossil Energy Review provides an update of key events in the Department of Energy's Fossil Energy Program. This issue contains topics relating to: clean coal technology; fossil energy research; and petroleum reserves. (JEF)

Not Available

1989-01-01

232

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

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.

Cuffey, R.J. (Pennsylvania State Univ., University Park (USA)); Pachut, J.F. (Indiana Univ.-Purdue Univ., Indianapolis (USA))

1990-12-01

233

Modern pollen–vegetation relationships in the Champsaur valley (French Alps) and their potential in the interpretation of fossil pollen records of past cultural landscapes  

Microsoft Academic Search

This study is an attempt to evaluate the relationships between the vegetation and the modern pollen rain as a contribution to palaeoecological research. Pollen analysis of surface moss polsters and floristic records has been undertaken for 51 sampling points distributed all over the study area (Champsaur valley, Hautes-Alpes, France), within different vegetation and land-use types and along a west–east altitudinal

Mona Court-Picon; Alexandre Buttler; Jacques-Louis de Beaulieu

2005-01-01

234

Ancient sun: fossil record in the earth, moon and meteorites. Proceedings of the Conference, Boulder, CO, October 16-19, 1979  

SciTech Connect

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.

Pepin, R.O.; Eddy, J.A.; Merrill, R.B.

1980-01-01

235

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)

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.

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

1980-01-01

236

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

SciTech Connect

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.

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

1985-01-01

237

Fossils, Rocks, and Time  

NSDL National Science Digital Library

This on-line book, published by the United States Geological Survey (USGS), discusses the use of fossils in determining the age of rocks. The publication covers how to place events in correct temporal order, a description of the geologic time scale, the use of fossils to indicate rock ages, the law of fossil succession, index fossils, and radioactive dating.

238

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

PubMed Central

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.

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

2014-01-01

239

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)

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.

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

2013-12-01

240

The oldest Asian record of Anthropoidea  

PubMed Central

Undisputed anthropoids appear in the fossil record of Africa and Asia by the middle Eocene, about 45 Ma. Here, we report the discovery of an early Eocene eosimiid anthropoid primate from India, named Anthrasimias, that extends the Asian fossil record of anthropoids by 9–10 million years. A phylogenetic analysis of 75 taxa and 343 characters of the skull, postcranium, and dentition of Anthrasimias and living and fossil primates indicates the basal placement of Anthrasimias among eosimiids, confirms the anthropoid status of Eosimiidae, and suggests that crown haplorhines (tarsiers and monkeys) are the sister clade of Omomyoidea of the Eocene, not nested within an omomyoid clade. Co-occurence of Anthropoidea, Omomyoidea, and Adapoidea makes it evident that peninsular India was an important center for the diversification of primates of modern aspect (euprimates) in the early Eocene. Adaptive reconstructions indicate that early anthropoids were mouse–lemur-sized (?75 grams) and consumed a mixed diet of fruit and insects. Eosimiids bear little adaptive resemblance to later Eocene-early Oligocene African Anthropoidea.

Bajpai, Sunil; Kay, Richard F.; Williams, Blythe A.; Das, Debasis P.; Kapur, Vivesh V.; Tiwari, B. N.

2008-01-01

241

Make a Fossil!  

NSDL National Science Digital Library

In this activity, make your own fossils using a shell, preferably with an interesting texture and strong edges. Use Plaster of Paris to create a mold fossil. This activity guide includes a step-by-step instructional video.

Center, Saint L.

2013-01-17

242

THE FOSSIL HISTORY OF THE LEGUMINOSAE: PHYLOGENETIC AND BIOGEOGRAPHIC IMPLICATIONS  

Microsoft Academic Search

his paper summarizes the lileralure dealing with systematic and biogeographic as~eLls orlhe fossil record oflhe ugllmLnosae II addresses the implications oflhe fossil recon.! wil h respecl to i) structural evolution within the family, ii) pattern and timing of lhvers,licallon in Ihe Lcguminosae, iii) biogeographic history, and iv) cU!Tent.hypotheses of phylogenelic relauonships within the family. The early fossil record of the

PATRICK S HERENDEEN; WILLIAM L CREPET; DAVID L DILCHER

243

Overcoming Fossilized English.  

ERIC Educational Resources Information Center

Causes of language fossilization and ways to overcome it are considered. Fossilization is the relatively permanent incorporation of incorrect linguistic forms into a person's second language competence. The discussion is focused on fossilization of incorrect syntactical rules, based on experiences with learners of English as a second language at…

Graham, Janet G.

244

Mass Extinctions and the Fossil Record  

NSDL National Science Digital Library

Students write a short essay that compares the Permo-Triassic (Permo is short for Permian) mass extinction with the Cretaceous-Tertiary (Tertiary is the beginning of the Cenozoic) mass extinction. The use online resources and their textbooks as source material for their essay. Students must include information about the magnitude of the extinction events. Additionally students describe the groups of organisms that were impacted by the event. Students discuss the cause(s) of each the extinction event and compare the different causes. They explain how the cause impacted the different groups of organisms or why those particular groups were impacted. The discussion must include some of the organisms that never recovered from the extinction.

Heise, Elizabeth

245

The Proterozoic Fossil Record of Heterotrophic Eukaryotes  

Microsoft Academic Search

Acknowledgments,................ ................ ................ .., 15, References . ............... ................ ................ ....... 15, 1.,INTRODUCTION Nutritional modes ,of eukaryotes ,can be divided ,into two ,types: autotrophy, where the organism makes its own food via photosynthesis; and heterotrophy, where the organism gets its food from the environment, either bytaking up dissolved organics (osmotrophy), or by ingesting particulate organic matter (phagotrophy). Heterotrophs dominate ,modern

Susannah M. Porter

246

Globular cluster formation - The fossil record  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

247

Fossil Record of Precambrian Life on Land  

NASA Technical Reports Server (NTRS)

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.

Knauth, Paul

2000-01-01

248

Physical Characteristics of Places: The Fossil Record  

NSDL National Science Digital Library

This lesson asks students to consider how the movement of tectonic plates alters the physical characteristics of places over geologic time. They investigate how climate has changed in specific world regions since the time of the dinosaurs and write paragraphs explaining their findings.

2001-01-01

249

Oldest fossil record of gliding in rodents  

Microsoft Academic Search

EOMYIDAE is an extinct family of rodents with a wide distribution in North America, Europe and Asia1-3. Of the modern rodent groups, eomyids are most closely related to New World pocket mice (heteromyids) and pocket gophers (geomyids)4. Eomyids occurred from the late Eocene through the Pliocene, spanning a time period of about 40 million years. From Europe alone, 11 genera

G. Storch; B. Engesser; M. Wuttke

1996-01-01

250

Determinants of extinction in the fossil record  

Microsoft Academic Search

The causes of mass extinctions and the nature of biological selectivity at extinction events are central questions in palaeobiology. It has long been recognized, however, that the amount of sedimentary rock available for sampling may bias perceptions of biodiversity and estimates of taxonomic rates of evolution. This problem has been particularly noted with respect to the principal mass extinctions. Here

Shanan E. Peters; Michael Foote

2002-01-01

251

Fossils of Kentucky  

NSDL National Science Digital Library

Information on Kentucky fossils is organized by type, age, and region. General fossil facts are given, and there are out-of-print technical reports available at this site. A fossil identification key helps users identify unknown fossils by shape or by descriptive terms. A Geologic and Paleontologic Cookbook offers directions for creating edible models that illustrate prehistoric and other Earth Science concepts (such as trilobite cookies and layer-cake geology). There are links to more K-12 activities and other fossil websites.

252

Summary statistics for fossil spider species taxonomy  

PubMed Central

Abstract Spiders (Araneae) are one of the most species-rich orders on Earth today, and also have one of the longest geological records of any terrestrial animal groups, as demonstrated by their extensive fossil record. There are currently around 1150 described fossil spider species, representing 2.6% of all described spiders (i.e. extinct and extant). Data for numbers of fossil and living spider taxa described annually (and various other metrics for the fossil taxa) were compiled from current taxonomic catalogues. Data for extant taxa showed a steady linear increase of approximately 500 new species per year over the last decade, reflecting a rather constant research activity in this area by a large number of scientists, which can be expected to continue. The results for fossil species were very different, with peaks of new species descriptions followed by long troughs, indicating minimal new published research activity for most years. This pattern is indicative of short bursts of research by a limited number of authors. Given the frequent discovery of new fossil deposits containing spiders, a wealth of new material coming to light from previously worked deposits, and the application of new imaging techniques in palaeoarachnology that allow us to extract additional data from historical specimens, e.g. X-ray computed tomography, it is important not only to ensure a sustained research activity on fossil spiders (and other arachnids) through training and enthusing the next generation of palaeoarachnologists, but preferably to promote increased research and expertise in this field.

Penney, David; Dunlop, Jason A.; Marusik, Yuri M.

2012-01-01

253

Phylogeny and biogeography of African Murinae based on mitochondrial and nuclear gene sequences, with a new tribal classification of the subfamily  

PubMed Central

Background Within the subfamily Murinae, African murines represent 25% of species biodiversity, making this group ideal for detailed studies of the patterns and timing of diversification of the African endemic fauna and its relationships with Asia. Here we report the results of phylogenetic analyses of the endemic African murines through a broad sampling of murine diversity from all their distribution area, based on the mitochondrial cytochrome b gene and the two nuclear gene fragments (IRBP exon 1 and GHR). Results A combined analysis of one mitochondrial and two nuclear gene sequences consistently identified and robustly supported ten primary lineages within Murinae. We propose to formalize a new tribal arrangement within the Murinae that reflects this phylogeny. The diverse African murine assemblage includes members of five of the ten tribes and clearly derives from multiple faunal exchanges between Africa and Eurasia. Molecular dating analyses using a relaxed Bayesian molecular clock put the first colonization of Africa around 11 Mya, which is consistent with the fossil record. The main period of African murine diversification occurred later following disruption of the migration route between Africa and Asia about 7–9 Mya. A second period of interchange, dating to around 5–6.5 Mya, saw the arrival in Africa of Mus (leading to the speciose endemic Nannomys), and explains the appearance of several distinctive African lineages in the late Miocene and Pliocene fossil record of Eurasia. Conclusion Our molecular survey of Murinae, which includes the most complete sampling so far of African taxa, indicates that there were at least four separate radiations within the African region, as well as several phases of dispersal between Asia and Africa during the last 12 My. We also reconstruct the phylogenetic structure of the Murinae, and propose a new classification at tribal level for this traditionally problematic group.

2008-01-01

254

Fossil bandicoots (marsupialia, peramelidae) and environmental change during the pleistocene on the darling downs, Southeastern Queensland, Australia  

Microsoft Academic Search

Systematic collecting from fluviatile Pleistocene fossil deposits of the Darling Downs, southeastern Queensland, Australia, has led to an increase in the region's fossil record of bandicoots. Isoodon obesulus, Perameles bougainville and P. nasuta are reported for the first time in the Darling Downs fossil record. Accelerator mass spectrometry C dates based on charcoal from bandicoot fossil?bearing stratigraphic horizons indicates deposition

Gilbert J. Price

2005-01-01

255

Biogeochemical record of ancient humans  

Microsoft Academic Search

The geochemical record of humans extends back to their first appearance on the landscape some one million years ago. Biochemical remains from humans, however, can be found in the fossil record for only the last 100?000 years, and even then these remains are only fragmentary. Stable carbon and nitrogen isotopes in organic and inorganic fossils of humans are providing a

Marilyn L Fogel; Noreen Tuross; Beverly J Johnson; Gifford H Miller

1997-01-01

256

New Fossils From Ethiopia Open a Window on Africa's "Missing Years"  

NSF Publications Database

... New Fossils From Ethiopia Open a Window on Africa's "Missing Years" Image: An example of the ... extremely rich fossil record encased in East Africa's rocks," says Rich Lane, program director in ...

257

Sustainable Fossil Fuels  

Microsoft Academic Search

More and more people believe we must quickly wean ourselves from fossil fuels - oil, natural gas and coal - to save the planet from environmental catastrophe, wars and economic collapse. Professor Jaccard argues that this view is misguided. We have the technological capability to use fossil fuels without emitting climate-threatening greenhouse gases or other pollutants. The transition from conventional

Mark Jaccard

258

Becoming a Fossil  

NSDL National Science Digital Library

This text and accompanying video provide an overview of how fossils are formed and preserved. A video clip from the NOVA television program, 'In Search of Human Origins', shows how the famous early hominid 'Lucy' might have died and been fossiliized, and points out the rare set of circumstances that must occur for an organism to be fossilized. Questions for discussion are included.

2005-01-01

259

Trace Fossil Image Database  

NSDL National Science Digital Library

This database from Emory University consists of images and basic information concerning trace fossils photographed by Anthony Martin. Included in this information is the formation, age, and locality of the specimen if known. Many of the images were originally photographed while in the field, and each type of trace fossil has numerous examples to browse through.

