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1

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

PubMed Central

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

Bibi, Faysal

2011-01-01

2

The Primate Fossil Record  

NASA Astrophysics Data System (ADS)

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 many intellectual debates surrounding the fossil record and provides a foundation of reference information on the last two decades of astounding discoveries and worldwide field research for physical anthropologists, paleontologists, and evolutionary biologists.

Hartwig, Walter Carl

2002-05-01

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

The Fossil Record  

NSDL National Science Digital Library

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

Wu, Lisa

5

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

6

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

7

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

8

Evolution and the Fossil Record  

NSDL National Science Digital Library

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

Pojeta Jr., John; Springer, Dale

9

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

10

International Organisation of Palaeobotany: Plant Fossil Record  

NSDL National Science Digital Library

Users are able to search an extensive database of information on the plant fossil record, including descriptions and occurrences of modern genera and fossil species. Searches can be performed in a variety of ways: by Genera, description, taxonomy, occurrences, and by palaeogeographic maps. After locating the specific plant of interest in the database, the occurrences of that plant are then displayed in a palaeogeographic map.

11

Insect Diversity in the Fossil Record  

Microsoft Academic Search

Insects possess a surprisingly extensive fossil record. Compilation of the geochronologic ranges of insect families demonstrates that their diversity exceeds that of preserved vertebrate tetrapods through 91 percent of their evolutionary history. The great diversity of insects was achieved not by high origination rates but rather by low extinction rates comparable to the low rates of slowly evolving marine invertebrate

Conrad C. Labandeira; J. John Sepkoski Jr.

1993-01-01

12

The fossil pollen record of Araceae  

Microsoft Academic Search

The fossil record of Araceae pollen beginning in the late Early Cretaceous and peaking in the Paleocene\\/Eocene is very sparse\\u000a up to now, consisting of three highly distinctive types: zona-aperturate pollen of the Monstera or Gonatopus type (very similar to Proxapertites operculatus), an ulcerate-spiny type typical for Limnobiophyllum, and a polyplicate, omniaperturate pollen type (an ephedroid pollen with non-gnetalean affinities)

M. Hesse; R. Zetter

2007-01-01

13

Neoproterozoic glaciations and the fossil record  

NASA Astrophysics Data System (ADS)

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

Xiao, Shuhai

14

Growth, function, and the conodont fossil record  

NASA Astrophysics Data System (ADS)

Interpretation of the fossil record of conodonts hinges on whether conodont elements were retained through the life of the animal or were periodically shed and replaced. Many quantitative analyses of conodont paleoecology and statistical techniques in conodont taxonomy, for example, rely on an assumed correspondence between numbers of elements and numbers of animals, but the possibility that conodonts shed their elements may undermine this assumption. As with many aspects of conodont paleobiology, hypotheses of shedding versus retention of elements have been difficult to test. Here, we describe recurrent patterns of damage resulting from element function in vivo which indicate that internal discontinuities within an element represent periods of use followed by further growth. The cyclical alternation of phases of growth and function provides compelling evidence that elements were retained through the life of the animal.

Donoghue, Philip C. J.; Purnell, Mark A.

1999-03-01

15

Rates of speciation in the fossil record.  

PubMed Central

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

Sepkoski, J J

1998-01-01

16

First Fossil Lamprey: A Record from the Pennsylvanian of Illinois  

Microsoft Academic Search

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

David Bardack; Rainer Zangerl

1968-01-01

17

MOLECULAR CLOCK DIVERGENCE ESTIMATES AND THE FOSSIL RECORD OF CETARTIODACTYLA  

Microsoft Academic Search

Molecular clock estimates of divergence times for artiodactyls and whales vary widely in their agreement with the fossil record. Recent estimates indicate that the divergence of whales from artiodactyls occurred 60 Ma, a date which compares well with the first appearances of fossil whales around 53.5 Ma, and artiodactyls at 55 Ma. Other estimates imply significant gaps in the fossil

JESSICA M. THEODOR

2004-01-01

18

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

PubMed

Traditionally, Middle Pleistocene hominin fossils that cannot be allocated to Homo erectus sensu lato or modern H. sapiens have been assigned to different specific taxa. For example, in eastern Asia, these hominin fossils have been classified as archaic, early, or premodern H. sapiens. An increasing number of Middle Pleistocene hominin fossils are currently being assigned to H. heidelbergensis. This is particularly the case for the African and European Middle Pleistocene hominin fossil record. There have been suggestions that perhaps the eastern Asian late Middle Pleistocene hominins can also be allocated to the H. heidelbergensis hypodigm. In this article, I review the current state of the late Middle Pleistocene hominin fossil record from eastern Asia and examine the various arguments for assigning these hominins to the different specific taxa. The two primary conclusions drawn from this review are as follows: 1) little evidence currently exists in the eastern Asian Middle Pleistocene hominin fossil record to support their assignment to H. heidelbergensis; and 2) rather than add to the growing list of hominin fossil taxa by using taxonomic names like H. daliensis for northeast Asian fossils and H. mabaensis for Southeast Asian fossils, it is better to err on the side of caution and continue to use the term archaic H. sapiens to represent all of these hominin fossils. What should be evident from this review is the need for an increase in the quality and quantity of the eastern Asian hominin fossil data set. Fortunately, with the increasing number of large-scale multidisciplinary paleoanthropological field and laboratory research projects in eastern Asia, the record is quickly becoming better understood. PMID:21086528

Bae, Christopher J

2010-01-01

19

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

20

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

21

Aestivation in the Fossil Record: Evidence from Ichnology  

Microsoft Academic Search

\\u000a Aestivation is a physiological and behavioral response to high temperature or low moisture conditions. Therefore, it is typically\\u000a not considered to be capable of being preserved in the fossil record. However, most aestivating organisms produce a burrow\\u000a to protect themselves from the harmful environmental conditions that trigger aestivation. These structures can be preserved\\u000a in the rock record as trace fossils.

Daniel I. Hembree

22

Connecting the Distant Universe with the Local Fossil Record  

Microsoft Academic Search

A successful theory of galaxy formation must explain properties of galaxies at low redshift as well as observed evolution of distant galaxies. Study of the fossil record of local stellar populations is complementary to high redshift studies. Main sequence photometry with current and planned facilities can test whether the oldest stars in all galaxies are the same age. The age

R. M. Rich

1999-01-01

23

Delayed biological recovery from extinctions throughout the fossil record  

Microsoft Academic Search

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

James W. Kirchner; Anne Weil

2000-01-01

24

The cambrian fossil record and the origin of the phyla.  

PubMed

Whilst the "Cambrian Explosion" continues to attract much attention from a wide range of earth and life scientists, the detailed patterns exhibited by the terminal Proterozoic-Early Cambrian biotas remain unclear, for reasons of systematics, biostratigraphy and biogeography. In particular, recent changes in absolute dating of the Cambrian have refined the period of time that the fossil record might be of most help in revealing the dynamics of the undoubted radiation taking place at this time. The famous exceptionally preserved faunas seem to be rather close temporally, and as yet reveal little about the earliest and critical period of evolution, deep in the Cambrian. Nevertheless, the most parsimonious interpretation of the Cambrian fossil record is that it represents a broadly accurate temporal picture of the origins of the bilaterian phyla. PMID:21680420

Budd, Graham E

2003-02-01

25

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

26

The Fossil Record of Vent and Seep Mollusks  

Microsoft Academic Search

\\u000a Mollusks have by far the most extensive and best-investigated fossil record of all organism groups inhabiting hydrothermal\\u000a vents and hydrocarbon seeps. More than 250 bivalve, gastropod, and polyplacophoran species have been reported from ancient\\u000a vents and seeps, nearly 200 of them from the Cenozoic alone. Members of at least five bivalve families live in symbiosis with\\u000a sulfur- or methane-oxidizing bacteria,

Steffen Kiel

27

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

28

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

NASA Astrophysics Data System (ADS)

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

Kidwell, Susan M.; Flessa, Karl W.

29

Self-similarity of extinction statistics in the fossil record  

NASA Astrophysics Data System (ADS)

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 appropriate theoretical framework. A consequence of this controversial conjecture is that the fluctuations should be self-similar, exhibiting scaling behaviour like that seen in other biological and socioeconomic, systems. The self-similar character is described by a 1/f power spectrum P(f), which measures the contributions of each frequency f to the overall time series. If self-similarity is present, then P(f) ~ f - ? with 0 < ? <2. This idea has not been sufficiently tested, however, owing to a lack of adequate data. Here we explore the statistical fluctuation structure of several time series obtained from available palaeontological data bases, particularly the new `Fossil Record 2'. We find that these data indeed show self-similar fluctuations characterized by a 1/f spectrum. These findings support the idea that a nonlinear response of the biosphere to perturbations provides the main mechanism for the distribution of extinction events.

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

1997-08-01

30

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

Microsoft Academic Search

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

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

2006-01-01

31

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

Microsoft Academic Search

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

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

2006-01-01

32

Cyclicity in the fossil record mirrors rock outcrop area  

PubMed Central

In a recent article, Rohde & Muller (Rohde & Muller 2005 Nature 434, 208–210) identified a strong 62?Myr cyclicity in the history of marine diversity through the Phanerozoic. The data they presented were highly convincing, yet they were unable to explain what process might have generated this pattern. A significant correlation between observed genus-level diversity (after removal of long-term trends) and the amount of marine sedimentary rock measured at a surface outcrop in Western Europe is demonstrated. This suggests that cyclicity originates from long-term changes in sedimentary depositional and erosional regimes, and raises the strong possibility that the cyclicity apparent in the record of marine fossils is not a biological signal but a sampling signal.

Smith, Andrew B; McGowan, Alistair J

2005-01-01

33

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

34

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

35

Fossil Chironomidae (Insecta: Diptera) as Paleothermometers in the African Tropics  

Microsoft Academic Search

Reconstruction of Africa's temperature history from natural climate archives such as lake sediments is essential to amend the current scarcity of information on natural tropical climate and ecosystem variability. Chironomids are well-established paleothermometers in north-temperate\\/boreal regions, but their potential in tropical lakes has never before been assessed. We surveyed sub-fossil chironomid assemblages in surface sediments from 65 lakes and permanent

H. Eggermont; O. Heiri; J. Russell; M. Vuille; L. Audenaert; G. Klaassen; D. Verschuren

2008-01-01

36

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

Microsoft Academic Search

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

Jonathan L. Payne

2003-01-01

37

Mass Extinctions Among Tetrapods and the Quality of the Fossil Record  

Microsoft Academic Search

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

M. J. Benton

1989-01-01

38

Cretaceous records of atmospheric CO2 from fossil conifers  

Microsoft Academic Search

Experimental studies indicate the stomatal characteristics of conifer shoots, like angiosperm leaves, are sensitive to changes in the global atmospheric CO2 concentration. Consequently, fossil conifers may serve as valuable archives of pre-Quaternary paleo-CO2 information, complementing that of other proxies and geochemical models of the long-term carbon cycle. Our study investigated this possibility by focussing on the fossil genus Frenelopsis, which

L. Llorens; B. Gomez; V. Daviero-Gomez; D. Beerling

2004-01-01

39

Using the fossil record to date splits in the primate tree  

Microsoft Academic Search

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

Simon Tavare; Richard Wilkinson

40

Evolutionary Transitions in the Fossil Record of Terrestrial Hoofed Mammals  

Microsoft Academic Search

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

Donald R. Prothero

2009-01-01

41

Phenotypic Evolution in the Fossil Record: Numerical Experiments  

Microsoft Academic Search

ABSTRACT 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, substrate properties, and sedimentation rate from a high-resolution sedimentary basin fill model.

Bjarte Hannisdal

2006-01-01

42

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!!

61

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

62

Early Cambrian metazoan fossil record of South China: Generic diversity and radiation patterns  

Microsoft Academic Search

South China with its rich fossil record is an important region for studying Early Cambrian metazoan diversity patterns. Compilation of a database of metazoan genera from the traditional Lower Cambrian (Cambrian Series 1–2) of South China allows a quantitative analysis of biodiversity changes. The dataset shows that about 876 genus names have been reported from the Lower Cambrian of South

Guoxiang Li; Michael Steiner; Xuejian Zhu; Aihua Yang; Haifeng Wang; Bernd D. Erdtmann

2007-01-01

63

BETWEEN DEATH AND DATA: BIASES IN INTERPRETATION OF THE FOSSIL RECORD OF CONODONTS  

Microsoft Academic Search

The fossil record of conodonts may be among the best of any group of organisms, but it is biased nonethe- less. Pre- and syndepositional biases, including predation and scavenging of carcasses, current activity, reworking and bioturbation, cause loss, redistribution and breakage of ele- ments. These biases may be exacerbated by the way in which rocks are collected and treated in

A. P URNELL; PHILIP C. J. D ONOGHUE

64

A neglected lineage of North American turtles fills a major gap in the fossil record  

Microsoft Academic Search

The fossil record of the two primary subclades of softshell turtles (Trionychidae) is exceedingly asymmetric, as a result of a ghost range of total clade Cyclanorbinae that is estimated at 80 Ma. Herein, we present the first phylogenetic analysis of Trionychidae that includes a representative of the poorly studied taxon Plastomenidae, which is known from the Campanian to Eocene of

WALTER G. JOYCE; TYLER R. LYSON

2010-01-01

65

Early Life on Earth: the Ancient Fossil Record  

NASA Astrophysics Data System (ADS)

The evidence for early life and its initial evolution on Earth is lin= ked intimately with the geological evolution of the early Earth. The environment of the early Earth would be considered extreme by modern standards: hot (50-80=B0C), volcanically and hydrothermally active, a= noxic, high UV flux, and a high flux of extraterrestrial impacts. Habitats = for life were more limited until continent-building processes resulted in= the formation of stable cratons with wide, shallow, continental platforms= in the Mid-Late Archaean. Unfortunately there are no records of the first appearance of life and the earliest isotopic indications of the exist= ence of organisms fractionating carbon in ~3.8 Ga rocks from the Isua greenst= one belt in Greenland are tenuous. Well-preserved microfossils and micro= bial mats (in the form of tabular and domical stromatolites) occur in 3.5-= 3.3 Ga, Early Archaean, sedimentary formations from the Barberton (South Afri= ca) and Pilbara (Australia) greenstone belts. They document life forms that = show a relatively advanced level of evolution. Microfossil morphology inclu= des filamentous, coccoid, rod and vibroid shapes. Colonial microorganism= s formed biofilms and microbial mats at the surfaces of volcaniclastic = and chemical sediments, some of which created (small) macroscopic microbi= alites such as stromatolites. Anoxygenic photosynthesis may already have developed. Carbon, nitrogen and sulphur isotopes ratios are in the r= ange of those for organisms with anaerobic metabolisms, such as methanogenesi= s, sulphate reduction and photosynthesis. Life was apparently distribute= d widely in shallow-water to littoral environments, including exposed, evaporitic basins and regions of hydrothermal activity. Biomass in t= he early Archaean was restricted owing to the limited amount of energy t= hat could be produced by anaerobic metabolisms. Microfossils resembling o= xygenic photosynthesisers, such as cyanobacteria, probably first occurred in = the later part of the Mid Archaean (~2.9 Ga), concurrent with the tectoni= c development of suitable shallow shelf environments.The development of= an oxygenic metabolism allowed a considerable increase in biomass and in= creased interaction with the geological environment.

Westall, F.

2004-07-01

66

Four well-constrained calibration points from the vertebrate fossil record for molecular clock estimates.  

PubMed

Recent controversy about the use of the vertebrate fossil record for external calibration of molecular clocks centers on two issues, the number of dates used for calibration and the reliability of the fossil calibration date. Viewing matters from a palaeontological perspective, we propose three qualitative, phylogenetic criteria that can be used within a comparative framework for the selection of well-constrained calibration dates from the vertebrate fossil record. On the basis of these criteria, we identify three highly suitable new fossil calibration dates for molecular clock estimates: the lungfish-tetrapod split (between 419 and 408 Ma), the bird-crocodile split (between 251 and 243 Ma), and the alligator-caiman split (between 71 and 66 Ma). Together with our previously suggested bird-lizard split (between 252 and 257 Ma), these four fossil dates span a range of very different ages. They are, in our opinion, more suitable for molecular clock calibration than the traditionally used mammal-bird split, which is less well constrained. We plea for closer interactions between paleontologists and molecular biologists in studying the timescale of vertebrate evolution. PMID:16163732

Müller, Johannes; Reisz, Robert R

2005-10-01

67

The status of the african fossil suids Kolpochoerus limnetes ( Hopwood, 1926), K. Phacochoeroides ( Thomas 1884) and “K.” Afarensis ( Cooke, 1978)  

Microsoft Academic Search

Kolpochoerus limnetes is the name widely used for an abundant suid in East African Plio-Pleistocene deposits. A recent publication (Pickford 1994) suggests that the holotype of “Sus limnetes” from Kaiso could be a Nyanzachoere and proposes that this specific name should be restricted to the Type specimen and also that the other East Africa fossils be given the prior name

H. B. S. Cooke

1997-01-01

68

Glutoxylon Chowdhury (Anacardiaceae): the first record of fossil wood from Bangladesh.  

PubMed

This paper documents the first record of silicified fossil wood from a previously undescribed wood-rich horizon in the Sitakund Anticline, Eastern Bangladesh. The outcrop is composed of cross-stratified, fine-medium grained sandstones with bidirectional cross stratification indicative of a tidal environment, deposited ca. 5-5.2 million years before present (Miocene/Pliocene). The wood is characterised by large solitary vessels with alternate intervascular pits, banded parenchyma, uniseriate rays, and multiseriate rays with one radial canal per ray. This character combination closely resembles the wood of extant Gluta L. of the Anacardiaceae. This specimen has been assigned to the organ genus Glutoxylon Chowdhury erected for fossil woods with anatomical similarity to Gluta (including Melanorrhoea Wall.). The excellent preservation of this mature wood specimen illustrates the potential for using fossil wood from the Sitakund locality for palaeoecological studies in terms of biodiversity and adaptational response to climate change. Moreover such investigations of fossil woods from Bangladesh will compliment studies undertaken on fossil plants in other parts of Central and Southeastern Asia which will further the understanding of plant migration routes between India and Southeast Asia during the Tertiary. PMID:11179716

Poole, I; Davies, C

2001-04-01

69

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

2011-10-12

70

Late Quaternary western Mediterranean pollen records and African winds  

NASA Astrophysics Data System (ADS)

Late Quaternary vegetation changes of regional and global significance in the Mediterranean region are generally interpreted as being controlled by changes in the circulation patterns of North Atlantic air masses. However, the possibility cannot be excluded that they may also be related to winds blowing from Africa. Long pollen records from southwest Europe show that Cedrus pollen of northwest African provenance is found during the glacial periods, and occasionally during abrupt deforestation events in the forest-dominated periods of the interglacials. A pollen concentration record from central Italy shows that during the Holocene the presence of Cedrus pollen coincides with two abrupt deforestation events, around 8.1 and 4.2 cal kyr BP. These observations raise the question of a possible influence of eolian activity on arboreal vegetation during phases of climatic stress towards aridity, and suggest the use of modern pollen monitoring as a strategy for revealing tendencies towards aridification in southwestern Europe.

Magri, D.; Parra, I.

2002-06-01

71

RECORDS OF THE AFRICAN CRAKE CREX EGREGIA IN WESTERN SOUTHERN AFRICA  

Microsoft Academic Search

Avery, G., Brooke, R. & Komen, J. 1988. Records of the African Crake Crex egregia in western southern Africa. Ostrich 59: 25–29.New records for the African Crake Crex egregia in the Skeleton Coast Park, Namibia, and on the west coast of South Africa are presented and all records west of 25 E are reviewed. The western distributional boundary in the

G. Avery; R. K. Brooke; J. Komen

1988-01-01

72

Optimizing the Search for a Fossil Record of Ancient Martian Life  

NASA Astrophysics Data System (ADS)

An important focus of the decade-long Mars Surveyor Program is the search for evidence of past or present life and or prebiotic chemistry. Based on studies of terrestrial analogs, the highest-priority sites for a martian fossil record include such lithologies as fine-grained, clay-rich detrital sediments, water-lain pyroclastics and evaporite deposits of terminal paleolake basins, the deposits of mineralizing springs (including hydrothermal), and mineralized zones (hard-pans) within ancient soils. The systematic exploration for a martian fossil record critically depends on locating accessible surface outcrops of these and other aqueously deposited sediments. The following discussion identifies the steps needed to optimize a plan for implementing the present strategy for Mars exopaleontology.

Farmer, J. D.

1998-01-01

73

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

Microsoft Academic Search

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

VERNER MICHELSEN

1996-01-01

74

Testing the quality of the fossil record: Paleontological knowledge is improving  

NASA Astrophysics Data System (ADS)

The value of the fossil record in giving a clear account of evolutionary history has been questioned because of its incompleteness. New evidence suggests, however, that this is not an overwhelming problem: a good match exists between sequences of lineage divergence as indicated by phylogenetic analysis (cladistic hypotheses of relation) and the order of appearance of groups in geologic time for 41 of 74 test-case cladograms of vertebrates. The relative completeness (ratio of known record to gap) of these test cases is highly variable, but there has been a clear improvement in paleontological knowledge (i.e., filling of the cladistically predicted gaps) over the past 25 years.

Benton, M. J.; Storrs, G. Wm.

1994-02-01

75

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

76

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

PubMed Central

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

Sanchez-Villagra, Marcelo R.

2010-01-01

77

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

PubMed Central

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

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

2009-01-01

78

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

NASA Astrophysics Data System (ADS)

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

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

2009-06-01

79

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

80

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

PubMed

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

Friedman, Matt; Brazeau, Martin D

2010-08-25

81

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

PubMed Central

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

Friedman, Matt; Brazeau, Martin D.

2011-01-01

82

What can we learn about ecology and evolution from the fossil record?  

PubMed

The increased application of abundance data embedded within a more detailed and precise environmental context is enabling paleontologists to explore more rigorously the dynamics and underlying processes of ecological and evolutionary change in deep time. Several recent findings are of special theoretical interest. Community membership is commonly more stable and persistent than expected by chance, even in the face of the extreme environmental changes of the Ice Ages, and major evolutionary novelties commonly lie dormant for tens of millions of years before the ecological explosions of the clades that possess them. As we discuss here, questions such as these cannot be adequately addressed without the use of the fossil record. PMID:16769432

Jackson, Jeremy B C; Erwin, Douglas H

2006-04-19

83

Filamentous fabrics in low-temperature mineral assemblages: are they fossil biomarkers? Implications for the search for a subsurface fossil record on the early Earth and Mars  

Microsoft Academic Search

The subsurface has been recognized as a possible habitat for microbial life on Mars. An analogous fossil record of subsurface life is nearly missing on Earth. Here we present evidence ofthe widespread occurrence of such a record: tubular filamentous structures with typical core diameters of 1–2?m were found as inclusions in minerals deposited from low-T (140 localities worldwide. Filaments are

B. A Hofmann; J. D Farmer

2000-01-01

84

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.

