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1

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

PubMed Central

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

Bibi, Faysal

2011-01-01

2

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.

3

Bacteria: Fossil Record  

NSDL National Science Digital Library

This description of the fossil record of bacteria focuses on one particular group of bacteria, the cyanobacteria or blue-green algae, which have left a fossil record that extends far back into the Precambrian. The oldest cyanobacteria-like fossils known are nearly 3.5 billion years old and are among the oldest fossils currently known. Cyanobacteria are larger than most bacteria and may secrete a thick cell wall. More importantly, cyanobacteria may form large layered structures, called stromatolites (if more or less dome-shaped) or oncolites (if round). The site also refers to pseudomorphs of pyrite and siderite, and a group of bacteria known as endolithic. Two links are available for more information. One provides information on the discovery of possible remains of bacteria-like organisms on a meteorite from Mars and the other has a research report on fossilized filamentous bacteria and other microbes, found in Cretaceous amber.

4

Dinoflagellata: Fossil Record  

NSDL National Science Digital Library

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

5

004118:a0001 Fossil Record  

E-print Network

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

Benton, Michael

6

Biodiversity of the Fossil Record  

E-print Network

Biodiversity of the Fossil Record Geology 331, Paleontology #12;Linnean Classification: Example of Life #12;Cyanobacteria? 3.5 BY old, Australia #12;Stromatolite, 3.5 BY old, Australia #12;Modern stromatolites produced by cyanobacteria, Sharks Bay, Australia Cambrian, NY #12;Fossil bacteria 2BY old from

Kammer, Thomas

7

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.

8

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.

Jennifer Johnson

9

Evidence of Evolution I. Fossils and the fossil record  

E-print Network

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

Dever, Jennifer A.

10

Biodiversity of the Fossil Record  

E-print Network

Biodiversity of the Fossil Record Geology 331, Paleontology #12;Linnean Classification: Example;www.evogeneao.com/tree.html The Tree of Life #12;Cyanobacteria? 3.5 BY old, Australia #12;Stromatolite, 3.5 BY old, Australia #12;Modern stromatolites produced by cyanobacteria, Sharks Bay, Australia

Kammer, Thomas

11

Extinction and the fossil record  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

12

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.

Dale Springer

2007-12-12

13

004144:a0001 Fossil Record: Quality  

E-print Network

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

Benton, Michael

14

Organic molecules as chemical fossils - The molecular fossil record  

NASA Technical Reports Server (NTRS)

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

Eglinton, G.

1983-01-01

15

The First Fossil Record of Caecilian Amphibians  

Microsoft Academic Search

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

Richard Estes; MARVALEE H. WAKE

1972-01-01

16

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

E-print Network

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

Heim, Noel A.

17

Fossil pollen records of extant angiosperms  

Microsoft Academic Search

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

Jan Muller

1981-01-01

18

Insect diversity in the fossil record  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

19

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

20

Adaptation, plant evolution, and the fossil record  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

21

SURVEY OF SOCIAL INSECTS IN THE FOSSIL RECORD*  

E-print Network

SURVEY OF SOCIAL INSECTS IN THE FOSSIL RECORD* BY LAURIE BURNHAM Museum of Comparative Zoology the fossil record for clues not only on the antiquity of sociality, but also on the nature of these early recognized by Emerson (1955) have a fossil record extending at least as far back as the Tertiary. In 1967

Villemant, Claire

22

Spatial Bias in the Marine Fossil Record  

PubMed Central

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

Vilhena, Daril A.; Smith, Andrew B.

2013-01-01

23

Models for simulating the fossil record  

NASA Astrophysics Data System (ADS)

Computer modeling of the distribution of fossils within depositional sequences provides a means for generating hypotheses and increasing understanding of the fossil record. The simulation presented here joins the basin-scale stratigraphic modeling program STRATA, a random-branching model of species origination and extinction, and a model relating the probability of species occurrence to sedimentary facies. Model results indicate that facies sensitivity of species has the strongest control on range offset, i.e., the time between last appearance in a stratigraphic column and the time of extinction within a basin or the time between first appearance in a column and time of origination in a basin. Model results also predict the distribution of zones of increased range offset within depositional sequences. In the results presented here, increased range offset occurs within the transgressive systems tract of the deep basin, in far updip settings, and near the shelf break of the late highstand to early lowstand. The model also demonstrates how incompleteness of the fossil record is partitioned among sampling bias, facies bias, and unconformity bias. In this simulation, sampling bias and facies bias are roughly equal in magnitude and constant across the basin, but unconformity bias increasingly dominates over these two in updip positions.

Holland, Steven M.; Patzkowsky, Mark E.

1999-06-01

24

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

E-print Network

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

Villemant, Claire

25

Evidence of Evolution I. Fossils and the fossil record  

E-print Network

to igneous & metamorphic rocks, so what about fossils & sedimentary rocks? · "bracketing" · And organic in some regions than others Eras defined by major changes in the types of fossils found in the rocks://www.pbs.org/wgbh/evolution/library/03/3/l_033_01.html Radiometric dating ­ the clock in the rock! Accurate method for determining

Dever, Jennifer A.