Martin, Anthony; University, Emory

260

Restoring Fossil Creek  

ERIC Educational Resources Information Center

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…

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

2004-01-01

261

Fossil Dig Site  

NSDL National Science Digital Library

In this activity (located on page 5 of PDF), learners work in groups to create dig sites for display. Learners arrange dry, uncooked pasta "bones" to resemble dinosaur fossils on a foam tray of wet soil. Use this activity to introduce learners to dinosaur anatomy, dig sites, fossils, and paleontology in general.

Museum, Chicago C.

2011-01-01

262

Dinosaur Footprints & Fossils  

NSDL National Science Digital Library

In this activity, early learners simulate fossil prints in play dough or clay. Using plastic dinosaur feet to make footprints on their âmudâ (much as dinosaurs walked around their habitat) and harvest items (leaves, corn, twigs, acorns) to make impressions, learners simulate fossil prints. This resource includes open-ended discussion questions to encourage reflection.

Omsi

2004-01-01

263

Make a Model Fossil  

NSDL National Science Digital Library

This activity is a combination outdoor/indoor lab where students will collect natural materials from the environment and use them to create both a mold and cast model of a fossil. Students will learn how a fossil is formed and why scientists use models to help them understand how things work and develop.

264

African Oral Tradition Literacy.  

ERIC Educational Resources Information Center

Presents the basic principles of two systems for notating African music and dance: Labanotation (created to record and analyze movements) and Greenotation (created to notate musical instruments of Africa and to parallel Labanotation whereby both music and dance are incorporated into one integrated score). (KH)

Green, Doris

1985-01-01

265

A report on biocompounds from palm fossil of India  

PubMed Central

The occurrence of a large number of fossil woods having resemblance in anatomical features with the modern palm genus, Phoenix L in Deccan Intertrappean fossil flora of Maastrichtian-Danian age (i. e. Late Cretaceous and Earliest Tertiary (65-67 my)) indicates the most primitive record of date palm. Present discovery of biocompounds from fossil wood of Phoenix collected from Deccan Intertrappean having affinity with the biocompounds known from modern plant further exemplify the earliest documentation of Phoenix in Indian peninsula.

Sharma, Dinesh Chandra; Khan, Mohd Sajid; Khan, M Salman; Srivastava, Rashmi; Srivastava, Ashwini Kumar; Shukla, Ritu

2014-01-01

266

Neanderthals: fossil evidence and DNA.  

PubMed

Neanderthals inhabited Western Eurasia from approximately 300 to 30 thousand years ago (ka). They are distinguished by a unique combination of anatomical traits, and are commonly associated with Middle Paleolithic lithic industries. Current consensus among paleoanthropologists is that they represented a separate Eurasian human lineage, which evolved in isolation from the rest of the Old World and which shared a common ancestor with modern humans in the Middle Pleistocene. It is thought that some aspects of the distinctive Neanderthal anatomy evolved in response to selection related to the extreme cold of the European glacial cycles. Nevertheless, genetic drift seems to be partially responsible for the evolution of these traits. The last appearance of Neanderthals in the fossil record ca. 30 ka BP dates a few millennia after the first appearance of modern humans in Europe. The retrieval of ancient mitochondrial and, more recently, nuclear DNA from Neanderthal fossil puts us in the unique position to combine fossil with genetic evidence to address questions about their evolution, paleobiology and eventual fate. PMID:21957644

Harvati, Katerina

2011-01-01

267

Geoconservation - a southern African and African perspective  

NASA Astrophysics Data System (ADS)

In contrast to Europe, where geoconservation is actively pursued in most countries and where two international symposia on this subject have been staged in 1991 and 1996, geoconservation in Africa has indeed a very poor record. Considering the wealth of outstanding geological sites and the importance African stratigraphy has within the global geological record, pro-active geoconservation on this continent has not featured very prominently to date. In the interest of science, education and tourism, unique and typical geosites need to be identified, catalogued, and prioritised with the aim being their protection. Most African countries do not have vibrant non-governmental organisations such as a strong geological society, which could drive projects like geoconservation, or strong support from the private sector for environmental work. Here, a case is made for the role that established National Geological Surveys, some of which are already involved with retroactive environmental geological work, could play in the forefront of pro-active geoconservation and site protection.

Reimold, Wolf Uwe

1999-10-01

268

Eumetazoan fossils in terminal Proterozoic phosphorites?  

PubMed Central

Phosphatic sedimentary rocks preserve a record of early animal life different from and complementary to that provided by Ediacaran fossils in terminal Proterozoic sandstones and shales. Phosphorites of the Doushantuo Formation, South China, contain eggs, egg cases, and stereoblastulae that document animals of unspecified phylogenetic position; small fossils containing putative spicules may specifically record the presence of sponges. Microfossils recently interpreted as the preserved gastrulae of cnidarian and bilaterian metazoans can alternatively be interpreted as conventional algal cysts and/or egg cases modified by diagenetic processes known to have had a pervasive influence on Doushantuo phosphorites. Regardless of this interpretation, evidence for Doushantuo eumetazoans is provided by millimeter-scale tubes that display tabulation and apical budding characteristic of some Cnidaria, especially the extinct tabulates. Like some Ediacaran remains, these small, benthic, colonial fossils may represent stem-group eumetazoans or stem-group cnidarians that lived in the late Proterozoic ocean.

Xiao, Shuhai; Yuan, Xunlai; Knoll, Andrew H.

2000-01-01

269

Small Mid-Pleistocene Hominin Associated with East African Acheulean Technology  

Microsoft Academic Search

Hominin fossils from the African mid-Pleistocene are rare despite abundant Acheulean tools in Africa and apparently African-derived hominins in Eurasia between 1.0 and 0.5 million years ago (Ma). Here we describe an African fossil cranium constrained by 40Ar\\/39Ar analyses, magnetostratigraphy, and sedimentary features to 0.97 to 0.90 Ma, and stratigraphically associated with Acheulean handaxes. Although the cranium represents possibly the

Richard Potts; Anna K. Behrensmeyer; Alan Deino; Peter Ditchfield; Jennifer Clark

2004-01-01

270

Nonrandom decay of chordate characters causes bias in fossil interpretation  

Microsoft Academic Search

Exceptional preservation of soft-bodied Cambrian chordates provides our only direct information on the origin of vertebrates. Fossil chordates from this interval offer crucial insights into how the distinctive body plan of vertebrates evolved, but reading this pre-biomineralization fossil record is fraught with difficulties, leading to controversial and contradictory interpretations. The cause of these difficulties is taphonomic: we lack data on

Robert S. Sansom; Sarah E. Gabbott; Mark A. Purnell

2010-01-01

271

Availability of Fossil-Fired Steam Power Plants.  

National Technical Information Service (NTIS)

Fossil-fired power plants of 600 MW or larger constitute a major proportion of the baseload capacity in the country but have the poorest availability record of any size category. Two primary aims of the EPRI Fossil Plant Performance and Reliability Progra...

D. Anson

1977-01-01

272

An interesting new fossil dragonfly (Anisoptera: Libellulidae: \\  

Microsoft Academic Search

Summary A new dragonfly species, Parabrachydiplax miocenica n. gen. n. sp. (Anisoptera: Libelluli- dae), is described from the early Middle Miocene of Heggbach in southern Germany. The holotype was collected by the priest J. PROBST in 1865 and represents the earliest record of fossil insect remains from the Upper Freshwater Molasse of Baden-Württemberg. The phylo- genetic position of this new

Volker J. Sach

273

Molecules, morphometrics and new fossils provide an integrated view of the evolutionary history of Rhinopomatidae (Mammalia: Chiroptera)  

PubMed Central

Background The Rhinopomatidae, traditionally considered to be one of the most ancient chiropteran clades, remains one of the least known groups of Rhinolophoidea. No relevant fossil record is available for this family. Whereas there have been extensive radiations in related families Rhinolophidae and Hipposideridae, there are only a few species in the Rhinopomatidae and their phylogenetic relationship and status are not fully understood. Results Here we present (a) a phylogenetic analysis based on a partial cytochrome b sequence, (b) new fossils from the Upper Miocene site Elaiochoria 2 (Chalkidiki, Greece), which represents the first appearance datum of the family based on the fossil record, and (c) discussion of the phylogeographic patterns in both molecular and morphological traits. We found deep divergences in the Rhinopoma hardwickii lineage, suggesting that the allopatric populations in (i) Iran and (ii) North Africa and the Middle East should have separate species status. The latter species (R. cystops) exhibits a shallow pattern of isolation by distance (separating the Middle East and the African populations) that contrasts with the pattern of geographic variation in the morphometrical traits. A deep genetic gap was also found in Rhinopoma muscatellum (Iran vs. Yemen). We found only minute genetic distance between R. microphyllum from the Levant and India, which fails to support the sub/species distinctness of the Indian form (R. microphyllum kinneari). Conclusion The mtDNA survey provided phylogenetic tree of the family Rhinopomatidae for the first time and revealed an unexpected diversification of the group both within R. hardwickii and R. muscatellum morphospecies. The paleobiogeographic scenario compiled in respect to molecular clock data suggests that the family originated in the region south of the Eocene Western Tethyan seaway or in India, and extended its range during the Early Miocene. The fossil record suggests a Miocene spread into the Mediterranean region, followed by a post-Miocene retreat. Morphological analysis compared with genetic data indicates considerable phenotypic plasticity in this group.

Hulva, Pavel; Horacek, Ivan; Benda, Petr

2007-01-01

274

CLANIMAE: Climatic and Anthropogenic Impacts on African Ecosystems  

NASA Astrophysics Data System (ADS)

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.

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

2009-04-01

275

Fossil Halls: Curator Videos  

NSDL National Science Digital Library

Part of a larger virtual tour of the Museum's famed Fossil Halls, this Web site has links to a library of 22 videos highlighting specific exhibits in the hall. The videos are available in broadband and dial-up versions.

276

Advances in Fossil Energy.  

National Technical Information Service (NTIS)

The Morgantown Technology Center is a US Department of Energy fossil fuel research center. It is reponsible for conducting research and development to extract, convert, and utilize coal, oil, and gas in an environmentally acceptable manner. METC performs ...

1984-01-01

277

Minerals and Fossils  

NSDL National Science Digital Library

This site is dedicated to rock and mineral collecting. It contains information for worldwide mineral and fossil collectors with articles, mineral photos, videos, a search engine and free classified ads.

Mineraltown.com

278

Fossil energy program  

NASA Astrophysics Data System (ADS)

The progress made during the period from July 1 through September 30 for the Oak Ridge National Laboratory research and development projects in support of the increased utilization of coal and other fossil fuels as sources of clean energy is reported. The following topics are discussed: coal conversion development, chemical research and development, materials technology, fossil energy materials program, liquefaction projects, component development, process analysis, environmental control technology, atmospheric fluidized bed combustion, underground coal gasification, coal preparation and waste utilization.

McNeese, L. E.

1981-12-01

279

African Fractals  

NSDL National Science Digital Library

The Center for Cultural Design presents this site on African Fractals. Fractals are both visually interesting and mathematically relevant patterns that repeat themselves at different scales. The site includes an interactive applet that helps students understand fractals as applied to geometric concepts. Examples from African culture are included, which makes the site an interesting interdisciplinary learning tool. Be sure to watch Ron Eglash's presentation on African fractals, which is linked to on the front page of the website.

2011-01-03

280

Modulation of Fossil Fuel Production by Global Temperature Variations, 2.  

National Technical Information Service (NTIS)

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 re...

B. W. Rust F. J. Crosby

1994-01-01

281

Genetic and Fossil Evidence for the Origin of Modern Humans.  

ERIC Educational Resources Information Center

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)

Stringer, C. B.; Andrews, P.

1988-01-01

282

Fossil Simulation in the Classroom  

ERIC Educational Resources Information Center

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)

Hoehn, Robert G.

1977-01-01

283

Pliocene northeast African vegetation change  

NASA Astrophysics Data System (ADS)

Plant leaf wax molecular fossils have yielded key insights into forest-grassland transitions in northeast Africa. The stable carbon isotopic composition (?13C) of sedimentary leaf waxes (including n-alkanoic acids) records variations in the proportions of plants using the C3 (Calvin-Benson) pathway including trees, most shrubs and cool-season grasses versus the C4 (Hatch-Slack) pathway including warm-season grasses and sedges. Here we apply this technique to marine sediments from the Gulf of Aden to characterize northeast African environmental variability during the Pliocene. We sample DSDP Site 231 integrating 3kyr intervals to generate a high-resolution reconstruction spanning 3.7-5.3Ma. The ?13C compositions of downcore C30 n-alkanoic acid analyses average -27.5‰ (?=1.2, n=177), ranging between -30.2 to -24.3‰ with repeated oscillations in the proportions of C4 biomass, presumably corresponding to the eccentricity and precessional modulation of insolation acting on monsoonal precipitation. Although ?13C values cannot be uniquely translated to C4 biomass given the spread in the C3 'endmember', we find complimentary evidence for proportions of C4 biomass from the isotopic spread of the n-alkanoic homologues (n-C28 to n-C32). Comparison to pollen data indicates that at times of low ?13C values, complete forest cover remains unlikely given the presence of grass pollen - taken together these records indicate the presence of C3 grasses. By evaluating our longer record from this site, as well as the terrestrial soil carbonate record, we find the Pliocene has low C4 proportions in comparison to higher proportions in Pleistocene and even late Miocene times. Intriguingly this drop in C4 plant biomass may correspond to a period of elevated atmospheric pCO2. Our ongoing reconstructions are of interest both for constraining environments of hominin evolution and tropical climate variability prior to the onset of Northern Hemisphere Glaciation, in particular during this Pliocene time period of interest as a 'modest greenhouse' world.