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

2011-01-01

85

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

PubMed Central

We have developed a model based on the analyses of modern and Pleistocene eggshells and mammalian bones which can be used to understand the preservation of amino acids and other important biomolecules such as DNA in fossil specimens. The model is based on the following series of diagenetic reactions and processes involving amino acids: the hydrolysis of proteins and the subsequent loss of hydrolysis products from the fossil matrix with increasing geologic age; the racemization of amino acids which produces totally racemized amino acids in 10(5)-10(6) years in most environments on the Earth; the introduction of contaminants into the fossil that lowers the enantiomeric (D:L) ratios produced via racemization; and the condensation reactions between amino acids, as well as other compounds with primary amino groups, and sugars which yield humic acid-like polymers. This model was used to evaluate whether useful amino acid and DNA sequence information is preserved in a variety of human, amber-entombed insect and dinosaur specimens. Most skeletal remains of evolutionary interest with respect to the origin of modern humans are unlikely to preserve useful biomolecular information although those from high latitude sites may be an exception. Amber-entombed insects contain well-preserved unracemized amino acids, apparently because of the anhydrous nature of the amber matrix, and thus may contain DNA fragments which have retained meaningful genetic information. Dinosaur specimens contain mainly exogenous amino acids, although traces of endogenous amino acids may be present in some cases. Future ancient biomolecule research which takes advantage of new methologies involving, for example, humic acid cleaving reagents and microchip-based DNA-protein detection and sequencing, along with investigations of very slow biomolecule diagenetic reactions such as the racemization of isoleucine at the beta-carbon, will lead to further enhancements of our understanding of biomolecule preservation in the fossil record.

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

1999-01-01

86

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

PubMed

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

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

2008-01-22

87

High Resolution Paleoclimate Records From Fossil Corals Recovered From Drowned Reefs Around Hawaii  

NASA Astrophysics Data System (ADS)

Marine Isotope Stage (MIS) 11 (423-362 ka) was the longest sustained warm interval during the past 500 ky and has been implicated in the ¡turn on¡" of major reef provinces around the world (ie. Great Barrier Reef). Reconstructions of the oxygen isotopic composition of seawater (ƒO18Osw) and apparent ice volume indicate that peak sea-level conditions may have lasted until as late as 370 ka (Shackleton, 2000, Lea et al., 2000). Despite these advances little is known about short term climate variability during this unique interglacial episode. The submerged fossil coral reef terraces around Hawaii represent a unique and untapped archive of past mean background climate, in addition to seasonal and interannual climate variability in the North Pacific Subtropical Gyre (NPG) over the past 500 ky. These terraces initiated during the highstands and continued growing through periods of eustatic ice sheet growth, as island subsidence (2-3 m/ky) and falling sea levels kept similar pace, and stable shoreline conditions prevailed. Coral reef growth terminated during the major deglaciations as rapid sea-level rise and subsidence combined to submerge the reefs below the photic zone. In 2001, several massive fossil Porites corals were collected using the ROV Tiburon during the Monterey Bay Aquarium Research Institute¡¦s (MBARI) expedition to Hawaii. Sampling for the current project focused on two deep marine plunge pools on the East side of Kohala Volcano, Hawaii. Fossil samples were selected for isotopic analysis based on general appearance and the presence of annual growth bands in x-ray photographs. Each sample passed preliminary x-ray diffraction scans, showing that diagenetic alteration to calcite in the skeleton is <2%. Corals were micro-sampled along major growth axes, and analyzed to quantify their oxygen and carbon isotopic composition. One set of samples, from Plunge Pool 1,were dated at 377 ka using U/Th ratios, and another set from nearby Pool 2 is of unknown age, but likely also grew during MIS 11. Though ƒO18O in Porites corals is affected by sea surface temperature (SST) and ƒO18Osw, ƒO18O of precipitation in Hawaii is relatively high, and seasonal rainfall should not affect ƒO18Osw greatly. Modern samples (P. evermanni and P. lobata) recorded seasonal SST cycles of 2.45oC and 2.03oC, 96% and 80% as large as that reported for a 1o x 1o grid by Levitus (2.54oC). Fossil samples from Plunge Pool 1 recorded a similar seasonal SST range, while those of Pool 2 suggest reduced seasonality (1.3oC) in MIS 11 compared to today. Phasing of the ƒO18O and ƒO13C cycles in the fossil samples is similar to that of the modern samples, indicating similar environmental and biological factors during the two periods. To estimate the average SST during the time the fossil corals grew, residual ƒO18O for each specimen was calculated from the average ƒO18O values by 1) correcting for extension rate effects, 2) subtracting the ƒ'ƒO18Osw between 377 ka and today, and 3) subtracting the average ƒO18O of the modern Porites lobata sample. Pool 1 sample ƒO18O residuals indicate that SST was 3oC cooler, while Pool 2 samples indicate 5oC cooler during MIS 11 compared to today. Further study will include use of Sr/Ca ratios as another SST proxy, and time series analyses of interannual variability in the records.

Rothwell, A. J.; Webster, J. M.; Ravelo, A. C.; Clague, D.; Potts, D.

2004-12-01

88

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

PubMed

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

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

2009-09-04

89

Geologic Time and the Fossil Record (title provided or enhanced by cataloger)  

NSDL National Science Digital Library

This interactive site demonstrates how fossil evidence and the principle of superposition are used to determine the age of rock layers and fossils. It contains several examples of index fossils and how they are used to date events. Geologic changes including continental drift are also related to fossil evidence.

90

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

PubMed

To understand better the link between atmospheric CO2 concentrations and climate over geological time, records of past CO2 are reconstructed from geochemical proxies. Although these records have provided us with a broad picture of CO2 variation throughout the Phanerozoic eon (the past 544 Myr), inconsistencies and gaps remain that still need to be resolved. Here I present a continuous 300-Myr record of stomatal abundance from fossil leaves of four genera of plants that are closely related to the present-day Ginkgo tree. Using the known relationship between leaf stomatal abundance and growing season CO2 concentrations, I reconstruct past atmospheric CO2 concentrations. For the past 300 Myr, only two intervals of low CO2 (<1,000 p.p.m.v.) are inferred, both of which coincide with known ice ages in Neogene (1-8 Myr) and early Permian (275-290 Myr) times. But for most of the Mesozoic era (65-250 Myr), CO2 levels were high (1,000-2,000 p.p.m.v.), with transient excursions to even higher CO2 (>2,000 p.p.m.v.) concentrations. These results are consistent with some reconstructions of past CO2 (refs 1, 2) and palaeotemperature records, but suggest that CO2 reconstructions based on carbon isotope proxies may be compromised by episodic outbursts of isotopically light methane. These results support the role of water vapour, methane and CO2 in greenhouse climate warming over the past 300 Myr. PMID:11357126

Retallack, G J

2001-05-17

91

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

92

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

2008-03-03

93

Selective preservation of organic matter in marine environments - processes and impact on the fossil record  

NASA Astrophysics Data System (ADS)

The present paper is the result of a workshop sponsored by the Research Centre Ocean Margins, the International Graduate College EUROPROX and the Alfred Wegener Institute for Polar Research. The workshop brought together specialists on organic matter degradation and on proxy-based environmental reconstruction. The paper deals with the main theme of the workshop, understanding the impact of selective degradation/preservation of organic matter (OM) in marine sediments on the interpretation of the fossil record. Special attention is paid to (A) the influence of the molecular composition of OM in relation to the biological and physical depositional environment, including new methods for determining complex organic biomolecules, (B) the impact of selective OM preservation on the interpretation of proxies for marine palaeoceanographic and palaeoclimatic reconstruction, and (C) past marine productivity and selective preservation in sediments.

Zonneveld, K. A. F.; Versteegh, G. J. M.; Kasten, S.; Eglinton, T. I.; Emeis, K.-C.; Huguet, C.; Koch, B. P.; de Lange, G. J.; de Leeuw, J. W.; Middelburg, J. J.; Mollenhauer, G.; Prahl, F. G.; Rethemeyer, J.; Wakeham, S. G.

2009-07-01

94

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

95

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

96

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

2005-06-27

97

IODP - ICDP Interactions: Comparing and contrasting the drilled paleoclimate records on the African continent with the ODP records offshore  

NASA Astrophysics Data System (ADS)

The Saharan dust records obtained from ocean drill sites off northwest and northeast Africa stood for years as the icons of African climate. They nicely illustrated a progression in aridification and in the dominant orbital forcing of aridity at precessional frequency prior to 2.8 Ma, then to obliquity forcing from 2.8 to 1.0 Ma, and finally to the eccentricity forcing of the past million years. African climate, in essence, was thought to be responding primarily to the ice sheet dynamics of the Northern Hemisphere. ICDP-sponsored drilling programs on Lake Malawi, East Africa and Lake Bosumtwi, West Africa, have revealed startling new insights into the history of tropical Africa, at least for the past few hundred thousand years. While the conditions of the last glacial maximum were relatively cool and dry, the aridity of the LGM paled in comparison to the megadroughts that occurred in the African tropics prior to 60,000 years ago, with strong precessional (not eccentrical) frequency. Paleotemperature records from East African lakes are a relatively new addition to our knowledge of past African climate, and they are providing surprising, new results as well. They indicate, for example, much cooler temperatures in marine isotope stage IV than during the LGM. High-resolution records derived from XRF scans of the Malawi core indicate strong evidence for D-O - scale variability in the climate of this region, at least in terms of wind and aridity, indicating a tropical role in the "bi-polar see-saw." Promising new records of climate change on the African continent have been coming out of marine sediment cores from the major river deltas of Africa - the Congo, the Nile, in the Gulf of Guinea, and the Zambezi. The results of these studies can nicely complement the lacustrine records, for example by reflecting regions on the African continent where lake sequences are not available. Future drilling by IODP into these marginal settings around the African continent will provide insightful contrasts with the records to be derived from new drilling in the lakes and selected outcrops on the African continent.

Johnson, T.

2009-04-01

98

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

Microsoft Academic Search

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

R. Cloutier

2010-01-01

99

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

2007-09-12

100

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

101

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

102

The spatial and temporal distribution of fossil-fuel dervied pollutants in the sediment record of Lake Baikal, east Siberia  

Microsoft Academic Search

Spatial and temporal patterns of spheroidal carbonaceous particles (SCP) extracted from lake sediments provide an unambiguous record of the distributions of fossil-fuel derived pollutants. When applied to sediment cores taken from Lake Baikal spatial patterns show good agreement with the distribution of industry, with the highest concentrations found in the southern basin nearest to Irkutsk. SCP were found to occur

N. L. Rose; P. G. Appleby; J. F. Boyle; A. W. Mackay; R. J. Flower

1998-01-01

103

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

PubMed Central

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

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

2012-01-01

104

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

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

105

Cell symbiosis [correction of symbioisis] theory: status and implications for the fossil record.  

PubMed

Recent geological treatises have presented three alternative models of the origins of eukaryotes as if they merited equal treatment. However, modern biological techniques, especially nucleic acid and protein sequencing, have clearly established the validity of the symbiotic theory of the origin of eukaryotic organelles. The serial endosymbiotic theory in its most extreme form states that three classes of eukaryotic cell organelles (mitochondria, plastids and undulipodia) originated as free-living bacteria (aerobic respirers, phototrophic bacteria and spirochetes respectively) in association with hosts that become the nucleocytoplasm (Thermoplasma-like archaebacterial hosts). Molecular biological information, primarily derived from ribosomal RNA nucleotide sequencing studies leads to the conclusion that the symbiotic origin theory for both mitochondria and plastids has been proven. The probability of an ancestral archaebacterial-Thermoplasma-like host for the nucleocytoplasm has been rendered more likely by discoveries by Dennis Searcy and his colleagues and Carl Woese and his colleagues. The most equivocal postulate of the symbiotic theory, the origin of undulipodia (cilia and other organelles of motility that develop from kinetosomes is under investigation now. The status of these postulates, as well as their implications for the fossil record, is briefly summarized here. PMID:11537775

Margulis, L; Stolz, J F

1984-01-01

106

The fossil record of North American mammals: evidence for a Paleocene evolutionary radiation.  

PubMed

Paleontologists long have argued that the most important evolutionary radiation of mammals occurred during the early Cenozoic, if not that all eutherians originated from a single common post-Cretaceous ancestor. Nonetheless, several recent molecular analyses claim to show that because several interordinal splits occurred during the Cretaceous, a major therian radiation was then underway. This claim conflicts with statistical evidence from the well-sampled latest Cretaceous and Cenozoic North American fossil record. Paleofaunal data confirm that there were fewer mammalian species during the latest Cretaceous than during any interval of the Cenozoic, and that a massive diversification took place during the early Paleocene, immediately after a mass extinction. Measurement data show that Cretaceous mammals were on average small and occupied a narrow range of body sizes; after the Cretaceous-Tertiary mass extinction, there was a rapid and permanent shift in the mean. The fact that there was an early Cenozoic mammalian radiation is entirely compatible with the existence of a few Cretaceous splits among modern mammal lineages. PMID:12078635

Alroy, J

1999-03-01

107

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

PubMed

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

Alroy, John

2008-08-11

108

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

NASA Astrophysics Data System (ADS)

Biological and geochemical CO2 proxies provide critical constraints on understanding the role of atmospheric CO2 in driving climate change during Earth history. As no single existing CO2 proxy is without its limitations, there is a clear need for new approaches to reconstructing past CO2 concentrations. Here we develop a new pre-Quaternary CO2 proxy based on the stable carbon isotope composition (?13C) of astomatous land plants. In a series of CO2-controlled laboratory experiments, we show that the carbon isotope discrimination (?13C) of a range of bryophyte (liverwort and moss) species increases with atmospheric CO2 across the range 375 to 6000 ppm. Separate experiments establish that variations in growth temperature, water content and substrate type have minor impacts on the ?13C of liverworts but not mosses, indicating the greater potential of liverworts to faithfully record past variations in CO2. A mechanistic model for calculating past CO2 concentrations from bryophyte ?13C (White et al., 1994) is extended and calibrated using our experimental results. The potential for fossil liverworts to record past CO2 changes is investigated by analyzing the ?13C of specimens collected from Alexander Island, Antarctica dating to the "greenhouse" world of the mid-Cretaceous. Our analysis and isotopic model yield mid-Cretaceous CO2 concentrations of 1000-1400 ppm, in general agreement with independent proxy data and long-term carbon cycle models. The exceptionally long evolutionary history of bryophytes offers the possibility of reconstructing CO2 concentrations back to the mid-Ordovician, pre-dating all currently used quantitative CO2 proxies.

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

2005-09-01

109

Taxonomic structure of the fossil record is shaped by sampling bias.  

PubMed

Understanding biases that affect how species are partitioned into higher taxa is critical for much of paleobiology, as higher taxa are commonly used to estimate species diversity through time. We test the validity of using higher taxa as a proxy for species diversity for the first time by examining one of the best fossil records we have, that of deep-sea microfossils. Using a new, taxonomically standardized, data set of coccolithophorid species and genera recorded from 143 deep-sea drilling sites in the North Atlantic, Caribbean, and Mediterranean, we show that there is a two-stepped change in the ratio of species to genera over the last 150 myr. This change is highly unexpected and correlates strongly with changes in both the number of deep-sea sites yielding coccolithophorids that have been studied and with the number of taxonomists who have published on those sections. The same pattern is present in both structurally complex heterococcoliths and the simpler nannoliths, suggesting that increasing complexity is not the driving factor. As a stepped species-to-genus ratio exists even after subsampling to standardize either the numbers of sites or numbers of papers, both factors must be contributing substantially to the observed pattern. Although some limited biological signature from major extinction events can be recognized from changes in the species-to-genus ratio, the numbers of sites and the numbers of taxonomists combined explain some 82% of the observed variation over long periods of geological time. Such a strong correlation argues against using raw species-to-genus ratios to infer biological processes without taking sampling into account and suggests that higher taxa cannot be taken as unbiased proxies for species diversity. PMID:21828083

Lloyd, Graeme T; Young, Jeremy R; Smith, Andrew B

2011-08-09

110

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

National Technical Information Service (NTIS)

Climate change plays an important role in determining as possible long term hydrological performance of the potential high level nuclear waste repository within Yucca Mountain, Nevada. Preliminary study of late-glacial fossil ostracodes from 'marsh deposi...

R. M. Forester A. J. Smith

1995-01-01

111

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

Microsoft Academic Search

The carbon isotope composition of terrestrial fossil organic matter (delta13Corg) 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 delta13Corg 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.)

I. P. Montanez

2006-01-01

112

Interpretation of the fossil record of Acanthaster planci from the Great Barrier Reef: a reply to criticism  

NASA Astrophysics Data System (ADS)

The nature and interpretation of the fossil record of Acanthaster planci from the GBR is reviewed in the light of comments from Keesing et al. (1992) and Pandolfi (1992). Skeletal remains of A. planci in reef-top sediment of many reefs has been derived from very large numbers of individuals, indicating substantial, long-term mortality at reef-top locations. The fossil record provides useful perspective on mortality patterns in the absence of substantive ecological data. The incidence of skeletal elements on reefs where they are abundant cannot be adequately accounted for by the mortality of non-outbreak populations as estimated by recent surveys. Analysis of all available data reaffirms a relationship between the incidence of skeletal elements in surface sediment and observed outbreak history. There is no presently identified taphonomic mechanism by which the accumulation of A. planci skeletal elements released on death might be systematically biased relative to other skeletal components of reefal sediment. Because of skeletal degradation, physical transport and extensive bioturbation that applies in shallow-water reefal sediment, reconstructive taphonomic analysis of A. planci skeletal remains is not achievable. Core sediment, on which interpretation of the longterm fossil record of A. planci is based, is homogeneous, unstratified, and has experienced substantial time averaging due to pervasive bioturbation. Extensive bulk sediment dating has shown that the cores have retained a general age structure but fine-scale stratigraphic detail, required for the recognition of outbreak events from the fossil record available in reefal sediment is unlikely. As required by the principle of simplicity, the proposition that abundant A. planci skeletal elements found in sediment from Green Island, John Brewer and other reefs of the GBR represent the time-averaged product of outbreaking populations should be adopted as the favoured working hypothesis. Other alternative explantions have been advanced but all require patterns or processes that have yet to be substantiated.

Henderson, R. A.; Walbran, P. D.

1992-07-01

113

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

PubMed

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

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

1995-03-01

114

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

PubMed

A major gap in our knowledge of the evolution of marsupial mammals concerns the Paleogene of the northern continents, a critical time and place to link the early history of metatherians in Asia and North America with the more recent diversification in South America and Australia. We studied new exceptionally well-preserved partial skeletons of the Early Oligocene fossil Herpetotherium from the White River Formation in Wyoming, which allowed us to test the relationships of this taxon and examine its adaptations. Herpetotheriidae, with a fossil record extending from the Cretaceous to the Miocene, has traditionally been allied with opossums (Didelphidae) based on fragmentary material, mainly dentitions. Analysis of the new material reveals that several aspects of the cranial and postcranial anatomy, some of which suggests a terrestrial lifestyle, distinguish Herpetotherium from opossums. We found that Herpetotherium is the sister group to the crown group Marsupialia and is not a stem didelphid. Combination of the new palaeontological data with molecular divergence estimates, suggests the presence of a long undocumented gap in the fossil record of opossums extending some 45Myr from the Early Miocene to the Cretaceous. PMID:17426007

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

2007-06-22

115

Differentiating sibling species in the Quaternary fossil record: a comparison of morphological and molecular methods to identify Microtus arvalis and M. rossiaemeridionalis (Arvicolinae, Rodenia)  

Microsoft Academic Search

The sibling species Microtus arvalis and Microtus rossiaemeridionalis are widely sympatric, North Eurasian species that are difficult to trace back in the fossil record due to the lack of criteria for taxonomic identification. This paper examines the potential of morphometric and molecular methods for differentiating their fossil remains. Discriminant function (DF) analysis of linear measurements of the lower first molar

Evgenia Markova; Zoé Beeren; Thijs van Kolfschoten; Tatyana Strukova; Klaas Vrieling

2012-01-01

116

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

117

Are the most durable shelly taxa also the most common in the marine fossil record?  

Microsoft Academic Search

This paper tests whether the most common fossil brachiopod, gastropod, and bivalve genera also have intrinsically more durable shells. Commonness was quantified using occurrence frequency of the 450 most frequently occurring genera of these groups in the Paleobiology Database (PBDB). Durability was scored for each taxon on the basis of shell size, thickness, reinforcement (ribs, folds, spines), mineralogy, and microstructural

Anna K. Behrensmeyer; Franz T. Fürsich; Robert A. Gastaldo; Susan M. Kidwell; Matthew A. Kosnik; Michal Kowalewski; Roy E. Plotnick; Raymond R. Rogers; John Alroy

2005-01-01

118

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

119

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

120

Fossil Crinoids  

Microsoft Academic Search

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,

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

2003-01-01

121

Fossil Crinoids  

Microsoft Academic Search

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,

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

1999-01-01

122

Uranium-series dating of fossil coral reefs: Extending the sea-level record beyond the last glacial cycle  

NASA Astrophysics Data System (ADS)

Absolutely dated records of past sea-level change are extremely important for understanding the advance and retreat of the large ice sheets. When combined with other complementary climate archives and climate models, such records offer the potential to gain an improved understanding of Earth's natural climate cycles, providing a firmer basis for assessing the role of anthropogenic effects, such as greenhouse gas emissions, in modifying climate. The U-series dating of fossil coral reefs has been widely utilized to provide absolutely dated records of past sea-level change and numerous observations now exist for the past 130,000 years spanning the last glacial cycle. Despite this, controversies still exist regarding the exact timing and character of sea-level events within this time interval, and extending the sea-level history further back in time on the basis of robust and independent age constraints for older fossil reefs remains very elusive. This is primarily due to a progressive loss in the resolution of the U-series chronometer as one goes further back in time, coupled to a lack of well-preserved, dateable coral in older fossil reefs. To overcome these limitations, the primary challenges are three-fold. First, new analytical protocols are required to improve the resolution of the U-series chronometer. Enhanced analytical precision must be coupled to accuracy through continued refinement of the U-series decay constant determinations and via the implementation of rigorous inter-laboratory calibration exercises. Second, efforts should continue to be focussed on gaining an improved understanding of the mechanisms controlling open-system exchange of the U-series isotopes in fossil reef systems. This will allow the number of 'reliable' U-series observations to be extended. Third, alternative dateable archives of past sea-level change must continue to be emphasized to further complement the coral reef database. These limitations are discussed in the context of current developments that further advance the application of U-series chronology to older fossil reef systems formed prior to the last glacial cycle.

Stirling, Claudine H.; Andersen, Morten B.

2009-07-01

123

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

NASA Astrophysics Data System (ADS)

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

Tomašových, Adam; Kidwell, Susan

2010-05-01

124

Scanning the fossil record: stratophenomics and the generation of primary evolutionary-ecological data  

Microsoft Academic Search

The amount and quality of paleontological data is rapidly increasing thanks to the new developments in geological dating,\\u000a 3D visualization and morphometrics, chemical and histological analysis, and database storage. However, despite the fact that\\u000a data from fossils, their assemblages, temporal successions, spatial gradients and environments are of an evolutionary-ecological\\u000a nature, their contribution to current mainstream evolutionary-ecological theory and methodology is

Jan A. van Dam

125

Early Holocene sea-level record from submerged fossil reefs on the southeast Florida margin  

Microsoft Academic Search

Massive fossil (outlier) reefs are preserved seaward of the modern shelf and reef tract along the southeast Florida margin. Thermal ionization mass-spectrometric (TIMS) U-Th dating of 16 pristine Acropora palmata and head corals cored from two transects document early Holocene reef growth from 8.9 to 5.0 ka, from approximately -13.5 to -7 m MSL (mean sea level). These samples fill

Marguerite A. Toscano; Joyce Lundberg

1998-01-01

126

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

127

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.

Belanger, Christina L.

