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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. PMID:21358825

Bibi, Faysal

2011-01-01

2

The Primate Fossil Record  

Microsoft Academic Search

The Primate Fossil Record is a profusely illustrated, up-to-date, and comprehensive treatment of primate paleontology that captures the complete history of the discovery and interpretation of primate fossils. Each chapter emphasizes three key components of the record of primate evolution: history of discovery, taxonomy of the fossils, and evolution of the adaptive radiations they represent. The volume objectively summarizes the

Walter Carl Hartwig

2002-01-01

3

Plant Fossil Record  

NSDL National Science Digital Library

The International Organization of Palaeobotany (IOP) manages the Plant Fossil Record (PFR) database. The recently released version of the database, PFR2.2, offers descriptive details of most plant fossil genera and modern genera with fossil species. Based on "the scientific literature ... or museum collections," the database is organized into five sections: Genera (references for plant fossil genera published mostly before 1985), Descriptions (containing descriptive details of "the type specimens of more than 10,000 extinct plant genera"), Taxonomy (an "informal system of vascular plant classification" based on published schemes), Occurrences (distribution information and references), and Palaeo Maps.

4

Dinoflagellata: Fossil Record  

NSDL National Science Digital Library

Information on this page pertains to dinoflagellates, the fossil record of which may extend into the Precambrian. Spherical organic-walled microfossils known as acritarchs, some of which may be dinoflagellate hystrichospheres, first appear in rocks about 1.8 billion years old. Exactly what the acritarchs were is not known with certainty; they probably included a number of clades of eukaryotic algae, and are thus a form taxon, including all those spore-like fossils which have not been conclusively assigned to another group.

5

Fossil records of volcanism  

NASA Astrophysics Data System (ADS)

Greenland glacial ice contains a fossil record of volcanic emissions transported in the stratosphere. C. V. Hammer, H. B. Clausen and W. Dansgaard (Nature, 288, 230, 1980) and M. W. Herron (Journal of Geophysical Research, 87, 3052, 1982) noted peaks of relatively high acidity in the Greenland glacial stratigraphic record that are assumed to be due to precipitation of sulfuric acid aerosols after major volcanic eruptions. R. B. Stothers and M. R. Rampino of the Goddard Institute for Space Studies in New York recently did a search of historical records and found an unexpected correlation of European volcano activity in the period 1500 B.C. to A.D. 1500 with dated acid maxima in Greenland ice (Science, 222, 411-412, 1983).Stothers and Rampino's soon-to-be-reported search (Journal of Geophysical Research, in press) included examination of “about one quarter of a million pages of modern English test” (Science). In their analysis they took into account the statistical uncertainty of the icecore dates and the time lags that would be expected to delay the arrival of acid rain from distant European volcano sources. Of course the problem of the analysis is that whereas there are extensive records of European volcanos, there is precious little information on volcano activity that must have occurred during the same period in the western Pacific and in the western hemisphere. Beginning with the volcano in Thera, Greece, set at about 1450 B.C. (the volcano date having been determined from “archeology and legend”) and its Greenland ice acid peak date set at about 1390 B.C. (± 50, by radiocarbon methods), Stothers and Rampino correlate historical data through Vesuvius (217-216 B.C), Etna (44 B.C.), and others. There seems to be an acid peak to correlate in each instance in the data of Hammer et al.

Bell, Peter M.

6

Biodiversity of the Fossil Record  

E-print Network

: Forams #12;Protista: Radiolarians #12;#12;Fossil Sponge, note the spicules #12;Archaeocyathid in crossBiodiversity of the Fossil Record Geology 331, Paleontology #12;Linnean Classification: Example stromatolites produced by cyanobacteria, Sharks Bay, Australia Cambrian, NY #12;Fossil bacteria 2BY old from

Kammer, Thomas

7

Evidence of Evolution I. Fossils and the fossil record  

E-print Network

Evidence of Evolution #12;I. Fossils and the fossil record � "First and foremost among in the rocks deposited in those Eras. #12;#12;Why is the fossil record incomplete? � fossilization - "lucky the step-by-step transition to becoming a tetrapod Origin of higher taxa recorded in the fossil record: 1

Dever, Jennifer A.

8

Speciation in the fossil record  

Microsoft Academic Search

It is easy to claim that the fossil record says nothing about speciation because the biological species concept (which relies on interbreeding) cannot be applied to it and genetic studies cannot be carried out on it. However, fossilized organisms are often preserved in sufficient abundance for populations of intergrading morphs to be recognized, which, by analogy with modern populations, are

Michael J. Benton; Paul N. Pearson

2001-01-01

9

Evidence of Evolution I. Fossils and the fossil record  

E-print Network

1 Evidence of Evolution I. Fossils and the fossil record · "First and foremost among the databases deposited in those Eras. #12;2 Why is the fossil record incomplete? · fossilization - "lucky accidents · conditions needed for fossilization ­ Rapid burial ­ Hard parts ­ Process unlikely in tropical regions http://www.pbs.org/wgbh/evolution

Dever, Jennifer A.

10

Learning from the Fossil Record  

NSDL National Science Digital Library

Another interesting and helpful resource from the University of California Berkeley Museum of Paleontology is the Learning from the Fossil Record Web site. Educators will find a list of over twenty fossil related classroom activities presented by different authors with titles such as Building a Topographic Model, Determining the Age Of Rocks and Fossils, Fossilization and Adaptation, the Dinosaur Body Structure, Microfossils, and other interesting subjects. The detailed descriptions include everything needed to complete the individual exercises including background information, procedures, and downloads. The unique collection should be a helpful addition to any junior high or high school science curriculum.

1996-01-01

11

Getting Into the Fossil Record  

NSDL National Science Digital Library

This computer activity provides a basic understanding of what a fossil is and the factors involved in becoming part of the fossil record. It is organized as an informational tour in two sections: one for middle school and one for high school. Students move at a self-selected pace by progressing and answering questions. A teacher's guide contains all necessary instructions as well as lesson plans, handouts, and assessment tools.

Johnson, Jennifer; Lindstrom, Kirsten

12

The Early Eukaryotic Fossil Record  

Microsoft Academic Search

The Precambrian era records the evolution of the domain Eucarya. Although the taxonomy of fossils is often impossible to resolve\\u000a beyond the level of domain, their morphology and chemistry indicate the evolution of major biological innovations. The late\\u000a Archean record for eukaryotes is limited to trace amounts of biomarkers. Morphological evidence appears in late Paleoproterozoic\\u000a and early Mesoproterozoic (1800–1300 Ma)

Emmanuelle J. Javaux

13

Evidence of Evolution the fossil record  

E-print Network

1 Evidence of Evolution the fossil record · spotty - more complete in some regions than others to becoming a tetrapod Origin of higher taxa recorded in the fossil record: 1) tetrapod evolution #12;4 Transitional species ­ 1st true frog: Vierealla, 190 mya 2) Frog evolution in the fossil record: Dinosaurs

Dever, Jennifer A.

14

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

15

Respiratory Mechanisms and the Metazoan Fossil Record  

Microsoft Academic Search

THE fossil record sheds little light on the problem of metazoan origins. Most of the major metazoan phyla appear in the fossil record in the Cambrian but no ancestral organisms have been found in the Precambrian, although suitable non-metamorphosed Precambrian rocks exist1. The oldest known metazoan fossils (latest Precambrian) are those from the Ediacara formation, Australia2. These fossils represent soft-bodied

Rudolf A. Raff

1970-01-01

16

Expected Anomalies in the Fossil Record  

Microsoft Academic Search

The problem of intermediates in the fossil record has been frequently discussed ever since Darwin. The extent of `gaps' (missing transitional stages) has been used to argue against gradual evolution from a common ancestor. Traditionally, gaps have often been explained by the improbability of fossilization and the discontinuous selection of found fossils. Here we take an analytical approach and demonstrate

Mareike Fischer; Mike Steel

2007-01-01

17

The fossil record of callitrichine primates Introduction  

E-print Network

The fossil record of callitrichine primates Introduction The ctiscovery offossils pertaining developed from horizontal comparisons against what is now a rapidly improving fossil record to the evolution of the cattitrichine New L2:ortd monke\\ s is a recognized objective of current field work and has

Rosenberger, Alfred H.

18

Global Completeness of the Bat Fossil Record  

Microsoft Academic Search

Bats are unique among mammals in their use of powered flight and their widespread capacity for laryngeal echolocation. Understanding\\u000a how and when these and other abilities evolved could be improved by examining the bat fossil record. However, the fossil record\\u000a of bats is commonly believed to be very poor. Quantitative analyses of this record have rarely been attempted, so it

Thomas P. Eiting; Gregg F. Gunnell

2009-01-01

19

Fossil record and ecology of Nyssa (Cornaceae)  

Microsoft Academic Search

The fossil record ofNyssa is critically reviewed on the basis of reports of fruits, wood, and leaves from numerous localities in the Northern Hemisphere.\\u000a Commonly overlooked features of fruit stone morphology, particularly the placement of vascular bundles relative to the surface\\u000a ribs, are used in grouping the fossil fruits and relating them to modern taxa. Aspects of the ecology of

Richard H. Eyde

1997-01-01

20

The Fossil Record of the Peronosporomycetes (Oomycota)  

E-print Network

. Petsamomyces, a new genus of organic-walled microfossils from the coal-bearing deposits of the Early Proterozoic, Kola Peninsula. Paleontol J 40: 465–475, doi:10.1134/S0031030106050017 Berry EW. 1916. Remarkable fossil fungi. Mycologia 8:73– 79, doi:10... to the Peronosporomycetes are discussed briefly and an explanation is provided as to why the fossil record of this group has remained inconsistent. In recent years there have been several new reports of fossil peronosporomycetes based on structurally preserved oogonium...

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

2011-01-01

21

BOOK REVIEWS The Fossil Record--  

E-print Network

reviews1 of the entire record of primate paleontology are few and far between. In fact, ironically, hominoids, and hu- man paleontology. Most of these have an introductory chapter with special reference with a history of discovery and debate (which readers might think too long compared to later sections), followed

Delson, Eric

22

GEOL 204: The Fossil Record Team Project  

E-print Network

the scope of the project: the history of paleontology; the societal aspects of paleontology Possible Topics--Picking a Topic: Your task is to research, record, and present information concerning a topic of paleontological (by no means an exhaustive list!): Particular Major Events in the History of Life: Archean Fossils

Holtz Jr., Thomas R.

23

The Future of the Fossil Record  

Microsoft Academic Search

The fossil record provides a powerful basis for analyzing the controlling factors and impact of biological evolution over a wide range of temporal and spatial scales and in the context of an evolving Earth. An increasingly interdisciplinary paleontology has begun to formulate the next generation of questions, drawing on a wealth of new data, and on methodological advances ranging from

David Jablonski

1999-01-01

24

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

25

Fossil Record Accurately Reflects Recent Flowering of Marine Biodiversity  

NSF Publications Database

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

26

Spatial Bias in the Marine Fossil Record  

PubMed Central

Inference of past and present global biodiversity requires enough global data to distinguish biological pattern from sampling artifact. Pertinently, many studies have exposed correlated relationships between richness and sampling in the fossil record, and methods to circumvent these biases have been proposed. Yet, these studies often ignore paleobiogeography, which is undeniably a critical component of ancient global diversity. Alarmingly, our global analysis of 481,613 marine fossils spread throughout the Phanerozoic reveals that where localities are and how intensively they have been sampled almost completely determines empirical spatial patterns of richness, suggesting no separation of biological pattern from sampling pattern. To overcome this, we analyze diversity using occurrence records drawn from two discrete paleolatitudinal bands which cover the bulk of the fossil data. After correcting the data for sampling bias, we find that these two bands have similar patterns of richness despite markedly different spatial coverage. Our findings suggest that i) long-term diversity trends result from large-scale tectonic evolution of the planet, ii) short-term diversity trends are region-specific, and iii) paleodiversity studies must constrain their analyses to well-sampled regions to uncover patterns not driven by sampling. PMID:24204570

Vilhena, Daril A.; Smith, Andrew B.

2013-01-01

27

RESEARCH LETTERS 161 The Fossil Record of Cretaceous  

E-print Network

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

Benton, Michael

28

The eukaryotic fossil record in deep time  

NASA Astrophysics Data System (ADS)

Eukaryotic organisms are defining constituents of the Phanerozoic biosphere, but they also extend well back into the Proterozoic record, primarily in the form of microscopic body fossils. Criteria for identifying pre-Ediacaran eukaryotes include large cell size, morphologically complex cell walls and/or the recognition of diagnostically eukaryotic cell division patterns. The oldest unambiguous eukaryote currently on record is an acanthomorphic acritarch (Tappania) from the Palaeoproterozoic Semri Group of central India. Older candidate eukaryotes are difficult to distinguish from giant bacteria, prokaryotic colonies or diagenetic artefacts. In younger Meso- and Neoproterozoic strata, the challenge is to recognize particular grades and clades of eukaryotes, and to document their macro-evolutionary expression. Distinctive unicellular forms include mid-Neoproterozoic testate amoebae and phosphate biomineralizing 'scale-microfossils' comparable to an extant green alga. There is also a significant record of seaweeds, possible fungi and problematica from this interval, documenting multiple independent experiments in eukaryotic multicellularity. Taxonomically resolved forms include a bangiacean red alga and probable vaucheriacean chromalveolate algae from the late Mesoproterozoic, and populations of hydrodictyacean and siphonocladalean green algae of mid Neoproterozoic age. Despite this phylogenetic breadth, however, or arguments from molecular clocks, there is no convincing evidence for pre-Ediacaran metazoans or metaphytes. The conspicuously incomplete nature of the Proterozoic record makes it difficult to resolve larger-scale ecological and evolutionary patterns. Even so, both body fossils and biomarker data point to a pre-Ediacaran biosphere dominated overwhelming by prokaryotes. Contemporaneous eukaryotes appear to be limited to conspicuously shallow water environments, and exhibit fundamentally lower levels of morphological diversity and evolutionary turnover than their Phanerozoic counterparts. I will argue here that this fundamental change of state was driven by the early Ediacaran appearance of Eumetazoa, a uniquely complex clade of heterotrophic eukaryotes that redefined how the planet worked.

Butterfield, N.

2011-12-01

29

RESEARCH PAPER The first fossil record of Polyrhachis (Hymenoptera: Formicidae  

E-print Network

taxon represents the first occurrence of the genus in the fossil record. The origin and rise of one Á Polyrhachis Á New species Á Miocene Á Fossil ant Kurzfassung Aus dem Obermioza¨n von Kreta (GrieRESEARCH PAPER The first fossil record of Polyrhachis (Hymenoptera: Formicidae: Formicinae) from

Villemant, Claire

30

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

31

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. PMID:11541734

Sepkoski, J J

1998-01-01

32

Uncovering Visitor Conceptions of Fossils and the Fossil Record  

Microsoft Academic Search

One of the common features of any natural history museum is its fossil collection. A visitor's prior knowledge of and experience with these prehistoric objects is expected to greatly influence how visitors make sense of these iconic displays. For this study, over 150 visitors to two natural history museums in Southern California were interviewed to find out what they knew

James Kisiel; Jeanine Ancelet

2009-01-01

33

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

34

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

35

The earliest fossil record of the animals and its significance.  

PubMed

The fossil record of the earliest animals has been enlivened in recent years by a series of spectacular discoveries, including embryos, from the Ediacaran to the Cambrian, but many issues, not least of dating and interpretation, remain controversial. In particular, aspects of taphonomy of the earliest fossils require careful consideration before pronouncements about their affinities. Nevertheless, a reasonable case can now be made for the extension of the fossil record of at least basal animals (sponges and perhaps cnidarians) to a period of time significantly before the beginning of the Cambrian. The Cambrian explosion itself still seems to represent the arrival of the bilaterians, and many new fossils in recent years have added significant data on the origin of the three major bilaterian clades. Why animals appear so late in the fossil record is still unclear, but the recent trend to embrace rising oxygen levels as being the proximate cause remains unproven and may even involve a degree of circularity. PMID:18192192

Budd, Graham E

2008-04-27

36

THE EARLIEST KNOWN FOSSIL ANT (FIRST SOUTHERN HEMISPHERE MESOZOIC RECORD)  

E-print Network

THE EARLIEST KNOWN FOSSIL ANT (FIRST SOUTHERN HEMISPHERE MESOZOIC RECORD) (HYMENOPTERA: FORMICIDAE are scarce in Cretaceous deposits. Sphecomyrma freyi Wilson & Brown (1967) was the first fossil ant assigned.S.A. (Magothy Formation). This formation was at the time referred to the lower part of the Upper Cretaceous

Villemant, Claire

37

Absolute measures of the completeness of the fossil record  

Microsoft Academic Search

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,

Mike Foote; J. John Sepkoski

1999-01-01

38

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

39

The fossil record and the early evolution of the Metazoa  

Microsoft Academic Search

The appearance of the multicellular animals, or Metazoa, in the fossil record about 600 million years ago marks a revolution in the history of life. Molecular biology is continuing to increase our understanding of metazoan evolution, yet information from fossils is still an important component in deciphering metazoan phylogeny, and data on rapidly radiating animal groups place early metazoan evolution

S. Conway Morris

1993-01-01

40

The Proterozoic Fossil Record of Heterotrophic Eukaryotes  

E-print Network

not by heterotrophs but by algae. Most of the fossils that can be assigned to a modern clade are algal (red), is interpreted as an alga (Han and Runnegar, 1992; Schneider et al., 2002). The presence of red algae in rocks diversity, in fact, autotrophy, which characterizes the algae and land plants, appears to be a derived

Porter, Susannah

41

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

42

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

43

PORTEREARLY EUKARYOTIC DIVERSIFICATION THE FOSSIL RECORD OF EARLY EUKARYOTIC  

E-print Network

, red algae, slime molds, brown algae, and at least twice in green algae. A substantial component and algae. It is these microbial groups that primarily contribute to the early fossil record of eukaryotes

Porter, Susannah

44

Coupled evolutionary rates and the fossil record  

Microsoft Academic Search

A model for speciation is given in which a taxon’s phenotypic variation and concomitant variation in fitness are related to\\u000a gradients within the environment. Phenotypic expressions within the population are shown to undergo abrupt transitions as\\u000a a result of discontinuous fitness-functions. Evidence for rapid and abrupt phenotypic variation is explored by analyses of\\u000a speciation (= origination) rates within the fossil

Karl J. Niklas

1978-01-01

45

When Pond Scum Ruled the Earth - The Proterozoic Fossil Record  

NSDL National Science Digital Library

In this laboratory exercise (2 hours), students explore the Proterozoic fossil record by examining two samples of microfossils, preserved in chert) and numerous samples of stromatolites. The laboratory exercise coincides with lecture discussions on the early history of life, and serves to illustrate the paleontological record of the Proterozoic. This exercise is the first laboratory exercise in the course that asks students to engage with and speculate upon the environmental and biological causes of the observed fossil record. The students' goal is to be able to identify some of the main environmental factors that combine to produce the diversity of stromatolite forms.

Bartley, Julie

46

Self-similarity of extinction statistics in the fossil record  

Microsoft Academic Search

The dynamical processes underlying evolution over geological timescales remain unclear,. Analyses of time series of the fossil record have highlighted the possible signature of periodicity in mass extinctions,, perhaps owing to external influences such as meteorite impacts. More recently the fluctuations in the evolutionary record have been proposed to result from intrinsic nonlinear dynamics for which self-organized criticality provides an

Ricard V. Solé; Susanna C. Manrubia; Michael Benton; Per Bak

1997-01-01

47

Excavating Your Recycling Bin as a Fossil Record  

NSDL National Science Digital Library

This activity simulates how scientists study the past by using layers of rock with fossils to understand events and life. Using this lesson teaches students about the relationship of rock layers (oldest deposited on bottom). Students will describe the objects in the trash as events occurring through time, understand that the fossil record is in 3-D, and learn that collecting accurate data is critical.

48

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

49

Environmental determinants of extinction selectivity in the fossil record  

E-print Network

LETTERS Environmental determinants of extinction selectivity in the fossil record Shanan E. Peters1 differential environmental turnover has contributed to extinction selectivity remains unknown. Here I use a new predict patterns of genus-level extinction, extinc- tion selectivity and diversity among Sepkoski

Peters, Shanan E.

50

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

51

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

52

The Cambrian Fossil Record and the Origin of the Phyla  

Microsoft Academic Search

SYNOPSIS. Whilst the ''Cambrian Explosion'' continues to attract much attention from a wide range of earth and life scientists, the detailed patterns exhibited by the terminal Proterozoic-Early Cambrian biotas remain unclear, for reasons of systematics, biostratigraphy and biogeography. In particular, recent changes in absolute dating of the Cambrian have refined the period of time that the fossil record might be

GRAHAM E. BUDD

2003-01-01

53

Geobiology and the fossil record: eukaryotes, microbes, and their interactions  

Microsoft Academic Search

Geobiology attempts to understand the interactions between Earth and the life which has evolved on it. It is an all-encompassing field that embraces both living systems on Earth as well as an understanding of the history of these systems since life first evolved. The fossil record and associated geological and geochemical data provide a major avenue towards understanding the evolution

David J. Bottjer

2005-01-01

54

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

55

Giving the early fossil record of sponges a squeeze.  

PubMed

Twenty candidate fossils with claim to be the oldest representative of the Phylum Porifera have been re-analysed. Three criteria are used to assess each candidate: (i) the diagnostic criteria needed to categorize sponges in the fossil record; (ii) the presence, or absence, of such diagnostic features in the putative poriferan fossils; and (iii) the age constraints for the candidate fossils. All three criteria are critical to the correct interpretation of any fossil and its placement within an evolutionary context. Our analysis shows that no Precambrian fossil candidate yet satisfies all three of these criteria to be a reliable sponge fossil. The oldest widely accepted candidate, Mongolian silica hexacts from c. 545 million years ago (Ma), are here shown to be cruciform arsenopyrite crystals. The oldest reliable sponge remains are siliceous spicules from the basal Cambrian (Protohertzina anabarica Zone) Soltanieh Formation, Iran, which are described and analysed here in detail for the first time. Extensive archaeocyathan sponge reefs emerge and radiate as late as the middle of the Fortunian Stage of the Cambrian and demonstrate a gradual assembly of their skeletal structure through this time coincident with the evolution of other metazoan groups. Since the Porifera are basal in the Metazoa, their presence within the late Proterozoic has been widely anticipated. Molecular clock calibration for the earliest Porifera and Metazoa should now be based on the Iranian hexactinellid material dated to c. 535 Ma. The earliest convincing fossil sponge remains appeared at around the time of the Precambrian-Cambrian boundary, associated with the great radiation events of that interval. PMID:24779547

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

2014-11-01

56

Fossils  

NSDL National Science Digital Library

This Topic in Depth begins with a Web site from the Royal Ontario Museum called Fossils!-Behind the Scenes at the Museum (1). It gives a light-hearted but informative introduction to what fossils are and how they're formed, collected, and identified. Next, the University of California Museum of Paleontology offers the Web site Learning From the Fossil Record (2), which contains several learning resources and lesson plans. Topics covered include Determining Age of Rocks and Fossils, Fossilization and Adaptation: Activities in Paleontology, and Microfossils. The third site is a US Geological Survey publication entitled Fossils, Rocks, and Time (3). Visitors can learn about succession, geologic time, and other relevant facts about how fossils are studied. The University of Arizona Department of Geosciences maintains the next site, which is entitled Petrified Wood (4). It provides information on Petrified Forest National Park, an interactive look at the process of petrification, and more. Offered by the Museum Victoria, the fifth site, Dating Rocks and Fossils (5), explains the difference between relative and absolute (radiometric) dating. It also includes a chart that gives the various isotopes used, their half-life, daughter isotope, and geologic application. The next site, provided by the BBC and their Walking With Dinosaurs series, is called Fossil Detectives (6). The site describes why dinosaur fossils are so rare, where the best place to find them is, how their age is estimated, and other interesting information that can be found on this page and the rest of the site. Next, from the Florida Museum of Natural History comes the Fossil Preparation and Conservation (7) Web site. A more in-depth and technical description of fossil preparation is presented, including the use of cosolidants, adhesives, and various tools. The last site is from the University of Kentucky Paleontological Society called Photographs of Fossils Found on KPS Fieldtrips (8). As you would expect, the site contains a large categorized list of fossils, each briefly described and linked to its respective photograph.