Liddy, H.; Sieracki, A.; Feakins, S. J.

2012-12-01

284

The thermal history of human fossils and the likelihood of successful DNA amplification  

Microsoft Academic Search

Recent success in the amplification of ancient DNA (aDNA) from fossil humans has led to calls for further tests to be carried out on similar material. However, there has been little systematic research on the survival of DNA in the fossil record, even though the environment of the fossil is known to be of paramount importance for the survival of

Colin I. Smith; Andrew T. Chamberlain; Michael S. Riley; Chris Stringer; Matthew J. Collins

285

Trace Fossil Analysis  

NASA Astrophysics Data System (ADS)

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

Hasiotis, Stephen T.

2009-05-01

286

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)

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.

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

2014-05-01

287

Plio-pleistocene African climate  

Microsoft Academic Search

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

P. B. deMenocal

1995-01-01

288

Plio-Pleistocene African Climate  

Microsoft Academic Search

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

Peter B. Demenocal

1995-01-01

289

Archives of African American Music and Culture  

NSDL National Science Digital Library

Indiana University's Archives of African American Music and Culture (AAAMC) contains a searchable and browsable collection of bibliographic records of its over 2500 sound recordings and 200 video cassettes, as well as a searchable-only collection of bibliographic records of its photographic archive. It also contains information about its Undine Smith Moore Collection of Original Scores and Manuscripts of Black Composers. AAAMC's usage policy is on the home page, as well as selected links to other African American Internet resources.

Culture., Indiana U.

1998-01-01

290

Further records of Amphipoda from Baltic Eocene amber with first evidence of prae-copulatory behaviour in a fossil amphipod and remarks on the taxonomic position of Palaeogammarus Zaddach, 1864.  

PubMed

Two pieces of Baltic amber with amphipod inclusions were studied. One of them contained approximately twenty individuals identified as belonging to the extinct genus Palaeogammarus and described as P. debroyeri sp. nov. Interestingly, among the individuals there are two pairs preserved in an evident prae-copula position. This is the first finding of such mating behaviour in fossil amphipods. Based on this behavioural trait and on the observed morphological features, we conclude that the genus Palaeogammarus should be placed in Gammaridae and not in Crangonyctidae. The second amber piece contains two individuals identified as belonging to the still extant genus Synurella and described as S. aliciae sp. nov.  PMID:24870911

Ja?d?ewski, Krzysztof; Grabowski, Micha?; Kupryjanowicz, Janusz

2014-01-01

291

What is a Fossil?  

NSDL National Science Digital Library

In this activity about dinosaurs, learners explore how and why fossils form. First, learners are introduced to dinosaur fossils by reading the book "Bones, Bones, Dinosaur Bones" by Byron Barton. Then, learners make impressions in clay using a seashell, pennies, dinosaur teeth and other items. Next, learners make dinosaur tracks in the clay as they "walk" plastic models across the soft clay. Learners also use sponges pre-cut in the shape of dinosaur feet to make more tracks. This activity is featured on page 29 of the "Dinosphere" unit of study for K-2 learners.

Crosslin, Rick; Fortney, Mary; Indianapolis, The C.

2004-01-01

292

FossilPlot  

NSDL National Science Digital Library

This spreadsheet application allows users to make graphs of the diversity and stratigraphic ranges of Phanerozoic marine animals. FossilPlot uses the compendium of marine animal genera compiled by J.J. Sepkoski and his associates at the University of Chicago, from 'A compendium of fossil marine animal genera', found in Bulletins of American Paleontology, v. 363, p. 1-560. The application operates in Microsoft Excel for PC or Mac, and is free for users to download. A slide show on how to use the application (also downloadable) is provided.

293

A new type of Precambrian megascopic fossils: the Jinxian biota from northeastern China  

Microsoft Academic Search

Precambrian fossils are crucial for our understanding of the evolution of early organisms. Megascopic body fossils are more\\u000a important because they potentially represent macroorganisms. However, the Precambrian fossil record is sparse and dominated\\u000a by microfossils and microbial structures. Here we show a new type of megascopic fossils recovered from the Xingmincun Formation\\u000a (probably Neoproterozoic age), northeastern China. The specimens are

Xingliang Zhang; Hong Hua; Joachim Reitner

2006-01-01

294

Experimental taphonomy shows the feasibility of fossil embryos  

PubMed Central

The recent discovery of apparent fossils of embryos contemporaneous with the earliest animal remains may provide vital insights into the metazoan radiation. However, although the putative fossil remains are similar to modern marine animal embryos or larvae, their simple geometric forms also resemble other organic and inorganic structures. The potential for fossilization of animals at such developmental stages and the taphonomic processes that might affect preservation before mineralization have not been examined. Here, we report experimental taphonomy of marine embryos and larvae similar in size and inferred cleavage mode to presumptive fossil embryos. Under conditions that prevent autolysis, embryos within the fertilization envelope can be preserved with good morphology for sufficiently long periods for mineralization to occur. The reported fossil record exhibits size bias, but we show that embryo size is unlikely to be a major factor in preservation. Under some conditions of death, fossilized remains will not accurately reflect the cell structure of the living organism. Although embryos within the fertilization envelope have high preservation potential, primary larvae have negligible preservation potential. Thus the paleo-embryological record may have strong biases on developmental stages preserved. Our data provide a predictive basis for interpreting the fossil record to unravel the evolution of ontogeny in the origin of metazoans.

Raff, Elizabeth C.; Villinski, Jeffrey T.; Turner, F. Rudolf; Donoghue, Philip C. J.; Raff, Rudolf A.

2006-01-01

295

Old fossils-young species: evolutionary history of an endemic gastropod assemblage in Lake Malawi  

PubMed Central

Studies on environmental changes provide important insights into modes of speciation, into the (adaptive) reoccupation of ecological niches and into species turnover. Against this background, we here examine the history of the gastropod genus Lanistes in the African Rift Lake Malawi, guided by four general evolutionary scenarios, and compare it with patterns reported from other endemic Malawian rift taxa. Based on an integrated approach using a mitochondrial DNA phylogeny and a trait-specific molecular clock in combination with insights from the fossil record and palaeoenvironmental data, we demonstrate that the accumulation of extant molecular diversity in the endemic group did not start before approximately 600?000 years ago from a single lineage. Fossils of the genus from the Malawi Rift, however, are over one million years older. We argue that severe drops in the lake level of Lake Malawi in the Pleistocene offer a potential explanation for this pattern. Our results also challenge previously established phylogenetic relationships within the genus by revealing parallel evolution and providing evidence that the endemic Lanistes species are not restricted to the lake proper but are present throughout the Malawi Rift.

Schultheiss, Roland; Van Bocxlaer, Bert; Wilke, Thomas; Albrecht, Christian

2009-01-01

296

Fossil Halls: Virtual Tours  

NSDL National Science Digital Library

Part of a larger online look at the Museum's famed Fossil Halls, this Web site has an overview of the halls' many highlights and four QuickTime virtual tours:Hall of Saurischian Dinosaurs, Hall of Ornithischian Dinosaurs, Hall of Primitive Mammals, and Hall of Advanced Mammals.

297

Fossil Halls: Cladistics  

NSDL National Science Digital Library

Part of a larger virtual tour of the Museum's famed Fossil Halls, this Web site has an overview explaining the cladistic method of scientific analysis as well as how to read cladograms. It answers the following questions: What is the best way to reconstruct evolutionary history? What is a cladogram? What is an advanced feature? Why use cladistics?

298

Fossilization of Acidophilic Microorganisms  

Microsoft Academic Search

This study examines fossil microorganisms found in iron-rich deposits in an extreme acidic environment, the Tinto River in SW Spain. Both electron microscopy (SEM and TEM) and non-destructive in situ microanalytical techniques (EDS, EMP and XPS) were used to determine the role of permineralization and encrustation in preserving microorganisms forming biofilms in the sediments. Unicellular algae were preserved by silica

Virginia Souza-Egipsy; Angeles Aguilera; Eva Mateo-Martí; José Angel Martín-Gago; Ricardo Amils

2010-01-01

299

Rethinking Fossil Fuels  

NSDL National Science Digital Library

Climate change and fossil fuel use are connected. It would serve the world well to: begin a moratorium on coal-fired power plants; explore and use renewable energy; insist on immediate action from world governments; and penalize industries putting excess CO2 into the atmosphere.

James Hansen (NASA Goddard Institute for Space Studies;)

2008-09-09

300

Genetic variants that confer resistance to malaria are associated with red blood cell traits in African-Americans: an electronic medical record-based genome-wide association study.  

PubMed

To identify novel genetic loci influencing interindividual variation in red blood cell (RBC) traits in African-Americans, we conducted a genome-wide association study (GWAS) in 2315 individuals, divided into discovery (n = 1904) and replication (n = 411) cohorts. The traits included hemoglobin concentration (HGB), hematocrit (HCT), RBC count, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC). Patients were participants in the electronic MEdical Records and GEnomics (eMERGE) network and underwent genotyping of ~1.2 million single-nucleotide polymorphisms on the Illumina Human1M-Duo array. Association analyses were performed adjusting for age, sex, site, and population stratification. Three loci previously associated with resistance to malaria-HBB (11p15.4), HBA1/HBA2 (16p13.3), and G6PD (Xq28)-were associated (P ? 1 × 10(-6)) with RBC traits in the discovery cohort. The loci replicated in the replication cohort (P ? 0.02), and were significant at a genome-wide significance level (P < 5 × 10(-8)) in the combined cohort. The proportions of variance in RBC traits explained by significant variants at these loci were as follows: rs7120391 (near HBB) 1.3% of MCHC, rs9924561 (near HBA1/A2) 5.5% of MCV, 6.9% of MCH and 2.9% of MCHC, and rs1050828 (in G6PD) 2.4% of RBC count, 2.9% of MCV, and 1.4% of MCH, respectively. We were not able to replicate loci identified by a previous GWAS of RBC traits in a European ancestry cohort of similar sample size, suggesting that the genetic architecture of RBC traits differs by race. In conclusion, genetic variants that confer resistance to malaria are associated with RBC traits in African-Americans. PMID:23696099

Ding, Keyue; de Andrade, Mariza; Manolio, Teri A; Crawford, Dana C; Rasmussen-Torvik, Laura J; Ritchie, Marylyn D; Denny, Joshua C; Masys, Daniel R; Jouni, Hayan; Pachecho, Jennifer A; Kho, Abel N; Roden, Dan M; Chisholm, Rex; Kullo, Iftikhar J

2013-07-01

301

African Arts  

NSDL National Science Digital Library

In this two-day activity (on pages 16-22), learners use a process like that of the Yoruba people of Nigeria to create an African symbol on cloth. Learners first make cassava gel, then paint decorative symbols on cloth, and finally dye it. Learners examine the significance of symbols in African culture and communication, and the use of natural plant products for human projects.

Museum, University O.; Nebraska Cooperative Extension 4-H Youth Development

2001-01-01

302

Sustainability of Fossil Fuels  

NASA Astrophysics Data System (ADS)

For a sustainable world economy, energy is a bottleneck. Energy is at the basis of a modern, technological society, but unlike materials it cannot be recycled. Energy or more precisely "negentropy" (the opposite of entropy) is always consumed. Thus, one either accepts the use of large but finite resources or must stay within the limits imposed by dilute but self-renewing resources like sunlight. The challenge of sustainable energy is exacerbated by likely growth in world energy demand due to increased population and increased wealth. Most of the world still has to undergo the transition to a wealthy, stable society with the near zero population growth that characterizes a modern industrial society. This represents a huge unmet demand. If ten billion people were to consume energy like North Americans do today, world energy demand would be ten times higher. In addition, technological advances while often improving energy efficiency tend to raise energy demand by offering more opportunity for consumption. Energy consumption still increases at close to the 2.3% per year that would lead to a tenfold increase over the course of the next century. Meeting future energy demands while phasing out fossil fuels appears extremely difficult. Instead, the world needs sustainable or nearly sustainable fossil fuels. I propose the following definition of sustainable under which fossil fuels would well qualify: The use of a technology or resource is sustainable if the intended and unintended consequences will not force its abandonment within a reasonable planning horizon. Of course sustainable technologies must not be limited by resource depletion but this is only one of many concerns. Environmental impacts, excessive land use, and other constraints can equally limit the use of a technology and thus render it unsustainable. In the foreseeable future, fossil fuels are not limited by resource depletion. However, environmental concerns based on climate change and other environmental effects of injecting excess carbon into the environment need to be eliminated before fossil fuels can be considered sustainable. Sustainable fossil fuel use would likely rely on abundant, low-grade hydrocarbons like coal, tar, and shale. It would require a closed cycle approach in which carbon is extracted from the ground, processed for its energy content, and returned into safe and stable sinks for permanent disposal. Such sequestration technologies already exist and more advanced approaches that could maintain access to fossil energy for centuries are on the drawing boards. I will review these options and outline a pathway towards a zero emission fossil fuel based economy that could provide energy at prices comparable to those of today for several centuries. A successful implementation will depend not only on technological advances but also on the development of economic institutions that allow one to pay for the required carbon management. If done correctly the markets will decide whether renewable energy, or sustainable fossil energy provides a better choice.