26

Rates of speciation in the fossil record  

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

27

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

28

The Quaternary fossil-pollen record and global change  

SciTech Connect

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

Grimm, E.C. (Illinois State Museum, Springfield, IL (United States). Research and Collections Center)

1993-03-01

29

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

30

Fossils  

NSDL National Science Digital Library

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

tassihj

2009-10-21

31

Body size of insular carnivores: evidence from the fossil record  

E-print Network

SPECIAL ISSUE Body size of insular carnivores: evidence from the fossil record George A. Lyras1 carnivores on islands; (2) offer causal explanations for this pattern and deviations from it ­ as far as fossil carnivores are concerned; and (3) estimate the speed of this trend. Location Oceanic and oceanic

Binford, Michael W.

32

RESEARCH LETTERS 161 The Fossil Record of Cretaceous  

E-print Network

RESEARCH LETTERS 161 The Fossil Record of Cretaceous Tetrapods EMMANUEL FARA and MICHAEL J. BENTON, independently, would have re- mained cryptic throughout the Cretaceous; (3) control sam- ples of exquisitely

Benton, Michael

33

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

34

The Proterozoic Fossil Record of Heterotrophic Eukaryotes  

E-print Network

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

Porter, Susannah

35

When Pond Scum Ruled the Earth - The Proterozoic Fossil Record  

NSDL National Science Digital Library

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

Julie Bartley

36

Evidence for Evolution from the Vertebrate Fossil Record.  

ERIC Educational Resources Information Center

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

Gingerich, Philip D.

1983-01-01

37

Absolute measures of the completeness of the fossil record  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

38

Evidence for GRB Induced Extinctions in the Fossil Record?  

Microsoft Academic Search

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

Thomas G. Kaye

2004-01-01

39

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

40

Evidence for GRB Induced Extinctions in the Fossil Record?  

NASA Astrophysics Data System (ADS)

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

Kaye, Thomas G.

2004-09-01

41

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

NASA Technical Reports Server (NTRS)

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

Awramik, Stanley M.

1989-01-01

42

An overview of the dinosaur fossil record from Chile  

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

43

Exopaleontology and the search for a fossil record on Mars  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

44

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

E-print Network

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

Benton, Michael

45

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

E-print Network

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

Benton, Michael

46

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

PubMed Central

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

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

2014-01-01

47

The fossil record and macroevolutionary history of the beetles.  

PubMed

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

Smith, Dena M; Marcot, Jonathan D

2015-04-22

48

At the Origin of Animals: The Revolutionary Cambrian Fossil Record  

PubMed Central

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

Budd, Graham E

2013-01-01

49

Integration of Bayesian molecular clock methods and fossil-based soft bounds reveals early Cenozoic origin of African lacertid lizards  

PubMed Central

Background Although current molecular clock methods offer greater flexibility in modelling evolutionary events, calibration of the clock with dates from the fossil record is still problematic for many groups. Here we implement several new approaches in molecular dating to estimate the evolutionary ages of Lacertidae, an Old World family of lizards with a poor fossil record and uncertain phylogeny. Four different models of rate variation are tested in a new program for Bayesian phylogenetic analysis called TreeTime, based on a combination of mitochondrial and nuclear gene sequences. We incorporate paleontological uncertainty into divergence estimates by expressing multiple calibration dates as a range of probabilistic distributions. We also test the reliability of our proposed calibrations by exploring effects of individual priors on posterior estimates. Results According to the most reliable model, as indicated by Bayes factor comparison, modern lacertids arose shortly after the K/T transition and entered Africa about 45 million years ago, with the majority of their African radiation occurring in the Eocene and Oligocene. Our findings indicate much earlier origins for these clades than previously reported, and we discuss our results in light of paleogeographic trends during the Cenozoic. Conclusion This study represents the first attempt to estimate evolutionary ages of a specific group of reptiles exhibiting uncertain phylogenetic relationships, molecular rate variation and a poor fossil record. Our results emphasize the sensitivity of molecular divergence dates to fossil calibrations, and support the use of combined molecular data sets and multiple, well-spaced dates from the fossil record as minimum node constraints. The bioinformatics program used here, TreeTime, is publicly available, and we recommend its use for molecular dating of taxa faced with similar challenges. PMID:19570207

Hipsley, Christy A; Himmelmann, Lin; Metzler, Dirk; Mller, Johannes

2009-01-01

50

Patterns of generic extinction in the fossil record  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

51

The fossil record of evolution: Data on diversification and extinction  

NASA Technical Reports Server (NTRS)

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

Sepkoski, J. J., Jr.

1991-01-01

52

Fossil records of cosmic reionization in galactic stellar halos  

E-print Network

Galactic stellar halos have long been considered to contain fossil information on early dynamical and chemical evolution of galaxies. We propose that the surface brightness distributions of old stellar halos contain the influence of reionization on early formation histories of galaxies. By assuming that reionization significantly suppresses star formation in small subgalactic clumps virialized after reionization redshift ($z_{\\rm reion}$), we first numerically investigate how structural and kinematical properties of stellar halos formed from merging of these subgalactic clumps depend on $z_{\\rm reion}$. We then discuss what observable properties of galactic stellar halos offer us the fossil records of reionization influence on hierarchical formation of halos based on the current results of numerical simulations. We particularly suggest that both the half-light radius of stellar halos and the slope of their surface brightness profile contain useful information on when star formation in subgalactic clumps were significantly influenced by reionization. By using the simulated surface brightness distributions of galactic stellar halos for models with different $z_{\\rm reion}$, we also discuss how wide-field imaging studies of extragalactic halos will help us to elucidate the epoch of cosmic reionization.

Kenji Bekki; Masashi Chiba

2005-05-27

53

The fossil record of evolution: Data on diversification and extinction  

NASA Technical Reports Server (NTRS)

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

Sepkoski, J. J., Jr.