2002-01-01

57

The Fossil Record of Drilling Predation on Bivalves and Gastropods  

Microsoft Academic Search

\\u000a The fossil record yields abundant data on the interaction between drilling predators and their shelled prey. Predatory drill\\u000a holes may date to the late\\u000a Precambrian (Bengtson and Zhao, 1992) and have been reported from various Paleozoic assemblages (e.g., Sheehan and Lesperance, 1978; Smith et al., 1985; Conway Morris and Bengtson, 1994). Paleozoic drill holes have been reported primarily from brachiopods,

Patricia H. Kelley; Thor A. Hansen

58

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

59

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

60

Exopaleontology and the search for a fossil record on Mars  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

61

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

PubMed

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

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

2014-01-01

62

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

PubMed Central

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

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

2014-01-01

63

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. PMID:18380861

Wood, Bernard; Lonergan, Nicholas

2008-01-01

64

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

65

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. PMID:24396267

Budd, Graham E

2013-01-01

66

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

67

The Fossil Record and Evolution: Comparing Cladistic and Paleontologic Evidence for Vertebrate History  

Microsoft Academic Search

The fossil record offers the only direct evidence of extinct life and thus has figured prominently in considerations of evolutionary patterns. But the incomplete nature of the fossil record has also been emphasized in arguments that fossils play only a secondary role in the recovery of phylogenetic histories based on extant taxa. Although these criticisms recently have been countered, there

Mark A. Norell; Michael J. Novacek

1992-01-01

68

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

69

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

70

The Fossil Record and Evolution of Bovidae: State of the Field  

Microsoft Academic Search

This paper presents a summary of the current state of knowledge on the evolution and fossil record of Bovidae and identifies topics and problems for further study. The earliest records of the different bovid tribes are reviewed, along with their geographic locations. Future work on the fossil bovid record should focus on: the reinvestigation of osteological characters that might distinguish

Faysal Bibi; Maia Bukhsianidze; Alan W. Gentry; Denis Geraads; Dimitris S. Kostopoulos; Elisabeth S. Vrba

71

Calibration and Error in Placental Molecular Clocks: A Conservative Approach Using the Cetartiodactyl Fossil Record  

Microsoft Academic Search

The nature of the molecular and fossil record and their limitations must be ascertained in order to gain the most precise and accurate evolutionary timescale using genetic information. Yet the majority of such timescales are based on point estimates using fossils or the molecular clock. Here we document from the primary literature minimum and maximum fossil age estimates of the

M. van Tuinen; E. A. HADLY

2004-01-01

72

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

73

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

Microsoft Academic Search

Fossil invertebrate shells and carapaces displaying preserved original color patterns are among the rarest fossils. The fossil record of color patterns extends into the Middle Cambrian where the trilobite Anomocare displays a fan-like array of stripes on the pygidium. About 180 Paleozic genera are known with patterns, including trilobites, cephalopods, gastropods, brachiopods, bivalves, crinoids, and crustaceans. Based upon an analysis

D. R. Kobluk; R. H. Mapes

1989-01-01

74

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

E-print Network

1 Primer Studying Function and Behavior in the Fossil Record Michael J. Benton* Department of Earth and fossil vertebrates and that anatomy could be reconstructed with confidence from incomplete fossil remains such exquisite adaptations as evidence for design rather than evolution. But we must be cautious of over

Benton, Michael

75

The first fossil owls (Aves: Strigiformes) from the Paleogene of Asia and a review of the fossil record of Strigiformes  

Microsoft Academic Search

The fossil record of owls (Strigiformes) is one of the most extensive among the neornithine birds, yet at the same time largely\\u000a restricted geographically to Europe and North America. Various fossil owls are known from the Paleocene (ca. 60 Ma) to Recent.\\u000a Here we present the first taxonomic description of new species of Paleogene owls from Asia, two new taxa

E. N. Kurochkin; G. J. Dyke

2011-01-01

76

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

77

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

E-print Network

Fossil bryophytes as recorders of ancient CO2 levels: Experimental evidence and a Cretaceous case. The potential for fossil liverworts to record past CO2 changes is investigated by analyzing the d13 C- Ordovician, pre-dating all currently used quantitative CO2 proxies. Citation: Fletcher, B. J., D. J. Beerling

Royer, Dana

78

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

79

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

Microsoft Academic Search

The fossil record of tetrapods is very patchy because of the problems of preservation in terrestrial sediments, and because vertebrates are rarely very abundant. However, the fossil record of tetrapods has the advantages that it is easier to establish a phylogenetic taxonomy than for many invertebrate groups (many characters; fast evolution), and there is the potential for more detailed ecological

Michael J. Benton

1990-01-01

80

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

Microsoft Academic Search

The fossil record of tetrapods is very patchy because of the problems of preservation in terrestrial sediments, and because vertebrates are rarely very abundant. However, the fossil record of tetrapods has the advantages that it is easier to establish a phylogenetic taxonomy than for many invertebrate groups (many characters; ‘fast’ evolution), and there is the potential for more detailed ecological

Michael Benton

81

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

82

Poor fossil record and major changes around 1 MaBP  

Microsoft Academic Search

The abundance of early fossil humans in African sites ceases at dates around 1.3MaBP; there is almost none until nearly 0.8MaBP.\\u000a Again these are scarce until less than 0.5 Ma. Most of Homo erectus fossils in Java are dated between c.1.3 and 0.70Ma; just\\u000a a few fossil humans are known in Eurasia for this time span. Questions arise on eventual

E. Aguirre

2000-01-01

83

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.

84

'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

85

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

PubMed

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). PMID:23625517

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

2013-05-01

86

Fossils  

NSDL National Science Digital Library

Fossils is an activity for grades 1-2 that enables students to apply their interest in dinosaurs to discovering how fossils tell us about our past. As a result of this activity, the students will be able to: tell a friend or parent who a paleontologist is and what he does; explain what a fossil is; explain how we use fossils to learn about the past; and make a fossil using clay, plaster of paris, and some sort of molding object such as a shell, leaf, bone, etc. A suggested extension of this activity is turning it into an archaeological "dig" by burying objects in plaster of paris and then using dull instruments to dig for the "fossils."

1998-01-01

87

Validation and application of fossil DNA as a recorder of past marine ecosystems and environmental conditions  

Microsoft Academic Search

The majority of planktonic species, including those that are informative in the reconstructions of past marine environmental conditions, do not produce diagnostic features (e.g., cysts, spores, or lipid biomarkers) and would therefore escape identification from the fossil record using traditional paleoecological tools (microscopy or lipid biomarker geochemistry). However, several studies have recently demonstrated that fossil DNA of planktonic species can

A. C. Boere

2010-01-01

88

Fossil Records of Cosmic Reionization in Galactic Stellar Halos  

Microsoft Academic Search

Galactic stellar halos have long been considered to contain fossil information on the early dynamical and chemical evolution of galaxies. We propose that the surface brightness distributions of old stellar halos contain the influence of reionization on early formation histories of galaxies. By assuming that reionization significantly suppresses star formation in small subgalactic clumps virialized after reionization redshift (zreion), we

Kenji Bekki; Masashi Chiba

2005-01-01

89

The hominin fossil record: taxa, grades and clades  

Microsoft Academic Search

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

Bernard Wood; Nicholas Lonergan

2008-01-01

90

Parrots in a nutshell: The fossil record of Psittaciformes (Aves)  

Microsoft Academic Search

Parrots (traditional order Psittaciformes) are one of the most instantly recognizable groups of modern birds. Their relatively large heads, squat necks and broad, curved bills help to make parrots so easily identifiable. However, the few early fossil parrots that have been discovered to date (Lower Eocene), do not necessarily possess this “parrot-like” cranial morphology. Even more surprisingly, early psittaciforms have

David M. Waterhouse

2006-01-01

91

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

92

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!!

101

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

Microsoft Academic Search

Vestigial structures occur at both the anatomical and molecular levels, but studies documenting the co-occurrence of morphological degeneration in the fossil record and molecular decay in the genome are rare. Here, we use morphology, the fossil record, and phylogenetics to predict the occurrence of “molecular fossils” of the enamelin (ENAM) gene in four different orders of placental mammals (Tubulidentata, Pholidota,

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

2009-01-01

102

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

ERIC Educational Resources Information Center

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

Smith, Grant Sackett

1988-01-01

103

Crustaceans from bitumen clast in Carboniferous glacial diamictite extend fossil record of copepods.  

PubMed

Copepod crustaceans are extremely abundant but, because of their small size and fragility, they fossilize poorly. Their fossil record consists of one Cretaceous (c. 115?Ma) parasite and a few Miocene (c. 14?Ma) fossils. In this paper, we describe abundant crustacean fragments, including copepods, from a single bitumen clast in a glacial diamictite of late Carboniferous age (c. 303?Ma) from eastern Oman. Geochemistry identifies the source of the bitumen as an oilfield some 100-300?km to the southwest, which is consistent with an ice flow direction from glacial striae. The bitumen likely originated as an oil seep into a subglacial lake. This find extends the fossil record of copepods by some 188?Ma, and of free-living forms by 289?Ma. The copepods include evidence of the extant family Canthocamptidae, believed to have colonized fresh water in Pangaea during Carboniferous times. PMID:20975721

Selden, Paul A; Huys, Rony; Stephenson, Michael H; Heward, Alan P; Taylor, Paul N

2010-01-01

104

Fossils  

NSDL National Science Digital Library

Paleontologists seldom have the good fortune to find a complete set of remains of an ancient organism that is wholly intact. For instance, the discovery of a frozen woolly mammoth carcass, preserved hair and all, was a truly rare event. More common are discoveries of incomplete remains, such as bones, teeth, or hair, and trace fossils, such as footprints or leaf impressions, which indicate an organism once existed even though its actual remains have not been found. This slide presentation reveals the variety of forms that fossils take, as well as examples of the kinds of life whose remains have been preserved. A background essay and discussion questions are included.

2011-05-17

105

Use of Paleomagnetic Secular Variation, Excursion, and Reversal Records to Correlate African Lake Climate Records  

NASA Astrophysics Data System (ADS)

Geomagnetic secular variation, excursions, and reversal records can provide an excellent means for high resolution correlation of sedimentary climate records. Recent drilling projects on Lake Bosumtwi, Ghana, and Lake Malawi, Malawi, have provided the opportunity to study long African climate records (<1 Ma). Magnetic studies of these sedimentary archives indicate that high quality SV records are preserved through most of the sequence despite the fact that anoxia is the usual condition of bottom waters in both lakes. We compare the magnetic records of Lake Bosumtwi and Lake Malawi to test our ability to correlate between West African and East African lakes. In addition, we compare the magnetic record of Lake Malawi to records from Lake Tanganyika in East Africa and the Indian Ocean region, and the record of Lake Bosumtwi to that of Lake Barombi Mbo in West Africa. Correlations within regions are straightforward and highly useful for intrasite correlation. Correlation between East and West Africa is also possible, although the resolution of the correlation is more limited.

King, J.; Heil, C.; Peck, J.; Scholz, C.; Shanahan, T.; Overpeck, J.

2005-12-01

106

The fossil record of evolution: Analysis of extinction  

NASA Technical Reports Server (NTRS)

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

Raup, D. M.

1986-01-01

107

100,000 Years of African monsoon variability recorded in sediments of the Nile margin  

E-print Network

100,000 Years of African monsoon variability recorded in sediments of the Nile margin Marie Revel a constitutes a first continuous high resolution record of the East African monsoon regime intensity over of the African monsoon over Ethiopia, the Nabtian period from 14 to 8 ka cal BP and the Saharan period from 98

Demouchy, Sylvie

108

Fossil Chironomidae (Insecta: Diptera) as quantitative indicators of past salinity in African lakes  

NASA Astrophysics Data System (ADS)

We surveyed sub-fossil chironomid assemblages in surface sediments of 73 low- to mid-elevation lakes in tropical East Africa (Uganda, Kenya, Tanzania, Ethiopia) to develop inference models for quantitative paleosalinity reconstruction. Using a calibration data set of 67 lakes with surface-water conductivity between 34 and 68,800 ?S/cm, trial models based on partial least squares (PLS), weighted-averaging (WA), weighted-averaging partial least squares (WA-PLS), maximum likelihood (ML), and the weighted modern analogue technique (WMAT) produced jack-knifed coefficients of determination ( r2) between 0.83 and 0.87, and root-mean-squared errors of prediction (RMSEP) between 0.27 and 0.31 log 10 conductivity units, values indicating that fossil assemblages of African Chironomidae can be valuable indicators of past salinity change. The new inference models improve on previous models, which were calibrated with presence-absence data from live collections, by the much greater information content of the calibration data set, and greater probability of finding good modern analogues for fossil assemblages. However, inferences still suffered to a greater (WA, WMAT) or lesser (WA-PLS, PLS and ML) extent from weak correlation between chironomid species distribution and salinity in a broad range of fresh waters, and apparent threshold response of African chironomid communities to salinity change near 3000 ?S/cm. To improve model sensitivity in freshwater lakes we expanded the calibration data set with 11 dilute (6-61 ?S/cm) high-elevation lakes on Mt. Kenya (Kenya) and the Ruwenzori Mts. (Uganda). This did not appreciably improve models' error statistics, in part because it introduced a secondary environmental gradient to the faunal data, probably temperature. To evaluate whether a chironomid-based salinity inference model calibrated in East African lakes could be meaningfully used for environmental reconstruction elsewhere on the continent, we expanded the calibration data set with 8 fresh (15-168 ?S/cm) lakes in Cameroon, West Africa, and one hypersaline desert lake in Chad. This experiment yielded poorer error statistics, primarily because the need to amalgamate East and West African sister taxa reduced overall taxonomic resolution and increased the mean tolerance range of retained taxa. However, the merged data set constrained better the salinity optimum of several freshwater taxa, and further increased the probability of finding good modern analogues. We then used chironomid stratigraphic data and independent proxy reconstructions from two fluctuating lakes in Kenya to compare the performance of new and previous African salinity-inference models. This analysis revealed significant differences between the various numerical techniques in reconstructed salinity trends through time, due to their different sensitivity to the presence or relative abundance of certain key taxa, combined with the above-mentioned threshold faunal response to salinity change. Simple WA and WMAT produced ecologically sensible reconstructions because their step-like change in inferred conductivity near 3000 ?S/cm mirrors the relatively rapid transitions between fresh and saline lake phases associated with climate-driven lake-level change in shallow tropical closed-basin lakes. Statistical camouflaging of this threshold faunal response in WA-PLS and ML models resulted in less trustworthy reconstructions of past salinity in lakes crossing the freshwater-saline boundary. We conclude that selection of a particular inference model should not only be based on statistical performance measures, but consider chironomid community ecology in the study region, and the amplitude of reconstructed environmental change relative to the modern environmental gradient represented in the calibration data set.

Eggermont, Hilde; Heiri, Oliver; Verschuren, Dirk

2006-08-01

109

Evidence for periodicity and nonlinearity in a high-resolution fossil record of long-term evolution  

Microsoft Academic Search

The application of new signal analysis techniques provides increased insight into the study of the fossil record and processes of evolution. The fossil record of 622 planktic foraminifera contains data from 200 stratigraphic stages of the past 127 m.y. Time-series analyses (wavelet and Fourier transform) of the planktic foraminifera fossil record were used to discern periodic components in long-term evolution.

Andreas Prokoph; Anthony D. Fowler; R. Timothy Patterson

2000-01-01

110

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

E-print Network

of molecular fossils that places the rise of the sponge lineage before 635 million years ago. Charles DarwinIn the absence of shells or bones, the fossil record of animals can fade away to localized snapshots, such as the remarkable diversity of early animal-like fossils in the Doushantuo biotaofsouthern

Brocks, Jochen J.

111

First fossil record of the genus Nageia (Podocarpaceae) in south China and its phytogeographic implications  

Microsoft Academic Search

The first fossil record of the genus Nageia Gaertner from the Tertiary of southern China is reported. Nageia hainanensis sp. nov. is described from the Eocene Changchang Formation of Hainan Island. The extant species of Nageia are widely distributed in southeastern Asia, from northeastern India to southeastern China and southern Japan, and southward\\u000a through Indochina to the Malay Archipelago and

Jianhua Jin; Jue Qiu; You’an Zhu; Tatyana M. Kodrul

2010-01-01

112

Detecting competition in the fossil record: Support for character displacement among Ordovician brachiopods  

Microsoft Academic Search

In an effort to further our understanding of ecosystem structure on multiple temporal and biogeographic scales, the influence of competitive interactions in an invasive setting was explored in the fossil record. Using brachiopod morphology as a proxy for niche space occupation, the external shapes of three pairs of potentially competing brachiopod species were analyzed via three-dimensional baseline shape co-ordinates. Morphology

Carrie L. Tyler; Lindsey R. Leighton

2011-01-01

113

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

Microsoft Academic Search

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

Kevin J. Peterson; Nicholas J. Butterfield

2005-01-01

114

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

115

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

116

Assessing the fidelity of the fossil record by using marine bivalves  

E-print Network

of the clade, but instead tend to have small body size, reactive shell structures, commensal or parasitic habit dynamics of clades and biotas. Clade inventories such as these can be used to develop protocols the fidelity and completeness of the fossil record has been important to evolutionary studies beginning

Boyce, C. Kevin

117

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

118

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

119

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. PMID:22761723

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

2012-01-01

120

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

PubMed

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. PMID:16509901

Donoghue, Philip C J; Kouchinsky, Artem; Waloszek, Dieter; Bengtson, Stefan; Dong, Xi-ping; Val'kov, Anatoly K; Cunningham, John A; Repetski, John E

2006-01-01

121

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

122

Yukon gold mine yields ancient horse fossil 700,000yearold fossil discovered in Yukon permafrost yields genome world record.  

E-print Network

Yukon gold mine yields ancient horse fossil 700,000yearold fossil discovered in Yukon permafrost an unusually large horse fossil in the Yukon permafrost, he knew it was important. Now, in a new study visiting Yukon placer gold mining exposures to understand the permafrost and the ice age environments

Machel, Hans

123

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

PubMed

The branching times of molecular phylogenies allow us to infer speciation and extinction dynamics even when fossils are absent. Troublingly, phylogenetic approaches usually return estimates of zero extinction, conflicting with fossil evidence. Phylogenies and fossils do agree, however, that there are often limits to diversity. Here, we present a general approach to evaluate the likelihood of a phylogeny under a model that accommodates diversity-dependence and extinction. We find, by likelihood maximization, that extinction is estimated most precisely if the rate of increase in the number of lineages in the phylogeny saturates towards the present or first decreases and then increases. We demonstrate the utility and limits of our approach by applying it to the phylogenies for two cases where a fossil record exists (Cetacea and Cenozoic macroperforate planktonic foraminifera) and to three radiations lacking fossil evidence (Dendroica, Plethodon and Heliconius). We propose that the diversity-dependence model with extinction be used as the standard model for macro-evolutionary dynamics because of its biological realism and flexibility. PMID:21993508

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

2012-04-01

124

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

NASA Astrophysics Data System (ADS)

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

Benton, Michael J.

125

The fossil record and the origin of ticks (Acari: Parasitiformes: Ixodida)  

Microsoft Academic Search

Ticks are obligate hematophagous ectoparasites of terrestrial vertebrates. Hypotheses on the origin of ticks have been proposed\\u000a based on tick-host associations and the total-evidence approach analysis of morphological and molecular characters. Nevertheless,\\u000a the origin of ticks remains a controversial issue. Here, I revised the tick fossil record including reports from the literature\\u000a and the description of 7 new specimens. The

José de la Fuente

2003-01-01

126

Morphological design and fossil record of the podocopid ostracod naupliar eye  

Microsoft Academic Search

The naupliar eye of podocopid ostracods is a useful character for considering evolution in photic environments. Based on external\\u000a morphologies and histological observations, naupliar eyes are here categorized into six types. The fossil record demonstrates\\u000a that the major evolutionary changes in podocopid naupliar eyes occured after the Ordovician. Eye types 1 and 2 are not joined\\u000a to the carapace by

Gengo Tanaka

2005-01-01

127

Opportunistic evolution: Abiotic environmental stress and the fossil record of plants  

Microsoft Academic Search

DiMichele, W.A., Phillips, T.L. and Olmstead, R.G., 1987. Opportunistic evolution: abiotic environmental stress and the fossil record of plants. Rev. Palaeobot. Palynol., 50: 151-178. Abiotic stress has played a major role in the evolution of vascular plants by creating or delimiting habitats with low interspecific competition. These are, in effect, opportunities for survival of divergent phenotypes through non- adaptive evolution.

WILLIAM A. DIMICHELE; TOM L. PHILLIPS; RICHARD G. OLMSTEAD

1987-01-01

128

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

Microsoft Academic Search

Criticism of molecular clock studies often centres on inadequate calibration and a perceived lack of correlation between reproductive isolation and recognisable morphological evolution. Since many major groups (e.g. birds, mammals, reptiles) have a poor fossil record, it is often difficult to test and refute these limitations. Planktic foraminifera represent an exception to this rule. Deep-sea sediments are super-abundant in foraminifera,

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

2004-01-01

129

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

130

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

SciTech Connect

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

Kobluk, D.R. (Univ. of Toronto, Ontario (Canada)); Mapes, R.H. (Ohio Univ., Athens (USA))

1989-02-01

131

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

PubMed Central

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

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

2014-01-01

132

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

PubMed

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

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

2014-01-01

133

Evolution of the semi-aquatic bugs (Hemiptera: Heteroptera: Gerromorpha) with a re-interpretation of the fossil record  

Microsoft Academic Search

The fossil history of semi-aquatic bugs (Gerromorpha) is reviewed in light of the many important recent records and new developments in our under- standing of the phylogeny of the group. Based on the age of its sister group, the Panheteroptera, the Gerromorpha probably extends back into the Triassic, even though the oldest fossil forms assigned to the group are dubious.