Lackner, K. S.

2002-05-01

303

Cancer and African Americans  

MedlinePLUS

... life expectancy for both African American men and African American women. In 2009, African American men were 1.3 ... compared to non-Hispanic white men. In 2009, African American women were 10% less likely to have been diagnosed ...

304

Synthesizing and databasing fossil calibrations: divergence dating and beyond  

PubMed Central

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.

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

2011-01-01

305

Florissant Fossil Beds National Monument  

NSDL National Science Digital Library

This National Park Service (NPS) website contains details about Florissant Fossil Beds National Monument in Colorado. It includes details about the geological history of the monument, fossils found there, history of the area, flora and fauna, and other details. There is an education page containing curricula for K-12 classes for teaching paleontology. It contains labs, activities, games, vocabulary and fossil identification information.

306

Modulation of fossil fuel production by global temperature variations, 2  

Microsoft Academic Search

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

B. W. Rust; F. J. Crosby

1994-01-01

307

Fossil Age Estimation Model  

NSDL National Science Digital Library

In this activity (page 1 of the PDF), learners will model how paleontologists estimate the age of fossil discoveries by extracting âfossilâ playing cards from newspapers stacked in chronological order. Learners identify the âageâ of the card based on the âevidenceâ (printed date) in the surrounding pages. They then create a data table and graph and analyze their findings. Use this activity to introduce learners to paleontology and geology. Relates to the linked video, DragonflyTV GPS: Dinosaurs.

Twin Cities Public Television, Inc.

2006-01-01

308

Fossil Halls: Timelines  

NSDL National Science Digital Library

Part of a larger virtual tour of the Museum's famed Fossil Halls, this Web site allows students to travel back in time to several prehistoric points in the history of Earth. At each, they'll find a fleshed-out portrait of the period's creatures and their environment. The eight periods students will visit, some of which include more than one point-in-time snapshot, are Pleistocene, Miocene, Oligocene, Eocene, Cretaceous, Jurassic, Permian and Devonian Periods.

309

Fossil Microbes on Mars?  

NSDL National Science Digital Library

This online article, from Cosmic Horizons: Astronomy at the Cutting Edge, reports on the controversial discovery of Martian meteorite ALH84001. In 1996, a team of scientists led by David McKay of NASAâs Johnson Space Flight Center announced that they had discovered evidence for microscopic fossil life in this meteorite from Mars. From the start, the evidence was both fascinating and controversial, and to this day it remains so.

310

Coral records of interannual, century and millenium scale climate dynamics in the tropical eastern Indian Ocean  

NASA Astrophysics Data System (ADS)

Climate in the tropical eastern Indian Ocean is dominated by the Asian monsoon but is also strongly influenced by the El Niño-Southern Oscillation (ENSO) and is the core area of activity for the Indian Ocean Dipole. We examined the interaction of these climate systems over the past 7000 years using the ?18O and Sr/Ca records of 5 modern and 33 fossil corals from the Mentawai Islands, southwest Sumatra, Indonesia. The mean ?18O and Sr/Ca values of the fossil corals define a maxima in sea surface temperature (SST) and salinity at 6.5 ka, which was followed by cooling and freshening to 4.5 ka. On the seasonal scale this cooling/freshening trend is manifest as an increase in the annual SST cycle and an increase in the frequency of Indian Ocean Dipole events. This suggests a stronger southeast Monsoon causing increased Ekman upwelling along the Sumatran coast. The fossil corals record rapid warming and drying from 4.5 to 4ka. The peak of this event corresponds to the timing of a major drought recorded in African lake levels and ice cores. The period around 2ka is characterised by rapid fluctuations in mean SST but relatively stable salinity at values close to the present day warm pool conditions. This variability in SST may reflect an increase in the strength of the ENSO system after 4ka. Changes in SST and salinity recorded by the fossil corals over the past 1000 years closely match variations in solar activity, with a distinct cool and fresh period between 0.5ka and 0.4ka that corresponds with the Sp&{uml;o}rer solar minima, as well as with high lake levels in Africa. High-resolution coral records for the past 150 years allow for a detailed examination of the interactions between the Asian Monsoon, ENSO and the Indian Ocean Dipole climate systems since 1857. This record shows that large Indian Ocean Dipole events, such as observed in 1994 and 1997, have been infrequent with only two other similar-scale events recorded since 1857. More frequent and stronger Indian Ocean Dipole events in the mid-Holocene coral records appear to be connected to a stronger Asian Monsoon. There is evidence that the Asian Monsoon has been strengthening and also becoming more independent from ENSO over the past couple of decades. If the Asian Monsoon continues to strengthen, the fossil coral records indicate we may be heading towards a period of more frequent and intense Indian Ocean Dipole events.

Abram, N. J.; Gagan, M. K.; Chappell, J.; McCulloch, M. T.; Hantoro, W. S.

2003-04-01

311

Organic preservation of fossil musculature with ultracellular detail  

PubMed Central

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.

McNamara, Maria; Orr, Patrick J.; Kearns, Stuart L.; Alcala, Luis; Anadon, Pere; Penalver-Molla, Enrique

2010-01-01

312

A report on biocompounds from palm fossil of India.  

PubMed

The occurrence of a large number of fossil woods having resemblance in anatomical features with the modern palm genus, Phoenix L in Deccan Intertrappean fossil flora of Maastrichtian-Danian age (i. e. Late Cretaceous and Earliest Tertiary (65-67 my)) indicates the most primitive record of date palm. Present discovery of biocompounds from fossil wood of Phoenix collected from Deccan Intertrappean having affinity with the biocompounds known from modern plant further exemplify the earliest documentation of Phoenix in Indian peninsula. PMID:24966541

Sharma, Dinesh Chandra; Khan, Mohd Sajid; Khan, M Salman; Srivastava, Rashmi; Srivastava, Ashwini Kumar; Shukla, Ritu

2014-01-01

313

Fossilization Processes in Thermal Springs  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

314

Fossil diatoms and neogene paleolimnology  

USGS Publications Warehouse

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.

Platt, Bradbury, J.

1988-01-01

315

Improvisation in West African Musics.  

ERIC Educational Resources Information Center

Discussed is music of the sub-Sahara. Vocal, instrumental, and dance drumming from the Sudan Desert, the North Coast, East Horn, Central and West Africa, and contrapuntal yodeling of Pygmies is described. For African musicians, the ability to improvise, and creativity, are gifts from God. Includes selected readings and recordings. (KC)

Locke, David

1980-01-01

316

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

PubMed Central

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.

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

2013-01-01

317

From Suns to Life: A Chronological Approach to the History of Life on Earth 7. Ancient Fossil Record and Early Evolution (ca. 3.8 to 0.5 Ga)  

NASA Astrophysics Data System (ADS)

Once life appeared, it evolved and diversified. From primitive living entities, an evolutionary path of unknown duration, likely paralleled by the extinction of unsuccessful attempts, led to a last common ancestor that was endowed with the basic properties of all cells. From it, cellular organisms derived in a relative order, chronology and manner that are not yet completely settled. Early life evolution was accompanied by metabolic diversification, i.e. by the development of carbon and energy metabolic pathways that differed from the first, not yet clearly identified, metabolic strategies used. When did the different evolutionary transitions take place? The answer is difficult, since hot controversies have been raised in recent years concerning the reliability of the oldest life traces, regardless of their morphological, isotopic or organic nature, and there are also many competing hypotheses for the evolution of the eukaryotic cell. As a result, there is a need to delimit hypotheses from solid facts and to apply a critical analysis of contrasting data. Hopefully, methodological improvement and the increase of data, including fossil signatures and genomic information, will help reconstructing a better picture of life evolution in early times as well as to, perhaps, date some of the major evolutionary transitions. There are already some certitudes. Modern eukaryotes evolved after bacteria, since their mitochondria derived from ancient bacterial endosymbionts. Once prokaryotes and unicellular eukaryotes had colonized terrestrial ecosystems for millions of years, the first pluricellular animals appeared and radiated, thus inaugurating the Cambrian. The following sections constitute a collection of independent articles providing a general overview of these aspects.

López-Garcia, Purificacón; Moreira, David; Douzery, Emmanuel; Forterre, Patrick; van Zuilen, Mark; Claeys, Philippe; Prieur, Daniel

2006-06-01

318

Cycles in fossil diversity  

SciTech Connect

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.

Rohde, Robert A.; Muller, Richard A.

2004-10-20

319

Interpreting Fossil Assemblages  

NSDL National Science Digital Library

Students are provided several fossiliferous samples to analyze in detail. I provide more than they need to snalyze so everyone in the class can be working. I give a range of specimens of different geologic ages, diversities, abundances, taxonomic compositions, depositional environments and taphonomic grades. The goal is for the students to identify all of the different fossil types to the lowest taxonomic level. I provide some that are well preserved and some that are highly fragmented making identification difficult. Next, students are tasked with assigning an age range of the sample by combining the age ranges of individual taxa, and make taphonomic descriptions and paleoecological analyses.

Boyer, Diana

320

Milankovitch Modulation of the Ecosystem Dynamics of Fossil Great Lakes  

NASA Astrophysics Data System (ADS)

Triassic and Early Jurassic lacustrine deposits of eastern North American rift basins preserve a spectacular record of precession-related Milankovitch forcing in the Pangean tropics. The abundant and well-preserved fossil fish assemblages from these great lakes demonstrate a sequence of cyclical changes that track the permeating hierarchy of climatic cycles. To detail ecosystem processes correlating with succession of fish communities, we measured bulk ?13Corg through a 100 ky series of Early Jurassic climatic precession-forced lake level cycles in the lower Shuttle Meadow Formation of the Hartford rift basin, CT. The deep-water phase of one of these cycles, the Bluff Head bed, has produced thousands of articulated fish. We observe fluctuations in the bulk ?13Corg of the cyclical strata that reflect differing degrees of lake water stratification, nutrient levels, and relative proportion of algal vs. plant derived organic matter that trace fish community changes. We can exclude extrinsic changes in the global exchangeable reservoirs as an origin of this variability because molecule-level ?13C of n-alkanes of plant leaf waxes from the same strata show no such variability. While at higher taxonomic levels the fish communities responded largely by sorting of taxa by environmental forcing, at the species level the holostean genus Semionotus responded by in situ evolution, and ultimately extinction, of a species flock. Fluctuations at the higher frequency, climatic precessional scale are mirrored at lower frequency, eccentricity modulated, scales, all following the lake-level hierarchical pattern. Thus, lacustrine isotopic ratios amplify the Milankovitch climate signal that was already intensified by sequelae of the end-Triassic extinctions. The degree to which the ecological structure of modern lakes responds to similar environmental cyclicity is largely unknown, but we suspect similar patterns and processes within the Neogene history of the East African great lakes, which may be modified in the future by anthropogenic CO2-driven intensification of the hydrological cycle.

Whiteside, J. H.; Olsen, P. E.; Eglinton, T. I.; Cornet, B.; Huber, P.; McDonald, N. G.

2008-12-01

321

African Aesthetics  

ERIC Educational Resources Information Center

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…

Abiodun, Rowland

2001-01-01

322

22 CFR 1502.5 - Records available at the Foundation.  

Code of Federal Regulations, 2013 CFR

...2009-04-01 true Records available at the Foundation. 1502.5 Section 1502.5 Foreign Relations AFRICAN DEVELOPMENT FOUNDATION AVAILABILITY OF RECORDS § 1502.5 Records available at the Foundation. The Administration and...

2013-04-01

323

22 CFR 1502.3 - Access to Foundation records.  

Code of Federal Regulations, 2013 CFR

... 2009-04-01 true Access to Foundation records. 1502.3 Section 1502...Foreign Relations AFRICAN DEVELOPMENT FOUNDATION AVAILABILITY OF RECORDS § 1502.3 Access to Foundation records. Any person desiring to...