2012-01-01

128

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

PubMed

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

2012-04-27

129

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

NASA Astrophysics Data System (ADS)

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

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

1992-02-01

130

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

131

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

Microsoft Academic Search

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

Gregory J. Retallack

2001-01-01

132

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

2012-06-11

133

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

NASA Astrophysics Data System (ADS)

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 REE in biogenic apatite of Recent fish debris occurs near the sediment-water interface soon after deposition and reflects characteristics of seawater. The original REE signature apparently survives subsequent burial and diagenesis. Cerium variations in fish debris from modern environments are controlled by redox potential. Ce is fractionated by co-precipitation with metallic oxides under oxidizing conditions. This fractionation produces a negative Ce anomaly (Ce anom ) in seawater that is reflected in the sedimented fish debris. Conversely, no fractionation of Ce occurs under reducing conditions, resulting in Ce concentrations that are normal to enriched in anoxic seawater and fish debris deposited under local or basinwide anoxic conditions. Extrapolation of observations of the redox control of Ce anom in modern oceans to fossil apatite indicates that anoxic conditions were prevalent in lower Paleozoic and Lower Triassic oceans, whereas in the upper Paleozoic, the world ocean was generally oxidizing.

Wright, Judith; Schrader, Hans; Holser, William T.

1987-03-01

134

Fossilized index: the linchpin of trustworthy non-alterable electronic records  

Microsoft Academic Search

As critical records are increasingly stored in electronic form, which tends to make for easy destruction and clandestine modification, it is imperative that they be properly managed to preserve their trustworthiness, i.e., their ability to provide irrefutable proof and accurate details of events that have occurred. The need for proper record keeping is further underscored by the recent corporate misconduct

Qingbo Zhu; Windsor W. Hsu

2005-01-01

135

Complex Records of Environmental Character and Change in Neogene African Rift Basins  

NASA Astrophysics Data System (ADS)

The Neogene rift basins of East Africa preserve complex environmental records encompassing the effects of tectonics and climate along with the influences of volcanism, landscape succession and biotic change. Detailed reconstruction of individual basin evolution, along with the integration of parallel basin histories can allow the isolation of controlling factors, particularly when they are represented by distinctive signatures. Major Neogene basins, such as the Turkana and Middle Awash systems, preserve long and detailed records, with critical correlation links based on tephrostratigraphic ties, isotopic age determinations and magnetic polarity stratigraphy. Smaller basinal systems, such as Olduvai, Konso and Olorgesailie often reflect shorter accumulation histories, but may add crucial data for distinguishing the influence of global climate, regional tectonics, and local environmental effects. Miocene sedimentary records provide important baseline data on environmental conditions across the African continent, including major tectonic effects initiating subsidence along with strong local climatic influences. Plio-Pleistocene records are far more complete, and demonstrate both short-term (seasonal) as well as long-term (Milankovitch scale) climatic influences superimposed on regional tectonic controls and episodically overwhelmed by explosive volcanic signals. Depositional and post-depositional features of these sedimentary sequences directly reflect habitat character and change through crucial intervals of development in African terrestrial ecosystems. These continental archives preserve direct evidence of the environmental patterns which influenced crucial steps in hominin evolution, the appearances, adaptation, behavioral innovation and extinctions of the hominin clade.

Feibel, C. S.

2004-12-01

136

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

137

Protoresinacarus brevipedis gen. n., sp. n. from Early Cretaceous Burmese amber: the first fossil record of mites of the Family Resinacaridae (Acari: Heterostigmata: Pyemotoidea)  

Microsoft Academic Search

A new genus and species of mites, Protoresinacarus brevipedis gen. n., sp. n. (Acari: Heterostigmata: Pyemotoidea), is described from Early Cretaceous Burmese amber. This represents the first fossil record of a member of the family Resinacaridae. It is represented by 21 phoretic females adjacent to an adult mantidfly (Neuroptera: Mantispidae). This is the first record of phoresy of pyemotid mites

Alexandr A. Khaustov; George Poinar Jr

2011-01-01

138

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

139

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

140

Stable carbon isotope records of carbonates tracing fossil seep activity off Indonesia  

Microsoft Academic Search

Stable isotope records of carbonates from up to 20 m long sediment cores from the forearc basin of the Sunda arc display significant 13C depletion, deviating from expected normal marine levels by 5 to 40‰ (Peedee belemnite (PDB)). This depletion is interpreted to be caused by methane seepage and associated authigenic carbonate precipitation in sediments near the seafloor. About 2-?m-sized

M. Wiedicke; W. Weiss

2006-01-01

141

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.

142

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

NSDL National Science Digital Library

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

Savarese, Michael

143

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

144

Genetic and Fossil Evidence for the Origin of Modern Humans  

Microsoft Academic Search

The origin of living Homo sapiens has once again been the subject of much debate. Genetic data on present human population relationships and data from the Pleistocene fossil hominid record are used to compare two contrasting models for the origin of modern humans. Both genetics and paleontology support a recent African origin for modern humans rather than a long period

C. B. Stringer; P. Andrews

1988-01-01

145

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

NASA Astrophysics Data System (ADS)

Paleo-earthquakes recorded by pseudotachylytes have recently been discovered in the blueschist facies subduction complex of Alpine Corsica. Pseudotachylytes occur in ophiolite gabbro and mantle peridotite belonging to the Schistes Lustrés of Cape Corse. Ultramafic pseudotachylyte fault- and injection veins are found within well-preserved peridotite lenses and are progressively hydrated together with the host rock along the margins of the lenses. Numerous pseudotachylytes ranging in thickness from less than 1 to 380 mm have been identified. Veins thicker than 3 mm may show flow banded chilled glassy margins and cores with dendritic to spherulitic quench textures. The newly formed minerals are zoned olivine (Fo 93-89), clino- and ortho-pyroxene with compositions indicative of high crystallization temperatures (1300-1400 °C), zoned Cr-spinel, and a glassy to micro-vesicular hydrous matrix showing that frictional melts contained up to 4% water. Frictional heating on co-seismic faults raised the temperature from ambient blueschist facies conditions (450 °C and 1-1.5 GPa) to more than 1700 °C, which is required for ˜75% disequilibrium melting of spinel peridotite at 1.5 GPa. The characteristic fault-vein thicknesses observed are 1 to 3 cm, but several fault-veins are thicker than 10 cm. Co-seismic displacement of 1 m, a stress of 300 MPa, and seismic efficiency of 5%, may melt ca 60 kg peridotite pr. m 2 fault surface corresponding to 20 mm thick layer of ultramafic pseudotachylyte. The ultramafic pseudotachylytes described here formed by disequilibrium melting of peridotite in the upper part of the Alpine subduction zone. If the interpretations of typical displacements of approximately 1 m are correct, the most common pseudotachylyte fault-veins are related to magnitude ca. 7 or larger subduction earthquakes.

Andersen, Torgeir B.; Austrheim, Håkon

2006-02-01

146

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

147

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

148

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

Microsoft Academic Search

Bone apatite acts as a natural, timed sampling device, scavenging trace elements from local pore waters over timescales of ca. 1–50ka. 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,

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

2006-01-01

149

Antiquity and long-term morphological stasis in a group of rove beetles (Coleoptera: Staphylinidae): Description of the oldest Octavius species from Cretaceous Burmese amber and a review of the “Euaesthetine subgroup” fossil record  

Microsoft Academic Search

The Staphylinine group of rove beetle subfamilies is a significant animal radiation, and one subordinate monophyletic clade – the ‘Euaesthetine subgroup’ – includes around 3000 species in subfamilies Euaesthetinae and Steninae and has a fossil record dating to the Early Cretaceous. Detailed morphological study of a new well-preserved Cretaceous Burmese amber fossil revealed strong evidence consistent with its taxonomic placement

Dave J. Clarke; Stylianos Chatzimanolis

2009-01-01

150

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

Microsoft Academic Search

Analysis of late Pleistocene fossils recovered from near the Huntington Beach, California (USA), pier (site LACM 7679) has revealed a diverse fauna dating to approximately 40 14C ka BP. Extinct megafauna (three genera) are present; however, a microfauna including three genera of fish, five genera of amphibians, twelve genera of reptiles, two genera of birds, and ten genera of small mammals

Thomas A. Wake; Mark A. Roeder

2009-01-01

151

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

Microsoft Academic Search

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

Charles R. Marshall

1990-01-01

152

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

PubMed Central

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.

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

2010-01-01

153

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

154

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

2009-11-18

155

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

156

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

157

The Mudfish and the European: An African Record of the Age of Discovery.  

ERIC Educational Resources Information Center

Explores the native artwork of the Benin people and discusses how it can be used to document an African perspective to the "Age of Discovery." Portugal established trade with Benin (a small country on the west coast of Africa) in 1486. Includes illustrations and suggested student activities. (MJP)

Vess, Deborah

1997-01-01

158

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

2012-08-23

159

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

160

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

161

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

NASA Astrophysics Data System (ADS)

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

Wierzchos, Jacek; Ascaso, Carmen

2002-01-01

162

Review of Paleontological Specimens and Related Records from the Vicinity of John Day Fossil Beds National Monument.  

National Technical Information Service (NTIS)

The purpose of the report is to describe those paleontological specimens and records from the John Day valley of eastern Oregon which are located at selected federal repositories and institutions in Washington, D.C. Research was conducted in the spring an...

J. A. Sikoryak

1988-01-01

163

Filling the gaps in the Neogene plant fossil record of eastern North America: New data from the Pliocene of Alabama  

Microsoft Academic Search

Nine angiosperm taxa are described, based on megafossils from the Citronelle Formation of Alabama, that are significant in either clarifying previous identifications, or in providing the first records of their kind in the North American Pliocene. Liquidambar styraciflua is identified from leaves. Stones are attributed to Cornus sp. and Nyssa aquatica. Although Nyssa stones from the Citronelle Formation were originally

Debra Z. Stults; Brian J. Axsmith

2011-01-01

164

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.

165

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

166

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

167

Teacher's Domain: 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

168

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

PubMed

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

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

2002-04-01

169

Age of the earliest african anthropoids.  

PubMed

The earliest fossil record of African anthropoid primates (monkeys and apes) comes from the Jebel Qatrani Formation in the Fayum depression of Egypt. Reevaluation of both geologic and faunal evidence indicates that this formation was deposited in the early part of the Oligocene Epoch, more than 31 million years ago, earlier than previous estimates. The great antiquity of the fossil higher primates from Egypt accords well with their primitive morphology compared with later Old World higher primates. Thus, the anthropoid primates and hystricomorph rodents from Fayum are also considerably older than the earliest higher primates and rodents from South America. PMID:17778006

Fleagle, J G; Bown, T M; Obradovich, J D; Simons, E L

1986-12-01

170

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

171

"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

172

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.

2011-01-01

173

Mesosaurus Fossil Site  

NSDL National Science Digital Library

This article describes the occurrence and habits of Mesosaurus, a small marine reptile that lived during the late Carboniferous and early Permian periods, as seen at a site in Namibia. Topics include the distribution of Mesosaurus fossils in both African and South American rock formations (evidence of continental drift), the shallow sea habitats in which Mesosuarus existed 280 to 320 million years ago, and some of its postulated living habits.

174

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 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

175

Fossil fuels  

Microsoft Academic Search

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

Herman Daly

1994-01-01

176

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

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

177

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

178

East African climate fluctuations over the last 1400 years recorded in southeastern Mediterranean sediments  

NASA Astrophysics Data System (ADS)

The southeastern Mediterranean Sea sedimentary history of the late Holocene was influenced by distinctive changes in Nile River sediment discharge and Saharan dust influx. We present high-resolution XRF element data of a marine sediment core of the southeastern Levantine Sea (GeoTü SL112, 32° 44.52´ N, 34° 39.02´ E, water depth: 892 m) spanning the last 1400 years. We suggest a strong relationship between humidity changes in east Africa and the corresponding sedimentological response in the Levantine Sea. The Fe record of our Levantine Sea sediment record shows a remarkable similarity with the lake level record of Lake Naivasha (Kenya) (Verschuren et al., Nature, 2000) and the pre-colonial drought history of Lake Malawi (east Africa). Several intervals of enhanced Saharan dust flux as indicated by high Fe values in the Levantine Sea core coincide with well-known droughts in equatorial east Africa and Lake Naivasha lowstands. Frequency analysis suggests that solar variability has been a major influence in these climate fluctuations. The Fe record of our core, which we interpret as Saharan dust influx to the southeast Levantine Sea, is dominated by cyclicities of approximately 90 and 200 years, known as the Gleissberg and Suess cycles. The most pronounced periods of decreased dust accumulation in the southeast Levantine Sea occurred at about 1.1 kyr BP, 0.7 kyr BP, 0.55 kyr BP, 0.3 kyr BP and 0.1 kyr BP, coincident with the solar minima of Oort, Wolf, Spoerer, Maunder and Dalton.

Hamann, Y.; Dulski, P.; Ehrmann, W.; Schmiedl, G.; Haug, G.

2008-12-01

179

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

180

Identification of Immunoreactive Material in Mammoth Fossils  

Microsoft Academic Search

The fossil record represents a history of life on this planet. Attempts to obtain molecular information from this record by analysis of nucleic acids found within fossils of extreme age have been unsuccessful or called into question. However, previous studies have demonstrated the long-term persistence of peptides within fossils and have used antibodies to extant proteins to demonstrate antigenic material.

Mary Schweitzer; Christopher L. Hill; John M. Asara; Seth H. Pincus

2002-01-01

181

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.

182

4He in Modern Cape Verde Corals: A High-Resolution Proxy Record of N. African Climate  

NASA Astrophysics Data System (ADS)

Mineral dust from arid and semi arid regions is an important component of climatic processes. The amount of dust emitted off continents is intimately linked with precipitation, which may itself be linked to atmospheric circulation driven by oceanic sea surface temperatures. Hence, reconstructing dust fluxes off continents with sub-decadal resolution can provide us with fundamental insights into feedbacks in the climate system. Unfortunately, such high-resolution dust flux records prior to the establishment of the Barbados dust sampling station are largely lacking. Here we show that 4He concentrations in annual bands in corals provides a high-resolution, reliable, and robust proxy record of dust flux from continents. Some traces phases in dust, such as zircons, are rich in U and Th and thus have extremely high concentrations of 4He. As some fraction of the dust settles out of the atmosphere and through the water column, corals incorporate the dust in their skeletons through filter feeding. Since the alpha stopping distance is greater than the particle size of wind blown dust, the mineral grains will not accumulate radiogenic helium after the dust is incorporated into the corals. We have measured the 4He concentration in annual bands dating back to 1960's in a modern coral that was collected in 1996 off the island of Sal, part of the Cape Verde archipelago. The coral is therefore, situated close to, and directly west of the dust source in the Sudano-Sahel region of the African continent. The 4He record from the coral shows remarkable similarity with the record from the Barbados dust sampling station. There is a continuous increase in 4He baseline values by a factor of two from the mid 1960's to the early 1990's as well as two pronounced peaks in the early 1970's and mid 1980's associated with severe drought in the Sudano-Sahel region. Our proxy record from the Cape Verde Island demonstrates that 4He concentrations in corals can be used reliably to reconstruct dust fluxes from continental land masses at sub-decadal resolution. Our results also imply that 4He concentration in deep-sea sediments can be utilized to provide quantitative information about dust flux off continents and atmospheric circulation patterns.

Mukhopadhyay, S.; Kreycik, P.; Schrag, D. P.

2005-12-01

183

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

184

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

185

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

186

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

187

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

188

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

NASA Astrophysics Data System (ADS)

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 high-resolution sedimentary record of the past 22ka BP and is anoxic below 250m, which enhances preservation of organic matter (OM). For these reasons, L. Malawi is an excellent location to examine the response of low-latitude African climate to global climate change. The climate of Malawi is strongly influenced by the position and seasonal migration of the ITCZ. During the rainy season from November to March, the ITCZ is positioned over L. Malawi (12-13° S) and the dominant winds are weak and northerly. Between April and May the ITCZ moves northward towards the equator and strong southerly winds prevail (Jury & Mwafulirwa, 2002). Previous studies of L. Malawi have shown responses to global climatic events, such as the Younger Dryas. Additionally, studies have demonstrated the response of L. Malawi to local or regional events, such as variability in the ITCZ. Based on BSi MAR, diatom, phosphorus, and trace metal data, Johnson et al. (2002) proposed that at times more frequent or stronger northerly winds promoted upwelling in the northern basin of L. Malawi, and suggested more southerly migrations of the ITCZ (reaching latitudes of >13\\deg S) as the cause of these increased winds. Additionally, a recent study of L. Malawi based on multiple bulk geochemical proxies provides evidence for both southward and northward displacements of the ITCZ during the past 23ka BP (Filippi and Talbot, submitted). In this study the molecular biomarker record of L. Malawi is examined. Previous studies of Lake Malawi have been based on bulk geochemical parameters, which are indicators of the type of OM preserved in sediments. These studies indicate that variations in primary productivity likely have occurred during the past 22ka BP, however, these bulk geochemical analyses have also yielded ambiguous results and have failed to adequately distinguish terrestrially and aquatically derived OM. Presently, the algal community of L. Malawi is dominated by four major groups: diatoms, cyanobacteria, dynoflagellates, and green algae, with diatoms being the major contributor to primary productivity. Each of these algal groups has characteristic biomarkers, therefore, from the molecular record we will examine primary production as a whole within L. Malawi. Molecular reconstructions will provide information on the response of the L. Malawi algal community to hydrological variations, which may be linked global climate events or to smaller regional events, such as fluctuations in position and intensity ITCZ.

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

2003-12-01

189

The Status of Archives and Records Management Systems and Services in African Member States: A RAMP Study.  

ERIC Educational Resources Information Center

|A comprehensive questionnaire was sent to 49 African national archival agencies in April 1982 to survey the needs of African Member States for assistance in the development of archives. This study is based on the 27 (55%) questionnaires that were returned. The participating agencies were grouped into three categories: agencies located in…

Van Laar, Evert

190

Fossil Evidence of Bipedalism  

NSDL National Science Digital Library

This video segment adapted from NOVA shows how scientists use the fossil record to trace when early human ancestors and related species began walking on two legs instead of four, and to determine whether they were more apelike or human in appearance.

Foundation, Wgbh E.

2010-04-05

191

A Fossil Buttercup  

Microsoft Academic Search

WHEN we examine a catalogue of fossil plants, such as that for North America recently published by Knowlton, we are struck by the enormous number of recorded species, and readily receive the impression that the flora of former ages is quite well known. It is only when we make a more critical investigation that we perceive the great gap in

T. D. A. Cockerell

1922-01-01

192

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.

193

Science Sampler : Fossil detectives  

NSDL National Science Digital Library

Middle school students are transformed into Fossil detectives as they examine the fossil record and use evidence about paleo-environments to develop an understanding of structure and function in living systems and changes over time in Earths history. In this enrichment activity, students work in teams to research an assigned geologic time period. They determine available habitats, food sources and types (animal, plant; woody, herbaceous, etc.), cover sources, methods of getting food, defense, and reproduction that would allow an animal to live in the assigned paleoenvironment. In culmination of their efforts, students create a diorama to display their findings.

Bourdeau, Virginia

2006-01-01

194

Suid evolution and correlation of African hominid localities.  

PubMed

Recently discovered Plio-Pleistocene vertebrate assemblages have allowed complete systematic revision of the sub-Saharan African Suidae. New phylogenies are proposed for the 7 genera and 16 species of fossil and extant representatives. Suids are common elements of African Plio-Pleistocene faunas, and their evolutionary trends, particularly in the species Mesochoerus limnetes and Metridiochoerus andrewsi, are of great correlative value. Suid data are employed in a refinement of stratigraphic correlations at Omo Shungura, Olduvai, and east of Lake Turkana (formerly East Rudolf) and in a correlation of East African and South African sites, with important implications for interpretation of hominid evolution. The suid record also bears significantly on questions of theoretical evolutionary biology. PMID:331477

White, T D; Harris, J M

1977-10-01

195

Fossilization of feathers  

NASA Astrophysics Data System (ADS)

Scanning electron microscopy of feathers has revealed evidence that a bacterial glycocalyx (a network of exocellular polysaccharide fibers) played a role in promoting their fossilization in some cases. This mode of preservation has not been reported in other soft tissues. The majority of fossil feathers are preserved as carbonized traces. More rarely, bacteria on the surface are replicated by authigenic minerals (bacterial autolithification). The feathers of Archaeopteryx are preserved mainly by imprintation following early lithification of the substrate and decay of the feather. Lacustrine settings provide the most important taphonomic window for feather preservation. Preservation in terrestrial and normal-marine settings involves very different processes (in amber and in authigenically mineralized coprolites, respectively). Therefore, there may be a significant bias in the avian fossil record in favor of inland water habitats.

Davis, Paul G.; Briggs, Derek E. G.

1995-09-01

196

Bird Fossils  

NSDL National Science Digital Library

A fossil of a small, feathered animal, Longisquama insignis, that lived approximately 220 million years ago (Ma) in what is now Central Asia, was re-discovered recently in the dusty drawers of a Moscow museum collection. This discovery has rocked the paleontological world because the fossil exhibits feather impressions, making it possibly the world's oldest known bird. Archaeopteryx, thought until now to be the oldest true bird, is from a limestone deposit in Germany dated at approximately 145 Ma. This new fossil discovery fires the debate over whether birds are descended from dinosaurs, or branched off from an earlier group of reptiles. This week's In The News takes a look at scientists' latest understanding of the reptile-bird evolutionary transition, and the surrounding controversies.

197

Fossil record of holococcoliths and selected hetero-holococcolith associations from the Mediterranean (Holocene–late Pleistocene): Evaluation of carbonate diagenesis and palaeoecological–palaeocenographic implications  

Microsoft Academic Search

The Holocene–late Pleistocene distribution of holococcoliths, is quantified by light microscopy from cores from the Western Mediterranean, the Aegean Sea and eight eastern Mediterranean cores recovering sapropel S1. The diversity of fossil holococcoliths is much lower than is seen in the plankton, indicating selective preservation. However the holococcolith phases of Syracosphaera pulchra and Helicosphaera carteri are abundantly preserved allowing a

Daniela Crudeli; Jeremy R. Young; Elisabetta Erba; Markus Geisen; Patrizia Ziveri; Gert J. de Lange; Caroline P. Slomp

2006-01-01

198

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

199

Taphonomy of a South African cave: geological and hydrological influences on the GD 1 fossil assemblage at Gondolin, a Plio-Pleistocene paleocave system in the Northwest Province, South Africa  

NASA Astrophysics Data System (ADS)

Occasional excavation of in situ and ex situ deposits at the formerly mined Gondolin paleocave system has yielded large and diverse samples of Plio-Pleistocene faunas, including isolated hominin and non-hominin primate remains. In 2003, new excavations into naturally decalcified, in situ sediments near the GD 1 datum point near the northwest corner of the cave system were undertaken. This paper describes the recovered faunal remains, taphonomy of the assemblage, and the geological and paleomagnetic context of the GD 1 deposits. The deposits represent a series of inter-stratified speleothem, in-washed sediments and talus deposits we suggest date to a time period prior to, and just after, the Olduvai normal-polarity event at around 1.7 1.8 Ma. Surface sediments and clasts were introduced into the cave by rain water runoff entering a vertically-oriented entrance that had formed along a rift in the area of GD 1. The faunal assemblage consists primarily of fragmentary diaphyseal fragments and isolated teeth. Taxonomically, the small collection of specifically identifiable bovid and equid fossils is generally consistent with remains previously excavated from in situ deposits in the Gondolin paleocave system (GD 2) and dated to around 1.8 Ma; however, the depositional histories of these two assemblages from Gondolin are remarkably different. The preservation and relative proportions of recovered skeletal elements at GD 1 is consistent with these materials having been initially accumulated outside the karstic system near the vertical cave entrance, and then later hydrologically sorted and deposited inside the cave. The sporadic to continuous water flow into the northwest corner of the cave system during the Pleistocene gradually decalcified the excavated fossilbearing breccias and further modified the composition and spatial distribution of the fossil assemblage by introducing potentially younger deposits and skeletal materials. This study highlights the variation in taphonomic processes that can occur within a single cave system, and the complex pre- and postdepositional geological and hydrological processes that can influence the taphonomic history of South African Plio-Pleistocene karstic fossil assemblages.