Jakob DAMGAARD

2008-01-01

134

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

PubMed

The Neoproterozoic era (1,000-542 Myr ago) was an era of climatic extremes and biological evolutionary developments culminating in the emergence of animals (Metazoa) and new ecosystems. Here we show that abundant sedimentary 24-isopropylcholestanes, the hydrocarbon remains of C(30) sterols produced by marine demosponges, record the presence of Metazoa in the geological record before the end of the Marinoan glaciation ( approximately 635 Myr ago). These sterane biomarkers are abundant in all formations of the Huqf Supergroup, South Oman Salt Basin, and, based on a new high-precision geochronology, constitute a continuous 100-Myr-long chemical fossil record of demosponges through the terminal Neoproterozoic and into the Early Cambrian epoch. The demosponge steranes occur in strata that underlie the Marinoan cap carbonate (>635 Myr ago). They currently represent the oldest evidence for animals in the fossil record, and are evidence for animals pre-dating the termination of the Marinoan glaciation. This suggests that shallow shelf waters in some late Cryogenian ocean basins (>635 Myr ago) contained dissolved oxygen in concentrations sufficient to support basal metazoan life at least 100 Myr before the rapid diversification of bilaterians during the Cambrian explosion. Biomarker analysis has yet to reveal any convincing evidence for ancient sponges pre-dating the first globally extensive Neoproterozoic glacial episode (the Sturtian, approximately 713 Myr ago in Oman). PMID:19194449

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

2009-02-01

135

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

136

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

NASA Astrophysics Data System (ADS)

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

Davis, Margaret Bryan; Botkin, Daniel B.

1985-05-01

137

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

PubMed

The power of molecular oxygen to drive many crucial biogeochemical processes, from cellular respiration to rock weathering, makes reconstructing the history of its production and accumulation a first-order question for understanding Earth's evolution. Among the various geochemical proxies for the presence of O(2) in the environment, molecular fossils offer a unique record of O(2) where it was first produced and consumed by biology: in sunlit aquatic habitats. As steroid biosynthesis requires molecular oxygen, fossil steranes have been used to draw inferences about aerobiosis in the early Precambrian. However, better quantitative constraints on the O(2) requirement of this biochemistry would clarify the implications of these molecular fossils for environmental conditions at the time of their production. Here we demonstrate that steroid biosynthesis is a microaerobic process, enabled by dissolved O(2) concentrations in the nanomolar range. We present evidence that microaerobic marine environments (where steroid biosynthesis was possible) could have been widespread and persistent for long periods of time prior to the earliest geologic and isotopic evidence for atmospheric O(2). In the late Archean, molecular oxygen likely cycled as a biogenic trace gas, much as compounds such as dimethylsulfide do today. PMID:21825157

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

2011-08-16

138

Microaerobic steroid biosynthesis and the molecular fossil record of Archean life  

PubMed Central

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

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

2011-01-01

139

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

140

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

E-print Network

availability. It is shown that in many cases formation counts will always correlate with fossil countsAssessing the quality of the fossil record: insights from vertebrates MICHAEL J. BENTON1 the quality of the fossil record is notoriously hard, and many recent attempts have used sampling proxies

Benton, Michael

141

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

NASA Astrophysics Data System (ADS)

Criticism of molecular clock studies often centres on inadequate calibration and a perceived lack of correlation between reproductive isolation and recognisable morphological evolution. Since many major groups (e.g. birds, mammals, reptiles) have a poor fossil record, it is often difficult to test and refute these limitations. Planktic foraminifera represent an exception to this rule. Deep-sea sediments are super-abundant in foraminifera, and large numbers of specimens and occurrences are easily garnered from Ocean Drilling Programme cores. Planktic foraminifera therefore represent an ideal model group with which to test and refine molecular clock studies. Since the 1990AƒAøAøâ_sA¬Aøâ_zAøs, genetic sequences (principally 18S r-RNA) have been extracted from living planktic foraminifera, and a large genetic library has developed. Our study attempts to contextualise and test molecular data, particularly AƒAøAøâ_sA¬A<Å"molecular clockAƒAøAøâ_sA¬Aøâ_zAø dates, utilising material from two ODP cores (Site 926A (Atlantic) and 806 (Pacific), to examine the evolutionary history of two sibling-species complexes (Globigerinella siphonifera and Globigerinoides ruber, both common shallow-water species and both of considerable palaeoceanographic utility). Recent genetic studies have suggested that these two AƒAøAøâ_sA¬A<Å"super-speciesAƒAøAøâ_sA¬Aøâ_zAø in fact consist of a number of isolated forms, with contrasting ecologies and longevities, which in Recent and sub-Recent sediments can be distinguished either on the basis of pore ultrastructure (Gl. siphonifera) or test colouration (Gs. ruber). In both cases, molecular clock estimates are indicative of ancient (7-11 Ma) intra-species cryptic divergences, which seem to be considerably older than fossil dates. In particular, the calculated molecular split between the two forms of Gs. ruber (AƒAøAøâ_sA¬A<Å"whiteAƒAøAøâ_sA¬Aøâ_zAø and AƒAøAøâ_sA¬A<Å"pinkAƒAøAøâ_sA¬Aøâ_zAø) of around 11 Ma is considerably discordant with the fossil date of around 0.7 Ma. At first glance, this may appear to be a classic case of molecular over-estimation, often a feature of clock models, especially where, as in the foraminifera, substitution rates may vary widely. However, there is good reason to suspect that fossil range of the derived AƒAøAøâ_sA¬A<Å"pinkAƒAøAøâ_sA¬Aøâ_zAø form may have been artificially truncated by diagenetic degradation of the meta-stable test pigmentation. The deep molecular splits for Gl. siphonifera (around 7 Ma for the two main morphologically distinguishable sub-types), whilst not so obviously at odds with the fossil record, still belie the very small amount of morphological evolution observed within the plexus. We have used morphometric methods on a large (over 2000 pooled specimens) dataset in an effort to independently test the molecular clock, using SEM-based measurement of pore metrics (for Gl. siphonifera) and a multivariate analysis of whole-test characteristics (for Gs. ruber). Comparison of results for the two species suggests interesting patterns; whilst the two cryptic sub-types of Gl. siphonifera seemingly can be traced through time and seem to respond to external oceanographic forcing, the sub-types of Gs. ruber appear to be truly cryptic, and cannot be distinguished in the fossil record beyond 0.7 Ma. This raises two important points; firstly, the molecular clock (at least for foraminifera) bears considerable scrutiny, appears to be relatively robust to substitution bias and is seemingly broadly in accordance with morphological data; and secondly, the relationship between form and function in planktic foraminifera appears to be ill-defined, raising important questions for functional morphology.

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

2004-12-01

142

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

PubMed Central

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

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

2009-01-01

143

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

Microsoft Academic Search

On the Australian continent the fossil record of the initial appearance and radiation of higher metazoans is strongly influenced by the distribution of facies suitable for fossil preservation. The limited stratigraphic range of the \\

Jeffrey F. Mount; Catherine McDonald

1992-01-01

144

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

NASA Astrophysics Data System (ADS)

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

Retallack, Gregory J.

2001-05-01

145

Mitochondrial relationships and divergence dates of the African colobines: evidence of Miocene origins  

E-print Network

the diverse colobine taxa seen in the African Plio- Pleistocene fossil record. The lack of early members from similar temporal depth and geographic distribution. The earliest colobine in the African fossil record relationships and estimating divergence dates among the living forms will provide insight into the evolution

Oregon, University of

146

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

PubMed

Extant pines of subsection Pinus (section Pinus, genus Pinus, Pinaceae) are predominantly distributed in Eastern Asia. However, the extent of diversification in the section has yet to be fully clarified. We reviewed fossil records of subsection Pinus from Japan and collected permineralized materials, in which anatomical details are preserved for better understanding of the diversification. Our results suggest that this subsection appeared in Japan no earlier than the Middle Eocene, with extant species (i.e., Pinus densiflora and Pinus thunbergii) appearing around the beginning of the Pleistocene. Pinus fujiii (Early Miocene to Early Pleistocene) is inferred to have a close affinity to P. thunbergii based on the medial arrangement of its leaf resin canals. Additionally, P. fujiii has a similar cone morphology to those of extant species living in China, bridging the morphological gap between P. thunbergii and Chinese relatives of P. thunbergii as inferred by molecular phylogenetic analyses. Our results also suggest that taxonomic revisions of Pinus miocenica and Pinus oligolepis are required among the Japanese fossil species reported to date. PMID:24402436

Yamada, Toshihiro; Yamada, Mariko; Tsukagoshi, Minoru

2014-03-01

147

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

148

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

149

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

PubMed Central

Abstract Calcification and silicification processes of cyanobacterial mats that form stromatolites in two caldera lakes of Niuafo‘ou Island (Vai Lahi and Vai Si‘i) were evaluated, and their importance as analogues for interpreting the early fossil record are discussed. It has been shown that the potential for morphological preservation of Niuafo‘ou cyanobacteria is highly dependent on the timing and type of mineral phase involved in the fossilization process. Four main modes of mineralization of cyanobacteria organic parts have been recognized: (i) primary early postmortem calcification by aragonite nanograins that transform quickly into larger needle-like crystals and almost totally destroy the cellular structures, (ii) primary early postmortem silicification of almost intact cyanobacterial cells that leave a record of spectacularly well-preserved cellular structures, (iii) replacement by silica of primary aragonite that has already recrystallized and obliterated the cellular structures, (iv) occasional replacement of primary aragonite precipitated in the mucopolysaccharide sheaths and extracellular polymeric substances by Al-Mg-Fe silicates. These observations suggest that the extremely scarce earliest fossil record may, in part, be the result of (a) secondary replacement by silica of primary carbonate minerals (aragonite, calcite, siderite), which, due to recrystallization, had already annihilated the cellular morphology of the mineralized microbiota or (b) relatively late primary silicification of already highly degraded and no longer morphologically identifiable microbial remains. Key Words: Stromatolites—Cyanobacteria—Calcification—Silicification—Niuafo‘ou (Tonga)—Archean. Astrobiology 12, 535–548. PMID:22794297

Kazmierczak, Jozef; Lukomska-Kowalczyk, Maja; Kempe, Stephan

2012-01-01

150

Fossil pollen records reveal a late rise of open-habitat ecosystems in Patagonia.  

PubMed

The timing of major turnovers in terrestrial ecosystems of the Cenozoic Era has been largely interpreted from the analysis of the assumed feeding preference of extinct mammals. For example, the expansion of open-habitat ecosystems (grasslands or savannas) is inferred to have occurred earlier in Patagonia than elsewhere because of the early advent of high-crowned teeth (hypsodont) mammals ?26?Ma ago. However, the plant fossil record from Patagonia implies another evolutionary scenario. Here we show that the dominance of key open-habitat species--amaranths, Ephedra, asters and grasses--occurred during the last 10?Ma, about 15?Ma later than previously inferred using feeding/habitat ecology of extinct mammals. This late rise of open-landscapes in southern South America brings into question whether the expansion of open-habitat vegetation could have been the prime factor of high-crowned mammal diversification. PMID:23250424

Palazzesi, Luis; Barreda, Viviana

2012-01-01

151

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. PMID:10860967

Dilcher, David

2000-01-01

152

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. PMID:15983372

Peterson, Kevin J.; Butterfield, Nicholas J.

2005-01-01

153

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

PubMed

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. PMID:15983372

Peterson, Kevin J; Butterfield, Nicholas J

2005-07-01

154

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

155

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

PubMed Central

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

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

2012-01-01

156

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

PubMed

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

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

2012-08-01

157

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

PubMed

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. PMID:17855566

Huntley, John Warren; Kowalewski, Michal

2007-09-18

158

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

159

Secular changes recorded in mineralization of African crust  

NASA Astrophysics Data System (ADS)

Variations in enrichment of mineral deposits in continental crust over time may be one way to test for secular changes in crustal genesis. We present spatial and chemical information about African mineral deposits with which to 'fingerprint' the metal endowment of African crust of different age. We then compare three regions of juvenile African crust, all with similar geology, tectonic history, and mineral deposits, but each of a different age. Each region was formed during rapid accretion of similar tectonic units derived from the mantle over ˜500 million years, and is apparently devoid of older recycled continental crust. Together, the three areas span 2500 million years of Earth history, from 0.5 Ga to 3.0 Ga, (e.g. the Zimbabwe Craton (2.5-3.0 Ga), the Birimian Shield (1.8-2.3 Ga), and the Arabian-Nubian Shield (0.5-1.0 Ga)). The three areas have a studied total of 2671 mineral deposits that are divided into six groups according to their geochemical affinities. Using these known deposits, a measure of spatial association (spatial coefficient) is derived. We show that each region has a unique metal endowment and that, per unit area, there is a greater concentration of mineral deposits in the crust of the Archean Zimbabwe Craton relative to the younger crust of the Birimian Shield and in turn the Arabian-Nubian Shield. This study quantitatively corroborates past studies that suggest older crust is more mineral diverse and enriched in mineral deposits than younger crust. Thus, a secular change in mineralization is implicated, and the mantle derived metal endowment of the African crust has undergone major evolutionary changes from Archean to Neoproterozoic time.

Mabidi, T.; Thiart, C.; de Wit, M. J.

2007-02-01

160

&p.1:Abstract While the evolutionary history of mammalian tooth shapes is well documented in the fossil record, the  

E-print Network

&p.1:Abstract While the evolutionary history of mammalian tooth shapes is well documented in the fossil record, the developmental basis of their tooth shape evolution is un- known. We investigated, in the initiation of tooth crown base formation, and in the initiation of each cusp's development. Furthermore

Jernvall, Jukka

161

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

162

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

163

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

E-print Network

; Babcock, 2003; Vannier and Chen, 2005). Adaptive responses to this predation are evident in the defensiveEditorial The dawn of animal life: Evolutionary and palaeoecological patterns in the Neoproterozoic-Cambrian animal fossil record 1. Introduction The Neoproterozoic­Cambrian radiation of complex animals is arguably

Dornbos, Stephen Q.

164

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. PMID:22718955

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

2012-01-01

165

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

PubMed Central

Background Molecular phylogenetics has provided unprecedented resolution in the ruminant evolutionary tree. However, molecular age estimates using only one or a few (often misapplied) fossil calibration points have produced a diversity of conflicting ages for important evolutionary events within this clade. I here identify 16 fossil calibration points of relevance to the phylogeny of Bovidae and Ruminantia and use these, individually and together, to construct a dated molecular phylogeny through a reanalysis of the full mitochondrial genome of over 100 ruminant species. Results The new multi-calibrated tree provides ages that are younger overall than found in previous studies. Among these are young ages for the origin of crown Ruminantia (39.3–28.8 Ma), and crown Bovidae (17.3–15.1 Ma). These are argued to be reasonable hypotheses given that many basal fossils assigned to these taxa may in fact lie on the stem groups leading to the crown clades, thus inflating previous age estimates. Areas of conflict between molecular and fossil dates do persist, however, especially with regard to the base of the rapid Pecoran radiation and the sister relationship of Moschidae to Bovidae. Results of the single-calibrated analyses also show that a very wide range of molecular age estimates are obtainable using different calibration points, and that the choice of calibration point can influence the topology of the resulting tree. Compared to the single-calibrated trees, the multi-calibrated tree exhibits smaller variance in estimated ages and better reflects the fossil record. Conclusions The use of a large number of vetted fossil calibration points with soft bounds is promoted as a better approach than using just one or a few calibrations, or relying on internal-congruency metrics to discard good fossil data. This study also highlights the importance of considering morphological and ecological characteristics of clades when delimiting higher taxa. I also illustrate how phylogeographic and paleoenvironmental hypotheses inferred from a tree containing only extant taxa can be problematic without consideration of the fossil record. Incorporating the fossil record of Ruminantia is a necessary step for future analyses aiming to reconstruct the evolutionary history of this clade. PMID:23927069

2013-01-01

166

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

PubMed

Climate refugia, locations where taxa survive periods of regionally adverse climate, are thought to be critical for maintaining biodiversity through the glacial-interglacial climate changes of the Quaternary. A critical research need is to better integrate and reconcile the three major lines of evidence used to infer the existence of past refugia - fossil records, species distribution models and phylogeographic surveys - in order to characterize the complex spatiotemporal trajectories of species and populations in and out of refugia. Here we review the complementary strengths, limitations and new advances for these three approaches. We provide case studies to illustrate their combined application, and point the way towards new opportunities for synthesizing these disparate lines of evidence. Case studies with European beech, Qinghai spruce and Douglas-fir illustrate how the combination of these three approaches successfully resolves complex species histories not attainable from any one approach. Promising new statistical techniques can capitalize on the strengths of each method and provide a robust quantitative reconstruction of species history. Studying past refugia can help identify contemporary refugia and clarify their conservation significance, in particular by elucidating the fine-scale processes and the particular geographic locations that buffer species against rapidly changing climate. PMID:25039238

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

2014-10-01

167

7. Ancient Fossil Record and Early Evolution (ca. 3.8 to 0.5 Ga) PURIFICACIO N LO PEZ-GARCI A and DAVID MOREIRA  

E-print Network

7. Ancient Fossil Record and Early Evolution (ca. 3.8 to 0.5 Ga) PURIFICACIO´ N LO´ PEZ the fossil record, based predominantly on macroscopic morphologic evidence, could only be traced-GARCI´ A and DAVID MOREIRA Unite´ d'Ecologie, Syste´matique et Evolution, Universite´ Paris-Sud, Orsay, France (E

Claeys, Philippe

168

Extending the African instrumental record to the early 19th century  

SciTech Connect

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

Nicholson, S.E.

1997-11-01

169

A fossil record of colonization and response of lacustrine fish populations to climate change  

Microsoft Academic Search

To study fish species colonization and the response of populations to climate change, we reexamined a well- preserved late Pleistocene to early Holocene fossil fish assemblage from lake deposits on the Missouri Coteau, North Dakota. The fossil fishes in the assemblage include complete specimens of yellow perch (Perca flavescens), brassy minnow (Hybognathus hankinsoni), blacknose shiner (Notropis heterolepis), banded killifish (Fundulus

Michael G. Newbrey; Allan C. Ashworth

2004-01-01

170

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

171

Late Quaternary hillslope evolution recorded in eastern South African colluvial badlands  

E-print Network

, South Africa c Council for Geoscience, P.O.Box 900, Pietermaritzburg 3200, South Africa d Institute Hillslopes in parts of Swaziland and the Kwa- Zulu^Natal province of South Africa are exten- sively blanketedLate Quaternary hillslope evolution recorded in eastern South African colluvial badlands M

Clarke, Michèle

172

Star Formation and Metallicity History of the SDSS galaxy survey: unlocking the fossil record  

E-print Network

Using MOPED we determine non-parametrically the star-formation and metallicity history of over 37,000 high-quality galaxy spectra from the Sloan Digital Sky Survey (SDSS) early data release. We use the entire spectral range, rather than concentrating on specific features, and we estimate the complete star formation history without prior assumptions about its form (by constructing so-called `population boxes'). The main results of this initial study are that the star formation rate in SDSS galaxies has been in decline for ~6 Gyr; a metallicity distribution for star-forming gas which is peaked ~3 Gyr ago at about solar metallicity, inconsistent with closed-box models, but consistent with infall models. We also determine the infall rate of gas in SDSS and show that it has been significant for the last 3 Gyr. We investigate errors using a Monte-Carlo Markov Chain algorithm. Further, we demonstrate that recovering star formation and metallicity histories for such a large sample becomes intractable without data compression methods, particularly the exploration of the likelihood surface. By exploring the whole likelihood surface we show that age-metallicity degeneracies are not as severe as by using only a few spectral features. We find that 65% of galaxies contain a significant old population (with an age of at least 8 Gyr), including recent starburst galaxies, and that over 97% have some stars older than 2 Gyr. It is the first time that the past star formation history has been determined from the fossil record of the present-day spectra of galaxies.

Benjamin Panter; Alan F. Heavens; Raul Jimenez

2002-11-25

173

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

PubMed

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

Jablonski, David

2005-11-15

174

Molecular Evolution of Myoglobin and the Fossil Record: a Phylogenetic Synthesis  

Microsoft Academic Search

An ancestral myoglobin chain has been deduced by comparing the differences in the amino acid sequences of eighteen living species and assessing from the fossil evidence the probable times of divergence of their ancestors.

A. E. Romero-Herrera; H. Lehmann; K. A. JOYSEY; A. E. FRIDAY

1973-01-01

175

The Fossil Record of Star Formation in the Leo i and Fornax Dwarf Galaxies: Cycle 4 Medium  

Microsoft Academic Search

Deep galaxy counts and redshift surveys have uncovered evidence that many dwarf systems may have undergone enhancements in their star formation rates between redshifts of 0.3 to 1.0 (roughly 2-7 Gyr ago). The fossil record of such bursts must exist in the present-day stellar populations of galaxies if this interpretation is correct. We propose HST WF\\/PC-2 observations of two of

Edward Olszewski

1994-01-01

176

Finding Fossils  

NSDL National Science Digital Library

This OLogy activity serves as a kid-friendly how-to manual about searching for fossils. In Not Just Any Rock Will Do, kids learn that fossils "hide out" in sedimentary rock and see examples of shale and sandstone. Do's and Don'ts for Fossil Hunters gives kids practical tips and a list of fossil-hunting supplies. In Fossils You May Find, there are photos of common invertebrate, vertebrate, and plant fossils to guide kids. Paleontology Clubs and Web Sites lists resources to help kids determine where to hunt for fossils. In Keeping a Field Journal, kids are shown a sample journal entry that points out the types of information they should record.

177

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

178

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

SciTech Connect

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

CoBabe, E.A. [Univ. of Massachusetts, Amherst, MA (United States)

1995-12-31

179

The impact of early smelting on the environment of Huoshiliang in Hexi Corridor, NW China, as recorded by fossil charcoal and chemical elements  

Microsoft Academic Search

Recent research has greatly increased our knowledge of early human impacts on the environment. Records of fossil charcoal and chemical elements from a bronze smelting site at Huoshiliang, in the Hexi corridor of northwest China, provide material with which to estimate the extent of smelting activity and its impact on the environment. Analysis of the microstructure of wood fossil charcoal

Xiaoqiang Li; Nan Sun; John Dodson; Ming Ji; Keliang Zhao; Xinying Zhou

2011-01-01

180

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

181

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

E-print Network

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

Benton, Michael

182

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

183

The fossil record of fish ontogenies: insights into developmental patterns and processes.  