2013-04-01

324

Unearthing Important Fossils  

NSDL National Science Digital Library

Over the past several weeks, a flurry of dinosaur and other fossil discoveries have reached the mainstream news. From the two 530-million-year-old fish-like creatures that could be the earliest known vertebrates found in China, to the bones of two dinosaurs in Madagascar that may be the oldest dinosaurs ever found, to the "60-ton giraffe-like creature" (3) found in Oklahoma (called Sauroposeidon proteles, or "thunder lizard"), paleontologists are immersed in discovery. The significance of the first discovery is triggering excitement among paleontologists, worldwide. In particular, the discovery of the two "fish-like" fossils in China (to be published in this week's journal Nature) indicates that fish (i.e., vertebrates) evolved much earlier than previously thought and that "the rates of evolution in the oceans during the Cambrian period must have been exceptionally fast" (1). This week's In The News discusses some of the recently unveiled discoveries and provides background information and resources on vertebrate paleontology.

Payne, Laura X.

325

Fossil Microorganisms in Archaean  

NASA Technical Reports Server (NTRS)

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.

Astafleva, Marina; Hoover, Richard; Rozanov, Alexei; Vrevskiy, A.

2006-01-01

326

African Cosmology  

NASA Astrophysics Data System (ADS)

Focusing on the African continent, this presentation selects origin stories in cosmologies scattered throughout Africa. This research diverges from my work on applied astronomy knowledge in livelihood systems, to begin to probe the meanings and importance people place on their cosmologies. Including both the general and the unique, I am looking for a latitude dependence that would echo Aveni's Tropical Archaeoastronomy Theory, examining origins from the sky (with a future return to the sky), and dynamic or evolving universes among these cosmologies.

Holbrook, J. C.

2009-08-01

327

Evolution in fossil lineages: paleontology and The Origin of Species.  

PubMed

Of all of the sources of evidence for evolution by natural selection, perhaps the most problematic for Darwin was the geological record of organic change. In response to the absence of species-level transformations in the fossil record, Darwin argued that the fossil record was too incomplete, too biased, and too poorly known to provide strong evidence against his theory. Here, this view of the fossil record is evaluated in light of 150 years of subsequent paleontological research. Although Darwin's assessment of the completeness and resolution of fossiliferous rocks was in several ways astute, today the fossil record is much better explored, documented, and understood than it was in 1859. In particular, a reasonably large set of studies tracing evolutionary trajectories within species can now be brought to bear on Darwin's expectation of gradual change driven by natural selection. An unusually high-resolution sequence of stickleback-bearing strata records the transformation of this lineage via natural selection. This adaptive trajectory is qualitatively consistent with Darwin's prediction, but it occurred much more rapidly than he would have guessed: almost all of the directional change was completed within 1,000 generations. In most geological sequences, this change would be too rapid to resolve. The accumulated fossil record at more typical paleontological scales (10(4)-10(6) years) reveals evolutionary changes that are rarely directional and net rates of change that are perhaps surprisingly slow, two findings that are in agreement with the punctuated-equilibrium model. Finally, Darwin's view of the broader history of life is reviewed briefly, with a focus on competition-mediated extinction and recent paleontological and phylogenetic attempts to assess diversity dependence in evolutionary dynamics. PMID:21043781

Hunt, Gene

2010-12-01

328

Solar/fossil Rankine cooling  

SciTech Connect

A technical and economic review is provided of the hybrid solar/fossil solar cooling concept in which a dual energy input Rankine engine is used to drive a vapor compression chiller. In the Rankine engine a solar energy input is used to evaporate the water working fluid and fossil fuel is used to superheat the steam. 12 refs.

Curran, H.M.

1981-01-01

329

FOSSIL ENERGY AND FOOD SECURITY  

Microsoft Academic Search

To fulfil the basic goal of delivering food for the tables of the citizens, modern Western agriculture is extremely dependent on supporting material flows, infrastructure, and fossil energy. According to several observers, fossil fuel production is about to peak, i.e., oil extraction is no longer capable of keeping pace with the increasing demand. This situation may trigger an unprecedented increase

Folke Günther

2001-01-01

330

Life of a Vertebrate Fossil  

NSDL National Science Digital Library

Unless you have a very large research grant, it can be difficult to find fossil bones. Fortunately, this very fine online learning module from the Smithsonian's Natural History Museum can help both young and old to learn about locating fossil bones, among other things. Through this multimedia feature created by the History Museum's department of paleobiology, visitors will learn what paleontologists do in each stage in the life of a vertebrate fossil. With the assistance of short video clips, interactive diagrams, and photographs, visitors will learn about how fossils are prepared for examination and how scientists unravel the stories of these paleontological finds. Finally, visitors will also learn how fossils are stored and preserved.

331

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

SciTech Connect

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.

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

1984-06-29

332

Plio-pleistocene African climate  

SciTech Connect

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.

deMenocal, P.B. [Lamont-Doherty Earth Observatory, Palisades, NY (United States)

1995-10-06

333

Fossil Energy Video Gallery  

DOE Data Explorer

DOE’s Office of Fossil Energy makes available an online video gallery to acquaint the public with its mission focus and activities. This is a list of the videos and the brief description that accompanies them. • An Introduction to Carbon Capture and Sequestration: FE's Carbon Sequestration Program is helping to develop technologies to capture, purify, and store carbon dioxide in order to reduce greenhouse gas emissions without adversely influencing energy use or hindering economic growth. Carbon sequestration technologies capture and store CO2 that would otherwise reside in the atmosphere for long periods of time. • SPR: The Energy Security of America (2009): Oil is only one aspect of the nation's Strategic Petroleum Reserve. See what it takes to run the world's largest underground crude oil storage facility. • Carbon Capture and Storage, 2008: In 2003, the Office of Fossil Energy's National Energy Technology Laboratory formed seven Regional Carbon Sequestration Partnerships to assess geologic formations suitable for carbon capture and storage, and determine the best approaches to implement carbon sequestration in each region. This video describes the work of these partnerships. • Geologic Carbon Sequestration: A Path Toward Zero Emission Energy from Coal: Carbon sequestration, the idea of capturing carbon dioxide before it is emitted to the atmosphere and storing it in underground rock formations or otherwise sequestering it, has progressed steadily over the past 10 years. It is now poised to become a key technology option for greenhouse gas emissions abatement. • Gasification û A Cornerstone Technology: The gasification process converts carbon-based materials such as coal into synthesis gas (syngas) that can be used to produce clean electrical energy, transportation fuels, and chemicals efficiently and cost-effectively. Gasification is a cornerstone technology of 21st century zero emissions powerplants. FE also provides links to several videos developed by their project partners. These are: • The CO2 Story Through Basin Electric • Carbon Capture and Storage at the Mountaineer Power Plants û American Electric Power • Hydrogen Energy California Project • Documentary Series (4 videos) from Prairie Public Broadcasting and the Plains CO2 Reduction (PCOR) Partnership • PCOR Partnership Video Clip Library

334

Submarine hydrothermal fossils confirmed  

NASA Astrophysics Data System (ADS)

Researchers from Princeton University (D. Crerrar et al, Econ. Geol., May 1982) have documented, in considerable detail, evidence for the formation of some of the 800 or more manganiferous chert deposits occurring in the central belt of the Fransiscan formation in northwestern California. They confirm the surprisingly old conclusion o f Tiaferro and Hudson (Cal. Div. Mines Bull., 125, 217-276, 1943) that the Fransiscan chert deposits probably represent the fossil remains of submarine hydrothermal vents.The deposits resemble recently discovered hydrothermal mounds near the Galapagos rift, the Gulf of Aden, and the Mid-Atlantic Ridge. As the Princeton investigators point out, there are important implications of the existence of deep hydrothermal circulation systems at oceanic spreading centers throughout geologic time. They note that the calculated annual flow of hydrothermal fluids in such processes is about 1017 g, which implies that the entire volume of the oceans could circulate completely every 10 million years. With such circulation, the hydrothermal processes along midocean ridges could control the composition of seawater and strongly influence the geochemical flux of elements in the marine environment.

Bell, Peter M.

335

Fossil fuel furnace reactor  

DOEpatents

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.

Parkinson, William J. (Los Alamos, NM)

1987-01-01

336

THE EFFECT OF EXTERNAL AND INTERNAL FOSSIL CALIBRATIONS ON THE AVIAN EVOLUTIONARY TIMESCALE  

Microsoft Academic Search

Molecular clocks can provide insights into the evolutionary timescale of groups with unusually biased or fragmentary fossil records, such as birds. In those cases, it is advantageous to establish internal anchor points—molecular time estimates—using the best external fossil calibrations. In turn, those anchor points can be used as calibrations for more detailed time estimation within the group under study. This

MARCEL van TUINEN; S. BLAIR HEDGES

2004-01-01

337

Amino Acid Components in Fossil Tortoiseshell from the Oligocene of the Isle of Wight  

Microsoft Academic Search

FOSSIL bones and teeth from Palaeozoic, Mesozoic and Tertiary rocks have yielded amino acid analyses which indicate the survival of collagenous material over hundreds of millions of years1. In contrast, fossil keratinous tissues have until now only been recorded in such Pleistocene animals as the South American giant ground sloth and the woolly mammoth2. We are not aware of any

L. B. Halstead

1973-01-01

338

The "Sudden Explosion" of Animal Fossils about 600 Million Years Ago: Why?  

ERIC Educational Resources Information Center

Discusses the "sudden explosion" of animal fossils during the Cambrian era, suggesting that the "explosion" is a result of organic evolution, leading to remarkably preservable calcareous skeletons. Suggests that earlier organisms were soft-bodied and consequently were poorly preserved in the fossil record. (JN)

Kaveski, Sharon; Margulis, Lynn

1983-01-01

339

We're Going on a Fossil Hunt!  

Microsoft Academic Search

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 recognize the tentative nature of science and experience differences in

Deborah A. Powell; Richard B. Aram; Roberta J. Aram; Terry L. Chase

2007-01-01

340

Ignoring Authentic African Literature Means Ignoring Africans  

ERIC Educational Resources Information Center

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.

Romano, Carlin

2005-01-01

341

Taxonomy and fossils: a critical appraisal.  

PubMed Central

Many compendia at the species, genus and family levels document the fossil record, but these are not standardized, nor usually critical in content, and few are available on the World Wide Web. The sampling of the available record is good for organisms with fossilizable parts, but preservational constraints on the entire morphology, life history and geographical distribution lead to difficulties in recognizing and naming species. We recommend abandoning some of the palaeontological species concepts such as chronospecies and stratospecies, and we advocate species recognition based on unique combinations of characters. The compilation of species lists is extremely time consuming, and given the inherent problems we suggest that compilation of generic lists is a more achievable goal because genera are recognized by definitive morphological characters. In calculating taxon duration, care must be taken to distinguish between mono-, para- and polyphyletic groups, the first being the only reliable unit for use in calculating diversity curves. We support the inclusion of fossils into classifications based on Recent organisms, but we recognize some of the problems this may pose for standard Linnaean classifications. Web-based taxonomy is the way forward, having the advantages of speed and currency of information dissemination, universal access with links to primary literature and increasingly sophisticated imagery. These advantages over conventional outlets will only be realized with careful Web design and a commitment to maintenance.

Forey, Peter L; Fortey, Richard A; Kenrick, Paul; Smith, Andrew B

2004-01-01

342

Dating Fossil Pollen: A Simulation.  

ERIC Educational Resources Information Center

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)

Sheridan, Philip

1992-01-01

343

Details of North African tectonics  

NSDL National Science Digital Library

Global Positioning System (GPS) and ground-based measurements were used to study coastal shoreline movement after the 2003 6.8-magnitude earthquake in Algeria. The authors recorded ground deformation and report a maximum uplift of approximately 0.75 meters and an average of nearly 0.5 meters along the North African coast. Data indicate that the fault likely initiated along the sea bottom between 5-10 kilometers offshore.

Al., Meghraoui E.; Agu

344

Molecules and fossils reveal punctuated diversification in Caribbean "faviid" corals  

PubMed Central

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.

2012-01-01

345

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

346

22 CFR 1507.7 - Contents of records systems.  

Code of Federal Regulations, 2013 CFR

...Foreign Relations AFRICAN DEVELOPMENT FOUNDATION RULES SAFEGUARDING PERSONAL INFORMATION...Contents of records systems. (a) The Foundation will maintain in its records only...statute or Executive Order. (b) The Foundation will collect information, to...

2013-04-01

347

22 CFR 1507.6 - Access to records.  

Code of Federal Regulations, 2013 CFR

...Foreign Relations AFRICAN DEVELOPMENT FOUNDATION RULES SAFEGUARDING PERSONAL INFORMATION...system of records maintained by the Foundation. The individual will be permitted...be notified, upon request, if any Foundation system of records contains a...