Adams, Justin W.; Herries, Andy I. R.; Kuykendall, Kevin L.; Conroy, Glenn C.

2007-10-01

200

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

PubMed Central

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

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

2008-01-01

201

Using extant patterns of dental variation to identify species in the primate fossil record: a case study of middle Eocene Omomys from the Bridger Basin, southwestern Wyoming.  

PubMed

Patterns of extant primate dental variation provide important data for interpreting taxonomic boundaries in fossil forms. Here I use dental data from several well-known living primates (as well as data from selected Eocene forms) to evaluate dental variation in Middle Eocene Omomys, the first North American fossil primate identified by paleontologists. Measurements were collected from a sample of 148 omomyid dental specimens recovered from Bridger B localities in the Bridger Basin, Wyoming. Most of these specimens have not previously been described. Nonmetric traits were also scored for this sample. Lower molar coefficients of variation range from 4.01 for M2 length (n = 80) to 6.73 for M3 talonid width (n = 57). All of the nonmetric traits scored exhibit less than 100% presence in the overall sample, including traits previously described as representative of Omomys (e.g., P4 metaconids present in 91%, n = 55; M2 pericones present in 80%, n = 15). Dental traits also vary in a set of spatially restricted localities from the same fossil horizon and in a separate, single fossil locality (DMNH 868, P4 metaconids present in 67%, n = 6). An increasing frequency in several premolar traits across time in these more restricted samples suggests an anagenetic change in Bridger B Omomys. However, this degree of morphological variability is consistent with that seen in extant primate species from single locations. Metric variation in this sample is comparable to that seen in other Eocene primates, such as new data presented here for the omomyid Arapahovius gazini from the Washakie Basin, southern Wyoming. Omomys metric variation is also comparable to that found in several samples of well-known extant primates from single localities (e.g., ring-tailed lemurs and gray-brown mouse lemurs). These metric data also correspond to the patterns of variability described in previously published studies of Omomyscarteri. In sum, a single species interpretation (O. carteri) for this new Bridger B Omomys sample from southern Wyoming is affirmed, and this study illustrates the usefulness of dental data from extant primates for evaluating primate fossil samples. PMID:18246298

Cuozzo, Frank P

2008-02-02

202

Understanding the long-term variability of African dust transport across the Atlantic as recorded in both Barbados surface concentrations and large-scale Total Ozone Mapping Spectrometer (TOMS) optical thickness  

Microsoft Academic Search

The interannual variability of African dust transport over the north tropical Atlantic is monitored using in situ surface concentrations measurements performed at Barbados since 1966, along with the Total Ozone Mapping Spectrometer (TOMS) and Meteosat dust optical thickness (DOT) records covering the last two decades. Despite their differences in spatial coverage, the two dust records are in good agreement at

Isabelle Chiapello; Cyril Moulin; Joseph M. Prospero

2005-01-01

203

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.

204

A New Interpretation of the Oldest Fossil Bee (Hymenoptera: Apidae)  

Microsoft Academic Search

The oldest fossil bee, '' Trigona'' prisca (Apidae: Meliponini), in Late Cretaceous (Maas- trichtian) amber from New Jersey, is redescribed and figured. Differences between T. prisca and extant Trigona are noted and the fossil is transferred into a new genus, Cretotrigona. An exploratory cladistic analysis of the Meliponini is undertaken and Cretotrigona supported as sister to the African genus Dactylurina.

MICHAEL S. ENGEL

2000-01-01

205

Cretaceous African life captured in amber  

PubMed Central

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

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

2010-01-01

206

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

2013-05-02

207

Evolution's Tempo and Mode during the Eocene Epoch: comparison of two long contemporaneous records of the fossil mammal Hyopsodus in the American West  

Microsoft Academic Search

The spatial and temporal record of the early Eocene mammal Hyopsodus exemplifies the complex and sinuous nature of evolution. I transform the dualism of punctuated equilibrium and phyletic gradualism patterns into a discussion of regional and local evolutionary patterns. In this paper, I show that evolution follows a gradual pattern at the local level, while punctuated changes occur through migration,

Benjamin John Burger

208

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

SciTech Connect

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

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

1990-12-01

209

The joints of the evolving foot. Part III. The fossil evidence.  

PubMed Central

The fossil record supports the conclusions derived from the study of extant species that the Primates evolved a unique suite of characters in the articulations of the foot. The tarsal bones of African Miocene apes show specializations characteristic of hominoid evolution and provide reasonable precursors for the morphology of Pan, Gorilla and even Pongo. The OH8 foot is essentially ape-like in it major features, with many close resemblances to Pan. Although fairly clearly from a bipedal primate, it lacked important functional specializations found in the human foot.

Lewis, O J

1980-01-01

210

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

PubMed

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

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

2009-09-15

211

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

PubMed Central

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

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

2009-01-01

212

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

Microsoft Academic Search

For many years paleoanthropologists and earth scientists have explored and debated the potential role of climate and environmental forcing in human evolution. Although no consensus has emerged as to the importance of climate history in understanding human origins, there is broad agreement that obtaining high quality records of paleoclimate is critical for evaluating any proposed relationships. Recent workshops on the

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

2009-01-01

213

Pan-African decompressional P-T path recorded by granulites from central Dronning Maud Land, Antarctica  

NASA Astrophysics Data System (ADS)

A high-grade metamorphic complex is exposed in Filchnerfjella (6-8°E), central Dronning Maud Land. The metamorphic evolution of the complex has been recovered through a study of textural relationships, conventional geothermobarometry and pseudosection modelling. Relicts of an early, high- P assemblage are preserved within low-strain mafic pods. Subsequent granulite facies metamorphism resulted in formation of orthopyroxene in rocks of mafic, intermediate to felsic compositions, whereas spinel + quartz were part of the peak assemblage in pelitic gneisses. Peak conditions were attained at temperatures between 850-885 °C and 0.55-0.70 GPa. Reaction textures, including the replacement of amphibole and garnet by symplectites of orthopyroxene + plagioclase and partial replacement of garnet + sillimanite + spinel bearing assemblages by cordierite, indicate that the granulite facies metamorphism was accompanied and followed by decompression. The observed assemblages define a clock-wise P-T path including near-isothermal decompression. During decompression, localized melting led to formation of post-kinematic cordierite-melt assemblages, whereas mafic rocks contain melt patches with euhedral orthopyroxene. The granulite facies metamorphism, decompression and partial crustal melting occurred during the Cambrian Pan-African tectonothermal event.

Elvevold, Synnøve; Engvik, Ane K.

2013-10-01

214

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.

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

2009-01-01

215

Calibration of an M L scale for South Africa using tectonic earthquake data recorded by the South African National Seismograph Network: 2006 to 2009  

NASA Astrophysics Data System (ADS)

A relation to determine local magnitude ( M L) based on the original Richter definition is empirically derived from synthetic Wood-Anderson seismograms recorded by the South African National Seismograph Network. In total, 263 earthquakes in the distance range 10 to 1,000 km, representing 1,681 trace amplitudes measured in nanometers from synthesized Wood-Anderson records on the vertical channel were considered to derive an attenuation relation appropriate for South Africa through multiple regression analysis. Additionally, station corrections were determined for 26 stations during the regression analysis resulting in values ranging between -0.31 and 0.50. The most appropriate M L scale for South Africa from this study satisfies the equation: {M_{{{L}}}} = {{lo}}{{{g}}_{{10}}}(A) + 1.149{{lo}}{{{g}}_{{10}}}(R) + 0.00063R + 2.04 - S The anelastic attenuation term derived from this study indicates that ground motion attenuation is significantly different from Southern California but comparable with stable continental regions.

Saunders, Ian; Ottemöller, Lars; Brandt, Martin B. C.; Fourie, Christoffel J. S.

2013-04-01

216

Mexican Fossil Mammals, Who, Where and When?  

Microsoft Academic Search

Although the earliest report of a fossil mammal from Mexico dates from 1799, our knowledge of the group is still poor. The\\u000a Mexican mammalian fossil record is biased towards the large-sized taxa and younger ages.\\u000a \\u000a The mammalian record in Mexico ranges from the Jurassic to the Quaternary. Most of the Cenozoic epochs, except for the Paleocene,\\u000a have mammal bearing deposits.

Marisol Montellano-Ballesteros; Eduardo Jimenez-Hidalgo

217

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

218

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

219

Fossils as Information  

NASA Astrophysics Data System (ADS)

This book discusses procedures for handling information derived from the fossil record, and the application of this information to solving problems in geological succession and earth history. The main purpose of the book is to analyze shortcomings of the existing procedures, and to propose in their place a new set of data-handling arrangements of much greater simplicity and efficiency. The author argues that the procedures in current use are cumbersome and inefficient, and that, partly as a consequence of these information-handling methods, palaeontology has failed to make advances commensurate with technological improvements. In this book he proposes a fundamentally new system which could make possible the integrated use of every detail of geological information taken from the rocks. This would achieve better resolution in sequence correlation, in paleoecologic interpretation and in logging the course of evolution. Compatibility of style with existing records has been maintained to avoid any danger of loss of valuable data, and to simplify the process of re-evaluating old records. The book will be of interest to all paleontologists, particularly those dealing with microfossils, and is intended to stimulate discussion and criticism of both the analysis and the proposal.

Hughes, Norman Francis

1989-11-01

220

Theropod Fossil Hunt Dispatch  

NSDL National Science Digital Library

This site outlines the step by step progression as a rare fossil is found, authenticated and identified. Follow along as a paleontologist pursues a well-preserved fossil of Sinosauropteryx, a feathered dromaeosaur. The site is enhanced with several photographs.

221

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

222

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

223

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.

224

Types of Fossils  

NSDL National Science Digital Library

The word fossil, derived from a Latin word meaning 'something dug up', refers to the preserved remains or traces of ancient life. Careful study of these remains can answer questions about life and evolution, and provide information about the history of Earth itself; for example, revealing that a tropical sea was present where only a desert exists today. This interactive feature explores the kinds of things we can learn from several types of fossils that scientists study. Viewers can see examples of body fossils (shells, bones, etc.), trace fossils (tracks, burrows, etc.), and an example of a fossil which has attributes of both.

225

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

226

Summary statistics for fossil spider species taxonomy.  

PubMed

Spiders (Araneae) are one of the most species-rich orders on Earth today, and also have one of the longest geological records of any terrestrial animal groups, as demonstrated by their extensive fossil record. There are currently around 1150 described fossil spider species, representing 2.6% of all described spiders (i.e. extinct and extant). Data for numbers of fossil and living spider taxa described annually (and various other metrics for the fossil taxa) were compiled from current taxonomic catalogues. Data for extant taxa showed a steady linear increase of approximately 500 new species per year over the last decade, reflecting a rather constant research activity in this area by a large number of scientists, which can be expected to continue. The results for fossil species were very different, with peaks of new species descriptions followed by long troughs, indicating minimal new published research activity for most years. This pattern is indicative of short bursts of research by a limited number of authors. Given the frequent discovery of new fossil deposits containing spiders, a wealth of new material coming to light from previously worked deposits, and the application of new imaging techniques in palaeoarachnology that allow us to extract additional data from historical specimens, e.g. X-ray computed tomography, it is important not only to ensure a sustained research activity on fossil spiders (and other arachnids) through training and enthusing the next generation of palaeoarachnologists, but preferably to promote increased research and expertise in this field. PMID:22639535

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

2012-05-08

227

Innovative tephra studies in the East African Rift System  

NASA Astrophysics Data System (ADS)

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

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

228

Fossil Shapes Extension Activity  

NSDL National Science Digital Library

In this activity students view photographs of 12 fossils and try to draw pictures of what the organisms looked like while they were alive. They then slice up fruit in various ways to get an idea of the difficulty of identifying an organism when only some of the hard parts may be exposed along a bedding surface, making it difficult to determine the true shape of the fossil, let alone the organism the fossil represents.

Greb, Stephen

229

Fossil Energy Program  

NASA Astrophysics Data System (ADS)

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

McNeese, L. E.

1981-01-01

230

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.

231

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

PubMed

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

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

2009-10-01

232

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

233

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

234

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

235

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

236

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

237

Trace Fossil Image Database  

NSDL National Science Digital Library

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

Martin, Anthony; University, Emory

238

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

239

Neanderthals: fossil evidence and DNA.  

PubMed

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

Harvati, Katerina

2011-01-01

240

A reappraisal of the evolution of Asian snakehead fishes (Pisces, Channidae) using molecular data from multiple genes and fossil calibration.  

PubMed

Freshwater snakehead fishes (Channidae) provide an interesting target for phylogenetic analysis for the following reasons, their unusual biology, potential for cryptic diversity and availability of a good fossil record. Here, a multi-locus molecular phylogeny was constructed and calibrated using two fossil dates to estimate divergence times within the family. Sampling aimed to explore interspecific divergence of Channa species across Southeast Asia and intra-specific variation where species possessed natural geographical ranges that were extensive. Results contradict divergence times estimated previously independently from single locus mitochondrial data or the fossil record and suggest that after divergence from African taxa 40-50 Ma, evolution of Asian snakeheads has been heavily influenced by multiple broad scale dispersal events across India and Southeast Asia. A similar pattern of divergence within multiple clades suggests that west-east dispersal was limited for many taxa during the Miocene. Deep intra-specific divergence was inferred for C. striata, indicating that long historical periods of isolation ( approximately 8Ma) have not resulted in the evolution of reproductive isolation within this species. Results support suggestions that C. marulia like fishes in northern Cambodia may constitute an undescribed species, and that Indian C. diplogramma warrants taxonomic recognition as being distinct from Southeast Asian C. micropeltes, with the two taxa last sharing a common ancestor in the mid- to late-Miocene. PMID:20359539

Adamson, Eleanor A S; Hurwood, David A; Mather, Peter B

2010-03-30

241

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

242

Fossil fuels -- future fuels  

SciTech Connect

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

NONE

1998-03-01

243

Fossil energy program  

NASA Astrophysics Data System (ADS)

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

McNeese, L. E.

1981-02-01

244

Fossilized Dinosaur Bones  

NSDL National Science Digital Library

This slide show presents images of dinosaur bones and shows paleotologists at work excavating and preserving these fossils, the best evidence remaining of these long-lost creatures. A background essay and discussion questons are included.

245

Minerals and Fossils  

NSDL National Science Digital Library

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

Mineraltown.com

246

Fossil energy program  

NASA Astrophysics Data System (ADS)

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

McNeese, L. E.

1981-03-01

247

Fossil energy program  

NASA Astrophysics Data System (ADS)

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

McNeese, L. E.

1981-12-01

248

The Great Fossil Find  

NSDL National Science Digital Library

In this imaginary fossil hunt, students learn about the uncertainty of science and the fact that, as new evidence is revealed, ideas may change. As they follow a script read by the teacher, students find (remove from envelope) paper fossils of some unknown creature, a few at a time. Each time, they attempt to reconstruct the creature and each time their interpretation tends to change as new pieces are found.

249

Small Mid-Pleistocene Hominin Associated with East African Acheulean Technology  

Microsoft Academic Search

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

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

2004-01-01

250

Soft-bodied fossils from a Silurian volcaniclastic deposit  

Microsoft Academic Search

FOSSIL deposits that preserve lightly sclerotized and soft-bodied organisms are fundamentally important to our understanding of the history of life on Earth. They provide a much more complete record of ancient communities than does the normal shelly fossil record. Conditions during the Cambrian may have favoured the preservation of soft-bodied organisms1. Burgess Shale-type2-5 and Orsten-type6 faunas are becoming increasingly known

Derek E. G. Briggs; David J. Siveter; Derek J. Siveter

1996-01-01

251

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

2012-06-01

252

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

253

Arthropod colonization of land – Linking molecules and fossils in oribatid mites (Acari, Oribatida)  

Microsoft Academic Search

Terrestrial fossils that document the early colonization of land are scarce for >100 my after the Cambrian explosion. This raises the question whether life on land did not exist or just did not fossilize. With a molecular dating technique, we analyzed the origin of terrestrial chelicerate microarthropods (Acari, Oribatida) which have a fossil record since the Middle Devonian that is

Ina Schaefer; Roy A. Norton; Stefan Scheu; Mark Maraun

2010-01-01

254

Trace Fossil Analysis  

NASA Astrophysics Data System (ADS)

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

Hasiotis, Stephen T.

2009-05-01

255

Fossil energy program  

NASA Astrophysics Data System (ADS)

Progress is reported for the period July 1 through September 30 for the Oak Ridge National Laboratory research and development projects that are carried out in support of the increased utilization of coal and other fossil fuels as sources of clean energy. These projects are supported by various parts of DOE including Fossil Energy, Basic Energy Sciences, Office of Health and Environmental Research, Office of Environmental Compliance and Overview, Economic Regulatory Administration, Power Research Institute, and by the Tennessee Valley Authority and the EPA Office of Research and Development through interagency agreements

McNeese, L. E.

1981-01-01

256

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

257

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

258

Fossil Halls: Virtual Tours  

NSDL National Science Digital Library

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

259

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.

260

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

261

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

262

African Fractals  

NSDL National Science Digital Library

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

2011-01-03

263

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

264

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

265

Predation on Recent and Fossil Echinoids  

Microsoft Academic Search

\\u000a Predator-prey interactions in marine ecosystems are documented in the fossil record by drill holes, repair scars, tooth marks\\u000a and other structural damage left by durophagous (“hard-eating”) predators on skeletons of their prey. Previous paleoecological\\u000a research focused primarily on benthic mollusks (e.g., Vermeij, 1977, 1983, 1987; Vermeij et al., 1980, 1981; Kitchell et al. 1981; Kitchell, 1986; Kelley and Hansen, 1993;

Micha? Kowalewski; James H. Nebelsick

266

Fossil Energy: Drivers and Challenges  

Microsoft Academic Search

Concerns about rapid economic growth, energy security, and global climate change have created a new landscape for fossil energy exploration, production, and utilization. Since 85% of primary energy supply comes from fossil fuels, and 85% of greenhouse gas emissions come from fossil fuel consumption, new and difficult technical and political challenges confront commercial, governmental, and public stakeholders. As such, concerns

Julio Friedmann

2007-01-01

267

Exceptional fossil preservation and the cambrian explosion.  

PubMed

Exceptionally preserved, non-biomineralizing fossils contribute importantly to resolving details of the Cambrian explosion, but little to its overall patterns. Six distinct "types" of exceptional preservation are identified for the terminal Proterozoic-Cambrian interval, each of which is dependent on particular taphonomic circumstances, typically restricted both in space and time. Taphonomic pathways yielding exceptional preservation were particularly variable through the Proterozoic-Cambrian transition, at least in part a consequence of contemporaneous evolutionary innovations. Combined with the reasonably continuous record of "Doushantuo-type preservation," and the fundamentally more robust records of shelly fossils, phytoplankton cysts and trace fossils, these taphonomic perturbations contribute to the documentation of major evolutionary and biogeochemical shifts through the terminal Proterozoic and early Cambrian.Appreciation of the relationship between taphonomic pathway and fossil expression serves as a useful tool for interpreting exceptionally preserved, often problematic, early Cambrian fossils. In shale facies, for example, flattened non-biomineralizing structures typically represent the remains of degradation-resistant acellular and extracellular "tissues" such as chaetae and cuticles, whereas three-dimensional preservation represents labile cellular tissues with a propensity for attracting and precipitating early diagenetic minerals. Such distinction helps to identify the acuticular integument of hyolithids, the chaetae-like nature of Wiwaxia sclerites, the chaetognath-like integument of Amiskwia, the midgut glands of various Burgess Shale arthropods, and the misidentification of deposit-feeding arthropods in the Chengjiang biota. By the same reasoning, putative lobopods in the Sirius Passet biota and putative deuterostomes in the Chengiang biota are better interpreted as arthropods. PMID:21680421

Butterfield, Nicholas J

2003-02-01

268

Archives of African American Music and Culture  

NSDL National Science Digital Library

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

Culture., Indiana U.

1998-01-01

269

Fossil Microbes on Mars?  

NSDL National Science Digital Library

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

270

Fossil Age Estimation Model  

NSDL National Science Digital Library

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

Twin Cities Public Television, Inc.

2006-01-01

271

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.

272

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

273

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 W.

274

Fossil diatoms and neogene paleolimnology  

USGS Publications Warehouse

Diatoms have played an important role in the development of Neogene continental biostratigraphy and paleolimnology since the mid-19th Century. The history of progress in Quaternary diatom biostratigraphy has developed as a result of improved coring techniques that enable sampling sediments beneath existing lakes coupled with improved chronological control (including radiometric dating and varve enumeration), improved statistical treatment of fossil diatom assemblages (from qualitative description to influx calculations of diatom numbers or volumes), and improved ecological information about analogous living diatom associations. The last factor, diatom ecology, is the most critical in many ways, but progresses slowly. Fortunately, statistical comparison of modern diatom assemblages and insightful studies of the nutrient requirements of some common freshwater species are enabling diatom paleolimnologists to make more detailed interpretations of the Quaternary record than had been possible earlier, and progress in the field of diatom biology and ecology will continue to refine paleolimnological studies. The greater age and geologic setting of Tertiary diatomaceous deposits has prompted their study in the contexts of geologic history, biochronology and evolution. The distribution of diatoms of marine affinities in continental deposits has given geologists insights about tectonism and sea-level change, and the distribution of distinctive (extinct?) diatoms has found utilization both in making stratigraphic correlations between outcrops of diatomaceous deposits and in various types of biochronological studies that involve dating deposits in different areas. A continental diatom biochronologic scheme will rely upon evolution, such as the appearance of new genera within a family, in combination with regional environmental changes that are responsible for the wide distribution of distinctive diatom species. The increased use of the scanning electron microscope for the detailed descriptions of fossil diatoms will provide the basis for making more accurate correlations and identifications, and the micromorphological detail for speculations about evolutionary relationships. ?? 1988.

Platt, Bradbury, J.

1988-01-01

275

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

276

The FORCLIM Eco-Physiological Growth Model for Planktic Foraminifera: a new Tool to Reconstruct Ecological Niches, Abundance and Potential Depth and Season of Growth for Fossil Foraminifera Species in Ocean Sediment Records  

NASA Astrophysics Data System (ADS)

Paleocean hydrological reconstructions derived from planktic foraminifera isotopic ratios (?18O and ?13C) or trace element ratio (Mg/Ca) are poorly constrained, for lack of precise knowledge on seasonality and water depth of test formation. This is particularly limiting for reconstruction of the thermocline characteristics. Various calibrations have been published, based on statistical correlation with core tops fossil fauna, sediment traps or plankton net collection. We present here what we think is the first eco-physiological model reproducing the growth of different foraminifera species in function of environmental parameter. By reproducing the main physiological rates of foraminifera (nutrition, respiration, symbiotic photosynthesis), this model estimates their growth in function of temperature, light availability and food concentration. The model is now calibrated for the species Neogloboquadrina pachyderma (dextral and sinistral forms), Neogloboquadrina dutertrei, Globigerina bulloides, Globigerinoides ruber, Globigerinoides sacculifer, Globigerinella siphonifera and Orbulina universa. Most of the model parameters are derived from newly performed experimental observations or from published data and only the influence of food concentration (in a Chl a basis) was calibrated with field observations. Using satellite data, the model predict the seasonal distribution of dominant foraminifer species over 576 field observations worldwide with efficiency higher than 60%. Moreover, the growth rate estimated for each foraminifera species can be used as an abundance indicator which allows prediction of the season and water depth at which most of the population has developed. This offers larges perspectives for both actual understanding of foraminifera role in the carbon/carbonate ocean cycle and for better quantification of paleoceanographic proxies. Forclim is a program supported by the Agence Nationale pour la Recherche and Institut National des Sciences de l'Univers, France.