PubMed

One of the properties of fossils is to provide unique ontogenies that have the potential to inform us of developmental patterns and processes in the past. Although fossilized ontogenies are fairly rare, size series of relatively complete specimens for more than 90 fish species have been documented in the literature. These fossilized ontogenies are known for most major phylogenetic groups of fishes and have a broad stratigraphic range extending from the Silurian to the Quaternary with a good representation during the Devonian. Classically, size series have been studied in terms of size and shape differences, where subsequently allometric changes were used as indicators of heterochronic changes in Paleozoic placoderms and sarcopterygians. Quantitative analyses of fossilized ontogenies of dipnoans have been interpreted in terms of morphological integration and fluctuating asymmetry. Recently, reconstructed sequences of ossification have been used to identify recurrent patterns of similar development in actinopterygians and sarcopterygians in order to infer phenotypic developmental modularity and saltatory pattern of development. Phylogenetic and temporal landmarks are put forward for some of the major developmental patterns in the evolution of fishes. PMID:19914384

Cloutier, R

2010-06-01

184

Supporting Information Late Paleocene fossils from the Cerrejn Formation, Colombia, are the earliest record of  

E-print Network

of coal marks the lower 50 m of the Cerrejón Formation. Sedimentary structures in this interval includeSupporting Information Late Paleocene fossils from the Cerrejón Formation, Colombia of the Cerrejón Formation and stratigraphic positions of the megafloral collections (Fig. S1); 2) source

Lyons, S. Kathleen

185

AR T ICLES Phenotypic Evolution in the Fossil Record: Numerical Experiments  

Microsoft Academic Search

Stratophenetic data document phenotypic changes in a fossil lineage and play a vital role in reconciling contemporary microevolution with long-term paleontological patterns. However, stratophenetic series represent multiscale geolog- ical and biological interactions, defying simple analysis and interpretation. A numerical model is presented that simulates stratophenetic series in shallow marine siliciclastic deposits. The model is driven by predictions of water depth,

Bjarte Hannisdal

186

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

PubMed Central

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

Belanger, Christina L.

2012-01-01

187

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. PMID:22689947

Boyce, C. Kevin; Zwieniecki, Maciej A.

2012-01-01

188

The Very Faint End of the UV Luminosity Function over Cosmic Time: Constraints from the Local Group Fossil Record  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

189

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

PubMed

Declining CO(2) 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-CO(2) regime would be lost as CO(2) concentrations increased but also implied that plants with very low vein densities (less than 3 mm mm(-2)) should experience substantial disadvantages with high CO(2). Thus, the hypothesized relationship between CO(2) and plant evolution can be tested through analysis of the concurrent histories of alternative lineages, because an extrinsic driver like atmospheric CO(2) should affect all plants and not just the flowering plants. No such relationship is seen. Regardless of CO(2) 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 CO(2), productivity changes are likely to have been limited before a substantial increase accompanying the evolution of flowering plants. PMID:22689947

Boyce, C Kevin; Zwieniecki, Maciej A

2012-06-26

190

Fossil Crinoids  

NASA Astrophysics Data System (ADS)

Crinoids have graced the oceans for more than 500 million years. Among the most attractive fossils, crinoids had a key role in the ecology of marine communities through much of the fossil record, and their remains are prominent rock forming constituents of many limestones. This is the first comprehensive volume to bring together their form and function, classification, evolutionary history, occurrence, preservation and ecology. The main part of the book is devoted to assemblages of intact fossil crinoids, which are described in their geological setting in twenty-three chapters ranging from the Ordovician to the Tertiary. The final chapter deals with living sea lilies and feather stars. The volume is exquisitely illustrated with abundant photographs and line drawings of crinoids from sites around the world. This authoritative account recreates a fascinating picture of fossil crinoids for paleontologists, geologists, evolutionary and marine biologists, ecologists and amateur fossil collectors.

Hess, Hans; Ausich, William I.; Brett, Carlton E.; Simms, Michael J.

1999-10-01

191

Fossil Crinoids  

NASA Astrophysics Data System (ADS)

Crinoids have graced the oceans for more than 500 million years. Among the most attractive fossils, crinoids had a key role in the ecology of marine communities through much of the fossil record, and their remains are prominent rock forming constituents of many limestones. This is the first comprehensive volume to bring together their form and function, classification, evolutionary history, occurrence, preservation and ecology. The main part of the book is devoted to assemblages of intact fossil crinoids, which are described in their geological setting in twenty-three chapters ranging from the Ordovician to the Tertiary. The final chapter deals with living sea lilies and feather stars. The volume is exquisitely illustrated with abundant photographs and line drawings of crinoids from sites around the world. This authoritative account recreates a fascinating picture of fossil crinoids for paleontologists, geologists, evolutionary and marine biologists, ecologists and amateur fossil collectors.

Hess, Hans; Ausich, William I.; Brett, Carlton E.; Simms, Michael J.

2003-01-01

192

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

193

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

SciTech Connect

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

Forester, R.M. [Geological Survey, Denver, CO (United States); Smith, A.J. [Kent State Univ., OH (United States)

1995-10-01

194

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

195

Sediment diagenesis, fossil preservation, and depositional environment in the Stone City/Lower Cook Mountain transgression (Middle Eocene, southeast Texas): a test of chemical taphofacies in the rock record  

E-print Network

The recognition of taphonomic loss in the fossil record is important because it provides information about the depositional environment, sediment geochemistry, and post-depositional bias present in the fossil assemblage. Because diagenetic mineral...

Thornton, Charles Anthony

2012-06-07

196

Fossils 1: Fossils and Dinosaurs  

NSDL National Science Digital Library

In this lesson, students will understand what can be learned from fossils and in doing so, realize the difference between fact and theory. This lesson is the first of a two-part series on fossils. These lessons will go beyond naming dinosaurs and give students a broad understanding of how we know about the great beasts. They will start to acquire knowledge of the fossil record in preparation for learning about evolution and natural selection, concepts they will study in high school. This particular lesson focuses on what we have learned and can learn from fossils. In the first part, students will discuss what we know about horses. They will then do the same for a Stegosaurus. Another part of the lesson briefly covers how fossils are formed.

197

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

E-print Network

/Ca records from Porites corals from the Malindi coral reef documenting the flux of suspended sediment fromEast African soil erosion recorded in a 300 year old coral colony from Kenya Dominik Fleitmann,1 in the early 1970's. We conclude that despite laudable attempts to instigate soil conservation measures

Massachusetts at Amherst, University of

198

Patterns, processes and geological biases in the fossil record of jawless vertebrates at the time of jawed vertebrate origins  

NASA Astrophysics Data System (ADS)

The dominance of the jawed vertebrates over their jawless vertebrates in the Middle Palaeozoic represents a landmark evolutionary event in the history of vertebrates and a potential episode of competitive replacement. The timing and nature of the origin, radiation and extinction of each of the relevant clades of stem- and crown- gnathostomes is not, however, well understood. Here, stratigraphic, phylogenetic and palaeoenvironmental data for the closest relatives of jawed vertebrates (Osteostraci, Galeaspida and Thelodonti) are analysed. The Osteostraci and Galeaspida are restricted to shallow-water environments, and as such, are subject to facies biases resulting from sea-level change. Confidence intervals calculated upon the basis of non-random models of fossil recovery in light of sea-level changes stretch the potential origins of Osteostraci and Galeaspida into the Upper Ordovician, and are thus more compatible with phylogenetic schemes. Diversity changes through time for the Osteostraci, Galeaspida and Thelodonti were found to lie within the expected limits predicted from estimations of fossil record quality indicating that it is geological factors rather than biological that are responsible for apparent patterns. The relative demise and eventual extinction of ostracoderms during the Mid-Late Devonian is suggested to result from their inability to adapt to changing environmental conditions and their limited geo-dispersal ability rather than competition with their more generalist and cosmopolitan jawed relatives.

Sansom, R.; Donoghue, P.

2012-04-01

199

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

200

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

PubMed

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

Webber, Andrew J; Hunda, Brenda R

2007-06-01

201

The Galactic globular cluster system as a fossil record of reionization  

E-print Network

We propose that structural, kinematical, and chemical properties of the Galactic globular clusters (GCs) can contain fossil information of the cosmic reionization history. We first summarize possible observational evidences for the influence of reionization on the Galactic GC formation. We then show how structural properties of the GC system (GCS) in the Galaxy can be influenced by suppression of GC formation due to reionization during the Galaxy formation through hierarchical merging of subgalactic clumps, by using numerical simulations with and without suppression of GC formation by reionization. In particular, we show that if GC formation in dwarf galaxies that are building blocks of the Galaxy and virialized after reionization era ($z_{reion}$) are completely suppressed, the present-day radial distribution of the Galactic GCs depends strongly on $z_{reion}$. Our numerical results imply that if GC formation after $z_{reion}$ $\\sim$ 15 is strongly suppressed, the origin of the observed structural properties of the Galactic GCS can be more naturally explained in the framework of the hierarchical clustering scenario.

Kenji Bekki

2005-06-22

202

The Star Formation History in Nearby Dwarf Galaxies: the Fossil Record in the Color-Magnitude Diagram  

E-print Network

Dwarf galaxies may play a key role in the formation and evolution of bigger systems. This make a topic of major interest knowing how they form and evolve and, in particular, how their star formation histories (SFHs) have proceed since their birth. For nearby galaxies, the color-magnitude diagram (CMD) contains stars formed over all their lifetime. It is hence a fossil record of their SFHs. The analysis with synthetic CMDs provides a powerful tool to retrieve them. In this paper, I discuss the critical issues related to the computation of synthetic CMDs, present a short summary of the currently available results for the SFH extending the full life of galaxies and make a few critical considerations about the powerfulness and back-draws of the method.

A. Aparicio

1998-11-11

203

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

NASA Astrophysics Data System (ADS)

The carbon isotope composition of terrestrial fossil organic matter (?13Corg) has been widely used as a proxy of global carbon cycling and to reconstruct perturbations to the ocean-atmosphere carbon budget. The degree to which terrestrial ?13Corg records local to regional environmental conditions versus the evolution of the global carbon cycle has been highly debated. The high-resolution (104 to 106 m.y.) terrestrial ?13Corg record presented here defines a long-term trend through the latest Devonian to Late Triassic that reveals significant and systematic variations that track independently inferred changes in climate, paleo-atmospheric pCO2, and major restructuring in paleotropical flora. This newly derived record is based on 350 carbon isotope analyses of compressed and permineralized plants, cuticle, charcoal and coal (including vitrinite and fusinite) collected from paleo-wetland mudstones and claystones, claystone-filled abandoned fluvial channels, floodplain mudstones, and ephemeral lacustrine deposits at paleo-tropical to paleo-temperate latitudes. Morphologic and geochemical analysis of contemporaneous paleosols and fluvial-alluvial deposits allow for correlation of terrestrial ?13Corg values to reconstructed paleo-environmental conditions. Terrestrial ?13Corg values of contemporaneous fossil organic matter exhibit systematic inter- and intra-basinal variation of up to 2‰ associated with differences in paleo-precipitation and burial history, and geomorphic position within depositional basins and paleo-fluvial systems. Variation in ?13Corg by organic matter type is minimal to less than 1.5‰; specifically, charcoal ?13Corg values overlap to are slightly less negative than those of thermally less mature organic components analyzed. Overall, variation within contemporaneous populations is significantly less than defined by the long-term terrestrial ?13Corg record. Moreover, paleo-floral pi/pa ratios, an established proxy of water-use efficiency of plant growth, estimated from measured terrestrial ?13Corg values and contemporaneous marine carbonate ?13C values define a relatively consistent and narrow range (0.45 to 0.6) throughout the 150 million year interval within each depositional basin, regardless of landscape or stratigraphic position. Their narrow range in conjunction with the statistically significant long-term ?13Corg trend indicates that local to regional environmental effects on ?13Corg were secondary to extrabasinal influences such as the carbon isotopic composition of the paleo-atmosphere. This suggests that the long-term terrestrial ?13Corgrecord archives first-order variations in atmospheric ?13C throughout the Late Paleozoic and Early Mesozoic.

Montanez, I. P.

2006-12-01

204

"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

205

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

PubMed

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

Pimiento, Catalina; Clements, Christopher F

2014-01-01

206

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

PubMed Central

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

Pimiento, Catalina; Clements, Christopher F.

2014-01-01

207

Southern East African climate recorded in laminated sediments of Lake Malawi  

NASA Astrophysics Data System (ADS)

Southern East African climate recorded in laminated sediments of Lake Malawi Annually laminated sediments from the northern basin of Lake Malawi (southern East Africa) provide a high-resolution record of regional environmental history for the past several centuries in a region where climate records are particularly scarce. The Lake Malawi Scientific Drilling Program recovered core (MAL05-2A) from this basin that yielded an 80 kyr record showing a tropical component of millennial scale climate fluctuations during MIS 3 and 4. In addition, northern Lake Malawi sediments recorded decade-to-century scale variations during the "Little Ice Age." To evaluate the response of this system to 21st Century changes in climate and shifts in regional land use, a series of multicores was recovered in January 2012. We developed a working varve-counting chronology that is consistent with previous studies of cores from nearby locations, but includes an additional 14 years of sediment accumulated since previous field programs, allowing evaluation of recent environmental changes in a broader context. Bulk elemental composition of sediments were evaluated using an ITRAX XRF core scanner; these results may be used as proxies for fluxes of terrigenous and biogenic sediments, as well as provenance indicators for the terrigenous material. During much of the 20th Century, lake productivity appears to increase in response to greater wind stress, and to positive Indian Ocean Dipole conditions. However, signals in the uppermost sediments appear to be overprinted by the impact of changing land use in the basin, notably conversion of hill-slope forests to agriculture, leading to enhanced input of terrigenous materials.

Brown, E. T.; Katsev, S.

2012-12-01

208

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

Microsoft Academic Search

The earliest evidence for animal life comes from the fossil record of 24-isopropylcholestane, a sterane found in Cryogenian deposits, and whose precursors are found in modern demosponges, but not choanoflagellates, calcareans, hexactinellids, or eumetazoans. However, many modern demosponges are also characterized by the presence of siliceous spicules, and there are no convincing demosponge spicules in strata older than the Cambrian.

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

2010-01-01

209

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. PMID:12495489

Kano, Yasunori; Chiba, Satoshi; Kase, Tomoki

2002-01-01

210

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

211

The Very Faint End of the UV Luminosity Function over Cosmic Time: Constraints from the Local Group Fossil Record  

E-print Network

We present a new technique to estimate the evolution of the very faint end of the UV luminosity function (LF) out to $z\\sim5$. Measured star formation histories (SFHs) from the fossil record of Local Group galaxies are used to reconstruct the LF down to M$_{UV}\\sim-5$ at $z\\sim5$ and M$_{UV}\\sim-1.5$ at $z<1$. Such faint limits are well beyond the current observational limits and are likely to remain beyond the limits of next generation facilities. The reconstructed LFs, when combined with direct measurements of the LFs at higher luminosity, are well-fit by a standard Schechter function with no evidence of a break to the faintest limits probed by this technique. The derived faint end slope, $\\alpha$, steepens from $\\approx-1.2$ at $z<1$ to $\\approx-1.6$ at $4

Weisz, Daniel R; Conroy, Charlie

2014-01-01

212

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

213

A socio-technical approach to continuity of care and electronic records in the South African context.  

PubMed

Paper-based techniques of record keeping are contributing greatly to the discontinuity of patient care among healthcare providers. To achieve continuity, access to the information contained in medical records collected by various healthcare providers is necessary. To improve the sharing of information contained in these medical records the use of electronic methods of record keeping as opposed to paper-based records becomes very important. Even though the benefits of using electronic methods of record keeping are widely documented, the majority of South African healthcare practitioners still use paper-based methods. This paper describes an explorative study to determine barriers to the adoption of electronic records in the private primary care sector of South Africa. An interpretive approach using a socio-technical systems theory perspective was used to conduct the study. Based on the analysis of the socio-technical subsystems in the South African context it was revealed that there is not sufficient information available on the barriers to adoption of electronic records and further research will be necessary to identify the barriers to the adoption of electronic records. PMID:20841718

Mostert-Phipps, Nicky; Pottas, Dalenca; Korpela, Mikko

2010-01-01

214

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

Microsoft Academic Search

The best reconstructions of the history of life will use both molecular time estimates and fossil data. Errors in molecular rate estimation typically are unaccounted for and no attempts have been made to quantify this uncertainty comprehensively. Here, focus is primarily on fossil calibration error because this error is least well understood and nearly universally disregarded. Our quantification of errors

Marcel van Tuinen; Elizabeth A. Hadly

2004-01-01

215

Galaxias fossils from Miocene lake deposits, Otago, New Zealand: The earliest records of the Southern Hemisphere family Galaxiidae (Teleostei)  

Microsoft Academic Search

Galaxiid fishes are commonly assumed to exhibit a Gondwanan distribution, but little fossil evidence has been available to support or refute this assumption until now. Here we report on three species of fossil Galaxias, represented by exquisitely preserved, almost entire skeletons, together with jaw and skull fragments, from several Miocene lacustrine deposits in Otago, South Island, New Zealand. These are

D. E. Lee; R. M. McDowall; J. K. Lindqvist

2007-01-01

216

Fun with Fossils  

NSDL National Science Digital Library

Fossils provide a valuable record of the plant and animal life and environmental conditions from millions, even billions of years ago. In this lesson, students create their own fossils, and then use multimedia resources to learn how real fossils form and what scientists can learn from them. They should understand that fossils provide evidence of plants and animals that lived long ago, as well as the environmental conditions at that time. Instructions, a materials list, and links to multimedia resources are provided.

2005-01-01

217

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

218

Silurian Fossils from New Zealand  

Microsoft Academic Search

IN spite of its relatively small land area, New Zealand contains a remarkably complete fossil record. Up to the present the Carboniferous and the Silurian have been the only two Phanerozoic geological periods not known to be represented by fossils. The apparent absence of Silurian fossils has been considered strange because upper Ordovician and lower Devonian fossils are present in

R. A. Cooper

1970-01-01

219

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

220

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

Microsoft Academic Search

The phylum Cnidaria is comprised of remarkably diverse and ecologically significant taxa, such as the reef-forming corals, and occupies a basal position in metazoan evolution. The origin of this phylum and the most recent common ancestors (MRCAs) of its modern classes remain mostly unknown, although scattered fossil evidence provides some insights on this topic. Here, we investigate the molecular divergence

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

221

First evidence of a bipartite medial cuneiform in the hominin fossil record: a case report from the Early Pleistocene site of Dmanisi.  

PubMed

A medial cuneiform exhibiting complete bipartition was discovered at the Early Pleistocene site of Dmanisi, Georgia. The specimen is the oldest known instance of this anatomical variant in the hominin fossil record. Here we compare developmental variation of the medial cuneiform in fossil hominins, extant humans and great apes, and discuss potential implications of bipartition for hominin foot phylogeny and function. Complete bipartition is rare among modern humans (< 1%); incomplete bipartition was found in 2 of 200 examined great ape specimens and also appears in the form of a divided distal articular surface in the Stw573c Australopithecus africanus specimen. Although various developmental pathways lead to medial cuneiform bipartition, it appears that the bipartite bone does not deviate significantly from normal overall morphology. Together, these data indicate that bipartition represents a phyletically old developmental variant of the medial cuneiform, which does not, however, affect the species-specific morphology and function of this bone. PMID:20579174

Jashashvili, Tea; Ponce de León, Marcia S; Lordkipanidze, David; Zollikofer, Christoph P E

2010-06-01

222

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

SciTech Connect

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

Mount, J.F.; McDonald, C. (Univ. of California, Davis, CA (United States))

1992-11-01

223

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

PubMed Central

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, Martin D.; Scheyer, Torsten M.; Butler, Richard J.

2014-01-01

224

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

PubMed

The earliest evidence for animal life comes from the fossil record of 24-isopropylcholestane, a sterane found in Cryogenian deposits, and whose precursors are found in modern demosponges, but not choanoflagellates, calcareans, hexactinellids, or eumetazoans. However, many modern demosponges are also characterized by the presence of siliceous spicules, and there are no convincing demosponge spicules in strata older than the Cambrian. This temporal disparity highlights a problem with our understanding of the Precambrian fossil record--either these supposed demosponge-specific biomarkers were derived from the sterols of some other organism and are simply retained in modern demosponges, or spicules do not primitively characterize crown-group demosponges. Resolving this issue requires resolving the phylogenetic placement of another group of sponges, the hexactinellids, which not only make a spicule thought to be homologous to the spicules of demosponges, but also make their first appearance near the Precambrian/Cambrian boundary. Using two independent analytical approaches and data sets--traditional molecular phylogenetic analyses and the presence or absence of specific microRNA genes--we show that demosponges are monophyletic, and that hexactinellids are their sister group (together forming the Silicea). Thus, spicules must have evolved before the last common ancestor of all living siliceans, suggesting the presence of a significant gap in the silicean spicule fossil record. Molecular divergence estimates date the origin of this last common ancestor well within the Cryogenian, consistent with the biomarker record, and strongly suggests that siliceous spicules were present during the Precambrian but were not preserved. PMID:19929965

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

2010-01-01

225

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

226

High-resolution records of location and stratigraphic provenance from the rare earth element composition of fossil bones  

NASA Astrophysics Data System (ADS)

Bone apatite acts as a natural, timed sampling device, scavenging trace elements from local pore waters over timescales of ca. 1-50 ka. The rare earth element (REE) and U/Th composition of fossil bones reflects associated pore water compositions during the period of recrystallisation. The REE composition of fossil bones is controlled by partitioning of REE between pore waters and particle surfaces, and the REE composition of fossil bones reflects the REE composition of pore waters which vary spatially and temporally. Light REE are preferentially sorped onto particle surfaces, thus the high La/Yb values seen in many bones from coastal marine and aeolian environments are best explained by release of REE from light REE-enriched particles to local pore waters and subsequent immobilisation in recrystallising bones. The REE compositions of bones recovered from pedogenically altered diatomite sediments of the Olorgesailie Formation of southern Kenya vary over spatial scales of less than 10 m. Location accounts for 48% of the observed variation in bone chemistry and bones recovered from eight discrete excavations within the same time-equivalent stratigraphic layer can be assigned to their excavation location with >70% accuracy based on a discriminant analysis of REE, U, and Th composition. Despite this within-layer variation, bones recovered from different stratigraphic horizons within the Olorgesailie Formation can also be distinguished on the basis of their trace element composition. Bones recovered from four stratigraphic horizons spanning ca. 0.5 million years were assigned to their correct stratigraphic layer with >90% accuracy. Where sedimentological conditions are favourable, the trace element composition of fossil bone may be used to test stratigraphic provenance and burial location in excavated bone with a temporal resolution of <10 ka and a spatial resolution of <10 m. The trace element composition of fossil bone may also be used to investigate the accumulation history of vertebrate assemblages and to reconstruct pore water variability across land surfaces.

Trueman, C. N.; Behrensmeyer, A. K.; Potts, R.; Tuross, N.