2013-04-01

348

Environmental determinants of extinction selectivity in the fossil record.  

PubMed

The causes of mass extinctions and the nature of biological selectivity during extinction events remain central questions in palaeobiology. Although many different environmental perturbations have been invoked as extinction mechanisms, it has long been recognized that fluctuations in sea level coincide with many episodes of biotic turnover. Recent work supports the hypothesis that changes in the areas of epicontinental seas have influenced the macroevolution of marine animals, but the extent to which differential environmental turnover has contributed to extinction selectivity remains unknown. Here I use a new compilation of the temporal durations of sedimentary rock packages to show that carbonate and terrigenous clastic marine shelf environments have different spatio-temporal dynamics and that these dynamics predict patterns of genus-level extinction, extinction selectivity and diversity among Sepkoski's Palaeozoic and modern evolutionary faunae. These results do not preclude a role for biological interactions or unusual physical events as drivers of macroevolution, but they do suggest that the turnover of marine shelf habitats and correlated environmental changes have been consistent determinants of extinction, extinction selectivity and the shifting composition of the marine biota during the Phanerozoic eon. PMID:18552839

Peters, Shanan E

2008-07-31

349

Impact Theory of Mass Extinctions and the Invertebrate Fossil Record  

Microsoft Academic Search

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

Walter Alvarez; Erle G. Kauffman; Finn Surlyk; Luis W. Alvarez; Frank Asaro; Helen V. Michel

1984-01-01

350

Climatic influences on species: Evidence from the fossil record  

USGS Publications Warehouse

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.

Cronin, T. M.; Schneider, C. E.

1990-01-01

351

Fossil Record of Evolution: Data on Diversification and Extinction.  

National Technical Information Service (NTIS)

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 ...

J. J. Sepkoski

1990-01-01

352

Early Life on Earth: The Ancient Fossil Record  

Microsoft Academic Search

The evidence for early life and its initial evolution on Earth is linked intimately with the geological evolution of the early\\u000a Earth. The environment of the early Earth would be considered extreme by modern standards: hot (50–80°C), volcanically and\\u000a hydrothermally active, anoxic, high UV flux, and a high flux of extraterrestrial impacts. Habitats for life were more limited\\u000a until continent-building

Frances Westall

2004-01-01

353

The Fossil Record of Plant-Insect Dynamics  

NASA Astrophysics Data System (ADS)

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.

Labandeira, Conrad C.; Currano, Ellen D.

2013-05-01

354

Search for Supernova ^60Fe in the Earth's Fossil Record  

NASA Astrophysics Data System (ADS)

Approximately 2.8 Myr before the present our planet was subjected to the debris of a supernova explosion. The terrestrial proxy for this event was the discovery of live atoms of ^60Fe in a deep-sea ferromanganese crust. The signature for this supernova event should also reside in magnetite (Fe3O4) magnetofossils produced by magnetotactic bacteria extant at the time of the Earth- supernova interaction, provided the bacteria preferentially uptake iron from fine-grained iron oxides and ferric hydroxides. Using empirically derived microfossil concentrations in a deep-sea drill core, we deduce a conservative estimate of the 60Fe fraction as ^60Fe/Fe = 3.6 x10-15. This value sits comfortably within the sensitivity limit of present accelerator mass spectrometry (AMS) capabilities. This talk will detail the present status of our ^60Fe AMS search in magnetofossils and (possibly) show our initial results.

Bishop, Shawn; Ludwig, Peter; Egli, Ramon; Chernenko, Valentina; Frederichs, Thomas; Merchel, Silke; Rugel, Georg

2013-04-01

355

Cell symbiosis theory - Status and implications for the fossil record  

NASA Technical Reports Server (NTRS)

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.

Margulis, L.; Stolz, J. F.

1984-01-01

356

The fossil record of evolution: Data on diversification and extinction  

NASA Technical Reports Server (NTRS)

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.

Sepkoski, J. John, Jr.

1990-01-01

357

Exopaleontology and the Search for a Fossil Record on Mars.  

National Technical Information Service (NTIS)

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...

J. D. Farmer D. J. Desmarais

1994-01-01

358

ConcepTest: Earth Timeline - the fossil record  

NSDL National Science Digital Library

Carefully examine the relative positions of the lettered arrows on the timeline below and estimate the ages represented by each arrow. Identify which letter corresponds most closely to the first appearance in the ...

359

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

NASA Astrophysics Data System (ADS)

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.

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

360

Scratching an ancient itch: an Eocene bird louse fossil.  

PubMed

Out of the 30 extant orders of insects, all but one, the parasitic lice (Insecta: Phthiraptera), have a confirmed fossil record. Here, we report the discovery of what appears to be the first bird louse fossil: an exceptionally well-preserved specimen collected from the crater of the Eckfeld maar near Manderscheid, Germany. The 44-million-year-old specimen shows close phylogenetic affinities with modern feather louse ectoparasites of aquatic birds. Preservation of feather remnants in the specimen's foregut confirms its association as a bird ectoparasite. Based on a phylogenetic analysis of the specimen and palaeoecological data, we suggest that this louse was the parasite of a large ancestor to modern Anseriformes (swans, geese and ducks) or Charadriiformes (shorebirds). The crown group position of this fossil in the phylogeny of lice confirms the group's long coevolutionary history with birds and points to an early origin for lice, perhaps inherited from early-feathered theropod dinosaurs. PMID:15503987

Wappler, Torsten; Smith, Vincent S; Dalgleish, Robert C

2004-08-01

361

Exceptional preservation of fossils in an Upper Proterozoic shale.  

PubMed

Late Proterozoic organisms must have been diverse and widely distributed, but in general their fossil record is both taxonomically and environmentally limited. Exceptional preservation of Proterozoic fossils is not unknown, but it is usually associated with silicified carbonates from restricted peritidal or playa lake environments. We report here an exceptionally well preserved and distinctive assemblage of Late Proterozoic fossils from subtidal marine shales. In addition to the sphaeromorphic acritarchs and cyanobacterial sheaths routinely preserved in Proterozoic rocks, this assemblage includes multicellular algae ('seaweeds'), a diverse assortment of morphologically complex protistan vesicles, and probable heterotrophic bacteria. Thus, it provides one of the clearest and most taxonomically varied views of Proterozoic life yet reported. PMID:11542151

Butterfield, N J; Knoll, A H; Swett, K

1988-08-01

362

Fossil papio cranium from !Ncumtsa (Koanaka) Hills, western Ngamiland, Botswana.  

PubMed

Three fossils, a cranium of Papio, a cercopithecid frontal bone, and a mandible of juvenile Papio, have been recovered from cave deposits in the !Ncumtsa (Koanaka) Hills of western Ngamiland, Botswana. These specimens are significant because well-preserved crania of Papio are extremely rare in the fossil record outside of South Africa and because this is the first report of fossil primate cranial remains from Botswana. Thermoluminescence dating of surrounding cave matrix indicates an age of ?317 ± 114 ka, within the Middle Pleistocene, although it may be older. Based on univariate and multivariate analyses, the adult !Ncumtsa specimen falls within the range of variation seen in extant forms of Papio, yet is distinct from any living species/subspecies and represents a new taxon, named here as a new subspecies of Papio hamadryas-Papio hamadryas botswanae. PMID:22639236

Williams, Blythe A; Ross, Callum F; Frost, Stephen R; Waddle, Diane M; Gabadirwe, Mohutsiwa; Brook, George A

2012-09-01

363

Scratching an ancient itch: an Eocene bird louse fossil.  

PubMed Central

Out of the 30 extant orders of insects, all but one, the parasitic lice (Insecta: Phthiraptera), have a confirmed fossil record. Here, we report the discovery of what appears to be the first bird louse fossil: an exceptionally well-preserved specimen collected from the crater of the Eckfeld maar near Manderscheid, Germany. The 44-million-year-old specimen shows close phylogenetic affinities with modern feather louse ectoparasites of aquatic birds. Preservation of feather remnants in the specimen's foregut confirms its association as a bird ectoparasite. Based on a phylogenetic analysis of the specimen and palaeoecological data, we suggest that this louse was the parasite of a large ancestor to modern Anseriformes (swans, geese and ducks) or Charadriiformes (shorebirds). The crown group position of this fossil in the phylogeny of lice confirms the group's long coevolutionary history with birds and points to an early origin for lice, perhaps inherited from early-feathered theropod dinosaurs.

Wappler, Torsten; Smith, Vincent S; Dalgleish, Robert C

2004-01-01

364

Phylogeny of the Infraorder Pentatomomorpha Based on Fossil and Extant Morphology, with Description of a New Fossil Family from China  

PubMed Central

Background An extinct new family of Pentatomomorpha, Venicoridae Yao, Ren & Cai fam. nov., with 2 new genera and 2 new species (Venicoris solaris Yao, Ren & Rider gen. & sp. nov. and Clavaticoris zhengi Yao, Ren & Cai gen. & sp. nov.) are described from the Early Cretaceous Yixian Formation in Northeast China. Methodology/Principal Findings A cladistic analysis based on a combination of fossil and extant morphological characters clarified the phylogenetic status of the new family and has allowed the reconstruction of intersuperfamily and interfamily relationships within the Infraorder Pentatomomorpha. The fossil record and diversity of Pentatomomorpha during the Mesozoic is discussed. Conclusions/Significance Pentatomomorpha is a monophyletic group; Aradoidea and the Trichophora are sister groups; these fossils belong to new family, treated as the sister group of remainder of Trichophora; Pentatomoidea is a monophyletic group; Piesmatidae should be separated as a superfamily, Piesmatoidea. Origin time of Pentatomomorpha should be tracked back to the Middle or Early Triassic.

Yao, Yunzhi; Ren, Dong; Rider, David A.; Cai, Wanzhi

2012-01-01

365

Fossils, rocks, and time  

USGS Publications Warehouse

We study out Earth for many reasons: to find water to drink or oil to run our cars or coal to heat our homes, to know where to expect earthquakes or landslides or floods, and to try to understand our natural surroundings. Earth is constantly changing--nothing on its surface is truly permanent. Rocks that are not on top of a mountain may once have been on the bottom of the sea. Thus, to understand the world we live on, we must add the dimension of time. We must study Earth's history. When we talk about recorded history, time is measured in years, centuries, and tens of centuries. When we talk about Earth history, time is measured in millions and billions of years. Time is an everyday part of our lives. We keep track of time with a marvelous invention, the calendar, which is based on the movements of the Earth in space. One spin of Earth on its axis is a day, and one trip around the sun is a year. The modern calendar is a great achievement, developed over many thousands of years as theory and technology improved. People who study Earth's history also use a type of calendar, called the geologic time scale. It looks very different from the familiar calendar. In some ways, it is more like a book, and the rocks are its pages. Some of the pages are torn or missing, and the pages are not numbered, but geology gives us the tools to help us read this book.

Edwards, Lucy E.; Pojeta, John, Jr.

1993-01-01

366

Fossil Plants as Indicators of the Phanerozoic Global Carbon Cycle  

NASA Astrophysics Data System (ADS)

Developments in plant physiology since the 1980s have led to the realization that fossil plants archive both the isotopic composition of atmospheric CO2 and its concentration, both critical integrators of carbon cycle processes through geologic time. These two carbon cycle signals can be read by analyzing the stable carbon isotope composition ([delta ]13) of fossilized terrestrial organic matter and by determining the stomatal characters of well-preserved fossil leaves, respectively. We critically evaluate the use of fossil plants in this way at abrupt climatic boundaries associated with mass extinctions and during times of extreme global warmth. Particular emphasis is placed on evaluating the potential to extract a quantitative estimate of the [delta ]13 of atmospheric CO2 because of the key role it plays in understanding the carbon cycle. We critically discuss the use of stomatal index and stomatal ratios for reconstructing atmospheric CO2 levels, especially the need for adequate replication, and present a newly derived CO2 record for the Mesozoic that supports levels calculated from geochemical modeling of the long-term carbon cycle. Several suggestions for future research using stable carbon isotope analyses of fossil terrestrial organic matter and stomatal measurements are highlighted.

Beerling, D. J.; Royer, D. L.

367

Observe how fossils can form  

NSDL National Science Digital Library

This Earth science animation demonstrates the formation of a cast and mold fossil to middle and high school students. The introduction provides a brief description of the process. The animation shows how a shelled animal becomes buried in mud that eventually turns into stone. The shell dissolves and is replaced by minerals and, when the layers of rock are split, a cast and mold fossil is revealed. Movie controls allow students to repeat, pause, or step through the animation, which can give students more time to analyze the images. Copyright 2005 Eisenhower National Clearinghouse

Education, Terc. C.; Littell, Mcdougal

2003-01-01

368

FOSSIL2 energy policy model documentation: FOSSIL2 documentation  

SciTech Connect

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.