Lombard, F.; Labeyrie, L.; Michel, E.; Lea, D.; Spero, H. J.; Forclim, M. O.

2007-12-01

277

Fossilized Dinosaur Teeth Adaptations  

NSDL National Science Digital Library

In this activity, learners use models of fossilized dinosaur teeth to understand how dinosaur teeth were used. Learners specifically research Tyrannosaurus rex and Triceratops horridus dinosaurs and determine that Triceratops teeth work the way pliers and scissors operate, and T. rex teeth are like sharp knives. Learners match and sort dinosaurs by the type and use of their teeth. This activity is featured on pp.14-18 (part of a lesson that begins on p.7) of the "Dinosphere" unit of study for grades 3-5.

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

2004-01-01

278

Fossil Mammal Research Group  

NSDL National Science Digital Library

This website presents the Fossil Mammal Research Group whose "members are palaeontologists and archaeologists as well as palaeoenvironmental specialists in the School of Biological & Earth Sciences, Liverpool John Moores University, UK." Subjects of study by the Research group include mammalian fauna development over the past 30 million years, Plio-Pleistocene and Holocene climate change, and more. The website links to subpages for a list of Publications from 1998-2004, Major Projects going on around the world, Conferences, and relevant links. The site also provides a page presenting group members along with their research interests and email addresses.

279

African Trypanosomiasis.  

National Technical Information Service (NTIS)

African trypanosomiasis is infection by protozoan hemoflagellates of the Trypanosoma brucei complex, subspecies of which cause disease in humans: Trypanosoma brucei gambiense causes Gambian (chronic) trypanosomiasis and Trypanosoma brucei rhodesiense caus...

M. K. Klassen-Fischer R. C. Neafie W. M. Meyers

2011-01-01

280

African Arts  

NSDL National Science Digital Library

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

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

2001-01-01

281

Termites of a South African savanna  

Microsoft Academic Search

This study describes the termite fauna of the South African Savanna Ecosystem Project study area at Nylsvley Reserve, Naboomspruit, northern Transvaal. Twenty species of fifteen genera and two families are recorded, and biological notes are given. The faunal composition is broadly similar to that of West African savannas, but a little impoverished. Main deficiencies are in variety of Macrotermitinae and

Paul Ferrar

1982-01-01

282

Fossil figure contribution to the lunar figure  

NASA Astrophysics Data System (ADS)

The unusual shape of the Moon given its present rotational and orbital state has been explained as due to a fossil figure preserving a record of remnant rotational and tidal deformation (Jeffreys, H. [1915]. Mem. R. Astron. Soc. 60, 187-217; Lambeck, K., Pullan, S. [1980]. Phys. Earth Planet. Interiors 22, 29-35; Garrick-Bethell, I., Wisdom, J., Zuber, M.T. [2006]. Science 313, 652-655). However, previous studies assume infinite rigidity and ignore deformation due to changes in the rotational and orbital potentials as the Moon evolves to the present state. We interpret the global lunar figure with a physical model that takes into account this deformation. Although the Moon deforms in response to rotational and orbital changes, a fossil figure capable of explaining the observed figure can be preserved by an elastic lithosphere.

Matsuyama, Isamu

2013-01-01

283

Measuring dental wear equilibriums—the use of industrial surface texture parameters to infer the diets of fossil mammals  

Microsoft Academic Search

Inferring the diet of fossil mammals is a major approach to mammalian palaeobiology and palaeoecology. Dental wear provides a unique record of oral behaviour, available for most extant and fossil mammals. Dental wear facets are thus one of the immediate habitat interfaces allowing analysis of food selection, food availability, and dietary segregation in fossil and extant communities based on the

Thomas M. Kaiser; Gesa Brinkmann

2006-01-01

284

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

PubMed

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

2012-08-10

285

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

286

Radioactivity in fossils at the Hagerman Fossil Beds National Monument.  

PubMed

Since 1996, higher than background levels of naturally occurring radioactivity have been documented in both fossil and mineral deposits at Hagerman Fossil Beds National Monument in south-central Idaho. Radioactive fossil sites occur primarily within an elevation zone of 900-1000 m above sea level and are most commonly found associated with ancient river channels filled with sand. Fossils found in clay rich deposits do not exhibit discernable levels of radioactivity. Out of 300 randomly selected fossils, approximately three-fourths exhibit detectable levels of natural radioactivity ranging from 1 to 2 orders of magnitude above ambient background levels when surveyed with a portable hand held Geiger-Muller survey instrument. Mineral deposits in geologic strata also show above ambient background levels of radioactivity. Radiochemical lab analysis has documented the presence of numerous natural radioactive isotopes. It is postulated that ancient groundwater transported radioactive elements through sand bodies containing fossils which precipitated out of solution during the fossilization process. The elevated levels of natural radioactivity in fossils may require special precautions to ensure that exposures to personnel from stored or displayed items are kept as low as reasonably achievable (ALARA). PMID:18442873

Farmer, C Neal; Kathren, Ronald L; Christensen, Craig

2008-04-28

287

AFRICAN PERSPECTIVES ON AFRICAN SECURITY CHALLENGES AND MODERN PEACE OPERATIONS  

Microsoft Academic Search

eacekeeping forces are deployed in record numbers in Africa today, working to support sustainable peace in regions from West Africa to the Horn of Africa and from the Western Sahara to the Great Lakes. While the United Nations (UN) leads many of these missions— more than 80 percent of its peacekeepers are deployed on the continent—African or ganizations are also

Alix J. Boucher; Victoria K. Holt

288

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

PubMed

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

Hunt, Gene

2010-12-01

289

How to Make a Fossil  

NSDL National Science Digital Library

Becoming a fossil is not easy. Most shells or bones decompose or get eaten. This radio broadcast describes how a group of scientists are dropping bags of potential fossils in the ocean to see just what it takes to turn them into stone. The clip is 2 minutes in length.

290

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

SciTech Connect

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

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

1984-06-29

291

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.

292

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

293

The African Lithosphere  

NASA Astrophysics Data System (ADS)

There have been a number of prior, large scale surface wave studies of Africa, the majority of which rely on fundamental mode observations. In this study we use a large data set of multi-mode surface waves recorded over epicentral distances most of which are shorter than 6000 km, to investigate the Sv wave speed heterogeneity of the upper mantle beneath Africa. The inclusion of the higher mode data allow us to build an upper mantle model for the African plate with a horizontal resolution of a few hundred kilometers and a vertical resolution of a few tens of kilometers extending to about 400 km depth. Our tomographic images of the upper mantle beneath Africa displays significant shear velocity features, much of which correlate with surface geology. High velocity mantle persists beneath the West African and Congo cratons to 225-250 km depth, but the high velocity root beneath Kalahari Craton extends to only about 175 km depth. Low velocity upper mantle underlies the Pan- African terranes of Africa with the exception of the Damara mobile belt separating the Congo and Kalahari Cratons. The Damara mobile belt is underlain by a thick high velocity upper mantle lid which is indistinguishable from that beneath the Congo Craton to the north and the Kalahari Craton to the south. Low velocity upper mantle underlie the Hoggar, Tebesti and Darfur volcanic areas of northern Africa, and very low velocities underlie the Afar region to at least 400 km depth. We use the relationship between shear velocity and temperature of Priestley & McKenzie (2006) to derive a model for the African thermal lithosphere. Two types of lithosphere underlie Africa. Thick lithosphere underlies most of western Africa and all of southern Africa; in the latter the extent of the thick lithosphere is significantly different from the distribution of Archean crust mapped at the surface. Thick lithosphere forms one continuous structure beneath the Congo and Kalahari Cratons. Other than the Pan-African Damara mobile belt, the only Pan-African terrane of Africa free of recent (<30 Ma) volcanism, all of the Pan- African is underlain by lithosphere whose thickness is too thin to be resolved by our current surface wave analysis.

Priestley, K.; Debayle, E.; McKenzie, D.; Pilidou, S.

2007-12-01

294

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

295

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

296

Past environmental and climatic changes during the last 7200 cal yrs BP in Adamawa Plateau (Northern-Cameroun) based on fossil diatoms and sedimentary 13C isotopic records from Lake Mbalang  

NASA Astrophysics Data System (ADS)

Past limnological conditions of Lake Mbalang (7°19´ N, 13°44´ E, alt: 1130 m) and vegetation type were reconstructed from diatoms and sedimentary stable carbon isotope records (?13C) since 7200 cal yrs BP. The data showed that before 3600 yrs cal BP the water column was preferentially cold and stable except around 5000-5300 cal yrs BP where diatom evidenced mixed upper water layer, ?13C data suggest more forested vegetation in the landscape. These stable conditions can be explained by a strong monsoonal flux and correlatively northern position of the ITCZ that entailed high/low rainfall well distributed over the year to allow the development mountainous forest taxa. The decreasing trend of the monsoonal flux towards mid-Holocene was however affected by several centennial to millennial time scale abrupt weakening at 6700, 5800-6000, 5000-5300, 4500 and 3600 cal yrs BP although their impact on vegetation is not visible probably because rainfall distribution was favourable to forest maintenance or extension. After 3600 cal yrs BP, water column became very mixed as a result of more intense NE trade winds (Harmattan) that led at ~3000 cal yrs BP to the instalment of savana in the vegetation landscape. At that time, rainfall was probably reduced following the southwards shift of the ITCZ and the distribution of yearly rainfall was no more favourable to forest development. Thus a strong seasonality with a well marked dry season was established, conditions that maintained the savana vegetation till today. Diatom data suggest the lake did not dried during the last 7200 cal yrs BP, however, a low lake level observed at 2400-2100 cal yrs BP is contemporaneous to a climatic event evidenced in several areas of tropical Africa and could correspond to the southernmost position of the ITCZ. Other low lake levels are observed at 1800 and 1400 cal yrs BP, after which lake rose to its present level.

Nguetsop, V. F.; Bentaleb, I.; Favier, C.; Martin, C.; Servant-Vildary, S.; Servant, M.

2011-01-01

297

Uncertainty in the Age of Fossils and the Stratigraphic Fit to Phylogenies  

Microsoft Academic Search

The ages of first appearance of fossil taxa in the stratigraphic record are inherently associated to an interval of error or uncertainty, rather than being precise point estimates. Contrasting this temporal information with topologies of phylogenetic relationships is relevant to many aspects of evolutionary studies. Several indices have been proposed to compare the ages of first appearance of fossil taxa

Diego Pol; MARK A. NORELL

2006-01-01

298

Fossil gap analysis supports early Tertiary origin of trophically diverse avian orders  

Microsoft Academic Search

Recent molecular studies have cited the general incompleteness of the fossil record to support claims that most extant avian orders diverged in the mid-Cretaceous, some 40 m.y. before their first fossil appearances in the early Cenozoic. To evaluate these assertions, I used gap analysis to estimate confidence intervals for the beginnings of the observed stratigraphic ranges for the related extant

Robert Bleiweiss

1998-01-01

299

REVIEW Developmental Evolution of Metazoan Bodyplans: The Fossil Evidence  

Microsoft Academic Search

Evidence from the fossil record, developmental biology and metazoan phylogeny demonstrates that the rapid origination of major metazoan bodyplans during the late Neoproterozoic and earliest Cambrian was intimately associated with a series of innovations in developmental control mechanisms that included the Hox gene cluster. The interval between about 565 Ma (million years ago) and 530 Ma evidently includes the protostome-deuterostome

James W. Valentine; Douglas H. Erwin; David Jablonski

300

We're Going on a Fossil Hunt!  

ERIC Educational Resources Information Center

|Scientists understand that scientific ideas are subject to change and improvement. Fourth- through eighth- graders develop this understanding about the nature of science as they gather and examine fossil evidence from the Paleozoic era, record their findings, and read and write about science for authentic purposes as scientists do. Students…

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

2007-01-01

301

Some fossil woods from the Palaeogene of Northern Kyushu, II  

Microsoft Academic Search

Four new species of petrified dicotyledonous woods obtained from the Oligocene of Tsuyazaki, fukuoka Prefecture have been\\u000a described in a continuation of work from the previous paper;Acer palmatoxylum (Aceraceae),Cornus tsuyazakiensis (Cornaceae),Fraxinus oligocenica (Oleaceae) andHovenia palaeodulcis (Rhamnaceae). The fossil woods of those families are new records from the Palaeogene of Japan.

Mitsuo Suzuki

1982-01-01

302

The Fine Structure of Fossil Plant Cell Walls  

Microsoft Academic Search

The cell walls of sieve elements in the primary phloem of the Carboniferous fern Tubicaulis contain structural features that morphologically resemble cellulose microfibrils in extant plants. This may be the oldest example of distinct fibrillar structures in the fossil record. The possible identity and significance of these features are discussed and their structure is compared with that of cell walls

Edith L. Smoot; Thomas N. Taylor

1984-01-01

303

Sr/Ca and early hominin diets revisited: new data from modern and fossil tooth enamel.  

PubMed

A previous study of strontium/calcium (Sr/Ca) ratios in Paranthropus suggested that it consumed more animal foods than was previously believed. However, that study looked at Sr/Ca in fossil bone, which is known to be highly susceptible to diagenesis. Enamel, in contrast, is resistant to post-mortem alteration making it a more appropriate material for Sr/Ca analysis of Plio-Pleistocene fossils. Yet, we know virtually nothing about Sr/Ca in the enamel of modern African mammals, much less fossil taxa. To address this gap, we studied Sr/Ca in tooth enamel from modern mammals in the greater Kruger National Park, South Africa, as well as fossil fauna from the Sterkfontein Valley. Grazing herbivores have the highest Sr/Ca, followed by browsers and carnivores in both modern and fossil fauna. This similarity in ecological Sr/Ca patterning between modern and fossil fauna shows that diagenesis has not obscured the primary dietary signals. Australopithecus has significantly higher Sr/Ca than Paranthropus, and higher Sr/Ca than fossil papionins, browsers, and carnivores. Paranthropus has lower Sr/Ca than grazers, but its Sr/Ca is higher or equal to that of fossil papionins, browsers, and carnivores. Thus, Sr/Ca for both hominins is relatively high, and provides no direct evidence for omnivory in either taxon. The consumption of underground resources or insects are among the possible explanations for the highly elevated Sr/Ca in Australopithecus. PMID:15701528

Sponheimer, Matt; de Ruiter, Darryl; Lee-Thorp, Julia; Späth, Andreas

2004-12-21

304

African-American Biography.  

ERIC Educational Resources Information Center

Suggests sources of information for African American History Month for library media specialists who work with students in grades four through eight. Gale Research's "African-American Reference Library," which includes "African-America Biography,""African-American Chronology," and "African-American Almanac," is reviewed, and a reference activity…

Martin, Ron

1995-01-01

305

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

2011-02-03

306

Araucariaceae macrofossil record from South America and Antarctica  

Microsoft Academic Search

Araucariaceae fossils are abundant in Patagonia and on Seymour (Marambio) and King George (25 de Mayo) islands, Antarctica. Araucariacean macrofossil suites are represented by records of 121 woods, leaves, ovuliferous scales, cones, one seed and seedlings, many of them placed in 50 formalized morphospecies. Although Araucariaceae fossil pollen is known since the Triassic, the oldest reliable macrofossil records in South

Carolina Panti; Roberto R. Pujana; María C. Zamaloa; Edgardo J. Romero

2011-01-01

307

Araucariaceae macrofossil record from South America and Antarctica  

Microsoft Academic Search

Araucariaceae fossils are abundant in Patagonia and on Seymour (Marambio) and King George (25 de Mayo) islands, Antarctica. Araucariacean macrofossil suites are represented by records of 121 woods, leaves, ovuliferous scales, cones, one seed and seedlings, many of them placed in 50 formalized morphospecies. Although Araucariaceae fossil pollen is known since the Triassic, the oldest reliable macrofossil records in South

Carolina Panti; Roberto R. Pujana; María C. Zamaloa; Edgardo J. Romero

2012-01-01

308

Plio-pleistocene African climate  

SciTech Connect

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

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

1995-10-06

309

Place names describing fossils in oral traditions  

Microsoft Academic Search

Folk explanations of notable geological features, including fossils, are found around the world. Observations of fossil exposures (bones, footprints, etc.) led to place names for rivers, mountains, valleys, mounds, caves, springs, tracks, and other geological and palaeonto- logical sites. Some names describe prehistoric remains and\\/or refer to traditional interpretations of fossils. This paper presents case studies of fossil-related place names

ADRIENNE MAYOR

2007-01-01

310

The Fossil Record of Feather Evolution in the Mesozoic  

Microsoft Academic Search

SYNOPSIS. The oldest known feathers from the Late Jurassic are already modern in form and microscopic detail. Because these oldest examples are assignable to an extinct branch (Sauriurae) of the basal avian dichotomy, their features must have been established at a significantly earlier date. The skin of a wide variety of di- nosaurs is now known and is unlikely to

Larry D. Martin; Stephan A. Czerkas

2000-01-01

311

Connecting the Distant Universe with the Local Fossil Record  

Microsoft Academic Search

This review considers implications regarding galaxy formationand evolution that can be drawn from study of the ages,abundances,\\u000a and kinematics of stellar populations in the LocalUniverse. The wide abundance range in the Galactic bulge and in thehalo\\u000a of M31 is consistent with chemical evolution in a starburstwith wind outflow. We question the notionthat the Galactic halo\\u000a population is assembled fromdisrupted dwarf

R. Michael Rich

1999-01-01

312

Connecting the Distant Universe with the Local Fossil Record  

Microsoft Academic Search

This review considers implications regarding galaxy formationand evolution that can be drawn from study of the ages,abundances, and kinematics of stellar populations in the LocalUniverse. The wide abundance range in the Galactic bulge and in thehalo of M31 is consistent with chemical evolution in a starburstwith wind outflow. We question the notionthat the Galactic halo population is assembled fromdisrupted dwarf

R. Michael Rich

1999-01-01

313

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 ...

314

Cell symbioisis theory: Status and implications for the fossil record  

NASA Astrophysics Data System (ADS)

Although the entire serial endosymbiotic theory has not been proven much progress has been made and the nature of the remaining critical observations can be now identified. There is little doubt that, regardless of the precise details, prokaryotes are single genomic systems and all eukaryotic cells are multigenomic ones. Eukaryotic cells are therefore best thought of as co-evolved microbial communities, entities that emerged as the symbiotic partnerships became tightly integrated by the late Late Proterozoic Aeon. Present address: Control and Energy Conversion Division, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, U.S.A.

Margulis, L.; Stolz, J. F.

315

Cell symbioisis theory: Status and implications for the fossil record  

Microsoft Academic Search

Although the entire serial endosymbiotic theory has not been proven much progress has been made and the nature of the remaining critical observations can be now identified. There is little doubt that, regardless of the precise details, prokaryotes are single genomic systems and all eukaryotic cells are multigenomic ones. Eukaryotic cells are therefore best thought of as co-evolved microbial communities,

L. Margulis; J. F. Stolz

1984-01-01

316

Predation on Bryozoans and its Reflection in the Fossil Record  

Microsoft Academic Search

\\u000a Bryozoans are present in many benthic marine habitats, where they range from minor to dominant ecological elements. At the\\u000a present day and apparently throughout their history, bryozoans reached peak levels of taxonomic richness in middle to outer\\u000a shelf locations (Bottjer and Jablonski, 1988; McKinney and Jackson, 1989; Clarke and Lidgard, 2000). Many shelf-depth carbonate deposits from the Middle Ordovician to

Frank K. Mckinney; Paul D. Taylor; Scott Lidgard

317

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

318

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

319

EVOLUTIONARY PALEONTOLOGY AND THE FOSSIL RECORD: A HISTORICAL INTRODUCTION  

Microsoft Academic Search

From the beginning of paleontology's existence as a distinct professional community in the early 20th century, paleontologists have argued about 'where' the discipline fi ts among the natural sciences. Long told that paleontologists ought to be content with a subsidiary role as mere documenters of evolutionary change or as stratigraphical 'handmaidens' to geology, over the past hundred years many paleontologists

DAVID SEPKOSKI

320

Early Life on Earth: The Ancient Fossil Record  

Microsoft Academic Search

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

Frances Westall

2004-01-01

321

Environmental determinants of extinction selectivity in the fossil record.  

PubMed

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

Peters, Shanan E

2008-06-15

322

Impact Theory of Mass Extinctions and the Invertebrate Fossil Record  

Microsoft Academic Search

There is much evidence that the Cretaceous-Tertiary boundary was marked by a massive meteorite impact. Theoretical consideration of the consequences of such an impact predicts sharp extinctions in many groups of animals precisely at the boundary. Paleontological data clearly show gradual declines in diversity over the last 1 to 10 million years in various invertebrate groups. Reexamination of data from

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

1984-01-01

323

Ancient Ephemeroptera-Collembola Symbiosis Fossilized in Amber Predicts Contemporary Phoretic Associations  

PubMed Central

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

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

2012-01-01

324

Gaps in fossil teeth: Saltations or sampling errors?  

PubMed

All evolutionists accept that there are gaps in the fossil record. To some, gaps are data: they mark sudden transitions, unlikely to be preserved, between one species and its descendants that have arisen by a brief genetic revolution within an otherwise stable lineage. However, recent studies of sediment gain and loss show that few fossil beds can be complete enough to give details of the process of speciation, so that most gaps are gaps, and nothing more. Differences in the perception of time and sampling completeness mean that paleontologists and geneticists see the rate and pattern of evolution in different ways. Just how misleading each view may be is seen by analysing the laws of life governing change in living populations using the limitations intrinsic to studies of past times; and by a new insight into the details of species formation now emerging from some remarkably complete primate fossil sequences. PMID:21227203

Jones, J S

1988-08-01

325

Scratching an ancient itch: an Eocene bird louse fossil.  

PubMed Central

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

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

2004-01-01

326

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

327

Fossils: Observing, Making and Learning  

NSDL National Science Digital Library

In this activity, learners explore how casts of fossilized bones are created and used to learn about dinosaurs. Learners make observations, draw diagrams and share their findings. Learners also make clay molds to create plaster copies of real fossils. Then, learners consider how animals' and dinosaurs' body parts were used for protection, hunting, eating, etc. This activity is featured on pp.11-13 (part of a lesson that begins on p.7) of the "Dinosphere" unit of study for grades 3-5.

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

2004-01-01

328

Hydrogen versus synthetic fossil fuels  

NASA Astrophysics Data System (ADS)

The fuels most considered for the post petroleum and natural gas era, hydrogen (gaseous and liquid) and synthetic fluid fossil fuels, have been compared by taking into account production costs, utilization efficiencies and environmental effects. Three different cost bases have been used for hydrogen depending on the primary energy sources used in its production. The results show that hydrogen is a much more cost effective energy carrier than synthetic fossil fuels. In addition to its environmental and efficiency benefits, hydrogen causes resource conservation, savings in transportation and capital investment, and reduction in inflation.