2006-09-01

227

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

NASA Astrophysics Data System (ADS)

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

Balintoni, Ioan; Balica, Constantin

2013-10-01

228

High density GWAS for LDL cholesterol in African Americans using electronic medical records reveals a strong protective variant in APOE.  

PubMed

Only one low-density lipoprotein cholesterol (LDL-C) genome-wide association study (GWAS) has been previously 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 comorbidities and medication (n= 618) and another dataset having median LDL-C calculated without any exclusions (n= 1,249). SNP rs7412 in APOE was strongly associated with LDL-C in both datasets (p < 5 × 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 comorbidities increased the percentage of trait variance explained by genetic variation. PMID:23067351

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

2012-10-01

229

Marquee Fossils  

ERIC Educational Resources Information Center

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

Clary, Renee; Wandersee, James

2008-01-01

230

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

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

231

Fossil Fondue  

NSDL National Science Digital Library

To understand how fossils are formed, students model the process of fossilization by making fossils using small toy figures and melted chocolate. They extend their knowledge to the many ways that engineers aid in the study of fossils, including the development of tools and technologies for determining the physical and chemical properties of fossilized organisms, and how those properties tell a story of our changing world.

Integrated Teaching And Learning Program

232

First fossil chimpanzee.  

PubMed

There are thousands of fossils of hominins, but no fossil chimpanzee has yet been reported. The chimpanzee (Pan) is the closest living relative to humans. Chimpanzee populations today are confined to wooded West and central Africa, whereas most hominin fossil sites occur in the semi-arid East African Rift Valley. This situation has fuelled speculation regarding causes for the divergence of the human and chimpanzee lineages five to eight million years ago. Some investigators have invoked a shift from wooded to savannah vegetation in East Africa, driven by climate change, to explain the apparent separation between chimpanzee and human ancestral populations and the origin of the unique hominin locomotor adaptation, bipedalism. The Rift Valley itself functions as an obstacle to chimpanzee occupation in some scenarios. Here we report the first fossil chimpanzee. These fossils, from the Kapthurin Formation, Kenya, show that representatives of Pan were present in the East African Rift Valley during the Middle Pleistocene, where they were contemporary with an extinct species of Homo. Habitats suitable for both hominins and chimpanzees were clearly present there during this period, and the Rift Valley did not present an impenetrable barrier to chimpanzee occupation. PMID:16136135

McBrearty, Sally; Jablonski, Nina G

2005-09-01

233

4th Grade Fossils  

NSDL National Science Digital Library

Introduction to Fossils What is a fossil What is a Fossil? Body and Trace Fossils Body and Trace Fossils Life of a Vertebrate fossil Life of a Vertebrate Fossil Finding Fossils Finding Fossils How fossils are found How fossils are formed Age of Fossils Age of Fossils in Sedimentary Rock Fossils found in Utah Fossils found in Utah Where fossils are found in Utah Where fossils are found in Utah Utah County Map Utah County Map ...

Richrigby

2010-01-26

234

African climate change and faunal evolution during the Pliocene-Pleistocene  

NASA Astrophysics Data System (ADS)

Environmental theories of African faunal evolution state that important evolutionary changes during the Pliocene-Pleistocene interval (the last ca. 5.3 million years) were mediated by changes in African climate or shifts in climate variability. Marine sediment sequences demonstrate that subtropical African climate periodically oscillated between markedly wetter and drier conditions, paced by earth orbital variations, with evidence for step-like (±0.2 Ma) increases in African climate variability and aridity near 2.8 Ma, 1.7 Ma, and 1.0 Ma, coincident with the onset and intensification of high-latitude glacial cycles. Analysis of the best dated and most complete African mammal fossil databases indicates African faunal assemblage and, perhaps, speciation changes during the Pliocene-Pleistocene, suggesting more varied and open habitats at 2.9-2.4 Ma and after 1.8 Ma. These intervals correspond to key junctures in early hominid evolution, including the emergence of our genus Homo. Pliocene-Pleistocene shifts in African climate, vegetation, and faunal assemblages thus appear to be roughly contemporary, although detailed comparisons are hampered by sampling gaps, dating uncertainties, and preservational biases in the fossil record. Further study of possible relations between African faunal and climatic change will benefit from the accelerating pace of important new fossil discoveries, emerging molecular biomarker methods for reconstructing African paleovegetation changes, tephra correlations between terrestrial and marine sequences, as well as continuing collaborations between the paleoclimatic and paleoanthropological communities.

deMenocal, Peter B.

2004-03-01

235

Discovering Fossils: Fossil Tools & Resources  

NSDL National Science Digital Library

Fossil enthusiasts Roy Shephard and Luci Algar combined their professional skills in media and education to develop this informative and entertaining website. Designed to be educational and accessible to children, this site presents a wide variety of information about fossils. The site contains a nice collection of images and diagrams; and includes a fossils guide for beginners, information on preparing fossils, a collection of fossil myths, information on ammonites, and more. The site also contains a Games & Activities section for teachers and students, a glossary of fossil terms, a neat diagram depicting the evolution of life on our planet, and even some free fossil desktop images.

236

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

237

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

PubMed

Modern manatees have a unique type of tooth development, continually forming identical new molars in the posterior end of each quadrant of their mouths, and then progressively moving teeth anteriorly, only to reabsorb roots and spit out worn crowns. This process is not only developmentally complex, but requires space in the oral cavity that imposes its own limitations on other uses of that space. To gain a clearer understanding of the anatomical constraints on the evolution of this unique developmental process, we identified the specialized craniodental features in modern Trichechus that permit this specialization using visual observation and CT. Furthermore, to better understand the evolution of these traits, we review the fossil record of trichechids for these traits, including CT analysis of the skull of Miosiren kocki, a possible early member of the family from the Early Miocene of Belgium. PMID:22777871

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

2012-09-01

238

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

239

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

USGS Publications Warehouse

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

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

2014-01-01

240

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

PubMed Central

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

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

2014-01-01

241

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

PubMed

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

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

2014-01-01

242

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

NASA Astrophysics Data System (ADS)

The information provided by modern instrumental approaches (molecular phylogeography, ancient DNA analyses, large scale radiocarbon datings etc.) refined the knowledge on Late Quaternary faunal development and range history of particular taxa in essential way. Nevertheless, the direct fossil record remains still an essential substrate in study of that topics, and to reveal all the information, that it may provide, and integrate it with the outputs of the other approaches presents one of the essential aim of the present meeting. Unfortunately, the immediate use of fossil record for the paleoecologic and paleobiogeographic inferences is often limited by its fragmentarity (both in temporal and spatial respects), taphonomic influences and/or locally specific post-sedimentary effects which all may bias it in a considerable degree. Hence, each particular record is to be carefully reexamined in respect to all factor which may bias it - unfortunately, often it is not too easy to respond that task, particularly when the record is retrived from secondary sources. It should also be remembered that the records representing narrow time slices without a robust lithostratigraphic context do not provide any information on the historical and contextual setting of the respective faunal situation. Such information that is essential for reconstructions of paleobiogeography of community development and similar locally-sensitive phenomena can only be retrived from the continuous sedimentary series which establish the sequence of particular faunal events by direct superposition. A sufficiently dense network of such series provides than a possibility of direct inter-regional comparisons and a high resolution information on the paleobiogeography of the Late Pleistocene-Holocene rearrangements of mammalian communities, local variation in history of particular species and its community context. We illustrate productivity of such approach on with aid of the fossil record obtained from continuous sedimentary sequences from different regions of Czech Republic and Slovakia (850 community samples, 29,800 MNI) and neighbouring countries of Central Europe. Despite common general trends we demonstrated stricking local and regional specificities. Among other they include (a) continuous survival of several woodland elements (Clethrionomys glareolus, Sorex araneus, Micotus subterraneus, Microtus agrestis) throughout Weichselian (including LGM) in the Carpathians, (b) prolonged survival of the glacial elements Ochotona pusilla and Microtus gregalis in Pannonian basin and (c) Dicrostonyx gulielmi in the Carpathian foredeep, contrasting to (d) the early disappearance of them in S-Germany and Bohemia, and (e) similar difference were found also in other cenologic traits. While the glacial communities were nearly homogenous in their structure throughout whole the region, the Holocene development produced a considerable faunal provincialism, which was the most pronounced during Boreal. In contrast to central Europe, the available sequences from the SE-Europe and Asia Minor show only minute faunal changes during the Vistulian and Holocene, no essential rearrangements in community structure were observed (at least as the core species are concerned) and except for Lagurus no glacial immigrant did invade the region. At the same time a degree of local provincialism was continuously high and, in a regional scale, it continuously exceeded that of the Boreal central Europe.

Horacek, Ivan; Lozek, Vojen

2010-05-01

243

The Relationship Between Continental Landscape Evolution and the Plant-Fossil Record: Long Term Hydrologic Controls on Preservation  

Microsoft Academic Search

\\u000a Continental depositional environments preserve the majority of the macrofloral record since the advent of land-plant colonization\\u000a in the mid-Paleozoic, and wetland representatives are encountered more commonly than those that grew under more seasonal conditions.\\u000a It has been assumed that preservation potential and future recovery of plant debris are high once detritus is introduced into\\u000a any appropriate environment of deposition (e.g.,

Robert A. Gastaldo; Timothy M. Demko

244

"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

245

U-Pb dated Speleothem records of Plio-Pleistocen climate variability from South African hominin bearing caves  

NASA Astrophysics Data System (ADS)

We use stable isotopes of carbon and oxygen to investigate the potential palaeoclimate records from the caves near Johannesburg in South Africa. The sediments in these caves contain early human (hominin) fossils, as well as speleothem material, providing an ideal opportunity to investigate the palaeo-enviroments of our earliest ancestors. These sites are dated via uranium-lead to between 2.8 and 1.5 Ma and provide a window into changing climatic conditions, rare from both this period and region. We micro-drilled stalagmite and flowstone samples from Sterkfontein (2.8 -2.0 Ma), Swartkrans (2.4 -1.7 Ma) and Cooper's Cave (1.5 - 1.4 Ma) at 0.5mm spacing to provide a total of five high resolution records. Oxygen isotope values range from -6.5 to -3‰, clustering around -4.5‰. Carbon isotopes range from -8 to 2‰ and show more variation. Both a Hendy test and a C vs. O plot show that the deposits in question were deposited in equilibrium with their surroundings and the data can be used for environmental interpretations. Care was also taken to examine the petrography of all the speleothem material to access the mineralogy (calcite vs aragonite) and the extent of re-crystallisation. Oxygen isotope values are interpreted as the product of the amount and type of rainfall, with wetter periods represented by enriched excursions. The contribution of the dolomite aquifer above the cave may, however, obscure the ?18O signal. The carbon isotopes reflect changes in the vegetational communities above the cave, with varying amounts of C3 and C4 plants. At present each speleothem piece has only one U-Pb date, the distribution of suitable uranium rich layers limits the spatial resolution of dates. The Cooper's Cave flowstone pieces display visible growth layers; should these be annual layers, then these two records represent as little as 60 years climate variability - specifically in the amount of rainfall. However, this would require very fast speleothem growth rates (0.5mm/year). The scale of variation observed in these records is within the same range as other speleothem records from southern Africa and these bands are more likely records of a longer term cycle of a few 1000 years. Still the records presented here do not document long-term climatic variations, but rather snap shot records of short term, detailed climate change. This is especially pertinent as the hominins (and other fauna) would have been more vulnerable to changes on these shorter, life-time time scales.

Pickering, Robyn; Göktürk, Ozan; Badertscher, Seraina; Fleitmann, Dominik; Kramers, Jan

2010-05-01

246

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

PubMed Central

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

2011-01-01

247

Schaeferiana (Gaboniella subgen. n.) incompleta sp. n. from Gabon, with notes on its relationships and new records from the Central African Republic (Hemiptera, Heteroptera, Pyrrhocoridae)  

PubMed Central

Abstract A new subgenus, Gaboniella subgen. n., of the genus Schaeferiana Stehlík, 2008, and its type species, Schaeferiana (Gaboniella) incompleta sp. n. are described from Gabon. In addition the first state records of Sericocoris (Depressoculus) albomaculatus Stehlík, 2008 and Schaeferiana (Schaeferiana) mirabilis Stehlík, 2008 from the Central African Republic are provided. PMID:21998541

Stehlik, Jaroslav L.; Jindra, Zdenek

2011-01-01

248

New fossil records of Tapirus (Mammalia, Perissodactyla) from Brazil, with a critical analysis of intra-generic diversity assessments based on lower molar size variability  

Microsoft Academic Search

A large set of South American fossils belonging to the genus Tapirus has been described on the basis of differences in size and proportions of lower molariform teeth. Nevertheless, the reliability of dental proportions for the diagnosis of fossil tapir species is controversial. In this paper, we describe new fossil material of Tapirus from the Quaternary of Serra da Bodoquena,

Fernando A. Perini; João A. Oliveira; Leandro O. Salles; Carlos R. Moraes Neto; Patrícia G. Guedes; Luiz Flamarion B. Oliveira; Marcelo Weksler

249

Fossil humans 1 Fossil humans  

E-print Network

Fossil humans 1 Fossil humans All prehistoric skeletal remains of humans which are archeologically, anatomically modern humans. In this sense, the term "humans" is used broadly to mean all primates related of the Neanderthal speci- men in 1856. Fossil human remains have come prin- cipally from Europe, Asia, China, Java

Delson, Eric

250

Fossils 1: Fossils and Dinosaurs  

NSDL National Science Digital Library

This lesson will go beyond naming dinosaurs and give students a broad understanding of how we know about the great beasts. This lesson focuses on what we have learned and can learn from fossils. The follow-up lesson, Dinosaurs Fossils - Uncovering the Facts, explores what information can be discerned by comparing fossils to living organisms.

Science Netlinks;

2001-10-20

251

"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

252

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

Microsoft Academic Search

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

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

2005-01-01

253

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

254

Fossil Find  

NSDL National Science Digital Library

In this classroom activity, middle school students simulate a "dinosaur dig." The activity opens with background information for teachers about fossils. Working in groups, students excavate fossil sites created in advance by the teacher, or other group of students, and try to reconstruct a chicken skeleton. The activity closes with a two-page student worksheet that directs students to diagram the fossil site and includes probing questions to help them decode their findings.

255

Influences of the Agulhas Current on South African terrestrial climate as inferred from speleothem stable isotope records  

NASA Astrophysics Data System (ADS)

South African (SA) climate is strongly influenced by the circulation systems surrounding the subcontinent. The warm tropical Agulhas Current provides large amounts of moisture, transported onshore by south-easterly trade winds during summer. As the trade wind shifts north during winter, the south-western tip of SA is especially affected by temperate westerlies. High amounts of rainfall from the Benguela region off the west coast then only affect the very south-west of the country. This seasonal pattern creates a highly variable terrestrial climate, characterized by strong E-W gradients in the seasonal distribution and amount of rainfall. As summer and winter rain is derived from sources with different properties (density, salinity, temperature), the rainfall also displays seasonal isotopic compositional variations, as for example the present mean ?18O of rainfall in Mossel Bay located in the transition region varies from ~0.13‰ in January to -6.05‰ in July. Vegetation type (C3 vs C4) also follows the rainfall regime with C4 vegetation dominating in the summer rainfall region. As part of the GATEWAYS project, speleothems are used as an excellent, high resolution, precisely dated archive of terrestrial paleoenvironmental conditions[1]. This study focuses on a speleothem record from Crevice Cave on the South African south coast (near Mossel Bay), covering the interval between ~111 and ~53 ka[1,2]. At present, the area is influenced by both summer and winter rainfall, and has mostly C3 type vegetation. Variations in the past show more positive ?18O and ?13C values in the interval corresponding to the glacial MIS 4 and indicate increased summer rainfall and C4 vegetation. This contradicts the common assumption that MIS 4 was characterized by a northward shift of the climatic belts over SA and an increase of winter rainfall and C3 vegetation in the cave area[3]. Comparison of the record to marine sediment cores from the Agulhas Retroflection area[4] and the Cape Basin[5,6] as well as an ice-core record from Antarctica[7] reveal that the speleothem ?18O and ?13C are more closely related to the sea surface temperature shifts in the Agulhas region and Antarctica (with lower ?18O and ?13C values corresponding to higher temperatures) than to the influence of global ice-volume related changes in the isotopic composition of the ocean. A contemporary record from a cave site situated ~92 km inland from Mossel Bay (E-Flux Cave, Klein Karoo) shows a very different signal, corresponding to overall changes in Obliquity[8]. The influence of the Agulhas Current is thus apparent on the coast, but reduced inland. [1] Bar-Matthews, M. et al. 2010. Quaternary Science Reviews 29 p2131. [2] Braun, K. et al. 2011. Conference Abstract, Climate Change - The Karst Record 6. Birmingham England p27. [3] Chase, B. M. & Meadows, M. E., 2007. Earth-Science Reviews 84 p103. [4] Cortese, G. et al. 2004. Earth and Planetary Science Letters 222 p767. [5] Martínez-Méndez, G. et al. (2010). Paleoceanography 25(PA4227): doi:10.1029/2009PA001879. [6] Peeters, F. J. C. et al. 2004. Nature 430 p661. [7] Petit, J. R. et al. 1999. Nature 399 p429. [8] Berger, A. L. 1978. Quaternary Research 9 p139.

Braun, K.; Bar-Matthews, M.; Ayalon, A.; Marean, C.; Herries, A. I. R.; Zahn, R.; Matthews, A.

2012-04-01

256

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

257

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

258

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

E-print Network

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 $^6$Li in such stars with supernova CRs is more problematic. Here we propose that gravitational shocks induced by infalling and merging sub-Galactic clumps during hierarchical structure formation of the Galaxy should dissipate enough energy at early epochs, and CRs accelerated by such shocks can provide a natural explanation of the observed $^6$Li. In clear constrast to supernovae, structure formation shocks do not eject freshly synthesized CNO nor Fe, so that the only effective production channel at low metallicity is $\\alpha-\\alpha$ fusion, capable of generating sufficient $^6$Li with no accompanying Be or B and no direct correspondence with Fe. Correlations between the $^6$Li abundance and the kinematic properties of the halo stars may also be expected in this scenario. Further, more extensive observations of $^6$Li in metal-poor halo stars, e.g. by the Subaru HDS or VLT/UVES, may offer us an invaluable fossil record of dissipative dynamical processes which occurred during the formation of our Galaxy.

Takeru K. Suzuki; Susumu Inoue

2002-01-12

259

Using extant morphological variation to understand fossil  

E-print Network

among populations in two living clades -- the New World tamarins (genus Saguinus) and the African greatUsing extant morphological variation to understand fossil relationships: a cautionary tale Rebecca of insights that are pertinent to how we evaluate relationships among our fossil human ancestors. Here I

Ackermann, Rebecca Rogers

260

Dynamics of Late Quaternary North African humid periods documented in the clay mineral record of central Aegean Sea sediments  

NASA Astrophysics Data System (ADS)

The ratio between the clay minerals kaolinite and chlorite has been investigated in high resolution in a late Quaternary sediment core from the central Aegean Sea. The record spans the last ca. 105 ka. The kaolinite/chlorite ratio was used to reconstruct the fine-grained aeolian dust influx from the North African deserts, mainly derived from desiccated lake depressions. It therewith can be used as a proxy for wind activity, aridity and vegetation cover in the source area. The data document three major humid phases in North Africa bracketing the formation of sapropel layers S4, S3 and S1. They occur at > 105-95 ka, 83.5-72 ka and 14-2 ka. The first two phases are characterised by relatively abrupt lower and upper boundaries suggesting a non-linear response of vegetation to precipitation, with critical hydrological thresholds. In contrast, the onset and termination of the last humid period were more gradual. Highest kaolinite/chlorite ratios indicating strongest aeolian transport and aridity occur during Marine Isotope Stage (MIS) 5b, at ca. 95-84 ka. The long-term decrease in kaolinite/chlorite ratios during the last glacial period indicates a gradual decline of deflatable lake sediments in the source areas.

Ehrmann, Werner; Seidel, Martin; Schmiedl, Gerhard

2013-08-01

261

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

262

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

263

Fossil Fuels  

NSDL National Science Digital Library

How much does the United States depend on fossil fuels? This web page, part of a site on the future of energy, introduces students to fossil fuels as an energy source. Here students read about the uses, benefits, and limitations of fossil fuels. There is also information on how these fuels are distributed geographically and how they affect the U.S. economy through supply and demand. Thought-provoking questions afford students opportunities to reflect on what they've read. Articles about clean coal, the national energy policy, and the formation of fossil fuels, together with a fossil fuels fact sheet, are accessible from a sidebar. In addition, five PBS NewsHour links to energy-related stories are included.

Project, Iowa P.

2004-01-01

264

Carbon-isotope record of the Early Jurassic (Toarcian) Oceanic Anoxic Event from fossil wood and marine carbonate (Lusitanian Basin, Portugal)  

NASA Astrophysics Data System (ADS)

The Toarcian Oceanic Anoxic Event (OAE) in the Early Jurassic (˜ 183 Ma ago) was characterized by widespread near-synchronous deposition of organic-rich shales in marine settings, as well as perturbations to several isotopic systems. Characteristically, two positive carbon-isotope excursions in a range of materials are separated by an abrupt negative shift. Carbon-isotope profiles from Toarcian fossil wood collected in England and Denmark have previously been shown to exhibit this large drop (˜ - 7‰) in ?13C values, interpreted as due to an injection of isotopically light CO 2 into the ocean-atmosphere system. However, the global nature of this excursion has been challenged on the basis of carbon-isotope data from nektonic marine molluscs (belemnites), which exhibit heavier than expected carbon-isotope values. Here we present new data, principally from fossil wood and bulk carbonate collected at centimetre scale from a hemipelagic section at Peniche, coastal Portugal. This section is low in organic carbon (average TOC = ˜ 0.5%), and the samples should not have suffered significant diagenetic contamination by organic carbon of marine origin. The carbon-isotope profile based on wood shows two positive excursions separated by a large and abrupt negative excursion, which parallels exactly the profile based on bulk carbonate samples from the same section, albeit with approximately twice the amplitude (˜ - 8‰ in wood versus ˜ - 3.5‰ in carbonate). These data indicate that the negative carbon-isotope excursion affected the atmosphere and, by implication, the global ocean as well. The difference in amplitude between terrestrial organic and marine carbonate curves can be explained by greater water availability in the terrestrial environment during the negative excursion, for which there is independent evidence from marine osmium-isotope records and, plausibly, changes in atmospheric CO 2 content, for which independent evidence is also available. The Peniche succession is also notable for the occurrence of re-deposited sediments: their lowest occurrence coincides with the base of the negative excursion and their highest occurrence coincides with its top. Thus, slope instability and sediment supply could have been strongly linked to the global environmental perturbation, an association that may misleadingly simulate the effects of sea-level fall.

Hesselbo, Stephen P.; Jenkyns, Hugh C.; Duarte, Luis V.; Oliveira, Luiz C. V.

2007-01-01

265

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

266

Darwin's Enigma: The Fossil Record.  