1986-01-01

54

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

E-print Network

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

Plotnick, Roy E.

55

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

PubMed Central

Background Given that most species that have ever existed on earth are extinct, it stands to reason that the evolutionary history can be better understood with fossil taxa. Bauhinia is a typical genus of pantropical intercontinental disjunction among the Asian, African, and American continents. Geographic distribution patterns are better recognized when fossil records and molecular sequences are combined in the analyses. Here, we describe a new macrofossil species of Bauhinia from the Upper Miocene Xiaolongtan Formation in Wenshan County, Southeast Yunnan, China, and elucidate the biogeographic significance through the analyses of molecules and fossils. Results Morphometric analysis demonstrates that the leaf shapes of B. acuminata, B. championii, B. chalcophylla, B. purpurea, and B. podopetala closely resemble the leaf shapes of the new finding fossil. Phylogenetic relationships among the Bauhinia species were reconstructed using maximum parsimony and Bayesian inference, which inferred that species in Bauhinia species are well-resolved into three main groups. Divergence times were estimated by the Bayesian Markov chain Monte Carlo (MCMC) method under a relaxed clock, and inferred that the stem diversification time of Bauhinia was ca. 62.7Ma. The Asian lineage first diverged at ca. 59.8Ma, followed by divergence of the Africa lineage starting during the late Eocene, whereas that of the neotropical lineage starting during the middle Miocene. Conclusions Hypotheses relying on vicariance or continental history to explain pantropical disjunct distributions are dismissed because they require mostly Palaeogene and older tectonic events. We suggest that Bauhinia originated in the middle Paleocene in Laurasia, probably in Asia, implying a possible Tethys Seaway origin or an Out of Tropical Asia, and dispersal of legumes. Its present pantropical disjunction resulted from disruption of the boreotropical flora by climatic cooling after the Paleocene-Eocene Thermal Maximum (PETM). North Atlantic land bridges (NALB) seem the most plausible route for migration of Bauhinia from Asia to America; and additional aspects of the Bauhinia species distribution are explained by migration and long distance dispersal (LDD) from Eurasia to the African and American continents. PMID:25288346

2014-01-01

56

Testing homogeneity with the fossil record of galaxies  

E-print Network

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

Alan F. Heavens; Raul Jimenez; Roy Maartens

2011-09-15

57

NGST: Exploring the Fossil Record of Galaxy Formation  

NASA Technical Reports Server (NTRS)

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

Rich, R. Michael

1998-01-01

58

Fossils  

NSDL National Science Digital Library

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

1998-01-01

59

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

African-American Band Music and Recordings  

NSDL National Science Digital Library

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

62

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

PubMed

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

Gilbert, Christopher C

2013-05-01

63

PORTEREARLY EUKARYOTIC DIVERSIFICATION THE FOSSIL RECORD OF EARLY EUKARYOTIC  

E-print Network

of acritarch and compression fossil diversity, suggest that while divergences among major eukaryotic clades representatives -- indeed, multicellularity evolved at least seven times within the eukaryotes, in animals, fungi of eukaryotic diversity, however, is microbial, comprising taxa traditionally grouped within the protozoa

Porter, Susannah

64

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

PubMed

The phylogenetic placement of siricid hymenopterans and especially the relationships among Siricidae are not resolved, and are in need of further investigation. The fossil record helps to illuminate the evolutionary history of this group. In this paper, Xoanon? eocenicus sp. nov. is newly described from the Eocene Fossillagersttte Grube Messel (Germany). Although several characters of the wing venation of this fossil are similar to the extant genus Xoanon, there remain some doubts concerning the generic placement. A newly found fossil is attributed to Urocerus ligniticus (Piton, 1940) from the Paloecene Fossillagersttte Menat (France) and provides more morphological information on this species. An overview of the fossil record of Siricidae in the strict sense is given and the state of knowledge on the different fossils is reviewed. PMID:25283896

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

2014-01-01

65

Integration of Bayesian molecular clock methods and fossil-based soft bounds reveals early Cenozoic origin of African lacertid lizards  

Microsoft Academic Search

BACKGROUND: Although current molecular clock methods offer greater flexibility in modelling evolutionary events, calibration of the clock with dates from the fossil record is still problematic for many groups. Here we implement several new approaches in molecular dating to estimate the evolutionary ages of Lacertidae, an Old World family of lizards with a poor fossil record and uncertain phylogeny. Four

Christy A Hipsley; Lin Himmelmann; Dirk Metzler; Johannes Mller

2009-01-01

66

Fossils  

NSDL National Science Digital Library

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

67

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

PubMed Central

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

Camens, Aaron Bruce; Carey, Stephen Paul

2013-01-01

68

The Fossil Record of Freshwater MicroAlgae Pediastrum Meyen (Chlorophyceae) in Southern South America  

Microsoft Academic Search

The fossil record of Pediastrum Meyen (Chlorophyceae) in southern South America is revised and 10 species\\/varieties are recognised within the genus. Previously published material is identified and new data are included. The oldest and most widespread variety for the region is P. boryanum var. boryanum, which appears in the Late Cretaceous age. P. tetras is recorded in the Early Eocene