None

1980-10-01

369

30 CFR 250.469 - What other well records could I be required to submit?  

Code of Federal Regulations, 2010 CFR

...250.469 What other well records could I be required to submit...or all of the following well records. (a) Well records as specified in § 250.466...reports identifying microscopic fossils by depth and/or...

2010-07-01

370

30 CFR 250.469 - What other well records could I be required to submit?  

Code of Federal Regulations, 2010 CFR

...250.469 What other well records could I be required to submit...or all of the following well records. (a) Well records as specified in § 250.466...reports identifying microscopic fossils by depth and/or...

2009-07-01

371

Stroke and African Americans  

MedlinePLUS

... content can be found in the these categories: Content Index > Data/Statistics > Data by Health Topic > Stroke Content Index > Health Topics > Stroke > Stroke Data/Statistics Stroke and African Americans African American adults ...

372

Immunizations and African Americans  

MedlinePLUS

... content can be found in the these categories: Content Index > Data/Statistics > Data by Health Topic > Immunizations Content Index > Health Topics > Immunizations > Immunizations Data/Statistics Immunizations and African Americans African American adults ...

373

Ectoparasites of African Mammals.  

National Technical Information Service (NTIS)

The study of ectoparasites of African mammals was an integral part of the contract on 'potential vectors and reservoirs of diseases in overseas areas.' The collection consisted of ectoparasites from approximately 100,000 African small mammals and represen...

C. S. Herrin V. J. Tipton

1976-01-01

374

Fossil evidence for early hominid tool use.  

PubMed

Although several Plio-Pleistocene hominids are found in association with stone and bone tools, it has been generally assumed that at any one time the hominid with the largest brain was the toolmaker. Fossils recovered over the last decade suggest that early hominids subsequent to 2.5 million years ago all might have used tools and occupied "cultural" niches. A test for humanlike precision grasping (the enhanced ability to manipulate tools) is proposed and applied to australopithecines and early Homo. The results indicate that tools were likely to have been used by all early hominids at around 2.0 million years ago. The earliest australopithecines, which predate the appearance of stone tools in the archaeological record, do not show signs of advanced precision grasping. PMID:8079169

Susman, R L

1994-09-01

375

FAST FOSSIL ROTATION OF NEUTRON STAR CORES  

SciTech Connect

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.

Melatos, A., E-mail: amelatos@unimelb.edu.au [School of Physics, University of Melbourne, Parkville, VIC 3010 (Australia)

2012-12-10

376

First report of fossil "keratose" demosponges in Phanerozoic carbonates: preservation and 3-D reconstruction  

NASA Astrophysics Data System (ADS)

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.

Luo, Cui; Reitner, Joachim

2014-06-01

377

First report of fossil "keratose" demosponges in Phanerozoic carbonates: preservation and 3-D reconstruction.  

PubMed

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

Luo, Cui; Reitner, Joachim

2014-06-01

378

First report of fossil "keratose" demosponges in Phanerozoic carbonates: preservation and 3-D reconstruction  

NASA Astrophysics Data System (ADS)

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.

Luo, Cui; Reitner, Joachim

2014-04-01

379

Astronomy for African development  

Microsoft Academic Search

In recent years there have been a number of efforts across Africa to develop the field of astronomy as well as to reap benefit from astronomy for African people. This presentation will discuss the case of the SALT (Southern African Large Telescope) Collateral Benefits Programme (SCBP) which was set up to ensure societal benefit from astronomy. With African society as

Kevindran Govender

2011-01-01

380

Fossils and Leonardo da Vinci  

Microsoft Academic Search

IN his valuable and sympathetic appreciation of Huxley on the occasion of the centenary celebrations on May 4, Prof. Poulton incidentally referred to the puzzled discussions of naturalists of former days concerning the fossil sharks' teeth (``glossopetræ'') that were found in Italy.

Percy Edwin Spielmann

1925-01-01

381

Fossil Cetacea of the Caucasus.  

National Technical Information Service (NTIS)

The book by Guram Andreevich Mchedlidze, reviews in detail the fossil cetaceans of the Caucasus. It is based on rich collections from the author's own excavations, supplemented by those preserved in the museums at Tbilisi, etc. A study of the material hel...

G. A. Mchedlidze

1989-01-01

382

Progress of Fossil Fuel Science  

Microsoft Academic Search

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

M. F. Demirbas

2007-01-01

383

The Oklo Fossil Fission Reactors  

NSDL National Science Digital Library

This web page gives an overview of the Oklo Fossil Fission Reactors, including the history of the area where the reactor is located, the science behind the nuclear reactions, and reasons for studying this nuclear reactor. This page also includes graphics describing the Physics behind the reactors, maps, and pictures of the reactor.

Loss, Robert

2012-06-15

384

Fossil Identification and Classification Lab  

NSDL National Science Digital Library

Students pick, sort, box, and identify fossils (mostly mollusks but also bryozoa, arthropods, cnidaria, and annelids) from richly fossiliferous, clastic marine sediment, compile a faunal list,compare the fauna with modern taxa, and make evaluate a paleogeographic model for the taxa found.

Willoughby, Ralph H.

385

CD Recorders.  

ERIC Educational Resources Information Center

Discussion of CD (compact disc) recorders describes recording applications, including storing large graphic files, creating audio CDs, and storing material downloaded from the Internet; backing up files; lifespan; CD recording formats; continuous recording; recording software; recorder media; vulnerability of CDs; basic computer requirements; and…

Falk, Howard

1998-01-01

386

Explosive growth in African combustion emissions from 2005 to 2030  

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

387

Molecular and Fossil Evidence on the Origin of Angiosperms  

NASA Astrophysics Data System (ADS)

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.

Doyle, James A.

2012-05-01

388

Microbial Cretaceous park: biodiversity of microbial fossils entrapped in amber  

Microsoft Academic Search

Microorganisms are the most ancient cells on this planet and they include key phyla for understanding cell evolution and Earth\\u000a history, but, unfortunately, their microbial records are scarce. Here, we present a critical review of fossilized prokaryotic\\u000a and eukaryotic microorganisms entrapped in Cretaceous ambers (but not exclusively from this geological period) obtained from\\u000a deposits worldwide. Microbiota in ambers are rather

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

2009-01-01

389

Identifying Fossils: Exploring the Mississippi River Bluffs  

NSDL National Science Digital Library

This activity is a geology lab where students learn about fossils found in sedimentary rocks and show their understanding by writing a literary nonfiction paper from the perspective of one of those fossils.

390

ConcepTest: Best Index Fossil  

NSDL National Science Digital Library

Four outcrops of rock are examined in different locations of a state. The rock types and the fossils they contain are illustrated in the adjacent diagram. Which fossil would be the best choice to use as an index ...

391

Assessing the role of cladogenesis in macroevolution by integrating fossil and molecular evidence  

PubMed Central

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.

Strotz, Luke C.; Allen, Andrew P.

2013-01-01

392

Fossilization and Adaptation Activities in Paleontology  

NSDL National Science Digital Library

This activity introduces students to the concepts of time, past life, and fossils. After completing these exercises students will be able to evaluate the importance of fossils to our knowledge of past life, identify conditions necessary for fossilization, construct a possible scenario for formation of fossils, understand how organisms are adapted to their environments, and understand the relationships of modern and ancient communities with their environments.

Breithaupt, Brent

393

Trends, rhythms and events in Plio-Pleistocene African climate  

NASA Astrophysics Data System (ADS)

We analyzed published records of terrigenous dust flux from marine sediments off subtropical West Africa, the eastern Mediterranean Sea, and the Arabian Sea, and lake records from East Africa using statistical methods to detect trends, rhythms and events in Plio-Pleistocene African climate. The critical reassessment of the environmental significance of dust flux and lake records removes the apparent inconsistencies between marine vs. terrestrial records of African climate variability. Based on these results, major steps in mammalian and hominin evolution occurred during episodes of a wetter, but highly variable climate largely controlled by orbitally induced insolation changes in the low latitudes.

Trauth, Martin H.; Larrasoaña, Juan C.; Mudelsee, Manfred

2009-03-01

394

Trends, rhythms and events in Plio-Pleistocene African climate  

NASA Astrophysics Data System (ADS)

We analyzed published records of terrigenous dust flux from marine sediments off subtropical West Africa, the eastern Mediterranean Sea, and the Arabian Sea, and lake records from East Africa using statistical methods to detect trends, rhythms and events in Plio-Pleistocene African climate. The critical reassessment of the environmental significance of dust flux and lake records removes the apparent inconsistencies between marine vs. terrestrial records of African climate variability. Based on these results, major steps in mammalian and hominin evolution occurred during episodes of a wetter, but highly variable climate largely controlled by orbitally-induced insolation changes in the low latitudes.

Trauth, M. H.; Larrasoaña, J. C.; Mudelsee, M.

2009-04-01

395

Early penguin fossils, plus mitochondrial genomes, calibrate avian evolution.  

PubMed

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

Slack, Kerryn E; Jones, Craig M; Ando, Tatsuro; Harrison, G L Abby; Fordyce, R Ewan; Arnason, Ulfur; Penny, David

2006-06-01

396

A surprise inside a T. Rex fossil  

NSDL National Science Digital Library

When scientists looked inside the leg bone of a recently discovered Tyrannosaurus rex fossil, they found something they weren't expecting. Typically, only the hard parts of an animal, like the bones, are preserved as fossils. This T. rex fossil, however, contained some beautifully preserved soft tissue inside the bone, where the marrow once was.

American Association for the Advancement of Science (AAAS;)

2005-03-24

397

Advanced Fossil Energy Technologies: Current reports  

Microsoft Academic Search

Advanced Fossil Energy Technologies (FET) is designed to keep fossil energy researchers informed of the latest scientific and technical reports in their area. The publication announces all DOE-sponsored reports and patent applications in the subject scope of fossil energy that have been received and processed into the Energy Data Base (EDB) in a two-week period prior to the publication date

Tamura

1988-01-01

398

Fossils in Antarctica: British Antarctic Survey  

NSDL National Science Digital Library

Although marching penguins add to Antarctica's allure, The British Antarctic Survey (BAS) has found fossil evidence that dinosaurs, marsupials, and forests inhabited the area long before penguins charmed the world with their trademark waddle. Since 1940, when the fossil collection of the BAS was started, it has grown to 40,000 specimens. The "Fossils" section of the BAS website can be found on the left side of the homepage in the "About Antarctica" area, and is divided into two explanatory sections: "Fossils from the Antarctic" and "Fossil Locations in Antarctica". There are also links in each section, near the top right hand corner of the page, to "Type and Figured Fossil Collection" and "Fossils Picture Gallery". In the "Fossils from the Antarctic" section, the types of fossils found are explained and include: molluscs, arthropods, echinoderms and plants. The "Fossil Locations in Antarctica" section has a map of the three islands where a large amount of fossils have been found, along with descriptions of each island and what general types of fossils have been found on them.

399

Cretaceous Fossils: Plants Quick Identification Gallery  

NSDL National Science Digital Library

This site forms a component of the CretaceousFossils.com page providing detailed information and high resolution photos of Cretaceous plants. The site supplies a practical, visual resource designed to facilitate identification of plant fossils from the Cretaceous Period. Educators and students alike may find this site and its links useful for viewing, identifying and downloading photos of exceptionally preserved fossil plant specimens.

Keith, Minor; Cretaceousfossils.com

400

Cycads: Fossil evidence of late paleozoic origin  

USGS Publications Warehouse

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.

Mamay, S. H.

1969-01-01

401

Looking at Fossils in New Ways  

ERIC Educational Resources Information Center

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.

Flannery, Maura C.

2005-01-01

402

Will the past be prologue: the past health effects of fossil fuel and nuclear electricity generation  

Microsoft Academic Search

Energy policy complexities are pointed up in this review of the safety record of nuclear power as compared to the estimated record if fossil fuels had been used. Fatality figures for the entire process, from fuel extraction to waste disposal, are taken during the period from 1967 to 1976, when nuclear power accounted for less than 6 percent of the

A. Van Horn; R. Wilson

1977-01-01

403

Further studies on the modulation of fossil fuel production by global temperature variations  

Microsoft Academic Search

This study extends the earlier work of Rust and Kirk (1982) on the inverse modulation of global fossil fuel production by variations in Northern Hemispheric temperatures. Recent revisions and extensions of the fuel production record are incorporated and a much improved temperature record in used. The new data are consistent with the predictions of the original Rust-Kirk model which is

B. W. Rust; F. J. Crosby

1994-01-01

404

A fossil albatross from the Early Oligocene of the North Sea Basin  

Microsoft Academic Search

We describe a stem group representative of Diomedeidae from the early Oligocene (Rupelian) of Belgium. The fossil remains, wing, and pectoral girdle bones of two individuals are described as Tydea septentrionalis, gen. et sp. nov., and constitute the earliest well-established record of the taxon and the first Paleogene record from the North Sea Basin. The new species was about the

Gerald Mayr; Thierry Smith

2012-01-01

405

FOSSIL SPRINGS ROADLESS AREA, ARIZONA.  