ERIC Educational Resources Information Center

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

Sunderland, Luther D.

267

Evolution and the Fossil Record  

E-print Network

population growth #12;Charles Darwin in 1837, age 28, after voyage of the Beagle #12;Age 40 Age 45 #12;Darwin in 1879, age 70. #12;#12;#12;One of the most famous books of science. #12;Darwin's home, Down House of Variation · Random mutations of DNA ­>>99.9% are harmful or neutral ­adaptive mutations are rare · Sexual

Kammer, Thomas

268

The Fossil Record of Gibbons  

Microsoft Academic Search

Modern gibbons of the family Hylobatidae are distinguished from other living apes by a suite of shared-derived characteristics (synapomorphies) related to their unique mode of overhead suspensory locomotion and territorial defense. These characteristics include a greatly elongated and highly mobile forelimb, greatly reduced or nonexistent sexual dimorphism in body and canine tooth size, a predominantly monogamous social organization, and stereotyped

Nina G. Jablonski; George Chaplin

269

Fossil Cetacea (whales) in the  

Microsoft Academic Search

The fossil whale Aetiocetus, first described from Oregon Coast Range exposures of the Oligocene Yaquina Formation in Lincoln County, could be one of the specimens most important to the evolutionary study of Cetacea. The origin of M ysticeti or baleen (whale-bone) whales is obscured by their poor mid-Tertiary fossil record. The recovery of Aetiocetus remains in Marion County, Oregon, is

1983-01-01

270

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

PubMed

More than a decade of phylogenetic research has yielded a well-sampled, strongly supported hypothesis of relationships within the large (?> 4000 species) plant family Acanthaceae. This hypothesis points to intriguing biogeographic patterns and asymmetries in sister clade diversity but, absent a time-calibrated estimate for this evolutionary history, these patterns have remained unexplored. Here, we reconstruct divergence times within Acanthaceae using fossils as calibration points and experimenting with both fossil selection and effects of invoking a maximum age prior related to the origin of Eudicots. Contrary to earlier reports of a paucity of fossils of Lamiales (an order of ? 23,000 species that includes Acanthaceae) and to the expectation that a largely herbaceous to soft-wooded and tropical lineage would have few fossils, we recovered 51 reports of fossil Acanthaceae. Rigorous evaluation of these for accurate identification, quality of age assessment and utility in dating yielded eight fossils judged to merit inclusion in analyses. With nearly 10 kb of DNA sequence data, we used two sets of fossils as constraints to reconstruct divergence times. We demonstrate differences in age estimates depending on fossil selection and that enforcement of maximum age priors substantially alters estimated clade ages, especially in analyses that utilize a smaller rather than larger set of fossils. Our results suggest that long-distance dispersal events explain present-day distributions better than do Gondwanan or northern land bridge hypotheses. This biogeographical conclusion is for the most part robust to alternative calibration schemes. Our data support a minimum of 13 Old World (OW) to New World (NW) dispersal events but, intriguingly, only one in the reverse direction. Eleven of these 13 were among Acanthaceae s.s., which comprises > 90% of species diversity in the family. Remarkably, if minimum age estimates approximate true history, these 11 events occurred within the last ? 20 myr even though Acanthaceae s.s is over 3 times as old. A simulation study confirmed that these dispersal events were significantly skewed toward the present and not simply a chance occurrence. Finally, we review reports of fossils that have been assigned to Acanthaceae that are substantially older than the lower Cretaceous estimate for Angiosperms as a whole (i.e., the general consensus that has resulted from several recent dating and fossil-based studies in plants). This is the first study to reconstruct divergence times among clades of Acanthaceae and sets the stage for comparative evolutionary research in this and related families that have until now been thought to have extremely poor fossil resources. PMID:24733412

Tripp, Erin A; McDade, Lucinda A

2014-09-01

271

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.

272

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

273

Hunting Invertebrate Fossils in the Classroom  

NSDL National Science Digital Library

This activity is designed to provide a general knowledge about paleontology and its intimate relationship to sedimentary geology. It will introduce the student to fossils with an emphasis on the invertebrate phyla. As a result of this activity students will acquire a general knowledge of fossils and paleontology, be able to identify the major invertebrate groups commonly found in the fossil record, and learn how fossils tell us about the history of the earth.

Garbisch, Jon

274

Remarkable Fossils  

Microsoft Academic Search

ONE of the most remarkable collections of Wealden fossils ever seen, was lately on loan for a few days to the exhibition then open at Horsham, and is one that is not to be equalled by any at our public museums in the country. So remarkable is it that I am induced to give you a short description. As you

Thomas Wm. Cowan

1874-01-01

275

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

276

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. PMID:19094183

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

2008-01-01

277

Fossil Fuels  

NSDL National Science Digital Library

The Department of Energy Web site Fossil Fuels is billed as an energy education site mainly for older kids, but can be enjoyed by adult kids as well. The site gives an introduction to energy, and then a more detailed look at the acquisition and uses of coal, oil, and gas. The good descriptions, illustrations, and animations, along with the frequent questions page and glossary of related terms, combine to give a clear and enlightening overview of the subject.

278

Recordings  

Microsoft Academic Search

The Radio Ballads, 8 CDs, Topic TSCD801–808, 1999. Ewan MacColl (song lyrics, music, script), Peggy Seeger (orchestration and music direction), Charles Parker (field recordings).The Ballad of John Axon is about the railwaymen of England, in particular the story of steam locomotive driver John Axon, who was posthumously awarded the George Cross for his heroic attempt to stop his train after

Carole Pegg

1999-01-01

279

Carbon-isotope record of the Early Jurassic (Toarcian) Oceanic Anoxic Event from fossil wood and marine carbonate (Lusitanian Basin, Portugal)  

Microsoft Academic Search

The Toarcian Oceanic Anoxic Event (OAE) in the Early Jurassic (?183 Ma ago) was characterized by widespread near-synchronous deposition of organic-rich shales in marine settings, as well as perturbations to several isotopic systems. Characteristically, two positive carbon-isotope excursions in a range of materials are separated by an abrupt negative shift. Carbon-isotope profiles from Toarcian fossil wood collected in England and Denmark

Stephen P. Hesselbo; Hugh C. Jenkyns; Luis V. Duarte; Luiz C. V. Oliveira

2007-01-01

280

Carbon-isotope record of the Early Jurassic (Toarcian) Oceanic Anoxic Event from fossil wood and marine carbonate (Lusitanian Basin, Portugal)  

Microsoft Academic Search

The Toarcian Oceanic Anoxic Event (OAE) in the Early Jurassic (˜ 183 Ma ago) was characterized by widespread near-synchronous deposition of organic-rich shales in marine settings, as well as perturbations to several isotopic systems. Characteristically, two positive carbon-isotope excursions in a range of materials are separated by an abrupt negative shift. Carbon-isotope profiles from Toarcian fossil wood collected in England

Stephen P. Hesselbo; Hugh C. Jenkyns; Luis V. Duarte; Luiz C. V. Oliveira

2007-01-01

281

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

282

Tropical African climate variability during the last glacial\\/interglacial transition: the molecular record from Lake Malawi  

Microsoft Academic Search

In general, information regarding tropical African climate variability is relatively limited, especially in comparison with high-latitude studies. Unlike the high-latitudes where climate change is often expressed by fluctuations in temperature, low-latitude climate change is often expressed as variability in zonal circulation, which can result in hydrological fluctuations. Lake Malawi, situated in low-latitude tropical Africa (9-14° S), contains a continuous and

I. S. Castañeda; J. P. Werne; T. C. Johnson

2003-01-01

283

Origin of Life on Earth: The Precambrian Fossil  

E-print Network

eukaryotes · 2.0-3.5 BY ­ formation of BIF's, stromatolites common · 3.5 BY ­ oldest probable fossilsOrigin of Life on Earth: The Precambrian Fossil Record Geology 230 Fossils and Evolution #12;Time · 4.0 BY ­ oldest rocks of sedimentary origin #12;Fossil Evidence · 3.8 BY ago: small carbon compound

Kammer, Thomas

284

Mud fossils  

USGS Publications Warehouse

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

1997-01-01

285

Interhemispheric symmetry vs. Meridional shifts in the African ITCZ during the late Quaternary: reconciling palaeo-records using climate model simulations  

NASA Astrophysics Data System (ADS)

The location of the Inter-Tropical Convergence Zone (ITCZ) is one of the main controls on tropical and subtropical precipitation in Africa. Its latitudinal position oscillates seasonally but has also varied on millennial time scales in response to changes in the seasonal distribution of low-latitude insolation due to orbital configuration, as well as abrupt climate changes initiated at high latitudes, such as Heinrich events. However, palaeoclimate proxy archives often disagree about the mode of these variations, with some records suggesting meridional shifts in mean ITCZ position and others proposing interhemispherically symmetric expansion and contraction. Here, we use climate model simulations of the last glacial cycle (120 kyr) to demonstrate that there is not one global mode of operation, but rather ITCZ movement is regionally variable. Some regions display expansion/contraction and some display meridional shifts in response to changes in low-latitude insolation (precession-dominated), depending on local continental configuration. In addition, palaeo-records of precipitation do not necessarily directly correspond to variation in ITCZ position, and interpretation of these records in terms of the ITCZ will be dependent on their latitude, particularly over Africa, which has a large seasonal movement of the rainbelt. Our simulations can reconcile palaeo-records that have appeared to be in opposition, with implications for interpretation of future palaeo-archives of African and global low-latitude palaeo-hydroclimate variation on millennial and multi-millennial time-scales.

Singarayer, Joy; Valdes, Paul

2014-05-01

286

The largest fossil rodent  

PubMed Central

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

Rinderknecht, Andres; Blanco, R. Ernesto

2008-01-01

287

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

PubMed

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

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

2013-01-01

288

Genomic Fossils Calibrate the Long-Term Evolution of Hepadnaviruses  

E-print Network

Because most extant viruses mutate rapidly and lack a true fossil record, their deep evolution and longGenomic Fossils Calibrate the Long-Term Evolution of Hepadnaviruses Cle�ment Gilbert*, Ce-term vertical inheritance. Such endogenous viruses are highly valuable as they provide a molecular fossil record

Feschotte, Cedric

289

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

PubMed Central

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

Srivastava, Gaurav; Mehrotra, R.C.

2014-01-01

290

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. PMID:25061387

Petrulevicius, Julian F.; Popov, Yuri A.

2014-01-01

291

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

NASA Astrophysics Data System (ADS)

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 were either absent or insignificant in the Linxia Basin prior to ˜2-3 Ma and only became a significant component of local ecosystems in the Quaternary. This is in striking contrast to what was observed in Pakistan, Nepal, Africa and the Americas where C4 plants expanded rapidly in the late Miocene as indicated by a positive ?13C shift in mammalian tooth enamel and paleosols. The ?18O results from the same herbivore species show several significant shifts in climate in the late Cenozoic. Most notably, a positive ?18O shift after ˜7 Ma indicates a shift to warmer and/or drier conditions and is comparable in timing and direction to the ?18O shift observed in paleosol carbonates in Pakistan and Nepal. This late Miocene climate change observed in the Indian sub-continent and in the Linxia Basin, however, seems to be a regional manifestation of a global climate change. The lack of evidence for C4 plants in the Linxia Basin prior to ˜2-3 Ma suggests that the East Asian summer monsoon, which brings precipitation into northern China during the summer and creates optimal conditions for the growth of C4 grasses, was probably not strong enough to affect this part of China throughout much of the Neogene. This implies that the Himalayan-Tibetan Plateau may not have reached the present-day elevation across its vast extent to support a strong East Asian monsoon system before ˜2-3 Ma. Our data also suggest that regional climatic conditions played an important role in controlling the expansion of C4 plants.

Wang, Yang; Deng, Tao

2005-07-01

292

African Governance Report 2009  

Microsoft Academic Search

The African Governance Report, which assesses and monitors the progress of governance in Africa, is the most comprehensive periodic report on governance on the continent. This second edition of the report covers 35 African countries. The main finding of the report is that Africa within the last five years recorded marginal progress on governance. The gains on political governance have

293

Trace Fossils Paleontology  

E-print Network

Trace Fossils Paleontology Geology 331 #12;Freshwater Hardgrounds and Firmgrounds and Shoreface abundant trace fossils, Cruziana Ichnofacies, Ordovician of Wyoming #12;Zoophycos, Miss., KY. Zoophycos clues: Skolithos burrows in Aladdin Sandstone, Black Hills, SD #12;Skolithos trace fossils

Kammer, Thomas

294

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

295

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

296

What Is a Fossil?  

NSDL National Science Digital Library

In this classroom activity, young students explore the differences between bone and trace fossils. The activity opens with background information for teachers about fossils. After describing what a fossil is in their own words, students learn that a fossil is "any evidence of life that is at least 10,000 years old." They then explore the differences between trace and bone fossils by examining pictures. The activity concludes with a student worksheet that challenges them to identify trace and bone fossils.

297

Fossil ovipositions of dragonflies: Review and interpretation  

Microsoft Academic Search

The paper deals with the stratigraphic range and morphology of fossil formations on plants interpreted as insect ovipositions.\\u000a Our analysis of the insect fossil record has shown that the endophytic ovipositions probably belong to the Kennedyina and\\u000a Triadophlebiina (in the Paleozoic and Lower Mesozoic) and to the Calopterygina (in the Upper Mesozoic and Cenozoic).

D. V. Vasilenko; A. P. Rasnitsyn

2007-01-01

298

Creature Features - Showcase of Living Fossils  

NSDL National Science Digital Library

This activity is a side project that students work on through the organismal portion of a course in paleobiology/paleontology. Students present on the lifestyle, habitat, and behavior of "living fossil" groups. The activity ties the fossil record to the modern living world and allows students to engage with ideas of evolutionary stasis, taphonomy, and functional morphology.

Sunderlin, David

299

Book reviews Just looking at fossils  

E-print Network

on human evolution based on fossils is one example of this pattern. There are groups of organisms, however of interest is Hydrozoa. There is very little in the fossil record with regard to animals of this group, so I and less clear-cut. Hybridization can lead to the merging of species that, then, can split again, leading

Tullberg, Birgitta

300

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

PubMed

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

Gilmore, Cassandra C

2013-06-01

301

Influence of cellulose oxygen isotope variability in sub-fossil Sphagnum and plant macrofossil components on the reliability of paleoclimate records at the Mer  

E-print Network

components on the reliability of paleoclimate records at the Mer Bleue Bog, Ottawa, Ontario, Canada Hafida El vascular plants could result in erroneous paleoclimate reconstructions. � 2011 Elsevier Ltd. All rights­15%) and various lipids (Haider, 1996). Cellulose from these bog environments is commonly used as a paleoclimate

Patterson, Timothy

302

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

PubMed Central

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

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

2009-01-01

303

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

NASA Astrophysics Data System (ADS)

Here we present a detailed radiocarbon-dated 936 cm long pollen record from Lake Billyakh (65°17'N, 126°47'E; 340 m a.s.l.) situated in the western part of the Verkhoyansk Mountains, about 140 km south of the Arctic Circle. A set of 53 surface pollen samples representing tundra, cold deciduous forest and taiga was collected in northern and central Yakutia communities to verify the accuracy of the quantitative biome reconstruction method and to obtain a more precise attribution of the identified pollen taxa to the main regional biomes. The adjusted method is then applied to the pollen record from Lake Billyakh to gain a reconstruction of vegetation and environments since about 50.7 kyr BP. The results of the pollen analysis and pollen-based biome reconstruction suggest that herbaceous tundra and steppe communities dominated the area from 50.7 to 13.5 kyr BP. Relatively low pollen concentrations and high percentages of herbaceous pollen taxa (mainly Cyperaceae, Poaceae and Artemisia) likely indicate a reduced vegetation cover and/or lower pollen production. On the other hand, extremely low percentages of drought-tolerant taxa, such as Chenopodiaceae and Ephedra, and the constant presence of various mesophyllous herbaceous ( Thalictrum, Rosaceae, Asteraceae) and shrubby taxa ( Betula sect. Nanae/Fruticosae, Duschekia fruticosa, Salix) in the pollen assemblages prevent an interpretation of the last glacial environments around Lake Billyakh as extremely arid. The lowest pollen percentages of woody taxa and the highest values of Artemisia pollen attest that the 31-15 kyr BP period as the driest and coldest interval of the entire record. A relative high content of taxa representing shrub tundra communities and the presence of larch pollen recorded prior to 31 kyr and after 13.5 kyr BP likely indicate interstadial climate amelioration associated with the middle and latest parts of the last glacial. An increase in pollen percentages of herbaceous taxa around 12 kyr BP suggests broader distribution of drier communities in response to the colder and drier than present climate of the Younger Dryas (YD). The onset of the Holocene is marked in the pollen record by the highest values of shrub taxa, mainly B. sect. Nanae/Fruticosae. Pollen percentages of arboreal taxa increase gradually and reach maximum values after 7 kyr BP. The latter maximum mainly reflects the spread of Pinus sylvestris in central Yakutia as a response to the mid-Holocene climatic optimum. The quasi-continuous presence of larch, shrubby birch and alder pollen throughout the whole record is the most striking feature of the pollen record. Noticeable variations in larch pollen percentages point to multiple short-term warming episodes, which might be synchronous with the Dansgaard-Oeschger cycles in the North Atlantic records. The Lake Billyakh pollen record suggests that larch possibly survived during the last 50 kyr BP in locally favourable environments in the study region.

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

2010-08-01

304

Deductions from Fossil Preservtion  

NSDL National Science Digital Library

Students will view fossils, sometimes with supporting illustrations, and answer questions about them via deductive reasoning. The exercise is highly interactive, with the instructor providing hints and helpful questions. The questions concern ways in which fossil preservation reveals information about things like what kind of organism the fossil represents, how that organism lived, and how the fossil came into being.

Stanley, Steven

305

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.

Edwards, Lucy E.; Pojeta Jr., John

1997-06-26

306

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

E-print Network

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

M. Omerbashich

2007-06-09

307

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

308

Hominid Fossil Record Geology 230: Fossils and Evolution  

E-print Network

,000 yrs? Java man Peking man · H. sapiens: archaic vs. modern #12;Skull of Homo habilis #12;H. rudolfensis of Nariokotome boy #12;The face of Homo erectus #12;Homo erectus from Indonesia, Java Man #12;Homo erectus using skeleton, Germany #12;Homo neadertalensis leading a nomadic existence #12;Neandertals were big-game hunters

Kammer, Thomas

309

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

310

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. PMID:25061858

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

2014-01-01

311

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

E-print Network

:319�337. NORELL, M. A., AND M. J. NOVACEK. 1992b. The fossil record and evolution: Comparing cladistic and pa:459�469. MAXWELL, W. D., AND M. J. BENTON. 1990. Historical tests of the absolute completeness of the fossil record superpositional and phylogenetic patterns: Comparing cladistic patterns with fossil records. Cladistics 8

Barker, F. Keith

312

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

313

Transitional Tetrapod Fossil  

NSDL National Science Digital Library

In this video segment from NOVA: Judgment Day: Intelligent Design on Trial, learn about the discovery of a well-preserved transitional fossil and how such transitional fossils support the theory of evolution.

Foundation, Wgbh E.

2007-11-01

314

Face-to-Fossil  

NSDL National Science Digital Library

This Web article is part of OLogy, where kids can collect virtual trading cards and create projects with them. Here they meet Deena Soris, who interviews the fossil of a Protoceratops. The more-than-20 questions answered by this dinosaur fossil cover topics such as what were you like when you were alive and how did you become a fossil.

315

Is It a Fossil?  

NSDL National Science Digital Library

This formative assessment item is used to uncover students' ideas about fossils before a lesson has begun. Students will determine whether examples are fossils, and what sort of inferences can be made about prior environments because of fossils. This probe is aligned with the National Science Education Standards. Resources are provided along with instructional suggestions.

Fries-Gaither, Jessica

316

Picture Matching Fossils  

NSDL National Science Digital Library

Teaching the students how to picture match fossils and to use the Treatise to find more information. Students are given a wide range of fossils to look at and appropriate material to match their fossil to an image which gives the genus and species name. With that information, the students turn to the Treatise of Invertebrate Paleontology to find upper level taxonomic names.

Rhenberg, Elizabeth

317

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. PMID:18685095

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

2008-01-01

318

Fossil-energy program  

NASA Astrophysics Data System (ADS)

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

McNeese, L. E.

1982-01-01

319

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.

320

An Indoor Fossil/Archeological Dig  

NSDL National Science Digital Library

In this activity, students will participate in a simulated fossil hunt or archeological excavation. Working in groups, they will excavate fossils or artifacts buried in a container and tag, number and label, and record the position and details of each object encountered. They will make site sketches as each layer is removed. When all the objects have been found, and all the information obtained, the group can compose a field report on the dig site that makes some inferences about the conditions that existed at the time the fossil/artifact was buried. A student worksheet is provided.

2011-06-24

321

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

322

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

323

Predation of Fishes in the Fossil Record  

Microsoft Academic Search

\\u000a This review covers selected highlights of predation of fishes. Understanding this group is important. Approximately one-half\\u000a of all named vertebrate species are fishes. Fishes are the original bauplan and evolutionary source for the rest of the vertebrates.\\u000a Our evolutionary history as vertebrates is explainable only with an understanding of fishes, which in turn can only be fully\\u000a understood in the

James MCallister

324

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

325

Fossil Mapping of Utah  

NSDL National Science Digital Library

Fossils are evidence of living organisms from the past and are usually preserved in sedimentary rocks. A fossil may be an impression left in sediments, the preserved remains of an organism, or a trace mark showing that an organism once existed. Fossils are usually made from the hard parts of an organism because soft parts decay quickly. Fossils provide clues to Earth's history. They provide evidence that can be used to make inferences about past environments. Fossils can be compared to one another, to living organisms, and to organisms that lived long ago. Students will understand how fossils are formed, where they may be found in Utah, and how they can be used to make inferences. Research locations where fossils are found in Utah and construct a simple fossil map. 4th Grade Utah Core Curriculum, Science Benchmark, Standard 4, Objective 1, UEN TASK Congratulations. You have all become Paleontologists. You study fossils and it is your job to map the fossils of Utah for the State. Students will be divided into 4 groups. Each group will be given a Utah County Map. Each group will focus on one category ...

Ramsey

2009-11-18

326

GEOL 102: Historical Geology Overview of Major Groups of Fossil Forming Organisms  

E-print Network

. The fossil record contains many stages of plant evolution. All land plants are phototrophs and multicellular cyanobacteria.) Rhodophytes ("red algae") have a fossil record back to Ectasian; green algae not before1 GEOL 102: Historical Geology Overview of Major Groups of Fossil Forming Organisms Prokaryote

Holtz Jr., Thomas R.