Veziroglu, T. N.; Awad, A. H.

329

Tour of Park Geology: Fossils  

NSDL National Science Digital Library

This National Park Service Geology site provides links to tours of individual National Parks, Monuments, and Recreation Areas that contain fossils. Where appropriate, for each park, links are provided to park geology, maps, photographs, geologic research, related links, visitor information, multimedia resources, and teacher features (resources for teaching geology with National Park examples). The list includes places such as the Grand Canyon, Dinosaur National Monument, Yellowstone, and Death Valley, along with less well-known areas such as the John Day Fossil Beds National Monument in Oregon.

330

Africans in America.  

ERIC Educational Resources Information Center

|This book introduces African-American history and culture to children. The first Africans in America came from many different regions and cultures, but became united in this country by being black, African, and slaves. Once in America, Africans began a long struggle for freedom which still continues. Slavery, the Civil War, emancipation, and the…

Hart, Ayanna; Spangler, Earl

331

African American Newspapers  

NSDL National Science Digital Library

This Web site offer useful information concerning African American news and culture. African American Newspapers, provides a connection to over 200 listings of African American US newspapers and publications sorted by State. This provides valuable resource links for those looking to delve into African American history and culture.

1996-01-01

332

African Outreach Workshop 1974.  

ERIC Educational Resources Information Center

This report discusses the 1974 African Outreach Workshop planned and coordinated by the African Studies Program at the University of Illinois at Urbana-Champaign. Its major aim was to assist teachers in developing curriculum units on African using materials available in their local community. A second aim was for the African Studies Program to…

Schmidt, Nancy J.

333

FAST FOSSIL ROTATION OF NEUTRON STAR CORES  

SciTech Connect

It is argued that the superfluid core of a neutron star super-rotates relative to the crust, because stratification prevents the core from responding to the electromagnetic braking torque, until the relevant dissipative (viscous or Eddington-Sweet) timescale, which can exceed {approx}10{sup 3} yr and is much longer than the Ekman timescale, has elapsed. Hence, in some young pulsars, the rotation of the core today is a fossil record of its rotation at birth, provided that magnetic crust-core coupling is inhibited, e.g., by buoyancy, field-line topology, or the presence of uncondensed neutral components in the superfluid. Persistent core super-rotation alters our picture of neutron stars in several ways, allowing for magnetic field generation by ongoing dynamo action and enhanced gravitational wave emission from hydrodynamic instabilities.

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

2012-12-10

334

Geology Fieldnotes: Fossil Butte National Monument, Wyoming  

NSDL National Science Digital Library

Fossil Butte National Monument preserves a 50-million year old bed of Eocene limestone that contains one of the richest fossil deposits in the world. Site features include park geology information, photographs of fossils, related links, visitor information, multimedia resources, and resources for teaching geology with National Park examples. The park geology section discusses the Monument's geologic history and fossil beds, focusing on the conditions that created the fossil-rich region and on the history of fossil collection in the area. A map of the Monument is also included.

335

The Oklo Fossil Fission Reactors  

NSDL National Science Digital Library

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

Loss, Robert

2012-06-15

336

Biomechanics in fossil plant biology  

Microsoft Academic Search

The use of biomechanics for the analysis of the form—function relationship in palaeobotany is reviewed. Four fields of application of biomechanics are discussed and illustrated, i.e. the functional analysis of plants and plant organs (examples: lianas, leaf margin types), reconstruction of fossil plants (growth habit, tree height), functional analysis of ontogeny (lianas, trees), and evolutionary pathways (evolution of early land

Volker Mosbrugger; Anita Roth

1996-01-01

337

Progress of fossil fuel science  

SciTech Connect

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

Demirbas, M.F.

2007-07-01

338

Fossil Cetacea of the Caucasus.  

National Technical Information Service (NTIS)

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

G. A. Mchedlidze

1989-01-01

339

Hydrogen versus synthetic fossil fuels  

Microsoft Academic Search

The fuels most considered for the post petroleum and natural gas era, hydrogen (gaseous and liquid) and synthetic fluid fossil fuels, have been compared by taking into account production costs, utilization efficiencies and environmental effects. Three different cost bases have been used for hydrogen depending on the primary energy sources used in its production. The results show that hydrogen is

T. N. Veziroglu; A. H. Awad

1984-01-01

340

Biological fossil CO 2 mitigation  

Microsoft Academic Search

Over ten times more CO2 is fixed by plants into biomass, and annually released by decomposers and food chains, than is emitted to the atmosphere due to the burning of fossil fuels. Human activity is already directly and indirectly affecting almost half of the terrestrial biological C cycle. Management of even a small fraction of the biological C cycle would

Evan Hughes; John R Benemann

1997-01-01

341

Progress of Fossil Fuel Science  

Microsoft Academic Search

Coal is the most abundant and widely distributed fossil fuel. More than 45% of the world's electricity is generated from coal, and it is the major fuel for generating electricity worldwide. The known coal reserves in the world are enough for more than 215 years of consumption, while the known oil reserves are only about 39 times of the world's

M. F. Demirbas

2007-01-01

342

Hagerman Fossil Beds National Monument  

NSDL National Science Digital Library

This National Park Service website offers descriptions of: the animal fossils found at this park, including the extinct Hagerman horse; the geology of the park which is mostly floodplain sediments of primarily silty clays; and the geological, hydrological, and hydrostratigraphical aspects of a landslide model. There are photos of park landslides, prehistoric projectile points, and the historical Oregon Trail.

343

Fossil Energy: Drivers and Challenges.  

NASA Astrophysics Data System (ADS)

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

Friedmann, Julio

2007-04-01

344

ConcepTest: Best Index Fossil  

NSDL National Science Digital Library

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

345

Energy: Analysing fossil-fuel displacement  

NASA Astrophysics Data System (ADS)

It is commonly assumed that fossil fuels can be replaced by alternative forms of energy. Now research challenges this assumption, and highlights the role of non-technological solutions to reduce fossil-fuel consumption.

Jorgenson, Andrew K.

2012-06-01

346

Identifying Fossils: Exploring the Mississippi River Bluffs  

NSDL National Science Digital Library

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

347

Microbial Cretaceous park: biodiversity of microbial fossils entrapped in amber  

Microsoft Academic Search

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

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

2009-01-01

348

DNA and morphology unite two species and 10 million year old fossils.  

PubMed

Species definition and delimitation is a non-trivial problem in evolutionary biology that is particularly problematic for fossil organisms. This is especially true when considering the continuity of past and present species, because species defined in the fossil record are not necessarily equivalent to species defined in the living fauna. Correctly assigned fossil species are critical for sensitive downstream analysis (e.g., diversification studies and molecular-clock calibration). The marine snail genus Alcithoe exemplifies many of the problems with species identification. The paucity of objective diagnostic characters, prevalence of morphological convergence between species and considerable variability within species that are observed in Alcithoe are typical of a broad range of fossilised organisms. Using a synthesis of molecular and morphometric approaches we show that two taxa currently recognised as distinct are morphological variants of a single species. Furthermore, we validate the fossil record for one of these morphotypes by finding a concordance between the palaeontological record and divergence time of the lineage inferred using molecular-clock analysis. This work demonstrates the utility of living species represented in the fossil record as candidates for molecular-clock calibration, as the veracity of fossil species assignment can be more rigorously tested. PMID:23284880

Hills, Simon F K; Crampton, James S; Trewick, Steven A; Morgan-Richards, Mary

2012-12-20

349

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

PubMed Central

Assessing the extent to which population subdivision during cladogenesis is necessary for long-term phenotypic evolution is of fundamental importance in a broad range of biological disciplines. Differentiating cladogenesis from anagenesis, defined as evolution within a species, has generally been hampered by dating precision, insufficient fossil data, and difficulties in establishing a direct link between morphological changes detectable in the fossil record and biological species. Here we quantify the relative frequencies of cladogenesis and anagenesis for macroperforate planktic Foraminifera, which arguably have the most complete fossil record currently available, to address this question. Analyzing this record in light of molecular evidence, while taking into account the precision of fossil dating techniques, we estimate that the fraction of speciation events attributable to anagenesis is <19% during the Cenozoic era (last 65 Myr) and <10% during the Neogene period (last 23 Myr). Our central conclusion—that cladogenesis is the predominant mode by which new planktic Foraminifera taxa become established at macroevolutionary time scales—differs markedly from the conclusion reached in a recent study based solely on fossil data. These disparate findings demonstrate that interpretations of macroevolutionary dynamics in the fossil record can be fundamentally altered in light of genetic evidence.

Strotz, Luke C.; Allen, Andrew P.

2013-01-01

350

Risk for Human African Trypanosomiasis, Central Africa, 2000-2009  

PubMed Central

Comprehensive georeference records for human African trypanosomiasis in Cameroon, Central African Republic, Chad, Congo, Equatorial Guinea, and Gabon were combined with human population layers to estimate a kernel-smoothed relative risk function. Five risk categories were mapped, and ?3.5 million persons were estimated to be at risk for this disease.

Cecchi, Giuliano; Franco, Jose R.; Paone, Massimo; Fevre, Eric M.; Diarra, Abdoulaye; Postigo, Jose Antonio Ruiz; Mattioli, Raffaele C.; Jannin, Jean G.

2011-01-01

351

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

PubMed

Testing models of macroevolution, and especially the sufficiency of microevolutionary processes, requires good collaboration between molecular biologists and paleontologists. We report such a test for events around the Late Cretaceous by describing the earliest penguin fossils, analyzing complete mitochondrial genomes from an albatross, a petrel, and a loon, and describe the gradual decline of pterosaurs at the same time modern birds radiate. The penguin fossils comprise four naturally associated skeletons from the New Zealand Waipara Greensand, a Paleocene (early Tertiary) formation just above a well-known Cretaceous/Tertiary boundary site. The fossils, in a new genus (Waimanu), provide a lower estimate of 61-62 Ma for the divergence between penguins and other birds and thus establish a reliable calibration point for avian evolution. Combining fossil calibration points, DNA sequences, maximum likelihood, and Bayesian analysis, the penguin calibrations imply a radiation of modern (crown group) birds in the Late Cretaceous. This includes a conservative estimate that modern sea and shorebird lineages diverged at least by the Late Cretaceous about 74 +/- 3 Ma (Campanian). It is clear that modern birds from at least the latest Cretaceous lived at the same time as archaic birds including Hesperornis, Ichthyornis, and the diverse Enantiornithiformes. Pterosaurs, which also coexisted with early crown birds, show notable changes through the Late Cretaceous. There was a decrease in taxonomic diversity, and small- to medium-sized species disappeared well before the end of the Cretaceous. A simple reading of the fossil record might suggest competitive interactions with birds, but much more needs to be understood about pterosaur life histories. Additional fossils and molecular data are still required to help understand the role of biotic interactions in the evolution of Late Cretaceous birds and thus to test that the mechanisms of microevolution are sufficient to explain macroevolution. PMID:16533822

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

2006-03-13

352

Looking at Fossils in New Ways  

ERIC Educational Resources Information Center

|Existing fossils could be studied from a different prospective with the use of new methods of analysis for gathering more information. The new techniques of studying fossils binds the new and the old techniques and information and provides another way to look at fossils.|

Flannery, Maura C.

2005-01-01

353

Cycads: Fossil evidence of late paleozoic origin  

USGS Publications Warehouse

Plant fossils from Lower Permian strata of the southwestern United States have been interpreted as cycadalean megasporophylls. They are evidently descended from spermopterid elements of the Pennsylvanian Taeniopteris complex; thus the known fossil history of the cycads is extended from the Late Triassic into the late Paleozoic. Possible implications of the Permian fossils toward evolution of the angiosperm carpel are considered.

Mamay, S. H.

1969-01-01

354

A surprise inside a T. Rex fossil  

NSDL National Science Digital Library

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

American Association for the Advancement of Science (AAAS;)

2005-03-24

355

Science 101: What is a fossil?  

NSDL National Science Digital Library

A fossil is a preserved trace of an organism or event. There are many types of fossils.Usually these are preserved in sedimentary rocks--like sandstone, limestone, and shale--laid downon the surface of the planet or under its oceans. A paleontologist provides the basic facts about fossils.

Norell, Mark A.

2003-02-01

356

Cretaceous Fossils: Plants Quick Identification Gallery  

NSDL National Science Digital Library

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

Keith, Minor; Cretaceousfossils.com

357

Holocene and Lateglacial summer temperature reconstruction in the Swiss Alps based on fossil assemblages of aquatic organisms: a review  

Microsoft Academic Search

The taxonomic composition of chironomid, cladoceran and diatom assemblages in small lakes in the Alpine region shows a strong relationship with summer temperature. Since fossils of all three organism groups pre- serve well and remain identifiable in lake sediments, summer temperature transfer-functions can be developed based on the modern distribution of these organisms and applied to fossil records to reconstruct

Oliver Heiri; ANDREF. LOTTER

2005-01-01

358

A reappraisal of the evolution of Asian snakehead fishes (Pisces, Channidae) using molecular data from multiple genes and fossil calibration  

Microsoft Academic Search

Freshwater snakehead fishes (Channidae) provide an interesting target for phylogenetic analysis for the following reasons, their unusual biology, potential for cryptic diversity and availability of a good fossil record. Here, a multi-locus molecular phylogeny was constructed and calibrated using two fossil dates to estimate divergence times within the family. Sampling aimed to explore interspecific divergence of Channa species across Southeast

Eleanor A. S. Adamson; David A. Hurwood; Peter B. Mather

2010-01-01

359

Fossil groups of galaxies: Are they groups? Are they fossils?  

NASA Astrophysics Data System (ADS)

Fossil groups present a puzzle to current theories of structure formation. Despite the low number of bright galaxies, their high velocity dispersions and high TX indicate cluster-like potential wells. Measured concentration parameters seem very high indicating early formation epochs in contradiction with the observed lack of large and well defined cooling cores. There are very few fossil groups with good quality X-ray data and their idiosyncrasies may enhance these apparent contradictions. The standard explanation for their formation suggests that bright galaxies within half the virial radii of these systems were wiped out by cannibalism forming the central galaxy. Since dry mergers, typically invoked to explain the formation of the central galaxies, are not expected to change the IGM energetics significantly, thus not preventing the formation of cooling cores, we investigate the scenario where recent gaseous (wet) mergers formed the central galaxy injecting energy and changing the chemistry of the IGM in fossil groups. We show a test for this scenario using fossil groups with enough X-ray flux in the Chandra X-ray Observatory archive by looking at individual metal abundance ratio distributions near the core. Secondary SN II powered winds would tend to erase the dominance of SN IA ejecta in the core of these systems and would help to erase previously existing cold cores. Strong SN II-powered galactic winds resulting from galaxy merging would be trapped by their deep potential wells reducing the central enhancement of SN Ia/SN II iron mass fraction ratio. The results indicate that there is a decrement in the ratio of SN Ia to SN II iron mass fraction in the central regions of the systems analyzed, varying from 99±1% in the outer regions to 85±2% within the cooling radius (Figure 1) and would inject enough energy into the IGM preventing central gas cooling. The results are consistent with a scenario of later formation epoch for fossil groups, as they are defined, when compared to galaxy clusters and normal groups.

Dupke, Renato de Alencar; Miller, Eric; de Oliveira, Claudia Mendes; Sodre, Laerte; Rykoff, Eli; de Oliveira, Raimundo Lopes; Proctor, Rob

2010-11-01

360

Face-to-Fossil: An Interview with a Fossil Protoceratops (title provided or enhanced by cataloger)  

NSDL National Science Digital Library

This "interview" with a fossil Protoceratops provides students with an introduction to fossils and paleontology. The information includes what the Protoceratops was like when it was alive, how it became a fossil and how it got to the museum, and what its name means. In addition, there is information about how fossils are treated and displayed at the museum.

361

The Figuring of Diasporic Africans in Continental African Literature  

Microsoft Academic Search

Although the African presence in African American literature has received considerable scholarly attention, the images of the African American in African literature have not been given the critical attention they deserve. Our presentation examines the figuring of the African American in the fictional works of African prose writers. We shall survey the presentations and examine whether there is any discernible

Evan Mwangi

362

First Caribbean Floricomus (Araneae: Linyphiidae), a new fossil species in Miocene Dominican Republic amber. A new synonymy for the extant North American fauna  

Microsoft Academic Search

The new species Floricomus fossilis (Araneae: Linyphiidae) is described from Miocene Dominican Republic amber. This is the first fossil record of Floricomus, extending its known geological range by 15–20 Ma, and is the first record of the genus outside North America and Canada. Extant species may exist on Hispaniola, given the similarities between the known fossil and extant faunas. Most

David Penney

2005-01-01

363

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

Microsoft Academic Search

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

A. Van Horn; R. Wilson

1977-01-01

364

FOSSIL SPRINGS ROADLESS AREA, ARIZONA.  

USGS Publications Warehouse

Based on field studies, the Fossil Springs Roadless Area in central Arizona is concluded to have little promise for the occurrence of mineral or energy resources. Rocks in the Supai Formation (Pennsylvanian-Permian) near the central part of the roadless area contain widespread but spotty copper mineralization and trace amounts of uranium. Analyses obtained during the study define geochemical anomalies in two portions of the area that remain unexplained. The suites of anomalous metals suggest the possibility of hydrothermal veins and the presence of ultramafic rocks; neither were found in the field. Although there is little promise for the occurrence of mineral resources in the Fossil Springs Roadless Area, studies to identify the source of the geochemical anomalies could have valuable implications for regional studies and mineral exploration in the surrounding area.

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

1984-01-01

365

Oldest fossil basidiomycete clamp connections  

Microsoft Academic Search

A rachis of the fossil filicalean fern Botryopteris antiqua containing abundant septate hyphae with clamp connections is preserved in a late Visean (Mississippian; ~330 Ma) chert from\\u000a Esnost (Autun Basin) in central France. Largely unbranched tubular hyphae pass from cell to cell, but may sometimes produce\\u000a a branch from a clamp connection. Other clamp-bearing hyphae occur clustered in individual cells or

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

2011-01-01

366

Liquid fossil-fuel technology  

NASA Astrophysics Data System (ADS)

Highlights of research activities at Bartlesville Energy Technology Center for the quarter ending March 1982 are summarized. Major research areas are: liquid fossil fuel cycle; extraction (resource assessment and enhanced production); processing (characterization, thermodynamics, processing technology); utilization; and product integration and technology transfer. Special reports include: EOR data base, major new industry tool; properties of crude oils available via telephone hookup; alternative fuels data bank stresses transportation.

1982-07-01

367

Dinosaurs: Ancient Fossils, New Discoveries  

NSDL National Science Digital Library

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

368

Plant fossils from White Island  

Microsoft Academic Search

During the D.S.I.R. expedition to White Island in January 1947, plant fossils were discovered in bedded tuffaceous sands on the south side of the island, about 17 chains north-west of Ohauora Point. On this and other coastal headlands a formation of well bedded tuffaceous sands, locally including water-worn pebbles, is exposed from high-tide level to a height of at least

C. A. Fleming

1963-01-01

369

Middle Cambrian fossils from the Doonerak anticlinorium, central Brooks Range, Alaska.  

USGS Publications Warehouse

Middle Cambrian fossils collected near Wolf Creek in the Wiseman quadrangle, northern Alaska, include trilobites and paraconodonts. Trilobites date the strata as early Middle Cambrian, correlative with the Amgan Stage of Siberia. The assemblage includes: Kootenia cf. K. anabarensis Lermontova, cf. 'Parehmania' lata Chernysheva and Pagetia sp. Specimens of the paracondont genus Westergaardodina, from the same sample as the megafossils, record the earliest known occurrence of this taxon. These fossils, the first to establish an age for part of the sedimentary sequence in the Doonerak Anticlinorium, are the oldest fossils yet taken from the central and western Brooks Range.-Authors

Dutro, Jr, J. T.; Palmer, A. R.; Repetski, J. E.; Brosge, W. P.

1984-01-01

370

Trace-fossil model for reconstruction of paleo-oxygenation in bottom waters  

NASA Astrophysics Data System (ADS)

Recognition of fluctuations in the degree of paleo-oxygenation of bottom waters recorded in fine-grained pelagic strata is important for interpretation of paleoceanographic and paleoclimatologic conditions. General sedimentary fabric, composition of trace-fossil assemblages, and burrow size and crosscutting relationships have been incorporated into a trace-fossil tiering model that permits detailed reconstruction of changes in paleo-oxygenation of bottom waters. Applications of this model to the Miocene Monterey Formation (California) and the Cretaceous Niobrara Formation (Colorado) indicate that the ichnologic approach is more sensitive to both magnitude and rates of change in oxygenation levels compared to macrobenthic body-fossil information.

Savrda, Charles E.; Bottjer, David J.

1986-01-01

371

Implications of trace fossil assemblages from Late Paleozoic Glaciomarine Talchir Formation, Raniganj Basin, India  

Microsoft Academic Search

The trace fossil assemblages of the ice-marginal shallow marine sediments of the Talchir Formation (Permo-Carboniferous), Raniganj Basin, India, record the adverse effect of extreme climatic conditions on biota. The glaciomarine Talchir succession starts with glacial sediments near the base and gradually passes to storm-laid shallow marine sediments up-section. The fine-grained storm sediments host abundant trace fossils. Although the studied ichnites

Biplab Bhattacharya; H. N. Bhattacharya

2007-01-01

372

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

Microsoft Academic Search

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

J. William Schopf; Anatoliy B. Kudryavtsev

373

Generalized individual dental age stages for fossil and extant placental mammals  

Microsoft Academic Search

The traditional age stages for eutherian mammals (infant, juvenile, adult, senile) can be difficult to apply in the fossil\\u000a record. Based on the tooth eruption and wear of the cheek teeth we propose six “individual dental age stages” (IDAS) that\\u000a can be applied to almost all fossil and extant mammalian dentitions. The six stages of IDAS cover the entire life

Ulrike Anders; Wighart von Koenigswald; Irina Ruf; B. Holly Smith

374

Missing fossils, molecular clocks, and the origin of the Melastomataceae.  

PubMed

In a recent analysis of the historical biogeography of Melastomataceae, Renner, Clausing, and Meyer (2001; American Journal of Botany 88(7): 1290-1300) rejected the hypothesis of a Gondwana origin. Using a fossil-calibrated chloroplast DNA (ndhF) phylogeny, they placed the early diversification of Melastomataceae in Laurasia at the Paleocene/Eocene boundary (ca. 55 Ma) and suggested that long-distance oceanic dispersals in the Oligocene and Miocene (34 to 5 Ma) account for its range expansion into South America, Africa, and Madagascar. Their critical assumption-that oldest northern mid-latitude melastome fossils reflect tribal ages and their geographic origins-may be erroneous, however, because of the sparse fossil record in the tropics. We show that rates of synonymous nucleotide substitutions derived by the Renner et al. (2001) model are up to three times faster than most published rates. Under a Gondwana-origin model advocated here, which includes dispersals from Africa to Southeast Asia via the "Indian ark" and emphasizes filter rather than either sweepstakes dispersal or strict vicariance, rates of nucleotide substitution fall within the range of published rates. We suggest that biogeographic reconstructions need to consider the paucity of Gondwanan fossils and that frequently overlooked interplate dispersal routes provide alternatives to vicariance, boreotropical dispersal, and long-distance oceanic dispersal as explanations for the amphi-oceanic disjunctions of many tropical rain forest plants. PMID:21653339

Morley, Robert J; Dick, Christopher W

2003-11-01

375

Mental Health: African Americans  

MedlinePLUS

... education, employment, and health care. However, strong social, religious, and family connections have helped many African Americans ... church and community to cope. The level of religious commitment among African Americans is high. In one ...