Mara del C. Zamaloa; Guillermo Tell

2005-01-01

69

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

PubMed

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

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

2010-01-01

70

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

PubMed Central

The fossil record of early vertebrates has been influential in elucidating the evolutionary assembly of the gnathostome bodyplan. Understanding of the timing and tempo of vertebrate innovations remains, however, mired in a literal reading of the fossil record. Early jawless vertebrates (ostracoderms) exhibit restriction to shallow-water environments. The distribution of their stratigraphic occurrences therefore reflects not only flux in diversity, but also secular variation in facies representation of the rock record. Using stratigraphic, phylogenetic and palaeoenvironmental data, we assessed the veracity of the fossil records of the jawless relatives of jawed vertebrates (Osteostraci, Galeaspida, Thelodonti, Heterostraci). Non-random models of fossil recovery potential using Palaeozoic sea-level changes were used to calculate confidence intervals of clade origins. These intervals extend the timescale for possible origins into the Upper Ordovician; these estimates ameliorate the long ghost lineages inferred for Osteostraci, Galeaspida and Heterostraci, given their known stratigraphic occurrences and stemgnathostome phylogeny. Diversity changes through the Silurian and Devonian were found to lie within the expected limits predicted from estimates of fossil record quality indicating that it is geological, rather than biological factors, that are responsible for shifts in diversity. Environmental restriction also appears to belie ostracoderm extinction and demise rather than competition with jawed vertebrates. PMID:25520359

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

2015-01-01

71

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

PubMed

Approaches quantifying the relative congruence, or incongruence, of molecular divergence estimates and the fossil record have been limited. Previously proposed methods are largely node specific, assessing incongruence at particular nodes for which both fossil data and molecular divergence estimates are available. These existing metrics, and other methods that quantify incongruence across topologies including entirely extinct clades, have so far not taken into account uncertainty surrounding both the divergence estimates and the ages of fossils. They have also treated molecular divergence estimates younger than previously assessed fossil minimum estimates of clade age as if they were the same as cases in which they were older. However, these cases are not the same. Recovered divergence dates younger than compared oldest known occurrences require prior hypotheses regarding the phylogenetic position of the compared fossil record and standard assumptions about the relative timing of morphological and molecular change to be incorrect. Older molecular dates, by contrast, are consistent with an incomplete fossil record and do not require prior assessments of the fossil record to be unreliable in some way. Here, we compare previous approaches and introduce two new descriptive metrics. Both metrics explicitly incorporate information on uncertainty by utilizing the 95% confidence intervals on estimated divergence dates and data on stratigraphic uncertainty concerning the age of the compared fossils. Metric scores are maximized when these ranges are overlapping. MDI (minimum divergence incongruence) discriminates between situations where molecular estimates are younger or older than known fossils reporting both absolute fit values and a number score for incompatible nodes. DIG range (divergence implied gap range) allows quantification of the minimum increase in implied missing fossil record induced by enforcing a given set of molecular-based estimates. These metrics are used together to describe the relationship between time trees and a set of fossil data, which we recommend be phylogenetically vetted and referred on the basis of apomorphy. Differences from previously proposed metrics and the utility of MDI and DIG range are illustrated in three empirical case studies from angiosperms, ostracods, and birds. These case studies also illustrate the ways in which MDI and DIG range may be used to assess time trees resultant from analyses varying in calibration regime, divergence dating approach or molecular sequence data analyzed. PMID:25281846

Clarke, Julia A; Boyd, Clint A

2015-01-01

72

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

NASA Astrophysics Data System (ADS)

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

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

2006-04-01

73

The fossil record of evolution: Analysis of extinction  

NASA Technical Reports Server (NTRS)

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

Raup, D. M.

1986-01-01

74

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

75

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

E-print Network

Yukon gold mine yields ancient horse fossil 700,000yearold fossil discovered in Yukon permafrost an unusually large horse fossil in the Yukon permafrost, he knew it was important. Now, in a new study published in the journal Nature, this fossil is rewriting the story of equine evolution as the ancient

Machel, Hans

76

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

E-print Network

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

Benton, Michael

77

Late Miocene to Pliocene carbon isotope record of differential diet change among East African herbivores  

PubMed Central

Stable isotope and molecular data suggest that C4 grasses first appeared globally in the Oligocene. In East Africa, stable isotope data from pedogenic carbonate and fossil tooth enamel suggest a first appearance between 1510 Ma and subsequent expansion during the Plio-Pleistocene. The fossil enamel record has the potential to provide detailed information about the rates of dietary adaptation to this new resource among different herbivore lineages. We present carbon isotope data from 452 fossil teeth that record differential rates of diet change from C3 to mixed C3/C4 or C4 diets among East African herbivore families at seven different time periods during the Late Miocene to the Pliocene (9.93.2 Ma). Significant amounts of C4 grasses were present in equid diets beginning at 9.9 Ma and in rhinocerotid diets by 9.6 Ma, although there is no isotopic evidence for expansive C4 grasslands in this part of the Late Miocene. Bovids and hippopotamids followed suit with individuals that had C4-dominated (>65%) diets by 7.4 Ma. Suids adopted C4-dominated diets between 6.5 and 4.2 Ma. Gomphotheriids and elephantids had mostly C3-dominated diets through 9.3 Ma, but became dedicated C4 grazers by 6.5 Ma. Deinotheriids and giraffids maintained a predominantly C3 diet throughout the record. The sequence of differential diet change among herbivore lineages provides ecological insight into a key period of hominid evolution and valuable information for future studies that focus on morphological changes associated with diet change. PMID:21464327

Uno, Kevin T.; Cerling, Thure E.; Harris, John M.; Kunimatsu, Yutaka; Leakey, Meave G.; Nakatsukasa, Masato; Nakaya, Hideo