327

Fossil Energy Website  

NSDL National Science Digital Library

This site serves as a gathering point for US Department of Energy (USDOE) materials related to fossil energy. Well-organized and easily navigated, the Fossil Energy Website hosts a wealth of resources, including fossil energy news, related USDOE budget information, an events calendar, in-depth explorations of selected issues, speeches and testimony, technical reports, statistics, and an overview of fossil energy-related global activities, among others. Additional resources include regulatory information, a news headlines ticker, a free email update service, related links, and professional notices.

328

Cretaceous and living colloniidae of the redefined subfamily Petropomatinae, with two new genera and one new species, with notes on opercular evolution in turbinoideans, and the fossil record of Liotiidae (Vetigastropoda: Turbinoidea)  

Microsoft Academic Search

Opercular characters are of major importance to understanding the living and fossil groups in the vetigastropod superfamily\\u000a TurbinoideaRafinesque. Here we evaluate current knowledge of fossil turbinoid opercula in the light of a newly discovered Recent colloniid with\\u000a an unfamiliar opercular morphology. The operculum ofLiotipoma n. gen. has a multispiral and conical inner surface; the outer surface is rugose with a

James H. McLean; Steffen Kiel

2007-01-01

329

NYSGA 2010 Trip 4 -Olsen Fossil Great Lakes of the Newark Supergroup  

E-print Network

NYSGA 2010 Trip 4 - Olsen 101 Fossil Great Lakes of the Newark Supergroup ­ 30 Years Later Paul E: THE TRIASSIC-JURASSIC GREAT LAKES OF CENTRAL PANGEA This guidebook focuses of the deposits, fossils dimension comparable to the scale of the American Great Lakes or the East African Great Lakes and perhaps

Olsen, Paul E.

330

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

331

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

332

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

333

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

334

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

335

Fossil energy program  

NASA Astrophysics Data System (ADS)

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

McNeese, L. E.

1981-12-01

336

Eumetazoan fossils in terminal proterozoic phosphorites?  

PubMed

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. PMID:11095754

Xiao, S; Yuan, X; Knoll, A H

2000-12-01

337

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

338

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

339

Fossil Identification Project  

NSDL National Science Digital Library

Students attend a class fieldtrip where over five locations across Tennessee representing three different geological time periods (Ordovician, Devonian, and Cretaceous) are visited. The students are required to collect 20 different taxa (5 of which must be unique to each student) and then using the knowledge they have gained in labs identify their taxa to species level. They must make a powerpoint presentation summarizing the paleocological and paleoclimatological information gained about each locality through the collection of the fossil taxa. The activity helps familiarize students with the geology of Tennessee and field collection of fossils in addition to lab identification of fossils.

Lobegeier, Melissa

340

Fossil Systematic Description Project  

NSDL National Science Digital Library

Students describe an unknown vertebrate fossil (or fossils, if multiple specimens are necessary for identification). This exercise is the culmination of their lab studies in the morphology of the vertebrate skeleton and requires them to integrate their ability to describe the morphology with research into the literature on their assigned animal. Students also become familiar with presentation of research through writing a formal scientific paper in the style of a particular journal.

Hopkins, Samantha

341

Dinosaur Trace Fossils  

NSDL National Science Digital Library

Anthony J. Martin, Senior Lecturer at Emory University, provides this interesting Website on dinosaur trace fossils -- namely tracks, trails, burrows, borings, gnawings, eggs, nests, gizzard stones, and dung of dinosaurs. The site offers a brief overview followed by illustrated descriptions of particular trace fossil types: Tracks and Trackways, Eggs and Nests, Tooth Marks, Gastroliths, and Coprolites. A series of links points users to further information, and a bibliography on Vertebrate Ichnology provides additional readings (through 1997).

Martin, Anthony J.

342

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

343

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

344

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

345

40Ar/39Ar record of late Pan-African exhumation of a granulite facies terrain, central Dronning Maud Land, East Antarctica  

NASA Astrophysics Data System (ADS)

40Ar/39Ar geochronological data on hornblende, biotite and K-feldspar provide constraints on the cooling path experienced by a high-grade metamorphic complex from the Mühlig-Hofmannfjella and Filchnerfjella (6-8°E), central Dronning Maud Land, Antarctica, during the late Neoproterozoic-early Palaeozoic Pan-African orogeny. Hornblende ages yield c. 481 Ma, biotite ages range from c. 466 Ma to c. 435 Ma, whereas K-feldspar ages of the gneisses are c. 437 Ma. The 40Ar/39Ar data suggest initial cooling at a rate of ~10 °C/Myr between 481 and 465 Ma, followed by a lower cooling rate of ~6 °C/Myr during the subsequent c. 30 million years. The K-feldspar 40Ar/39Ar ages place a lower time limit on the duration of the exhumation, by the time of thermal relaxation to a stable continental geotherm. The 40Ar/39Ar data reflecting cooling indicate tectonic exhumation related to orogenic collapse during a later phase of the Pan-African orogeny.

Hendriks, Bart W. H.; Engvik, Ane K.; Elvevold, Synnøve

2013-10-01

346

A Virtual Museum of Fossils  

NSDL National Science Digital Library

This collection of fossils contains 300 fossils of vertebrates and invertebrates and casts of fossils from national museums, universities and private collections. For each geologic time period, the website provides ancient world configurations, important ancient world physiographic features, ancient world locations where the fossils were found, and a comprehensive table with thumbnails of all fossils in the collection. A separate page is devoted to each specimen where multiple high resolution photographs are displayed. Reference skeletal reconstructions are shown where available from the literature.

Chatelain, Edward; Barnbaum, Cecilia

2002-05-01

347

Fossil turbulence revisited  

E-print Network

A theory of fossil turbulence presented in the 11th Liege Colloquium on Marine turbulence is "revisited" in the 29th Liege Colloquium "Marine Turbulence Revisited". The Gibson (1980) theory applied universal similarity theories of turbulence and turbulent mixing to the vertical evolution of an isolated patch of turbulence in a stratified fluid as it is constrained and fossilized by buoyancy forces. Towed oceanic microstructure measurements of Schedvin (1979) confirmed the predicted universal constants. Universal constants, spectra, hydrodynamic phase diagrams (HPDs) and other predictions of the theory have been reconfirmed by a wide variety of field and laboratory observations. Fossil turbulence theory has many applications; for example, in marine biology, laboratory and field measurements suggest phytoplankton species with different swimming abilities adjust their growth strategies differently by pattern recognition of several days of turbulence-fossil-turbulence dissipation and persistence times above threshold values, signaling a developing surface layer sea change. In cosmology, self-gravitational structure masses are interpreted as fossils of primordial hydrodynamic states.

Carl H. Gibson

1999-04-19

348

The Fossil Episode ?  

E-print Network

We build a two-sector dynamic general equilibrium model with one-sided substitutability between fossil carbon and biocarbon. One shock only, the discovery of the technology to use fossil fuels, leads to a transition from an inital pre-industrial phase to three following phases: a pure fossil carbon phase, a mixed fossil and biocarbon phase and an absorbing biocarbon phase. The increased competition for biocarbon during phase 3 and 4 leads to increasing food prices. We provide closed form expressions for this price increase. Our calibration leads to a price increase of 40 % if capital and labor are allowed to move to the biocarbon sector. Otherwise, the price increase is much higher. We also use the model to analyze the consequences of restrictions on using biocarbon as fuel. We show that such restrictions can lead to a substantially slower global warming due to an endogenous slowdown of fossil fuel extraction. This version: Dec 4, 2012. We are greatful for comments from Per Krusell and Rick van der Ploeg as

John Hassler; Hans-werner Sinn

349

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

350

Fossil evidence of the zygomycetous fungi.  

PubMed

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

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

2013-06-01

351

ANTH 361: Human Evolution (CRN 16403) Discovering & Interpreting the Fossil Evidence Fall 2010  

E-print Network

-1- ANTH 361: Human Evolution (CRN 16403) Discovering & Interpreting the Fossil Evidence Fall 2010 of the discovery and interpretation of the fossil evidence for human evolution. How have human beings become what they are today? What biological traits encouraged the development of cultural behavior? How can the fossil record

352

Local Molecular Clocks in Three Nuclear Genes: Divergence Times for Rodents and Other Mammals and Incompatibility Among Fossil Calibrations  

E-print Network

of mam- malian evolution is a debated issue between molecule- and fossil-based inferences -- Divergence times -- Phylogeny -- Fossil record -- Evolutionary rates -- Nuclear genes -- Mammals -- Rodents their origin in the incompleteness of the fossil record or, possibly, in methodological shortcomings associated

Huchon, Dorothée

353

Hypothesized resource relationships among African planktonic diatoms  

Microsoft Academic Search

Several hypotheses are advanced for resource relationships among planktonic diatoms in African freshwater lakes that are consistent with the light and nutrient conditions of the lakes and the extant and fossil distributions of the diatom species in them. The hypotheses are all testable and are potentially powerful tools for interpreting past climatic conditions. A ranking is proposed along a Si

Peter Kilham; Susan S. Kilham; Robert E. Hecky

1985-01-01

354

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

355

Fossil Fuels: Capstone  

NSDL National Science Digital Library

This lesson summarizes our dependency upon fossil fuels, pointing out that there are very few aspects of our daily life that are not impacted by their use. The discussion centers around whether these fuels could be replaced and makes the point that there is a significant percentage of them which is used to manufacture products and is not simply burned for energy. The lesson includes an activity in which students use an online calculator to estimate how much of each fossil fuel they are responsible for consuming each year.

Pratte, John

356

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

357

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

358

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

359

Fossil-energy  

NASA Astrophysics Data System (ADS)

Progress in the following areas of fossil energy is reported: physiochemical cleaning and recovery of fine coal; a systematic investigation of the organosulfur components in coal; microstructures of coal; rapid analysis of mineral content in coal; coal blending experiments; performance characteristics of heavy media cyclones using fly ash derived heavy media; briquetting solvent treated coal; and coal preparation and testing.

1981-08-01

360

Fossil Halls: Vertebrate Evolution  

NSDL National Science Digital Library

Part of a larger virtual tour of the Museum's famed Fossil Halls, this Web site has an interactive cladogram with 20 clickable evolutionary branching points. It shows vertebrate evolution for the following three AMNH halls: Hall of Vertebrate Origins, Hall of Dinosaurs and Hall of Mammals and Their Extinct Relatives.

361

Therapod Fossil Hunt Dispatch  

NSDL National Science Digital Library

This online article reports on the finding of a dromaeosaur fossil, the best specimen to date to show that feathers existed long before modern birds and flight. The research was a collaboration between the American Museum of Natural History and the Geological Museum of China.

362

Hydrogen and fossil fuels  

Microsoft Academic Search

A technological forecast is attempted of how fossil fuels will fare during the period of build-up of the hydrogen energy economy. If the latter is inevitable many might expect their death. However, they will probably always be needed as a source of chemicals, and arguments are given for the thesis that synthetic methane will remain a useful fuel even after

J. Rothstein

1995-01-01

363

Fossils and Minerals  

NSDL National Science Digital Library

This site from the Black Hills Institute features information about different types of fossils, minerals, meteorites, and geology in general. Each topic has a brief description, with links to a more detailed explanation. Various samples and books are abailable for purchase on the site.

Research, Inc. B.

364

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?

365

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

366

Advanced fossil energy utilization  

SciTech Connect

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

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

2010-01-01

367

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

368

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. PMID:16571655

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

2006-01-01

369

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. PMID:19439440

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

2009-01-01

370

Evolution of the African continental crust as recorded by U-Pb, Lu-Hf and O isotopes in detrital zircons from modern rivers  

NASA Astrophysics Data System (ADS)

To better understand the evolutionary history of the African continental crust, a combined U-Pb, Lu-Hf and O isotopic study has been carried out by in situ analyses of approximately 450 detrital zircon grains from the Niger, Nile, Congo, Zambezi and Orange Rivers. The U-Pb isotopic data show age peaks at ca. 2.7, 2.1-1.8, 1.2-1.0, ca. 0.8, 0.7-0.5 and ca. 0.3 Ga. These peaks, with the exception of the one at ca. 0.8 Ga, correspond with the assembly of supercontinents. Furthermore, the detrital zircons that crystallized during these periods of supercontinent assembly have dominantly non-mantle-like O and Hf isotopic signatures, in contrast to the ca. 0.8 Ga detrital zircons which have juvenile characteristics. These data can be interpreted as showing that continental collisions during supercontinent assembly resulted in supermountain building accompanied by remelting of older continental crust, which in turn led to significant erosion of young igneous rocks with non-mantle-like isotopic signatures. Alternatively, the data may indicate that the major mode of crustal development changed during the supercontinent cycle: the generation of juvenile crust in extensional settings was dominant during supercontinent fragmentation, whereas the stabilization of the generated crust via crustal accretion and reworking was important during supercontinent assembly. The Lu-Hf and O isotope systematics indicate that terreigneous sediments could attain elevated 18O/16O via prolonged sediment-sediment recycling over long crustal residence time, and also that reworking of carbonate and chert which generally have elevated 18O/16O and low Hf contents is minor in granitoid magmatism. The highest 18O/16O in detrital zircon abruptly increased at ca. 2.1 Ga and became nearly constant thereafter. This indicates that reworking of mature sediments increased abruptly at that time, probably as a result of a transition in the dynamics of either granitoid crust formation or sedimentary evolution. To estimate the mantle-extraction age of the reworked crust, we have calculated arc mantle Hf model ages for the detrital zircons using O isotopic data to constrain the Lu/Hf used in the model age calculation. The Hf model age histograms for each period of detrital zircons suggest that a significant amount of the African continental crust was generated in the Paleo-Mesoproterozoic likely by mafic magmatism, and subsequently reworked into younger granitoid crust with varying crustal residence times.

Iizuka, Tsuyoshi; Campbell, Ian H.; Allen, Charlotte M.; Gill, James B.; Maruyama, Shigenori; Makoka, Frédéric

2013-04-01

371

SYSTEMATICS First Mesozoic Record of a Parasitiform Mite: a Larval Argasid  

E-print Network

lineage of chelicerate arthropods, but their fossil record is somewhat mixed. The record for the order, Selden 1993). In contrast, the fossil record of its pu- tative sistergroup, the order Parasitiformes (Poinar 1995). The discrepancy between the fossil records of the two orders may very well be an artifact

Kubatko, Laura S.

372

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

373

AB IRTH RECORDS ANALYSIS OF THE MATERNAL INFANT HEALTH ADVOCATE SERVICE PROGRAM :AP ARAPROFESSIONAL INTERVENTION AIMED AT ADDRESSING INFANT MORTALITY IN AFRICAN AMERICANS  

Microsoft Academic Search

Recognizing that no single intervention was likely to eliminate racial disparities, the Genesee County REACH 2010 partnership, utilizing both ''bench'' science and ''trench'' knowledge, developed 13 broad-based, multi- faceted interventions to eliminate infant mor- tality. This article provides highlights from a re- cent birth records comparison analysis of the Maternal Infant Health Advocate Service (MI- HAS) intervention, and is solely

Haslyn E. R. Hunte; Tonya M. Turner; Harold A. Pollack; E. Yvonne Lewis

374

Centering on Fossils and Dinosaurs.  

ERIC Educational Resources Information Center

Describes a set of 10 activities which introduce mainstreamed junior high school students to concepts relating to fossils and dinosaurs. Provides students with opportunities for learning the concepts of change and adaptation, as well as fossil facts and terminology. (TW)

Coble, Charles R.; McCall, Gregory K.

1986-01-01

375

Laser-Raman imagery of Earth's earliest fossils  

NASA Astrophysics Data System (ADS)

Unlike the familiar Phanerozoic history of life, evolution during the earlier and much longer Precambrian segment of geological time centred on prokaryotic microbes. Because such microorganisms are minute, are preserved incompletely in geological materials, and have simple morphologies that can be mimicked by nonbiological mineral microstructures, discriminating between true microbial fossils and microscopic pseudofossil `lookalikes' can be difficult. Thus, valid identification of fossil microbes, which is essential to understanding the prokaryote-dominated, Precambrian 85% of life's history, can require more than traditional palaeontology that is focused on morphology. By combining optically discernible morphology with analyses of chemical composition, laser-Raman spectroscopic imagery of individual microscopic fossils provides a means by which to address this need. Here we apply this technique to exceptionally ancient fossil microbe-like objects, including the oldest such specimens reported from the geological record, and show that the results obtained substantiate the biological origin of the earliest cellular fossils known.

Schopf, J. William; Kudryavtsev, Anatoliy B.; Agresti, David G.; Wdowiak, Thomas J.; Czaja, Andrew D.

2002-03-01

376

Laser--Raman imagery of Earth's earliest fossils.  

PubMed

Unlike the familiar Phanerozoic history of life, evolution during the earlier and much longer Precambrian segment of geological time centred on prokaryotic microbes. Because such microorganisms are minute, are preserved incompletely in geological materials, and have simple morphologies that can be mimicked by nonbiological mineral microstructures, discriminating between true microbial fossils and microscopic pseudofossil 'lookalikes' can be difficult. Thus, valid identification of fossil microbes, which is essential to understanding the prokaryote-dominated, Precambrian 85% of life's history, can require more than traditional palaeontology that is focused on morphology. By combining optically discernible morphology with analyses of chemical composition, laser--Raman spectroscopic imagery of individual microscopic fossils provides a means by which to address this need. Here we apply this technique to exceptionally ancient fossil microbe-like objects, including the oldest such specimens reported from the geological record, and show that the results obtained substantiate the biological origin of the earliest cellular fossils known. PMID:11882894

Schopf, J William; Kudryavtsev, Anatoliy B; Agresti, David G; Wdowiak, Thomas J; Czaja, Andrew D

2002-03-01

377

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. PMID:21525049

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

378

Synthesizing and databasing fossil calibrations: divergence dating and beyond.  

PubMed

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

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

2011-12-23

379

Kunta Kinte's Struggle to be African  

ERIC Educational Resources Information Center

This article reveals the differences between the character Kunta Kinte and the historical record concerning African males in the preslavery period. Kunta's non-African behaviors include displays of blind anger and rage, prudishness, and actions unknown in his Mandinka culture. These represent the many misrepresentations and ambiguities in Alex…

Courlander, Harold

1986-01-01

380

The Unknown Fossil Report  

NSDL National Science Digital Library

This project challenges the students ingenuity, creativity, and resourcefulness! They each receive a fossil of unknown identity (general geographic locality may be given, e.g., I-55 south of St. Louis, MO). The specimen is described in as much detail as possible. Their report should include taxonomic classification (as complete as they can), age, paleoecology, Earth history, and other interpretations they can infer. Identification may require library work, Internet search, etc.

Reams, Max

381

Bibliography of Fossil Vertebrates  

NSDL National Science Digital Library

The Society of Vertebrate Paleontology (SVP), one of most reputable American paleontological societies, sponsors this online edition of its Bibliography of Fossil Vertebrates. The database, which currently covers the years 1509-1958 and 1981-1993 with approximately 112,000 references, is searchable by author, subject, taxon, language, editor, and journal book or volume title. A help page with query instructions for the somewhat finicky search engine is provided.

1997-01-01

382

Fossil fish studies  

E-print Network

histologically unsuited for fossilization in the black-shale depo- sitional environment (i.e., it was probably not composed of the same type of calcified cartilage as were other chondrichthyans in the environ- ment). Skull material from two species of edestids... have recently been reported from the Lower Triassic of Wapiti Lake, British Columbia (Schaeffer & Mangus, 1976), whereas Edestus is unknown from rocks later than Per- mian in age. REFERENCES Bradley, F. H., 1870, Geology of Vermillion County: Geol...

Chorn, John; Reavis, E. A.; Stewart, J. D.; Whetstone, K. N.

1978-02-17

383

Fossil crinoid studies  

E-print Network

THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS November 15, 1974 Paper 73 FOSSIL CRINOID STUDIES' ROGER K. PABIAN and HARRELL L. STRIMPLE University of Nebraska, Lincoln; University of Iowa, Iowa City CONTENTS PAGE PART I. MISCELLANEOUS..., NEBRASKA 31 PART 4. BIOMETRICAL STUDY OF THE MORPHOLOGY AND DEVELOPMENT OF A NLW SPECIES OF TERPNOCRINUS STRIMPLE AND MOORE, PENNSYLVANIAN, NEBRASKA 38 REFERENCES (Pans 1-4) 52 ADDENDUM 53 ' Manuscript received February 21, 1974. 2 The University...

Pabian, R. K.; Strimple, H. L.

1974-11-15

384

Fossil crinoid studies  

E-print Network

THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS October 1, 1969 Paper 42 FOSSIL CRINOID STUDIES HARRELL L. STRIMPLE, C. O. LEVORSON, MICHAEL R. MCGINNIS, RAYMOND C. MooRE, and AMEL PRIEST CONTENTS PAGE PART 1. NEW LECANOCRINID FROM... PENNSYLVANIAN OF OKLAHOMA (Harrell L. Strimple, with Addendum by Raymond C. Moore) 1 PART 2. UPPER PENNSYLVANIAN ANOBASICRINID FROM NEW MEXICO (Harrell L. Strimple) 8 PART 3. PENNSYLVANIAN CRINOIDS FROM OHIO AND OKLAHOMA (Harrell L. Strimple) 11 PART 4...

Strimple, H. L.; Levorson, C. O.; McGinnis, M. R.; Moore, R. C.; Priest, A.

1969-10-01

385

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.

386

YZC Animal of the Month, September 2012 African Elephant  

E-print Network

YZC Animal of the Month, September 2012 African Elephant Loxodonta africana Go to the lower gallery. The African Elephant is the largest land-living animal alive today. The biggest animal on record measured up. University Museum of Zoology, Cambridge September 2012 African Elephants live in a range

387

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. PMID:19828545

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

2010-01-01

388

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. PMID:24966541

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

2014-01-01

389

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

PubMed Central

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

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

2012-01-01

390

Department of African American and African Studies  

E-print Network

by the Faculty of the Department of African American and African Studies in March 1988 and Amended by the Faculty...................................................................... Procedures for Fourth-Year Review

391

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

392

Female African wild dogs emigrate  

Microsoft Academic Search

AMONG mammals, the common mechanism of individual transfer between social groups is male emigration. While studying the African wild dog (Lycaon pictus Temminck) over a period of 2 yr, we have recorded four positive cases of female group emigration, three possible cases of single female emigration, and only one possible case of male group emigration. From this we conclude that

Lory Herbison Frame; George W. Frame

1976-01-01

393

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

394

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

PubMed

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

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

2013-01-01

395

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.