376

Ectoparasites of African Mammals.  

National Technical Information Service (NTIS)

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

C. S. Herrin V. J. Tipton

1976-01-01

377

Stroke and African Americans  

MedlinePLUS

... are several risk factors related to stroke. Some of these risk factors are: Obesity and Overweight – See Obesity and African Americans Hypertension – See Heart Disease and African Americans High ...

378

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

SciTech Connect

We use SDSS-DR4 photometric and spectroscopic data out to redshift z {approx} 0.1 combined with ROSAT All Sky Survey X-ray data to produce a sample of 25 fossil groups (FGs), defined as bound systems dominated by a single, luminous elliptical galaxy with extended X-ray emission. We examine possible biases introduced by varying the parameters used to define the sample, and the main pitfalls are also discussed. The spatial density of FGs, estimated via the V/V {sub MAX} test, is 2.83 x 10{sup -6} h {sup 3} {sub 75} Mpc{sup -3} for L{sub X} > 0.89 x 10{sup 42} h {sup -2} {sub 75} erg s{sup -1} consistent with Vikhlinin et al., who examined an X-ray overluminous elliptical galaxy sample (OLEG). We compare the general properties of FGs identified here with a sample of bright field ellipticals generated from the same data set. These two samples show no differences in the distribution of neighboring faint galaxy density excess, distance from the red sequence in the color-magnitude diagram, and structural parameters such as a {sub 4} and internal color gradients. Furthermore, examination of stellar populations shows that our 25 FGs have similar ages, metallicities, and {alpha}-enhancement as the bright field ellipticals, undermining the idea that these systems represent fossils of a physical mechanism that occurred at high redshift. Our study reveals no difference between FGs and field ellipticals, suggesting that FGs might not be a distinct family of true fossils, but rather the final stage of mass assembly in the universe.

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

2009-04-15

379

The Nature of Fossil Galaxy Groups: Are They Really Fossils?  

NASA Astrophysics Data System (ADS)

We use SDSS-DR4 photometric and spectroscopic data out to redshift z ~ 0.1 combined with ROSAT All Sky Survey X-ray data to produce a sample of 25 fossil groups (FGs), defined as bound systems dominated by a single, luminous elliptical galaxy with extended X-ray emission. We examine possible biases introduced by varying the parameters used to define the sample, and the main pitfalls are also discussed. The spatial density of FGs, estimated via the V/V MAX test, is 2.83 × 10-6 h 3 75 Mpc-3 for LX > 0.89 × 1042 h -2 75 erg s-1 consistent with Vikhlinin et al., who examined an X-ray overluminous elliptical galaxy sample (OLEG). We compare the general properties of FGs identified here with a sample of bright field ellipticals generated from the same data set. These two samples show no differences in the distribution of neighboring faint galaxy density excess, distance from the red sequence in the color-magnitude diagram, and structural parameters such as a 4 and internal color gradients. Furthermore, examination of stellar populations shows that our 25 FGs have similar ages, metallicities, and ?-enhancement as the bright field ellipticals, undermining the idea that these systems represent fossils of a physical mechanism that occurred at high redshift. Our study reveals no difference between FGs and field ellipticals, suggesting that FGs might not be a distinct family of true fossils, but rather the final stage of mass assembly in the universe.

La Barbera, F.; de Carvalho, R. R.; de la Rosa, I. G.; Sorrentino, G.; Gal, R. R.; Kohl-Moreira, J. L.

2009-04-01

380

The African Connection  

ERIC Educational Resources Information Center

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

Oguntoyinbo, Lekan

2012-01-01

381

Traditional African American foods and African Americans  

Microsoft Academic Search

Traditional African American foods, also referred to as “soul food,” are often given a blanket label of “poor food choices.” The cultural value of these ethnic foods may be disregarded without sufficient study of their nutrient content. This study showed that of the various foods perceived as traditionally African American by the local sampled population, greens were the most often

Drucilla Byars

1996-01-01

382

Record Production  

NSDL National Science Digital Library

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

2006-12-18

383

Record reviews  

Microsoft Academic Search

Tom Paxton, Bulletin . . . Hogeye Records. HOB 004.Eddy Raven. I COULD USE ANOTHER YOU. RCA Victor. AHL 1–5040.Hoyt Axton. DOWN AND OUT. Allegiance Records Ltd. AV 5023 (budget?line).Dio, THE LAST IN LINE. Warner Bros. Records 25100–1.J.D. Souther, HOME BY DAWN. Warner Bros. Records 25081–1.James Lee Stanley, RACING THE MOON. Takoma TAK 7110.BILLY SATELLITE. Capitol Records. ST?12340.WOLF AND WOLF.

R. Serge Denisoff; James K. Skipper Jr; Lajos Vincze

1983-01-01

384

Record reviews  

Microsoft Academic Search

Nitty Gritty Dirt Band, HOLD ON Warner Brothers Records 25573–1INCREDIBLE INVINCIBLE SAMPLER Invincible INV 121Gabriel Lee, IMPRESSIONS Narada Records LP 1005Frank Mills TRANSITIONS Capitol Records CLT?46461Waylon Jennings, A MAN CALLED HOSS. MCA Records MCA 42038Archie Green. Work's Many Voices—Volumes I and II. (JEMF 110\\/111). El Cerrito, California: John Edwards Memorial Forum (Arhoolie Records), 1987. $8.98 per album.CANNONBALL ADDERLEY. Cannonball In

R. Serge Denisoff; B. Lee Cooper; James K. Skipper Jr

1988-01-01

385

Record reviews  

Microsoft Academic Search

The Grapes of Wrath, SEPTEMBER BOWL of GREEN. Capitol 12537–1.Sawyer Brown, OUT GOIN CATTIN’. Capital Records ST?12517Ian Messenger, HANDS ACROSS THE NIGHT. Quest Records 25401–1.WILD CHERRY. RCA Victor AEL 1–5810.Hank Williams THE FIRST RECORDINGS. CMF Records CMF 00BRUCE SPRINGSTEEN & THE E STREET BAND LIVE 1975–1985 Columbia Records C5X 40558.John Fogerty, EYE OF THE ZOMBIE. Warner Bros. 1–25449Creedence Clearwater Revival,

R. Serge Denisoff; James K. Skipper Jr

1987-01-01

386

Scaling relations in fossil galaxy groups  

NASA Astrophysics Data System (ADS)

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

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

2007-05-01

387

Prosodic Rhythm and African American English  

Microsoft Academic Search

Prosodic rhythm was measured for a sample of 20 African American and 20 European American speakers from North Carolina using the metric devised by Low, Grabe, and Nolan (2000), which involves comparisons of the durations of vowels in adjacent syllables. In order to gain historical perspective, the same technique was applied to the ex-slave recordings described in Bailey, Maynor, and

Erik R. Thomas; Phillip M. Carter

2006-01-01

388

Breast masses in African American teenage girls  

Microsoft Academic Search

Purpose: The aim of this study was to evaluate the incidence of malignancy in breast lumps excised from African American teenagers.Methods: The authors reviewed the pathology records at King's County Hospital Center between January 1982 and December 1992. The pathology reports and charts of all patients who had breast masses excised during this period were reviewed. Data for this study

Mahmoud B. El-Tamer; Mark Song; Richard B. Wait

1999-01-01

389

INFANT AFRICAN ELEPHANT RUMBLE VOCALIZATIONS VARY ACCORDING TO SOCIAL INTERACTIONS WITH ADULT FEMALES  

Microsoft Academic Search

Research on African elephant (Loxodonta africana) vocal communication has increased in recent years, yet there has been very little data collected on the vocal production of infant African elephants. Vocalizations were recorded from a group of five adult female African elephants and 3 dependent offspring (1 male and 2 female) at Disney's Animal Kingdom, Florida, U.S.A., using custom-designed audio-recording collars

CHRISTINA M. WESOLEK; JOSEPH SOLTIS; KATHERINE A. LEIGHTY; ANNE SAVAGE

2009-01-01

390

Three-dimensional Magnetic Resonance Imaging of fossils across taxa  

NASA Astrophysics Data System (ADS)

The visibility of life forms in the fossil record is largely determined by the extent to which they were mineralised at the time of their death. In addition to mineral structures, many fossils nonetheless contain detectable amounts of residual water or organic molecules, the analysis of which has become an integral part of current palaeontological research. The methods available for this sort of investigations, though, typically require dissolution or ionisation of the fossil sample or parts thereof, which is an issue with rare taxa and outstanding materials like pathological or type specimens. In such cases, non-destructive techniques could provide an interesting methodological alternative. While Computed Tomography has long been used to study palaeontological specimens, a number of complementary approaches have recently gained ground. These include Magnetic Resonance Imaging (MRI) which had previously been employed to obtain three-dimensional images of pathological belemnites non-invasively on the basis of intrinsic contrast. The present study was undertaken to investigate whether 1H MRI can likewise provide anatomical information about non-pathological belemnites and specimens of other fossil taxa. To this end, three-dimensional MR image series were acquired from intact non-pathological invertebrate, vertebrate and plant fossils. At routine voxel resolutions in the range of several dozens to some hundreds of micrometers, these images reveal a host of anatomical details and thus highlight the potential of MR techniques to effectively complement existing methodological approaches for palaeontological investigations in a wide range of taxa. As for the origin of the MR signal, relaxation and diffusion measurements as well as 1H and 13C MR spectra acquired from a belemnite suggest intracrystalline water or hydroxyl groups, rather than organic residues.

Mietchen, D.; Aberhan, M.; Manz, B.; Hampe, O.; Mohr, B.; Neumann, C.; Volke, F.

2007-08-01

391

Three-dimensional Magnetic Resonance Imaging of fossils across taxa  

NASA Astrophysics Data System (ADS)

The frequency of life forms in the fossil record is largely determined by the extent to which they were mineralised at the time of their death. In addition to mineral structures, many fossils nonetheless contain detectable amounts of residual water or organic molecules, the analysis of which has become an integral part of current palaeontological research. The methods available for this sort of investigations, though, typically require dissolution or ionisation of the fossil sample or parts thereof, which is an issue with rare taxa and outstanding materials like pathological or type specimens. In such cases, non-destructive techniques could provide a valuable methodological alternative. While Computed Tomography has long been used to study palaeontological specimens, a number of complementary approaches have recently gained ground. These include Magnetic Resonance Imaging (MRI) which had previously been employed to obtain three-dimensional images of pathological belemnites non-invasively on the basis of intrinsic contrast. The present study was undertaken to investigate whether 1H MRI can likewise provide anatomical information about non-pathological belemnites and specimens of other fossil taxa. To this end, three-dimensional MR image series were acquired from intact non-pathological invertebrate, vertebrate and plant fossils. At routine voxel resolutions in the range of several dozens to some hundreds of micrometers, these images reveal a host of anatomical details and thus highlight the potential of MR techniques to effectively complement existing methodological approaches for palaeontological investigations in a wide range of taxa. As for the origin of the MR signal, relaxation and diffusion measurements as well as 1H and 13C MR spectra acquired from a belemnite suggest intracrystalline water or hydroxyl groups, rather than organic residues.

Mietchen, D.; Aberhan, M.; Manz, B.; Hampe, O.; Mohr, B.; Neumann, C.; Volke, F.

2008-01-01

392

Fossil Cercopithecidae from the Hadar Formation and surrounding areas of the Afar Depression, Ethiopia.  

PubMed

Hadar is well known as one of the most productive early hominin sites in the world. Between 1972 and 1994 a large sample of fossil cercopithecid specimens was collected from Hadar and the nearby sites of Geraru, Ahmado, and Leadu. At least five, and possibly six, species are present in the sample, including two chronological subspecies of Theropithecus oswaldi. T. o. cf. darti is known from the Middle Pliocene deposits in the Hadar area, along with Parapapio cf. jonesi, cf. Rhinocolobus turkanaensis, and a new species of Cercopithecoides, C. meaveae. There are also isolated molars from the Middle Pliocene of a large colobine which most likely represent cf. R. turkanaensis, but may also represent another large colobine known from the nearby site of Maka in the Middle Awash. T. o. oswaldi is represented from younger deposits of Late Pliocene and Early Pleistocene age, along with the large colobine Cercopithecoides kimeui. Throughout the sequence Theropithecus oswaldi is by far the most abundant cercopithecid, with the other taxa being comparatively rare. The Parapapio material from Hadar is important as the only securely identifiable material of the genus in the East African Pliocene. Furthermore, the Hadar material includes the only associated postcranial remains for the genus. If the tentative identification of Rhinocolobus is correct, then the Hadar sample is the only known occurrence outside of the Turkana Basin. Cercopithecoides meaveae is a new species, currently only known from the Hadar region, most importantly by the associated partial skeleton from Leadu. It appears to show adaptations for terrestrial locomotion. Finally, Cercopithecoides kimeui, a very large colobine previously known from Olduvai Gorge, Koobi Fora, and Rawi is recorded from the uppermost part of the Formation. PMID:12457855

Frost, Stephen R; Delson, Eric

2002-11-01

393

Layered Fossil Parfait: Deeper is Older  

NSDL National Science Digital Library

In this activity, learners explore dinosaur fossils by making an edible treat. First, learners read "Dinosaur Bones" by Aliki to examine how fossils are formed. Then, the educator sifts through the class garbage to demonstrate that the deeper something is buried the older it may be. Next, learners make a layered dinosaur fossil model using candy and other treats. This activity is featured on page 30 of the "Dinosphere" unit of study for K-2 learners.

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

2004-01-01

394

Teaching Through Trade Books: Fascinating Fossil Finds  

NSDL National Science Digital Library

This month's Teaching Through Trade Books column engages students in "unearthing" fossils and exploring the processes scientists use in uncovering these fascinating finds and interpreting Earth's past.

Royce, Chrstine A.

2004-10-01

395

Fossil evidence for the early ant evolution.  

PubMed

Ants are one of the most studied insects in the world; and the literature devoted to their origin and evolution, systematics, ecology, or interactions with plants, fungi and other organisms is prolific. However, no consensus yet exists on the age estimate of the first Formicidae or on the origin of their eusociality. We review the fossil and biogeographical record of all known Cretaceous ants. We discuss the possible origin of the Formicidae with emphasis on the most primitive subfamily Sphecomyrminae according to its distribution and the Early Cretaceous palaeogeography. And we review the evidence of true castes and eusociality of the early ants regarding their morphological features and their manner of preservation in amber. The mid-Cretaceous amber forest from south-western France where some of the oldest known ants lived, corresponded to a moist tropical forest close to the shore with a dominance of gymnosperm trees but where angiosperms (flowering plants) were already diversified. This palaeoenvironmental reconstruction supports an initial radiation of ants in forest ground litter coincident with the rise of angiosperms, as recently proposed as an ecological explanation for their origin and successful evolution. PMID:17891532

Perrichot, Vincent; Lacau, Sébastien; Néraudeau, Didier; Nel, André

2007-09-19

396

Fossil evidence for the early ant evolution  

NASA Astrophysics Data System (ADS)

Ants are one of the most studied insects in the world; and the literature devoted to their origin and evolution, systematics, ecology, or interactions with plants, fungi and other organisms is prolific. However, no consensus yet exists on the age estimate of the first Formicidae or on the origin of their eusociality. We review the fossil and biogeographical record of all known Cretaceous ants. We discuss the possible origin of the Formicidae with emphasis on the most primitive subfamily Sphecomyrminae according to its distribution and the Early Cretaceous palaeogeography. And we review the evidence of true castes and eusociality of the early ants regarding their morphological features and their manner of preservation in amber. The mid-Cretaceous amber forest from south-western France where some of the oldest known ants lived, corresponded to a moist tropical forest close to the shore with a dominance of gymnosperm trees but where angiosperms (flowering plants) were already diversified. This palaeoenvironmental reconstruction supports an initial radiation of ants in forest ground litter coincident with the rise of angiosperms, as recently proposed as an ecological explanation for their origin and successful evolution.

Perrichot, Vincent; Lacau, Sébastien; Néraudeau, Didier; Nel, André

2008-02-01

397

Fossilization causes organisms to appear erroneously primitive by distorting evolutionary trees  

PubMed Central

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

Sansom, Robert S.; Wills, Matthew A.

2013-01-01

398

Fossil fuel biodegradation: Laboratory studies  

SciTech Connect

Biodegradation of the polycyclic: aromatic hydrocarbons of creosote by undefined bacterial cultures was shown to be accompanied by the accumulation of neutral and acidic oxidation products. Formation of a number of identified neutral products is accounted for by demonstration of anomalous actions of an arene dioxygenase on the benzylic methylene and methylene carbons of napthencaromatic hydrocarbons. Both neutral and acidic water-soluble fractions are also formed when various mixed bacterial cultures degrade weathered crude oil. While constituents of these fractions are not yet identified, the neutral materials have been shown to be toxic to developing embryos of invertebrates. These observations are discussed in relation to chemical and toxicological assessments of biodegradation of the complex chemical mixtures of fossil fuels. 14 refs., 3 figs., 1 tab.

Chapman, P.J. [Environmental Research Lab., Gulf Breeze, FL (United States); Shelton, M.; Selifonov, S. [Univ. of West Florida, Pensacola, FL (United States); Grifoll, M. [Univ. of Barcelona (Spain)

1995-06-01

399

Fossil fuel biodegradation: laboratory studies.  

PubMed Central

Biodegradation of the polycyclic aromatic hydrocarbons of creosote by undefined bacterial cultures was shown to be accompanied by the accumulation of neutral and acidic oxidation products. Formation of a number of identified neutral products is accounted for by demonstration of anomalous actions of an arene dioxygenase on the benzylic methylene and methylene carbons of napthenoaromatic hydrocarbons. Both neutral and acidic water-soluble fractions are also formed when various mixed bacterial cultures degrade weathered crude oil. While constituents of these fractions are not yet identified, the neutral materials have been shown to be toxic to developing embryos of invertebrates. These observations are discussed in relation to chemical and toxicological assessments of biodegradation of the complex chemical mixtures of fossil fuels.

Chapman, P J; Shelton, M; Grifoll, M; Selifonov, S

1995-01-01

400

Proposing Explanations for Fossil Footprints  

NSDL National Science Digital Library

This activity will allow students to observe and interpret fossil footprint evidence. From the evidence, they are asked to construct defensible hypotheses or explanations for events that took place in the geological past. Students will be asked to propose explanations and make predictions based on evidence, recognize and analyze alternative explanations and predictions, understand that scientific explanations are subject to change as new evidence becomes available, and understand that scientific explanations must meet certain criteria. Students learn that scientific explanations must be consistent with experimental and observational evidence, should also be logical, respect the rules of evidence, be open to criticism, report methods and procedures, and make knowledge public. The site contains all of the information and instructions needed to complete the activity.

401

Some Quantitative Dental Characters of Fossil Anthropoids  

Microsoft Academic Search

Comparisons have been made by means of appropriate statistical methods between the dental dimensions and indices of several species of fossil anthropoids and those of modern apes. In nearly all cases the fossil teeth have been found not to differ significantly from one or other type of extant great ape, and in several a strong resemblance exists between all the

E. H. Ashton; S. Zuckerman

1950-01-01

402

Silica-replaced fossils through the Phanerozoic  

Microsoft Academic Search

A systematic survey of 1863 papers on macrobenthic assemblages reveals that an average of 21% of published Paleozoic papers concern silicified fossils, but that average drops to just 4% for post-Paleozoic papers. During the Paleozoic, silicified fossil occurrences do not significantly correlate with the amount of shelf chert, outcrop area, time, duration of geologic intervals, or carbonate rock volume. This

Jennifer K. Schubert; David L. Kidder; Douglas H. Erwin

1997-01-01

403

Forty Years Later: Updating the Fossilization Hypothesis  

ERIC Educational Resources Information Center

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

Han, ZhaoHong

2013-01-01

404

Accuracy of Fossils and Dating Methods  

NSDL National Science Digital Library

The issue-focused, peer-reviewed article asserts that fossil dating is accurate because the method follows strict scientific guidelines: the age of rocks around a fossil can be considered, mathematical calculations are used, the state of decay, carbon-14, and isotopes figure in calculations, and tree of life relationships often help sort the dates.

Michael Benton (University of Bristol, UK;)

2001-01-01

405

Safe venting for fossil fuel fired equipment  

Microsoft Academic Search

Energy conservation in the residential heating market is one of the used methods to reduce the use of fossil fuels and extend the life of the known North American fossil fuel reserves. The other benefit, is the reduction of combustion by-products that are produced and then injected into the atmosphere. The drive for energy conservation has not been without its

H. R. West; K. D. Bryant

1988-01-01

406

Fossil energy program report, 1975--1976  

Microsoft Academic Search

The newly created Energy Research and Development Administration greatly expanded its horizons for Fossil Energy technology in 1975-76, especially in moving toward large demonstration projects for converting coal to clean fuels. Significant progress was achieved in developing the Fossil Energy research program, notably the enlistment of universities, and in securing industry participation in cost-sharing projects for the enhanced recovery of

R. C. Jr. Seamans; P. C. White

1976-01-01

407

Fossil fuel usage and the environment  

Microsoft Academic Search

The Greenhouse Effect and global warming, ozone formation in the troposphere, ozone destruction in the stratosphere, and acid rain are important environmental issues. The relationship of fossil fuel usage to some of these issues is discussed. Data on fossil fuel consumption and the sources and sinks of carbon dioxide, carbon monoxide, methane, nitrogen and sulfur oxides, and ozone indicate that

Klass

1990-01-01

408

When will fossil fuel reserves be diminished?  

Microsoft Academic Search

Crude oil, coal and gas are the main resources for world energy supply. The size of fossil fuel reserves and the dilemma that “when non-renewable energy will be diminished” is a fundamental and doubtful question that needs to be answered. This paper presents a new formula for calculating when fossil fuel reserves are likely to be depleted and develops an

Shahriar Shafiee; Erkan Topal

2009-01-01

409

Do alternative energy sources displace fossil fuels?  

NASA Astrophysics Data System (ADS)

A fundamental, generally implicit, assumption of the Intergovernmental Panel on Climate Change reports and many energy analysts is that each unit of energy supplied by non-fossil-fuel sources takes the place of a unit of energy supplied by fossil-fuel sources. However, owing to the complexity of economic systems and human behaviour, it is often the case that changes aimed at reducing one type of resource consumption, either through improvements in efficiency of use or by developing substitutes, do not lead to the intended outcome when net effects are considered. Here, I show that the average pattern across most nations of the world over the past fifty years is one where each unit of total national energy use from non-fossil-fuel sources displaced less than one-quarter of a unit of fossil-fuel energy use and, focusing specifically on electricity, each unit of electricity generated by non-fossil-fuel sources displaced less than one-tenth of a unit of fossil-fuel-generated electricity. These results challenge conventional thinking in that they indicate that suppressing the use of fossil fuel will require changes other than simply technical ones such as expanding non-fossil-fuel energy production.