2011-01-01

78

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

E-print Network

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

Newman, Mark

79

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

E-print Network

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

Andersen, Torgeir Bjørge

80

In situ fossil hermit crabs (Paguroidea) from northwest Europe and Russia. Preliminary data on new records  

Microsoft Academic Search

For reasons still unknown, the record of fossil paguroids preserved in situ is scanty. Here we present four examples from the Mesozoic and Cenozoic of northwest Europe and Russia, either collected recently or contained in old museum collections and recognised previously, but not yet published. The fi rst concerns a right propodus, and the imprint of the left chela, preserved

John W. M. Jagt; Barry W. M. van Bakel; Ren H. B. Fraaije; Christian Neumann

2006-01-01

81

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

E-print Network

, California2 8/11 0/12 0/11 California ground squirrel (S. beecheyi) Hamel Ranch, Davis, California2 0/6 0/4 0; table A2). The limited fossil records of the proposed direct ancestors of California ground squirrels, rock squirrels, Baja California rock squirrels and golden-mantled ground squirrels - S. shotwelli and S

Ord, Terry

82

First Quaternary Fossil Record of Caecilians from a Mexican Archaeological Site  

Microsoft Academic Search

A single vertebra from an Early Formative period archaeological site in coastal Chiapas, Mxico, is identified as belonging to the amphibian Dermophis mexicanus (Dumril and Bibron) 1841 (Amphibia: Gymnophiona: Caeciliidae). The vertebra was recovered from deposits dated to approximately 12001350 B.C. The specimen represents the first Quaternary fossil record for gymnophiones. Its presence suggests the possible role of the species

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

1999-01-01

83

Fossil isotope records of seasonal climate and ecology: Straight from the horse's mouth  

Microsoft Academic Search

Isotope analysis of a bulk fossil tooth gives a ``snapshot'' impression of paleoclimatic conditions---a single point in time. However, hypsodont teeth grow over a period of a year or more, so that stable carbon and oxygen isotope variations along their length are a ``tape recorder'' of short-term seasonal variations from the distant past. We have used a new in situ

Z. D. Sharp; T. E. Cerling

1998-01-01

84

Patterns of extinction and biodiversity in the fossil record Ricard V. Sole and Mark Newman  

E-print Network

plants. It ended about 65 mil- lion years ago with the Cretaceous??Tertiary (KT) extinction 500 400 300Patterns of extinction and biodiversity in the fossil record Ricard V. Sol´e and Mark Newman Santa in biodiversity towards the present, punctuated by a number of large extinction events which wiped out a signi#2

Newman, Mark

85

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

PubMed

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

Meijer, Hanneke J M

2014-01-01

86

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

PubMed Central

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

2014-01-01

87

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

NASA Astrophysics Data System (ADS)

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

Rodrguez-Tovar, Francisco J.

2014-05-01

88

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

PubMed Central

Many palaeobiological analyses have concluded that modern birds (Neornithes) radiated no earlier than the Maastrichtian, whereas molecular clock studies have argued for a much earlier origination. Here, we assess the quality of the fossil record of Mesozoic avian species, using a recently proposed character completeness metric which calculates the percentage of phylogenetic characters that can be scored for each taxon. Estimates of fossil record quality are plotted against geological time and compared to estimates of species level diversity, sea level, and depositional environment. Geographical controls on the avian fossil record are investigated by comparing the completeness scores of species in different continental regions and latitudinal bins. Avian fossil record quality varies greatly with peaks during the Tithonian-early Berriasian, Aptian, and ConiacianSantonian, and troughs during the Albian-Turonian and the Maastrichtian. The completeness metric correlates more strongly with a sampling corrected residual diversity curve of avian species than with the raw taxic diversity curve, suggesting that the abundance and diversity of birds might influence the probability of high quality specimens being preserved. There is no correlation between avian completeness and sea level, the number of fluviolacustrine localities or a recently constructed character completeness metric of sauropodomorph dinosaurs. Comparisons between the completeness of Mesozoic birds and sauropodomorphs suggest that small delicate vertebrate skeletons are more easily destroyed by taphonomic processes, but more easily preserved whole. Lagersttten deposits might therefore have a stronger impact on reconstructions of diversity of smaller organisms relative to more robust forms. The relatively poor quality of the avian fossil record in the Late Cretaceous combined with very patchy regional sampling means that it is possible neornithine lineages were present throughout this interval but have not yet been sampled or are difficult to identify because of the fragmentary nature of the specimens. PMID:22761723

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

2012-01-01

89

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

USGS Publications Warehouse

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

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

2006-01-01

90

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

Microsoft Academic Search

Changing downcore distributions of hydrocarbon, long-chain alkenone, and sterol lipid molecular fossils from an 8.1 m piston core taken from Lake Titicaca, South America (152 m depth, 16 S, 69 W) reveal a record of significant paleoecological change in the lake for the past ~30,000 years. Trends in lipid abundances and distributions follow previously reported changes in lake water balance

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

2002-01-01

91

First Quaternary Fossil Record of Caecilians from a Mexican Archaeological Site  

NASA Astrophysics Data System (ADS)