396

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

397

Variation in enamel development of South African fossil hominids  

Microsoft Academic Search

Dental tissues provide important insights into aspects of hominid palaeobiology that are otherwise difficult to obtain from studies of the bony skeleton. Tooth enamel is formed by ameloblasts, which demonstrate daily secretory rhythms developing tissue-specific structures known as cross striations, and longer period markings called striae of Retzius. These enamel features were studied in the molars of two well known

Rodrigo S. Lacruz; Fernando Ramirez Rozzi; Timothy G. Bromage

2006-01-01

398

Oxygen and carbon isotopes in terrestrial mollusk shells. From modern to fossil values, climatic impact on the mollusk diet  

Microsoft Academic Search

Stable isotope studies on fossil material as well as on sediment have been very successful these past years indicating such method a very promising Quaternary paleonvironmental index for continental studies. Although most of the studies on fossil material was related to modern material collected near the fossil record, no precise analysis of the impact of the diet and precipitation was

S. Metref; M. Labonne; D. Rousseau; I. Bentaleb; M. Vianey-Liaud

2001-01-01

399

Fossils 2: Uncovering the Facts  

NSDL National Science Digital Library

In Fossils and Dinosaurs, the first lesson of this two lesson series, students learned the differences between facts and ideas that are extrapolated from fossil evidence. This lesson allows students to go through an 'interview' with the remains of a Protoceratops. In preparation for the interview, students first brainstorm the questions they would like answers to, and then narrow their questions to those that can be answered by studying the Protoceratops fossils.

Science Netlinks;

2001-10-20

400

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

401

African Union  

NSDL National Science Digital Library

As visitors enter this site, they will be presented with a collage of African nations coming together to form the entire continent, accompanied by the words âÂÂAfrica must unite.â It is a visually stimulating image, and one that sets the tone quite nicely for the content within. The site is the homepage of the African Union (AU), which was created in 1999 as part of a declaration from the Organisation of African Unity (OAU). While their mission is complex to say the least, their primary goal is to promote the âÂÂâ¦accelerated socio-economic integration of the continent, which will lead to greater unity and solidarity between African countries and peoples.â The site presents a cornucopia of material on their work, contained within sections titled âÂÂMember StatesâÂÂ, âÂÂConferences & EventsâÂÂ, and âÂÂDocumentsâÂÂ. One of the best places to start is the âÂÂNews and Eventsâ area, which contains a sampling of information on their recent work on gender equity, sustainable development, higher education systems, and so on. As might be expected, visitors can also browse through many of these materials in Arabic, French, and Portuguese.

402

African Pentecostalism  

ERIC Educational Resources Information Center

The diversity of African Pentecostalism, its early colonial and missionary history and its current characteristics are described and analysed. Reference is made to methods of training and forms of leadership, and suggestions are made about the reasons for its growth and persistence. (Contains 19 notes.)

Garrard, David J.

2009-01-01

403

Fossils 2: Uncovering the Facts  

NSDL National Science Digital Library

This lesson is the second in a two-part series on fossils. It explores the information that can be discerned by comparing fossils to living organisms. Students explore fossils and are responsible for using what they have learned to do their own extrapolating. Students conduct an interview with the remains of a Protoceratops. In preparation for the interview, they brainstorm the questions for which they would like answers and then narrow their questions to those that can really be answered by studying the Protoceratops fossils.

404

New material of Anancus kenyensis (proboscidea, mammalia) from Toros-Menalla (Late Miocene, Chad): Contribution to the systematics of African anancines  

NASA Astrophysics Data System (ADS)

New fossil remains of the proboscidean genus Anancus are described. Among them, a complete skull allows us to revisit for the first time the entire Chadian Anancus fossil record. This genus occurred in the Old World from the late Miocene up to the early Pleistocene. The analysis of dental and cranial characters was allowed individual variations from specific characters to be distinguished. In this study we show that Anancus kenyensis and Anancus osiris are very likely synonym taxa which leads us to emend the diagnosis of A. kenyensis. In addition, this study shows that dental characters in anancines lineage are of little significance for biostratigraphical inference, by contrast to previous works. This study brings new data about the phylogenetical and palaeobiogeographical history of the African anancines.

Hautier, Lionel; Mackaye, Hassane Taisso; Lihoreau, Fabrice; Tassy, Pascal; Vignaud, Patrick; Brunet, Michel

2009-03-01

405

A scratch circle origin for the medusoid fossil Kullingia SO REN JENSEN, JAMES G. GEHLING, MARY L. DROSER AND STEPHEN W.F. GRANT  

E-print Network

are the Chondrophorina, characterized by a chitinoid oat (the pneumatophore) consisting of a series of concentrically the relatively rich fossil record to the resistant oat. Fossils attributed to the Chondro- phorina are generally

Lyubomirsky, Ilya

406

Substituting fossil fuels with biomass  

Microsoft Academic Search

Replacing fossil fuels with sustainably-produced biomass reduces net CO2 emissions. We express the efficiency of this substitution in reduced emissions per unit of used land or biomass. The substitution costs are calculated as the cost difference between a continued use of fossil fuels at current prices and a use of biomass. The biomass technologies are assumed to be implemented when

Leif Gustavsson; Per Svenningsson

1996-01-01

407

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.

408

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.

2007-09-21

409

Obesity and African Americans  

MedlinePLUS

... Data > Minority Population Profiles > Black/African American > Obesity Obesity and African Americans African American women have the ... ss6104.pdf [PDF | 3.5MB] HEALTH IMPACT OF OBESITY More than 80 percent of people with type ...

410

Phenotypic Evolution in Fossil Species: Pattern and Process  

NASA Astrophysics Data System (ADS)

Since Darwin, scientists have looked to the fossil record with the hope of using it to document how the phenotypes of species change over substantial periods of time. How best to interpret this record has been controversial, but empirical and methodological advances have resolved at least two issues about pattern: (a) directional transformations are seldom sustained over geological timescales, and (b) net rates of morphological change in fossil species are usually quite slow. Considerable uncertainty remains, however, about the processes responsible for these patterns, but most fruitful explanations use the framework of adaptive landscapes to consider the role of natural selection and other processes. An additional, unresolved issue is the claim that most phenotypic change is associated with speciation. A variety of methods, using data from both fossil and extant species, have supported such a link, at least in some clades and traits, but its prevalence and underlying mechanism remain unresolved.

Hunt, Gene; Rabosky, Daniel L.

2014-05-01

411

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

412

Report on Mammalian Fossils of Chinji Formation, Dhulian, Pakistan  

Microsoft Academic Search

Twenty mammalian fossil specimens of varying preservational state are described from the Chinji Formation of Dhulian, Pakistan. The remains desribed in this study are all teeth and represent the Proboscidea, Perissodactyla and Artiodactyla. All the dental specimens are new variants recorded here for the first time. Pliotriplopus dhulianensis is new to science having small size and absence of crista than

Muhammad Akbar Khan; Abdul Ghaffar; Farooq Zafar; Hameed Bhatti; Muhammad Akhtar

2005-01-01

413

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 III lists the model equations and a one line definition for equations, in a short, readable format.

None

1980-10-01

414

New fossil species of Nymphidae (Neuroptera) from the Eocene of North America and Europe  

Microsoft Academic Search

Two new fossil species of Nymphidae (Neuroptera) are described: Nymphes georgei sp. nov. from the Early Eocene locality at Republic, Washington, U.S.A., and Pronymphes hoffeinsorum sp. nov. from Late Eocene Baltic amber. The assignment of the new Republic species to Nymphes Leach maintains some doubt. This is the first fossil record of the genus (or one very closely related), today

S. BRUCE ARCHIBALD; VLADIMIR N. MAKARKIN; JÖRG ANSORGE

415

Early Pliocene sediments and fossils from the northern Kenya Rift Valley.  

PubMed

Mammalian fossils, which include the tooth of an early hominid, have been recovered from the newly mapped Ngorora Formation in the Baringo District. Preliminary dating suggests that this formation is aged between 9 and 12 million years, and the new finds thus help to span a ten million year gap in the fossil mammal record in Africa south of the Sahara. PMID:16057593

Bishop, W W; Chapman, G R

1970-06-01

416

Fossil evidence for the early ant evolution Vincent Perrichot & Sbastien Lacau &  

E-print Network

REVIEW Fossil evidence for the early ant evolution Vincent Perrichot & Sébastien Lacau & Didier of the first Formicidae or on the origin of their eusociality. We review the fossil and biogeographical record for their origin and successful evolution. Keywords Formicidae . Evolution . Sociobiology. Palaeobiogeography

Villemant, Claire

417

vol. 163, no. 2 the american naturalist february 2004 Exploring Developmental Modes in a Fossil Arthropod  

E-print Network

to explore postem- bryonic development within the fossil record of arthropod evolution. In contrast to mostvol. 163, no. 2 the american naturalist february 2004 Exploring Developmental Modes in a Fossil-0147/2004/16302-30122$15.00. All rights reserved. Keywords: Arthropoda, Trilobita, growth, segmentation, evolution, development

418

Microbial Fossilization in Mineralizing Environments: Relevance for Mars "EXOPALEONTOLOGY"  

NASA Technical Reports Server (NTRS)

The goals of post-Viking exobiology include the search for a Martian fossil record. How can we optimize future exploration efforts to search for fossils on Mars? The Precambrian fossil record indicates that key factors for the long-term preservation of microbial fossils include: 1) the rapid entombment and/or replacement of organisms and organic matter by fine-grained, stable mineral phases (e.g. silica, phosphate, and to a lesser extent, carbonate), 2) low-permeability host sediments (maintaining a closed chemical system during early diagenesis), and 3) shallow burial (maintaining post-depositional temperatures and pressures within the stability range for complex organic molecules). Modem terrestrial environments where early mineralization commonly occurs in association with microbial organisms include: subaerial thermal springs and shallow hydrothermal systems, sub-lacustrine springs and evaporites of alkaline lakes, and subsoil environments where hardpans (e.g. calcretes, silcretes) and duricrusts form. Studies of microbial fossilization in such environments provide important insights preservation patterns in Precambrian rocks, while also playing a role in the development of strategies for Mars exopaleontology. The refinement of site priorities for Mars exopaleontology is expected to benefit greatly from high resolution imaging and altimetry acquired during upcoming orbital missions, and especially infrared and gamma ray spectral data needed for determining surface composition. In anticipation of future orbital missions, constraints for identifying high priority mineral deposits on Mars are being developed through analog remote sensing studies of key mineralizing environments on Earth.

Farmer, Jack D.; DesMarais, David J.; Morrison, David (Technical Monitor)

1994-01-01

419

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

420

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

E-print Network

Size: 25 Description: Applicable English Cluster: American and African-American Studies. This courseThe College: Arts & Sciences African & African-American Studies Department: African & African-American for the course description. Department: African & African-American Studies Course: AAS 122 Title: History of Jazz

Mahon, Bradford Z.

421

The legacy of fossil fuels.  

PubMed

Currently, over 80% of the energy used by mankind comes from fossil fuels. Harnessing coal, oil and gas, the energy resources contained in the store of our spaceship, Earth, has prompted a dramatic expansion in energy use and a substantial improvement in the quality of life of billions of individuals in some regions of the world. Powering our civilization with fossil fuels has been very convenient, but now we know that it entails severe consequences. We treat fossil fuels as a resource that anyone anywhere can extract and use in any fashion, and Earth's atmosphere, soil and oceans as a dump for their waste products, including more than 30?Gt/y of carbon dioxide. At present, environmental legacy rather than consistence of exploitable reserves, is the most dramatic problem posed by the relentless increase of fossil fuel global demand. Harmful effects on the environment and human health, usually not incorporated into the pricing of fossil fuels, include immediate and short-term impacts related to their discovery, extraction, transportation, distribution, and burning as well as climate change that are spread over time to future generations or over space to the entire planet. In this essay, several aspects of the fossil fuel legacy are discussed, such as alteration of the carbon cycle, carbon dioxide rise and its measurement, greenhouse effect, anthropogenic climate change, air pollution and human health, geoengineering proposals, land and water degradation, economic problems, indirect effects on the society, and the urgent need of regulatory efforts and related actions to promote a gradual transition out of the fossil fuel era. While manufacturing sustainable solar fuels appears to be a longer-time perspective, alternatives energy sources already exist that have the potential to replace fossil fuels as feedstocks for electricity production. PMID:21290608

Armaroli, Nicola; Balzani, Vincenzo

2011-03-01

422

72 FR 2721 - Proposed Standards on Smart Metering Interconnection, Net Metering, Fuels Sources, and Fossil...  

Federal Register 2010, 2011, 2012, 2013

...Standards on Smart Metering Interconnection, Net Metering, Fuels Sources, and Fossil Fuel...Smart Metering''), Interconnection, and Net Metering standards promulgated by section...The record for the Interconnection and Net Metering standards is due to close on...

2007-01-22

423

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

424

Archean molecular fossils and the early rise of eukaryotes.  

PubMed

Molecular fossils of biological lipids are preserved in 2700-million-year-old shales from the Pilbara Craton, Australia. Sequential extraction of adjacent samples shows that these hydrocarbon biomarkers are indigenous and syngenetic to the Archean shales, greatly extending the known geological range of such molecules. The presence of abundant 2alpha-methylhopanes, which are characteristic of cyanobacteria, indicates that oxygenic photosynthesis evolved well before the atmosphere became oxidizing. The presence of steranes, particularly cholestane and its 28- to 30-carbon analogs, provides persuasive evidence for the existence of eukaryotes 500 million to 1 billion years before the extant fossil record indicates that the lineage arose. PMID:10446042

Brocks, J J; Logan, G A; Buick, R; Summons, R E

1999-08-13

425

Ancient biomolecules: their origins, fossilization, and role in revealing the history of life.  

PubMed

The discovery of traces of a blood meal in the abdomen of a 50-million-year-old mosquito reminds us of the insights that the chemistry of fossils can provide. Ancient DNA is the best known fossil molecule. It is less well known that new fossil targets and a growing database of ancient gene sequences are paralleled by discoveries on other classes of organic molecules. New analytical tools, such as the synchrotron, reveal traces of the original composition of arthropod cuticles that are more than 400 my old. Pigments such as melanin are readily fossilized, surviving virtually unaltered for ?200 my. Other biomarkers provide evidence of microbial processes in ancient sediments, and have been used to reveal the presence of demosponges, for example, more than 635 mya, long before their spicules appear in the fossil record. Ancient biomolecules are a powerful complement to fossil remains in revealing the history of life. PMID:24623098

Briggs, Derek E G; Summons, Roger E

2014-05-01

426

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

427

Travels with the Fossil Hunters  

NASA Astrophysics Data System (ADS)

Whether dodging bullets in West Africa, or rabid dogs in Pakistan, surviving yak-butter tea in Tibet, or eating raw fish in China, the life of a globe-trotting fossil hunter is often hazardous and always filled with surprises. Travels with the Fossil Hunters lets readers share the wonder, joys of discovery, and excitement of these intrepid scientists. Packed with more than 100 beautiful, full-color photographs, the volume takes readers on twelve expeditions to remote parts of the world in search of diverse fossil remains, from those of dinosaurs to human ancestors. Each expedition by paleontologists from London's Natural History Museum reveals the problems and challenges of working in extreme conditions, from the deserts of the Sahara and Yemen to the frozen wastes of Antarctica, from the mountains of India to the forests of Latvia. Along the way they also describe the paleontology and geology of the countries they visit and the scientific reasons for their expeditions. With a foreword from Sir David Attenborough and an introduction from Richard Fortey, this fascinating book will appeal to amateur and professional fossil hunters alike and to readers interested in accounts of exotic locales. Peter Whybrow is a research scientist at the Natural History Museum, London. His research interests include Arabian Miocene vertebrates, paleoclimates, paleogeography, and biotic diversity. He is senior editor with A. Hill of Fossil Vertebrates of Arabia (Yale University Press, New Haven, 1999).

Whybrow, Peter J.

2000-04-01

428

A Galactic Fossil  

NASA Astrophysics Data System (ADS)

How old are the oldest stars? Using ESO's VLT, astronomers recently measured the age of a star located in our Galaxy. The star, a real fossil, is found to be 13.2 billion years old, not very far from the 13.7 billion years age of the Universe. The star, HE 1523-0901, was clearly born at the dawn of time. "Surprisingly, it is very hard to pin down the age of a star", the lead author of the paper reporting the results, Anna Frebel, explains. "This requires measuring very precisely the abundance of the radioactive elements thorium or uranium, a feat only the largest telescopes such as ESO's VLT can achieve." ESO PR Photo 23a/07 ESO PR Photo 23a/07 The 'Cosmic Clock' This technique is analogous to the carbon-14 dating method that has been so successful in archaeology over time spans of up to a few tens of thousands of years. In astronomy, however, this technique must obviously be applied to vastly longer timescales. For the method to work well, the right choice of radioactive isotope is critical. Unlike other, stable elements that formed at the same time, the abundance of a radioactive (unstable) isotope decreases all the time. The faster the decay, the less there will be left of the radioactive isotope after a certain time, so the greater will be the abundance difference when compared to a stable isotope, and the more accurate is the resulting age. Yet, for the clock to remain useful, the radioactive element must not decay too fast - there must still be enough left of it to allow an accurate measurement, even after several billion years. "Actual age measurements are restricted to the very rare objects that display huge amounts of the radioactive elements thorium or uranium," says Norbert Christlieb, co-author of the report. ESO PR Photo 23b/07 ESO PR Photo 23b/07 Uranium Line in the Spectrum of an Old Star Large amounts of these elements have been found in the star HE 1523-0901, an old, relatively bright star that was discovered within the Hamburg/ESO survey [1]. The star was then observed with UVES on the Very Large Telescope (VLT) for a total of 7.5 hours. A high quality spectrum was obtained that could never have been achieved without the combination of the large collecting power Kueyen, one of the individual 8.2-m Unit Telescopes of the VLT, and the extremely good sensitivity of UVES in the ultraviolet spectral region, where the lines from the elements are observed. For the first time, the age dating involved both radioactive elements in combination with the three other neutron-capture elements europium, osmium, and iridium. "Until now, it has not been possible to measure more than a single cosmic clock for a star. Now, however, we have managed to make six measurements in this one star", says Frebel. Ever since the star was born, these "clocks" have ticked away over the eons, unaffected by the turbulent history of the Milky Way. They now read 13.2 billion years. The Universe being 13.7 billion years old, this star clearly formed very early in the life of our own Galaxy, which must also formed very soon after the Big Bang. More Information This research is reported in a paper published in the 10 May issue of the Astrophysical Journal ("Discovery of HE 1523-0901, a Strongly r-Process Enhanced Metal-Poor Star with Detected Uranium", by A. Frebel et al.). The team includes Anna Frebel (McDonald Observatory, Texas) and John E. Norris (The Australian National University), Norbert Christlieb (Uppsala University, Sweden, and Hamburg Observatory, Germany), Christopher Thom (University of Chicago, USA, and Swinburne University of Technlogy, Australia), Timothy C. Beers (Michigan State University, USA), Jaehyon Rhee (Center for Space Astrophysics, Yonsei University, Korea, and Caltech, USA).

2007-05-01

429

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

430

Fossils, rocks, and time  

USGS Publications Warehouse

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

Edwards, Lucy E.; Pojeta, John

1999-01-01

431

Replaying evolutionary transitions from the dental fossil record.  

PubMed

The evolutionary relationships of extinct species are ascertained primarily through the analysis of morphological characters. Character inter-dependencies can have a substantial effect on evolutionary interpretations, but the developmental underpinnings of character inter-dependence remain obscure because experiments frequently do not provide detailed resolution of morphological characters. Here we show experimentally and computationally how gradual modification of development differentially affects characters in the mouse dentition. We found that intermediate phenotypes could be produced by gradually adding ectodysplasin A (EDA) protein in culture to tooth explants carrying a null mutation in the tooth-patterning gene Eda. By identifying development-based character inter-dependencies, we show how to predict morphological patterns of teeth among mammalian species. Finally, in vivo inhibition of sonic hedgehog signalling in Eda null teeth enabled us to reproduce characters deep in the rodent ancestry. Taken together, evolutionarily informative transitions can be experimentally reproduced, thereby providing development-based expectations for character-state transitions used in evolutionary studies. PMID:25079326

Harjunmaa, Enni; Seidel, Kerstin; Häkkinen, Teemu; Renvoisé, Elodie; Corfe, Ian J; Kallonen, Aki; Zhang, Zhao-Qun; Evans, Alistair R; Mikkola, Marja L; Salazar-Ciudad, Isaac; Klein, Ophir D; Jernvall, Jukka

2014-08-01

432

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

433

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 ...

434

OB Associations and the Fossil Record of Star Formation  

Microsoft Academic Search

Introduction, Definition, Nomenclature The Nearest Associations OSCA and CAS-TAU; ORI-OB1 The Ophiuchus-Scorpius-Centaurus Association (OSCA) Ages in OSCA and Progression of Star Formation OSCA and the Model of Sequential Star Formation Stellar Content of OSCA Relation of OSCA to the Interstellar Medium Kinematic Properties of OSCA Double Star Properties and Run-Away Star In OSCA The Cassiopeia-Taurus Association (CAS-TAU) The Association ORI-OB1

Adriaan Blaauw

1991-01-01

435

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

436

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

437

The Future of the Fossil Record David Jablonski  

E-print Network

de- velopmental biology, paleontology is beginning to take a renewed approach to a wide array of new and old scientific issues. A battery of new ways to generate and test hypotheses by using the ever scales? The overall trend of plant and animal biodiversity--whether measured in terms of taxa, range

Boyce, C. Kevin

438

Theoretical evolutionary rates in plant groups and the fossil record  

Microsoft Academic Search

An attempt is made to estimate a mathematical expression for the underlying mean rate of evolution in organic systems, and\\u000a in particular those of various plant groupings. This was done by considering the thermodynamic constraints on any system tending\\u000a towards greater levels of complexity with time (or showing a progressive decrease in randomness). Orderliness is here equated\\u000a with genetic-information, and

Karl J. Niklas

1977-01-01

439

Atmospheric carbon dioxide, past climates and the plant fossil record  

Microsoft Academic Search

Isotopic evidence and geochemical modelling indicate that the course of evolution of terrestrial vegetation has been marked by continuously changing climate and atmospheric concentrations of CO2 and O2. Consequently, there is a need to understand their impact on plant function. Data from CO2 enrichment experiments and vegetation models indicate the need to consider CO2 effects when interpreting plant-climate interactions from

D. J. Beerling

1999-01-01

440

The Cosmic Evolution of Metallicity from the SDSS Fossil Record  

E-print Network

We present the time evolution of the stellar metallicity for SDSS galaxies, a sample that spans five orders of magnitude in stellar mass (10^7 - 10^{12} Msun). Assuming the BC03 stellar population models, we find that more massive galaxies are more metal-rich than less massive ones at all redshifts; the mass-metallicity relation is imprinted in galaxies from the epoch of formation. For galaxies with present stellar masses > 10^{10} Msun, the time evolution of stellar metallicity is very weak, with at most 0.2-0.3 dex over a Hubble time- for this reason the mass-metallicity relation evolves little with redshift. However, for galaxies with present stellar masses evolution is significant, with metallicity increasing by more than a decade from redshift 3 to the present. By being able to recover the metallicity history, we have managed to identify the origin of a recent discrepancy between the metallicity recovered from nebular lines and absorption lines. As expected, we show that the young ...

Panter, Benjamin; Heavens, Alan F; Charlot, Stephane

2008-01-01