York, Richard

2012-06-01

410

Global Warming and Future Fossil Fuel Consumption  

Microsoft Academic Search

This paper reviews the potential for reducing emissions of CO, by reducing the use of fossil fuels. Following a brief review of current data on greenhouse gas emissions and global warming\\/ the author considers three ways of decreasing fossil fuel consumption: doing without; maximizing conversion efficiencies; and reducing the use of energy intensive products through better design and extensive recycling

Vaclav Smil

1989-01-01

411

The Microbial Origin of Fossil Fuels  

Microsoft Academic Search

The authors have investigated the genesis of fossil fuels and different kinds of sedimentary deposits by studying the structure of individual fossil compounds in order to deduce the structure of their precursors in living organisms. Analysis revealed unexpected similarities, specifically in the pattern of peaks in gas chromatograms in the Cââ to Cââ region. Thousands of samples taken from all

Guy Ourisson; Pierre Albrecht; Michel Rohmer

1984-01-01

412

Forty Years Later: Updating the Fossilization Hypothesis  

ERIC Educational Resources Information Center

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

Han, ZhaoHong

2013-01-01

413

African-American Alcoholics  

Microsoft Academic Search

It is estimated that two million African-Americans suffer directly and indirectly from alcoholism and its related problems. Yet, because of their cultural background, African-American alcoholics do not readily accept that alcoholism is a disease. This study explores how African-American alcoholics modify the steps and traditions of AA to affiliate with the organization. Data was collected from intensive and semi-structured interviews

Arthur Durant

2005-01-01

414

African-Americans and Alzheimer's  

MedlinePLUS

Home > Living with Diverse Communities > African Americans and Alzheimer's African Americans and Alzheimer's African-Americans may be at a higher risk for Alzheimer's disease. Know the warning signs and be aware. ...

415

John Day Fossil Beds National Monument  

NSDL National Science Digital Library

This National Park Service website offers an education section which includes: programs for visiting school groups involving the geological and evolutionary processes of the park, working with fossil casts, and other fossil activities; a list of classroom materials to send for (some have cost) including a horse fossil study kit, a general fossil kit, a teacher packet, and a videotape on the paleontology work at the park and evolution of the horse; and a list of teacher workshops in Oregon. There are species lists for vertebrate and plant fossils, diagrams of the major geologic formations and illustrations of different paleobiomes, species lists for existing flora and fauna, and a fire management plan. Regional and park history is covered as well as the history of the Chinookan, Sahaptian, Shoshonean, and Salishan Indians of Eastern Oregon. There is also information for planning a visit to the park.

416

Mesoscale Fossil Diversity and Ecosystem Modeling in the Cenozoic  

NASA Astrophysics Data System (ADS)

Numerous experiments of extant ecosystems have tested aspects of modern niche theory as they relate to the development and maintenance of species richness in a geographic area. As such, species richness has often been observed to be a consequence of heterogeneous conditions within the ecosystem provided by environmental gradients, moderate levels of disturbance, and complex trophic interactions that give rise to niche partitioning. By contrast some studies of the fossil record have focused on identifying governing parameters for paleodiversity using instead simplified models of ecosystem interaction, which violate principles of niche theory. To examine ecosystem diversity within the most recent 60 Ma, we analyzed the depositional environment and lithologies of 17,984 globally distributed marine fossil assemblages, focusing on the relationship between diversity and ecosystem gradients. Our results indicate that although there is a myriad of factors that can provide for high fossil diversity within a geographic area, only a few ecosystem gradients are needed to explain the majority of that diversity. Our findings are consistent with modern niche theory and may extend the robustness of this concept significantly through time.

Brooks, B.; Cervato, C.

2008-12-01

417

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

418

Altered states: Effects of diagenesis on fossil tooth chemistry  

SciTech Connect

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

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

1999-09-01

419

Small mid-Pleistocene hominin associated with East African Acheulean technology.  

PubMed

Hominin fossils from the African mid-Pleistocene are rare despite abundant Acheulean tools in Africa and apparently African-derived hominins in Eurasia between 1.0 and 0.5 million years ago (Ma). Here we describe an African fossil cranium constrained by 40Ar/39Ar analyses, magnetostratigraphy, and sedimentary features to 0.97 to 0.90 Ma, and stratigraphically associated with Acheulean handaxes. Although the cranium represents possibly the smallest adult or near-adult known between 1.7 and 0.5 Ma, it retains features observed in larger Homo erectus individuals, yet shows a distinct suite of traits indicative of wide population variation in the hominins of this period. PMID:15232102

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

2004-07-01

420

Fossil oak galls preserve ancient multitrophic interactions  

PubMed Central

Trace fossils of insect feeding have contributed substantially to our understanding of the evolution of insect–plant interactions. The most complex phenotypes of herbivory are galls, whose diagnostic morphologies often allow the identification of the gall inducer. Although fossil insect-induced galls over 300?Myr old are known, most are two-dimensional impressions lacking adequate morphological detail either for the precise identification of the causer or for detection of the communities of specialist parasitoids and inquilines inhabiting modern plant galls. Here, we describe the first evidence for such multitrophic associations in Pleistocene fossil galls from the Eemian interglacial (130?000–115?000 years ago) of The Netherlands. The exceptionally well-preserved fossils can be attributed to extant species of Andricus gallwasps (Hymenoptera: Cynipidae) galling oaks (Quercus), and provide the first fossil evidence of gall attack by herbivorous inquiline gallwasps. Furthermore, phylogenetic placement of one fossil in a lineage showing obligate host plant alternation implies the presence of a second oak species, Quercus cerris, currently unknown from Eemian fossils in northwestern Europe. This contrasts with the southern European native range of Q. cerris in the current interglacial and suggests that gallwasp invasions following human planting of Q. cerris in northern Europe may represent a return to preglacial distribution limits.

Stone, Graham N; van der Ham, Raymond W.J.M; Brewer, Jan G

2008-01-01

421

Cycling operation of fossil plants  

SciTech Connect

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

Bhatnagar, U.S.; Weiss, M.D.; White, W.H. (Potomac Electric Power Co., Washington, DC (USA)); Buchanan, T.L.; Harvey, L.E.; Shewchuk, P.K.; Weinstein, R.E. (Gilbert/Commonwealth, Inc., Reading, PA (USA))

1991-05-01

422

Systematics of some enigmatic "fossils"  

NSDL National Science Digital Library

Students are given sets of different shaped fasteners (staples, paper clips, tacks, etc.) and work with the instructor through a guided exercise in which they construct a character matrix and cladogram depicting the phylogeny of the "organisms". Students are then divided into small groups; each group receives a set of various shapes/colors of pasta. (The sets are all the same.) Each group must decide how many species are present in their sample (considering the potential for ontogenetic and sexual variation within species), choose and define characters for a cladistic analysis, and construct a character matrix. The instructor runs the matrices through cladistic analysis software, and the following week the students receive the results from analysis of each group's data. The class then discusses the effects of species definition, character choice, etc. on phylogenetic hypotheses. The activity allows students to directly confront issues of identifying and distinguishing morphological species. Conflicting results obtained by different groups analyzing the same data set drive home the complicated nature of character choice and definition in construction of a character matrix for cladistic analysis, and underscore the fact that individual cladograms represent phylogenetic hypotheses subject to modification by further analysis. (This last point becomes necessary background as students encounter different/competing hypotheses of phylogenetic relationships during study of fossil invertebrates.)

Tumarkin-Deratzian, Allison

423

Assessing fluctuating odontometric asymmetry among fossil hominin taxa through alternative measures of central tendency: Effect of outliers and directional components on reported results  

Microsoft Academic Search

Preliminary inquires into the distribution and expression of fluctuating odontometric asymmetry (FOA), among selected fossil hominins, have revealed results that may be serviceable within studies that assess, among others, palaeobiological, evolutionary processes and events. Though several intricate statistical applications have aided in the advancement of FOA to the hominin fossil record, little is known regarding the influence of outliers and

A. D. T. Kegley; J. Hemingway

2007-01-01

424

Ptychoptera deleta Nov?k, 1877 from the Early Miocene of the Czech Republic: redescription of the first fossil attributed to Ptychopteridae (Diptera)  

PubMed Central

Abstract The first fossil that was described in Ptychopteridae, Ptychoptera deletaNovák, 1877 from the classical Early Miocene locality Mok?ina (Krottensee) in western Bohemia is re-examined. The re-description of the holotype including a new line drawing and remarks summarizing the scarce fossil record of this group is provided.

Krzeminski, Wieslaw; Prokop, Jakub

2011-01-01

425

Fossil groups origins. I. RX J105453.3+552102 a very massive and relaxed system at z ~ 0.5  

Microsoft Academic Search

Context. The most accepted scenario for the origin of fossil groups is that they are galaxy associations in which the merging rate was fast and efficient. These systems have assembled half of their mass at early epoch of the Universe, subsequently growing by minor mergers, and therefore could contain a fossil record of the galaxy structure formation. Aims: We have

J. A. L. Aguerri; M. Girardi; W. Boschin; R. Barrena; J. Méndez-Abreu; R. Sánchez-Janssen; S. Borgani; N. Castro-Rodriguez; E. M. Corsini; C. Del Burgo; E. D'Onghia; J. Iglesias-Páramo; N. Napolitano; J. M. Vilchez

2011-01-01

426

Keeping African Masks Real  

ERIC Educational Resources Information Center

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

Waddington, Susan

2012-01-01

427

Trypanosomiasis: African and American  

Microsoft Academic Search

Human African trypanosomiasis has increased in many endemic areas in recent years. It is caused by Trypanosoma brucei gambiense or T. b. rhodesiense, and is transmitted by the tsetse fly. Diagnosis is difficult, particularly in the West African type, in which organisms are scanty. Determination of the stage of infection (early haemolymphatic stage or late meningoencephalitic stage) is also problematic,

Sanjeev Krishna; August Stich

2005-01-01

428

The African Ephemeridae (Ephemeroptera)  

Microsoft Academic Search

The known African Ephemeridae presently consists of three genera and seven nominal species. Adults and larvae of Afromera evae sp. n. aredescribed from The Gambia. The genus Afromera is recognized as being distinct from Ephemera and is evidently equivalent to the subgenus Dicrephemera (of Ephemera) which is thus synonymized. Larvae of African Ephemeridae are keyed to genus, and adults are

W. P. McCafferty; M. T. Gillies

1979-01-01

429

Dictionary of African Biography  

Microsoft Academic Search

Giovanni Ruffini is a contributing author, “Flavius Apion,” “Flavius Dioskoros,” “Bishop Georgios” and “Bishop Timotheos.”\\u000aBook description: A major biographical dictionary covering the lives and legacies of notable African men and women from all eras and walks of life. This resource tells the full story of the African continent through the lives of its people.

Gates Henry Louis Jr; Emmanuel Akyeampong; Giovanni Ruffini

2011-01-01

430

African Literature as Celebration.  

ERIC Educational Resources Information Center

Describes the Igbo tradition of "Mbari," a communal creative enterprise that celebrates the world and the life lived in it through art. Contrasts the cooperative, social dimension of pre-colonial African culture with the exclusion and denial of European colonialism, and sees new African literature again celebrating human presence and dignity. (AF)

Achebe, Chinua

1989-01-01

431

16 Extraordinary African Americans.  

ERIC Educational Resources Information Center

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

Lobb, Nancy

432

Identification of Africanized honeybees  

Microsoft Academic Search

Gas chromatography and pattern recognition methods were used to develop a potential method for differentiating European honeybees from Africanized honeybees. The test data consisted of 237 gas chromatograms of hydrocarbon extracts obtained from the wax glands, cuticle, and exocrine glands of European and Africanized honeybees. Each gas chromatogram contained 65 peaks corresponding to a set of standardized retention time windows.

Barry K. Lavine; Mehul N. Vora

2005-01-01

433

New fossil bee flies (Diptera: Bombylioidea) in the Lowermost Eocene amber of the Paris Basin  

Microsoft Academic Search

A new genus and two new species of bee flies are described from the Lowermost Eocene amber of the Paris basin: Paradolichomyia eocenica n. gen, n. sp. (Bombyliidae: Toxophorinae) and Proplatypygus matilei n. sp. (Mythicomyiidae). Paradolichomyia eocenica n. gen, n. sp. represents the oldest fossil record of Bombyliidae. It is closely related to the two modern genera Dolichomyia WIEDEMANN 1830

André Nel; Ga?l De Ploëg

2004-01-01

434

Upper Cretaceous trace fossils in permineralized plant remains from Patagonia, Argentina  

Microsoft Academic Search

Four new ichnogenera and six new ichnospecies are described from permineralized plant remains from an unnamed Upper Cretaceous formation, of northern Patagonia in Argentina. This association of traces is the second ichnocenosis described for permineralized wood. Traces are interpreted as insect borings in wood and fruits. Cycalichnus garciorum n. ichnosp. is the first trace fossil recorded in a cycad stem

Jorge F. Genise

1995-01-01

435

Biofuel: An alternative to fossil fuel for alleviating world energy and economic crises  

Microsoft Academic Search

The time has come when it is desirable to look for alternative energy resources to confront the global energy crisis. Consideration of the increasing environmental problems and the possible crisis of fossil fuel availability at record high prices dictate that some changes will need to occur sooner rather than later. The recent oil spill in the Gulf of Mexico is

Keshav Bhattarai; Wayne M. Stalick; Scott Mckay; Gija Geme; Nimisha Bhattarai

2011-01-01

436

Influence of Microbial Biofilms on the Preservation of Primary Soft Tissue in Fossil and Extant Archosaurs  

Microsoft Academic Search

BackgroundMineralized and permineralized bone is the most common form of fossilization in the vertebrate record. Preservation of gross soft tissues is extremely rare, but recent studies have suggested that primary soft tissues and biomolecules are more commonly preserved within preserved bones than had been presumed. Some of these claims have been challenged, with presentation of evidence suggesting that some of

Joseph E. Peterson; Melissa E. Lenczewski; Reed P. Scherer

2010-01-01

437

Évolution « graduelle » à l’échelle géologique chez les rongeurs fossiles du Cénozoïque européen  

Microsoft Academic Search

Cases of gradualism in rodent evolution during the Cainozoic in Europe. Since several decades, conflicting interpretations of the fossil record are well known when the latter is used to understand mechanisms and modes of biological evolution. Once recalled peculiarities of the paleontological material and approach, several cases studies conducted by teams of the laboratory of Montpellier are presented. It clearly

Monique Vianey-Liaud; Jacques Michaux

2003-01-01

438

Comparison of some morpho-anatomical features at fossil vegetal species and their actual correspondent species  

Microsoft Academic Search

The values of some morpho-anatomical features (the size and shape of the epidermic cells of the leaves, as well as the size and features of the stomata) recorded in some fossil vegetal species and their actual correspondent species were analysed. These differences offer information about the evolution process. In the case of the analysed species (Ginkgo sp., Taxus sp., Magnolia

Gabriel C. Corneanu; Mihaela Corneanu; Rodica Bercu

2012-01-01

439

Gender Differences Among African-American Substance Abusers  

Microsoft Academic Search

The purpose of this investigation was to determine if there were gender differences in 80 medical records (37 African-American men and 43 African-American women) from one drug treatment facility located in a midwest ern city. Using independent t-tests and chi square analyses to determine group differences, there were significant gender differences relative to childhood sexual abuse experiences and maternal alcohol

Carol J. Boyd; Frederic Blow; Linda S. Orgain

1993-01-01

440

[Osteo-articular tuberculosis in African (author's transl)].  

PubMed

General, clinical and therapeutic features of osteo-articular tuberculosis in African, excluding vertebral localizations, are compiled from 81 records: The are: -- a frequency lower than in expatriated Africans and this indicates their special physical resistance when they live in their natural environment; -- frequently an easy diagnosis because of infected advanced foci with associated lesions; -- a surgical indication (curettage, resection, arthrodesis) as frequent as in vertebral localizations. PMID:491909

Ferro, R; Barnaud, P; Carayon, A

441

African Elephant Specialist Group  

NSDL National Science Digital Library

The African Elephant Specialist Group (AfESG) operates under the auspices of the Species Survival Commission of the World Conservation Union (IUCN). The AfESG is composed "of technical experts focusing on the conservation and management of African elephants. The broad aim of the AfESG is to promote the long-term conservation of Africa's elephants and, where possible, the recovery of their population to viable levels." The AfESG website contains useful information for conservationists, wildlife managers and others such as a number of downloadable Human-Elephant Conflict Reviews and Case Studies; African Elephant Status Reports (from the years 1995, 1998, and 2002); and a small section of Tools for Elephant Management and Research. Site visitors can also peruse (or download) current or back issues of _Pachyderm_, a peer-reviewed, scientific journal focused on management and conservation issues concerning Asian and African rhinos, as well as African elephants.

442

C-isotope composition of fossil sedges and grasses  

NASA Astrophysics Data System (ADS)

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

Kurschner, Wolfram M.

2010-05-01

443

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

PubMed Central

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

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

2013-01-01

444

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

PubMed Central

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

2012-01-01

445

Records Theory  

NASA Astrophysics Data System (ADS)

In quantum gravity, one seeks to combine quantum mechanics and general relativity. In attempting to do so, one comes across the "problem of time" impasse: the notion of time is conceptually different in each of these theories. In this paper, I consider the timeless records approach to resolving this. Records are localized, information-containing subconfigurations of a single instant. Records theory is the study of these and of how science (or history) is to be abstracted from correlations between them. I critically evaluate motivations for this approach that have previously appeared in the literature. I provide a ground-level structure for records theory and discuss what kind of further tools are needed, illustrated with some toy models: ordinary mechanics, relational particle dynamics, detector models and inhomogeneous perturbations about homogeneous cosmology.

Anderson, Edward

446

Compression fossil Mymaridae (Hymenoptera) from Kishenehn oil shales, with description of two new genera and review of Tertiary amber genera  

PubMed Central

Abstract Compression fossils of three genera and six species of Mymaridae (Hymenoptera: Chalcidoidea) are described from 46 million year old Kishenehn oil shales in Montana, USA. Two new genera are described: Eoeustochus Huber, gen. n., with two included species, Eoeustochus kishenehn Huber (type species) and Eoeustochus borchersi Huber, sp. n., and Eoanaphes, gen. n., with Eoanaphes stethynioides Huber, sp. n. Three new species of Gonatocerus are also described, Gonatocerus greenwalti Huber, sp. n. , Gonatocerus kootenai Huber, sp. n., and Gonatocerus rasnitsyni Huber, sp. n. Previously described amber fossil genera are discussed and five genera in Baltic amber are tentatively recorded as fossils: Anagroidea, Camptoptera, Dorya, Eustochus, and Mimalaptus.

Huber, John T.; Greenwalt, Dale

2011-01-01

447

Compression fossil Mymaridae (Hymenoptera) from Kishenehn oil shales, with description of two new genera and review of Tertiary amber genera.  

PubMed

Compression fossils of three genera and six species of Mymaridae (Hymenoptera: Chalcidoidea) are described from 46 million year old Kishenehn oil shales in Montana, USA. Two new genera are described: Eoeustochus Huber, gen. n., with two included species, Eoeustochus kishenehn Huber (type species) and Eoeustochus borchersi Huber, sp. n., and Eoanaphes, gen. n., with Eoanaphes stethynioides Huber, sp. n. Three new species of Gonatocerus are also described, Gonatocerus greenwalti Huber, sp. n. , Gonatocerus kootenai Huber, sp. n., and Gonatocerus rasnitsyni Huber, sp. n. Previously described amber fossil genera are discussed and five genera in Baltic amber are tentatively recorded as fossils: Anagroidea, Camptoptera, Dorya, Eustochus, and Mimalaptus. PMID:22259294

Huber, John T; Greenwalt, Dale

2011-09-24

448

Fossil Finds Expand Early Hominid Anatomy.  

ERIC Educational Resources Information Center

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

Bower, B.

1991-01-01

449

How a Dinosaur Became a Fossil  

NSDL National Science Digital Library

This interactive resource adapted from the Museum of Paleontology at the University of California, Berkeley shows how a dinosaur can be buried under sediment after it dies, become a fossil, and then become exposed and discovered by paleontologists.

Foundation, Wgbh E.

2005-12-17

450

Fossil energy program. Progress report, July 1980  

SciTech Connect

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

McNeese, L. E.

1980-10-01

451

Proceedings: 1990 fossil plant cycling conference  

SciTech Connect

Fossil plant cycling continues to be a key issue for many electric utilities. EPRI's previous cycling workshops, held in 1983, 1985, and 1987, allowed utilities to benefit from collective industry experience in the conversion of baseload fossil units to cyclic operation. Continued improvements in equipment, retrofits, diagnostics, and controls were highlighted at the 1990 conference. The objective is to provide a forum for utility discussions of the cycling operation of fossil fuel power plants. Potomac Electric Power Company (PEPCO) hosted the 1990 EPRI Fossil Fuel Cycling Conference in Washington, DC, on December 4--6, 1990. More than 130 representatives from utilities, vendors, government agencies, universities, and industry associations attended the conference. Following the general session, technical sessions covered such topics as plant modifications, utility retrofit experience, cycling economics, life assessment, controls, environmental controls, and energy storage. Attendees also toured PEPCO's Potomac River generating station, the site of an earlier EPRI cycling conversion study.

Not Available

1991-12-01

452

Fossil energy program. Progress report, August 1981  

SciTech Connect

This report - the eighty-fifth of a series - is a compendium of monthly progress reports for the ORNL research and development programs that are in support of the increased utilization of coal and other fossil fuel alternatives as sources of clean energy. The projects reported this month include those for coal conversion development, chemical research and development, materials technology, component development and process evaluation, technical support to major liquefaction projects, process analysis and engineering evaluations, fossil energy environmental programs, environmental control technology, coal preparation and waste utilization, atmospheric fluidized bed coal combustor for cogeneration, Tennessee Valley Authority Fluidized Bed Combustion demonstration plant program technical support, PFBC systems analysis, fossil fuel applications assessment, performance assurance system support for fossil energy projects, and international energy technology assessment.

McNeese, L.E.

1981-10-01

453

Fossil habrotrochid rotifers in Dominican amber  

Microsoft Academic Search

Flask-shaped microfossils are reported from bracts of a moss in Eocene-Oligocene amber from the northern Dominican Republic. These microfossils are identical with the thecae of certain living moss-dwelling rotifers in the genusHabrotrocha (Bdelloidea), which have previously been reported as fossils only from Holocene peat. What may be an egg and a rotifer body fossil are associated with these thecae and

B. M. Waggoner; G. O. Poinar

1993-01-01

454

Hydrogen and electricity from decarbonised fossil fuels  

Microsoft Academic Search

Hydrogen and electricity may become the favoured twin energy carriers in a possible “greenhouse driven” future due to their lack of CO2-emissions at the point of use. It is shown that decarbonising fossil fuels to hydrogen with CO2 being stored in deep geological formations represents the least expensive way of producing CO2-free hydrogen. For fossil fuels there seems to be

Olav Kaarstad; Harry Audus

1997-01-01

455

Quantifying Fossil Fuel CO 2 over Europe  

Microsoft Academic Search

Europe is responsible for more than 25% of global fossil fuel CO2 emissions (Marland et al. 2006), and these emissions account for about 30–50% of the observed CO2 variability in this region (see Sect. 4.2.1). To balance greenhouse gases over Europe, therefore, also requires quantification\\u000a of CO2 emissions from fossil fuel (i.e. coal, oil and natural gas) burning. Reliable continuous

Ingeborg Levin; Ute Karstens

456

Dissecting the South African miracle: African parallels  

Microsoft Academic Search

This article analyses the establishment of an inclusive liberal?democracy in South Africa. It contends that the representation of the South African transition as a miracle rests on two common myths: the myth of non?racialism and the myth of the South Africa model. It is argued that the 1994 elections revealed an electorate polarized on racial lines and that the notion

Adrian Guelke

1996-01-01

457