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

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

1999-07-01

92

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

PubMed Central

Background Modern selachians and their supposed sister group (hybodont sharks) have a long and successful evolutionary history. Yet, although selachian remains are considered relatively common in the fossil record in comparison with other marine vertebrates, little is known about the quality of their fossil record. Similarly, only a few works based on specific time intervals have attempted to identify major events that marked the evolutionary history of this group. Methodology/Principal Findings Phylogenetic hypotheses concerning modern selachians interrelationships are numerous but differ significantly and no consensus has been found. The aim of the present study is to take advantage of the range of recent phylogenetic hypotheses in order to assess the fit of the selachian fossil record to phylogenies, according to two different branching methods. Compilation of these data allowed the inference of an estimated range of diversity through time and evolutionary events that marked this group over the past 300 Ma are identified. Results indicate that with the exception of high taxonomic ranks (orders), the selachian fossil record is by far imperfect, particularly for generic and post-Triassic data. Timing and amplitude of the various identified events that marked the selachian evolutionary history are discussed. Conclusion/Significance Some identified diversity events were mentioned in previous works using alternative methods (Early Jurassic, mid-Cretaceous, K/T boundary and late Paleogene diversity drops), thus reinforcing the efficiency of the methodology presented here in inferring evolutionary events. Other events (Permian/Triassic, Early and Late Cretaceous diversifications; Triassic/Jurassic extinction) are newly identified. Relationships between these events and paleoenvironmental characteristics and other groups evolutionary history are proposed. PMID:22957091

Guinot, Guillaume; Adnet, Sylvain; Cappetta, Henri

2012-01-01

93

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

94

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. PMID:20071389

Snchez-Villagra, Marcelo R.

2010-01-01

95

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

PubMed Central

Neotropical rainforests have a very poor fossil record, making hypotheses concerning their origins difficult to evaluate. Nevertheless, some of their most important characteristics can be preserved in the fossil record: high plant diversity, dominance by a distinctive combination of angiosperm families, a preponderance of plant species with large, smooth-margined leaves, and evidence for a high diversity of herbivorous insects. Here, we report on an ?58-my-old flora from the Cerrejn Formation of Colombia (paleolatitude ?5 N) that is the earliest megafossil record of Neotropical rainforest. The flora has abundant, diverse palms and legumes and similar family composition to extant Neotropical rainforest. Three-quarters of the leaf types are large and entire-margined, indicating rainfall >2,500 mm/year and mean annual temperature >25 C. Despite modern family composition and tropical paleoclimate, the diversity of fossil pollen and leaf samples is 6080% that of comparable samples from extant and Quaternary Neotropical rainforest from similar climates. Insect feeding damage on Cerrejn fossil leaves, representing primary consumers, is abundant, but also of low diversity, and overwhelmingly made by generalist feeders rather than specialized herbivores. Cerrejn megafossils provide strong evidence that the same Neotropical rainforest families have characterized the biome since the Paleocene, maintaining their importance through climatic phases warmer and cooler than present. The low diversity of both plants and herbivorous insects in this Paleocene Neotropical rainforest may reflect an early stage in the diversification of the lineages that inhabit this biome, and/or a long recovery period from the terminal Cretaceous extinction. PMID:19833876

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

2009-01-01

96

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

E-print Network

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

Benton, Michael

97

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 sitesEckfeld 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

98

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

PubMed

Aside from pollen and nectar, bees of the subfamily Megachilinae are closely associated with plants as a source of materials for nest construction. Megachilines use resins, masticated leaves, trichomes and other plant materials sometimes along with mud to construct nests in cavities or in soil. Among these, the leafcutter bees (Megachile s.l.) are the most famous for their behaviour to line their brood cells with discs cut from various plants. We report on fossil records of one body fossil of a new non-leafcutting megachiline and of 12 leafcuttings from three European sites-Eckfeld and Messel, both in Germany (Eocene), and Menat, France (Paleocene). The excisions include the currently earliest record of probable Megachile activity and suggest the presence of such bees in the Paleocene European fauna. Comparison with extant leafcuttings permits the interpretation of a minimal number of species that produced these excisions. The wide range of size for the leafcuttings indirectly might suggest at least two species of Megachile for the fauna of Messel in addition to the other megachiline bee described here. The presence of several cuttings on most leaves from Eckfeld implies that the preferential foraging behaviour of extant Megachile arose early in megachiline evolution. These results demonstrate that combined investigation of body and trace fossils complement each other in understanding past biodiversity, the latter permitting the detection of taxa not otherwise directly sampled and inferences on behavioural evolution. PMID:19296064

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

2009-06-01

99

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

PubMed Central

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

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

2014-01-01

100

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 recordthe 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 microRNAsgenes that encode approximately 22 nucleotide non-coding regulatory RNAsto the problem of annelid phylogenetics. We show that annelids are monophyletic with respect to sipunculans, and polychaetes are paraphyletic with respect to the clitellate Lumbricus, conclusions that are consistent with the fossil record. Further, sipunculans resolve as the sister group of the annelids, rooting the annelid tree, and revealing the polarity of the morphological change within this diverse lineage of animals. PMID:19755470

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

2009-01-01

101

Project EARTH-12-MF1: Form and Function In The Fossil Record: Using Exceptionally Preserved Skulls to  

E-print Network

Project EARTH-12-MF1: Form and Function In The Fossil Record: Using Exceptionally Preserved Skulls). An extensive body of biomechanical research targets fish skulls (Westneat 2004; Wainwright et al. 2007