USGS Publications Warehouse

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.

Beard, L. S.; Ellis, C. E.

1984-01-01

406

Dinosaurs: Ancient Fossils, New Discoveries  

NSDL National Science Digital Library

This Web site, created to complement the Museum's Dinosaurs: Ancient Fossils, New Discoveries exhibit, offers a virtual visit to the Museum, complete with text, photos, video clips, audio interviews, and more and includes much of the information which was in the original exhibit which is now closed. The site includes information on the bio-mechanics of dinosaurs and the reasons behind some of their strange appearances.

407

Microbial denitrogenation of fossil fuels.  

PubMed

The microbial degradation of nitrogen compounds from fossil fuels is important because of the contribution these contaminants make to the formation of nitrogen oxides (NOx) and hence to air pollution and acid rain. They also contribute to catalyst poisoning during the refining of crude oil, thus reducing process yields. We review the current status of microbial degradation of aromatic nitrogen compounds and discuss the potential of microbial processes to alleviate these problems. PMID:9744113

Benedik, M J; Gibbs, P R; Riddle, R R; Willson, R C

1998-09-01

408

Fossil Collection and Museum Curation  

NSDL National Science Digital Library

Before we go into the field, students are exposed to field collection techniques and appropriate information to collect at the outcrop. This assignment is good for field trips because students each collect 1 or few samples, but spend time on the outcrop measuring a section and collecting associated lithologic and other fossil data if available (locality information, exposure, over and underlying sedimentology, details of host rock, sedimentary structures, assocaited fossils, diversity and abundance, taphonomic condition of fossils, etc). The field locality can be anywhere where there are resaonably well preserved fossils (and should give students an appreciation of museum quality specimens). This allows this exercise to be flexible as field trip localities change. All of the information that they collect in the field will be included in their field notebook that is handed in at the end of the field trip for evaluation. In the lab-I used class time-students are asked to make a detailed sketch of their sample that they can take to the library with them, and a discussion is held as to where to look for information to identify specimens with. Students are given a week (variable depending on the availability of resources, for example if monographs need to be aquired through inter-library loan) to idenitfy their specimen and then asked to catalog them for the museum. They fill out a SUNY Oswego Paleontology Museum card, which they have seen all semester for their sample and are given the option to donate it to the collection or keep it.

Boyer, Diana

409

Hydrological and Vegetation Variability from Mediterranean Leaf Wax Biomarkers Before and After the Rise of East African C4 Grasslands  

NASA Astrophysics Data System (ADS)

Terrestrial and marine paleoclimate records and changes in African fossil mammal taxa indicate that a transition towards more open, C4-dominated grasslands occurred in East Africa near 2 Ma. In contrast, the Mediterranean sapropel record documents pervasive precession-paced wet/dry cycles in the strength of the African monsoon and Nile runoff since at least the late Miocene. This study investigates whether the East African vegetation shift after 2 Ma was accompanied by a change in the monsoonal wet/dry cycle response to orbital precession forcing. We sampled eastern Mediterranean ODP Site 967 at 2-3 ka resolution in two 200 kyr intervals near 3.0 and 1.7 Ma. Nearly identical orbital configurations in these intervals allow us to compare mean conditions and orbital-paced variations before and after the 2 Ma transition. We used leaf wax biomarker concentrations and ?D and ?13C compositions as proxies for monsoonal strength and vegetation type, and the ?18O composition of G. ruber as a proxy for Nile River runoff. Leaf wax biomarker concentrations varied over three orders of magnitude, with much higher concentrations in sapropels. During sapropel intervals, large-amplitude negative excursions occur in ?Dwax, ?13Cwax, and ?18Oruber, corresponding to a strengthened monsoon and less abundant C4 plants. Carbonate-rich intervals have positive isotope excursions indicating a weakened monsoon and more abundant C4 plants. The mean and variance of ?Dwax and ?13Cwax values are not significantly different between the 3.0 Ma and 1.7 Ma intervals indicating Northern Africa did not experience the vegetation and climate shifts observed in East Africa. While surprising, our finding suggests that the average monsoonal response to precession forcing, and corresponding vegetation variability, did not substantially change across the 2 Ma transition. This implies that North and East Africa exhibited different climate and vegetation behavior since 3 Ma.

Meyers, C.; deMenocal, P. B.; Tierney, J. E.; Polissar, P. J.

2012-12-01

410

African Music in the Americas  

ERIC Educational Resources Information Center

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…

Goines, Leonard

1977-01-01

411

Fossils of hydrothermal vent worms from Cretaceous sulfide ores of the Samail ophiolite, Oman  

USGS Publications Warehouse

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.

Haymon, R. M.; Koski, R. A.; Sinclair, C.

1984-01-01

412

Confocal Laser Scanning Microscopy and Raman (and Fluorescence) Spectroscopic Imagery of Permineralized Cambrian and Neoproterozoic Fossils  

Microsoft Academic Search

\\u000a Among all problems confronting the study of permineralized (petrified) ­fossils—the most life-like remnants preserved in the\\u000a fossil record—two stand out, the need for (1) accurate documentation of their three-dimensional morphology, and (2) direct\\u000a analysis of their chemical composition and that of their embedding mineral matrix. These problems can be addressed effectively\\u000a by the use of two techniques recently introduced to

J. William Schopf; Anatoliy B. Kudryavtsev

413

A Fossil Grass (Gramineae: Chloridoideae) from the Miocene with Kranz Anatomy  

Microsoft Academic Search

A fossil leaf fragment collected from the Ogallala Formation of northwestern Kansas exhibits features found in taxa of the modern grass subfamily Chloridoideae. These include bullet-shaped, bicellular microhairs, dumbbell-shaped silica bodies, cross-shaped suberin cells, papillae, stomata with low dome- to triangular-shaped subsidiary cells, and Kranz leaf anatomy. The leaf fragment extends the fossil record of plants that show both anatomical

Joseph R. Thomasson; Michael E. Nelson; Richard J. Zakrzewski

1986-01-01

414

Glaciation and ~ 770 Ma Ediacara (?) Fossils from the Lesser Karatau Microcontinent, Kazakhstan  

Microsoft Academic Search

The Cambrian explosion, c. 530–515Ma heralded the arrival of a diverse assembly of multicellular life including the first hard-shelled organisms. Fossils found in Cambrian strata represent the ancestors of most modern animal phyla. In contrast to the apparent explosiveness seen in the Cambrian fossil record, studies of molecular biology hint that the diversification observed in Cambrian strata was rooted in

Joseph G. Meert; Anatoly S. Gibsher; Natalia M. Levashova; Warren C. Grice; George D. Kamenov; Alexander B. Ryabinin

2011-01-01

415

Profound 62 Myr Cycle in Fossil Diversity  

NASA Astrophysics Data System (ADS)

By combining the Sepkoski Compendium of Marine Fossil Genera with the new ICS 2004 geologic time scale, we have shown that the fossil record contains a 62 +/- 3 Myr cycle in the diversity of genera. This cycle has a very high statistical significance and while the associated changes in diversity are frequently gradual, all of the sharp drops known as major mass extinctions have occurred during declining phases of this cycle. This suggests that the timing or magnitude of these extinctions has been influenced by this periodic process; however, it remains unclear whether extinction events actually cause the cycle. While, we cannot explain the origin of the 62 Myr cycle, we believe it indicates a profound influence of some periodic physical process on Earth's environment throughout at least the last 540 Myr. In addition, the diversity data contain a statistically ambiguous 140 +/- 15 Myr cycle which could be due to changes of the same frequency reported in climate and cosmic rays. While all major mass extinctions seem to bear some relation to this cycle, we also find that the Permian-Triassic extinction was qualitatively unique. This extinction, the most severe in Earth's history, had substantial impact on classes of organisms that were historically resistant to the 62 Myr changes. This suggests that the processes leading to the P-T extinction may have included factors that were unique to that point in the Phanerozoic. It should be noted that the 62 Myr hypothesis is originally due to Thomson (Thomson KS, Nature 261, 578-580 (1976); Devs. in Palaeo. and Strat. 5, 377-404 (1977)) and Ager (Ager DV, Proc. Geologists' Assoc. 87, 131-159 (1977)), though their work has largely been forgotten. At the time of this submission, our revival of the 62 Myr hypothesis and related analysis is currently undergoing peer review at Nature.

Muller, R. A.; Rohde, R. A.

2004-12-01

416

Cracks in fossil enamels resulting from premortem vs. postmortem events.  

PubMed

Vertebrate enamel preserves a record of fracture-producing strain. Fracturing during the life of the individual is potentially a source of selection for stronger enamel in the course of evolution. To determine if it is possible to recognize such fractures in fossil enamel, cracks in a variety of fossil materials, including enamel-covered holostean scales, crocodilian teeth, theropod and hadrosaurid dinosaur teeth, and mammalian teeth were examined. Cracks that occurred during the life of the individual could be recognized by abrasive wear on edges exposed at the surface of the enamel in areas worn by oral or locomotor abrasion. Certain distinctive crack patterns were identified as results of specific stress states occurring during life. Transverse cracks on the anterior parts of Lepisosteus scales were probably caused by external loading. Hertzian cracks and shallow, arcuate, lateral cracks on the occlusal edges of tooth enamel appear to be caused by stress concentrating impacts. Horizontal cracks arranged asymmetrically on the sides of conical teeth were reproduced in models subjected to bending stresses. Oblique cracks near the tips of conical fossil teeth were produced in models by oblique loads near the tip. Vertical cracks around cylindrical or conical tooth surfaces may be caused by several different sources of stress, including lateral "wind" loads and vertical "snow" loads. Of the postmortem causes of fracturing of fossil enamel, drying cracks seem to be the most important. Experimental drying produced from 25% to 50% of the cracks in dry teeth. PMID:3616562

Rensberger, J M

1987-06-01

417

THE NATURE OF FOSSIL GALAXY GROUPS: ARE THEY REALLY FOSSILS?  

SciTech Connect

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.

La Barbera, F.; Sorrentino, G. [INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli (Italy); De Carvalho, R. R. [VSTceN, via Moiariello 16, 80131 Napoli (Italy); De la Rosa, I. G. [Instituto de Astrofisica de Canarias, Tenerife (Spain); Gal, R. R. [Institute for Astronomy, 2680 Woodlawn Dr., Honolulu, HI 96822 (United States); Kohl-Moreira, J. L. [Observatorio Nacional, Rua General Jose Cristino 77, Rio de Janeiro (Brazil)

2009-04-15

418

Mental Health and African Americans  

MedlinePLUS

... are Non-Hispanic Blacks. The death rate from suicide for African American men was almost four times ... for African American women, in 2009. However, the suicide rate for African Americans is 60% lower than ...

419

Magnetic Recording.  

ERIC Educational Resources Information Center

A guide to the technology of magnetic recorders used in such fields as audio recording, broadcast and closed-circuit television, instrumentation recording, and computer data systems is presented. Included are discussions of applications, advantages, and limitations of magnetic recording, its basic principles and theory of operation, and its…

Lowman, Charles E.

420

Fossils, molecules and embryos: new perspectives on the Cambrian explosion  

NASA Technical Reports Server (NTRS)

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.

Valentine, J. W.; Jablonski, D.; Erwin, D. H.

1999-01-01

421

Record Production  

NSDL National Science Digital Library

Record Production is a website that has been created by record production professionals. Its main draw is the over 200 high quality streaming videos that feature tours of recording studios and interviews with the top record producers in the industry. Aside from the videos, the site also provides reviews of home and studio recording equipment, a news page that highlights updates to the site, as well as a forum.

2006-12-18

422

Fossil energy program. Summary document  

SciTech Connect

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.

None

1980-05-01

423

Fossil energy biotechnology: A research needs assessment  

NASA Astrophysics Data System (ADS)

The Office of Program Analysis of the U.S. Department of Energy commissioned this study to evaluate and prioritize research needs in fossil energy biotechnology. The objectives were to identify research initiatives in biotechnology that offer timely and strategic options for the more efficient and effective uses of the Nation's fossil resource base, particularly the early identification of new and novel applications of biotechnology for the use or conversion of domestic fossil fuels. Fossil energy biotechnology consists of a number of diverse and distinct technologies, all related by the common denominator -- biocatalysis. The expert panel organized 14 technical subjects into three interrelated biotechnology programs: (1) upgrading the fuel value of fossil fuels; (2) bioconversion of fossil feedstocks and refined products to added value chemicals; and (3) the development of environmental management strategies to minimize and mitigate the release of toxic and hazardous petrochemical wastes.

1993-11-01

424

Educating African American Males  

ERIC Educational Resources Information Center

Background: Schools across America spend money, invest in programs, and sponsor workshops, offer teacher incentives, raise accountability standards, and even evoke the name of Obama in efforts to raise the academic achievement of African American males. Incarceration and college retention rates point to a dismal plight for many African American…

Bell, Edward E.

2010-01-01