Henderson, Gideon

102

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

PubMed

The fossil record of tetrapods is very patchy because of the problems of preservation, in terrestrial sediments in particular, and because vertebrates are rarely very abundant. However, the fossil record of tetrapods has the advantages that it is easier to establish a phylogenetic taxonomy than for many invertebrate groups, and there is the potential for more detailed ecological analyses. The relative incompleteness of a fossil record may be assessed readily, and this can be used to test whether drops in overall diversity are related to mass extinctions or to gaps in our knowledge. Absolute incompleteness cannot be assessed directly, but a historical approach may offer clues to future improvements in our knowledge. One of the key problems facing palaeobiologists is paraphyly, the fact that many higher taxa in common use do not contain all of the descendants of the common ancestor. This may be overcome by cladistic analysis and the identification of monophyletic groups. The diversity of tetrapods increased from the Devonian to the Permian, remained roughly constant during the Mesozoic, and then began to increase in the late Cretaceous, and continued to do so during the Tertiary. The rapid radiation of 'modern' tetrapod groups--frogs, salamanders, lizards, snakes, turtles, crocodilians, birds and mammals--was hardly affected by the celebrated end-Cretaceous extinction event. Major mass extinctions among tetrapods took place in the early Permian, late Permian, early Triassic, late Triassic, late Cretaceous, early Oligocene and late Miocene. Many of these events appear to coincide with the major mass extinctions among marine invertebrates, but the tetrapod record is largely equivocal with regard to the theory of periodicity of mass extinctions. PMID:2574883

Benton, M J

1989-11-01

103

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. PMID:20739322

Friedman, Matt; Brazeau, Martin D.

2011-01-01

104

A new African fossil caprin and a combined molecular and morphological Bayesian phylogenetic analysis of caprini (Mammalia: Bovidae).  

PubMed

Given that most species that have ever existed on Earth are extinct, no evolutionary history can ever be complete without the inclusion of fossil taxa. Bovids (antelopes and relatives) are one of the most diverse clades of large mammals alive today, with over a hundred living species and hundreds of documented fossil species. With the advent of molecular phylogenetics, major advances have been made in the phylogeny of this clade; however, there has been little attempt to integrate the fossil record into the developing phylogenetic picture. We here describe a new large fossil caprin species from ca. 1.9-Ma deposits from the Middle Awash, Ethiopia. To place the new species phylogenetically, we perform a Bayesian analysis of a combined molecular (cytochrome b) and morphological (osteological) character supermatrix. We include all living species of Caprini, the new fossil species, a fossil takin from the Pliocene of Ethiopia (Budorcas churcheri), and the insular subfossil Myotragus balearicus. The combined analysis demonstrates successful incorporation of both living and fossil species within a single phylogeny based on both molecular and morphological evidence. Analysis of the combined supermatrix produces superior resolution than with either the molecular or morphological data sets considered alone. Parsimony and Bayesian analyses of the data set are also compared and shown to produce similar results. The combined phylogenetic analysis indicates that the new fossil species is nested within Capra, making it one of the earliest representatives of this clade, with implications for molecular clock calibration. Geographical optimization indicates no less than four independent dispersals into Africa by caprins since the Pliocene. PMID:22816969

Bibi, F; Vrba, E; Fack, F

2012-09-01

105

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

PubMed

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

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

2011-08-16

106

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

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

2011-01-01

107

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

PubMed Central

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, Jrgen; Witzmann, Florian; Klug, Stefanie; Heidtke, Ulrich H.J

2007-01-01

108

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

PubMed

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

Kidwell, Susan M

2015-04-21

109

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

PubMed Central

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

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

2009-01-01

110

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

NASA Astrophysics Data System (ADS)

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

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

2004-12-01

111

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 (O18Osw) 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 Institutes (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 O18O in Porites corals is affected by sea surface temperature (SST) and O18Osw, O18O of precipitation in Hawaii is relatively high, and seasonal rainfall should not affect O18Osw 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 O18O and O13C 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 O18O for each specimen was calculated from the average O18O values by 1) correcting for extension rate effects, 2) subtracting the 'O18Osw between 377 ka and today, and 3) subtracting the average O18O of the modern Porites lobata sample. Pool 1 sample O18O 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

112

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.

113

Late Quaternary hillslope evolution recorded in eastern South African colluvial badlands  

E-print Network

Late Quaternary hillslope evolution recorded in eastern South African colluvial badlands M badland topography that exposes a stratigraphic sequence frequently containing several palaeosols, with periods of active colluviation and intervening pedogenesis, to wide- spread badland erosion reported

Clarke, Michle

114

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, Jzef; Lukomska-Kowalczyk, Maja; Kempe, Stephan

2012-06-01

115

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

PubMed Central

Abstract Calcification and silicification processes of cyanobacterial mats that form stromatolites in two caldera lakes of Niuafoou Island (Vai Lahi and Vai Sii) 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 Niuafoou cyanobacteria is highly dependent on the timing and type of mineral phase involved in the fossilization process. Four main modes of mineralization of cyanobacteria organic parts have been recognized: (i) primary early postmortem calcification by aragonite nanograins that transform quickly into larger needle-like crystals and almost totally destroy the cellular structures, (ii) primary early postmortem silicification of almost intact cyanobacterial cells that leave a record of spectacularly well-preserved cellular structures, (iii) replacement by silica of primary aragonite that has already recrystallized and obliterated the cellular structures, (iv) occasional replacement of primary aragonite precipitated in the mucopolysaccharide sheaths and extracellular polymeric substances by Al-Mg-Fe silicates. These observations suggest that the extremely scarce earliest fossil record may, in part, be the result of (a) secondary replacement by silica of primary carbonate minerals (aragonite, calcite, siderite), which, due to recrystallization, had already annihilated the cellular morphology of the mineralized microbiota or (b) relatively late primary silicification of already highly degraded and no longer morphologically identifiable microbial remains. Key Words: StromatolitesCyanobacteriaCalcificationSilicificationNiuafoou (Tonga)Archean. Astrobiology 12, 535548. PMID:22794297

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

2012-01-01

116

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

PubMed

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

Yamada, Toshihiro; Yamada, Mariko; Tsukagoshi, Minoru

2014-03-01

117

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 Caada 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

118

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

PubMed Central

Angiosperm paleobotany has widened its horizons, incorporated new techniques, developed new databases, and accepted new questions that can now focus on the evolution of the group. The fossil record of early flowering plants is now playing an active role in addressing questions of angiosperm phylogeny, angiosperm origins, and angiosperm radiations. Three basic nodes of angiosperm radiations are identified: (i) the closed carpel and showy radially symmetrical flower, (ii) the bilateral flower, and (iii) fleshy fruits and nutritious nuts and seeds. These are all coevolutionary events and spread out through time during angiosperm evolution. The proposal is made that the genetics of the angiosperms pressured the evolution of the group toward reproductive systems that favored outcrossing. This resulted in the strongest selection in the angiosperms being directed toward the flower, fruits, and seeds. That is why these organs often provide the best systematic characters for the group. PMID:10860967

Dilcher, David

2000-01-01

119

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

PubMed Central

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

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

2012-01-01

120

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

PubMed Central

Molecular clocks have the potential to shed light on the timing of early metazoan divergences, but differing algorithms and calibration points yield conspicuously discordant results. We argue here that competing molecular clock hypotheses should be testable in the fossil record, on the principle that fundamentally new grades of animal organization will have ecosystem-wide impacts. Using a set of seven nuclear-encoded protein sequences, we demonstrate the paraphyly of Porifera and calculate sponge/eumetazoan and cnidarian/bilaterian divergence times by using both distance [minimum evolution (ME)] and maximum likelihood (ML) molecular clocks; ME brackets the appearance of Eumetazoa between 634 and 604 Ma, whereas ML suggests it was between 867 and 748 Ma. Significantly, the ME, but not the ML, estimate is coincident with a major regime change in the Proterozoic acritarch record, including: (i) disappearance of low-diversity, evolutionarily static, pre-Ediacaran acanthomorphs; (ii) radiation of the high-diversity, short-lived Doushantuo-Pertatataka microbiota; and (iii) an order-of-magnitude increase in evolutionary turnover rate. We interpret this turnover as a consequence of the novel ecological challenges accompanying the evolution of the eumetazoan nervous system and gut. Thus, the more readily preserved microfossil record provides positive evidence for the absence of pre-Ediacaran eumetazoans and strongly supports the veracity, and therefore more general application, of the ME molecular clock. PMID:15983372

Peterson, Kevin J.; Butterfield, Nicholas J.

2005-01-01

121

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

E-print Network

-interpretation, perhaps assuming that everything is an adaptation and that adaptations are all perfect [2]. Fossils can and behavior from fossils--empirical evidence, comparison with modern analogs, and biomechanical modeling and predator relationships. Trace fossils, such as tracks and burrows, can sometimes be linked

Benton, Michael

122

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

123

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

124

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

Microsoft Academic Search

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

Christina L. Belanger

2012-01-01

125

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

E-print Network

Editorial The dawn of animal life: Evolutionary and palaeoecological patterns in the Neoproterozoic-Cambrian animal fossil record 1. Introduction The NeoproterozoicCambrian radiation of complex animals is arguably to the earliest undisputed evidence for macroscopic animals in the Ediacaran to the dominance of fully

Dornbos, Stephen Q.

126

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

PubMed Central

Background Molecular phylogenetics has provided unprecedented resolution in the ruminant evolutionary tree. However, molecular age estimates using only one or a few (often misapplied) fossil calibration points have produced a diversity of conflicting ages for important evolutionary events within this clade. I here identify 16 fossil calibration points of relevance to the phylogeny of Bovidae and Ruminantia and use these, individually and together, to construct a dated molecular phylogeny through a reanalysis of the full mitochondrial genome of over 100 ruminant species. Results The new multi-calibrated tree provides ages that are younger overall than found in previous studies. Among these are young ages for the origin of crown Ruminantia (39.328.8Ma), and crown Bovidae (17.315.1Ma). These are argued to be reasonable hypotheses given that many basal fossils assigned to these taxa may in fact lie on the stem groups leading to the crown clades, thus inflating previous age estimates. Areas of conflict between molecular and fossil dates do persist, however, especially with regard to the base of the rapid Pecoran radiation and the sister relationship of Moschidae to Bovidae. Results of the single-calibrated analyses also show that a very wide range of molecular age estimates are obtainable using different calibration points, and that the choice of calibration point can influence the topology of the resulting tree. Compared to the single-calibrated trees, the multi-calibrated tree exhibits smaller variance in estimated ages and better reflects the fossil record. Conclusions The use of a large number of vetted fossil calibration points with soft bounds is promoted as a better approach than using just one or a few calibrations, or relying on internal-congruency metrics to discard good fossil data. This study also highlights the importance of considering morphological and ecological characteristics of clades when delimiting higher taxa. I also illustrate how phylogeographic and paleoenvironmental hypotheses inferred from a tree containing only extant taxa can be problematic without consideration of the fossil record. Incorporating the fossil record of Ruminantia is a necessary step for future analyses aiming to reconstruct the evolutionary history of this clade. PMID:23927069

2013-01-01

127

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

PubMed

The behaviour of fossil organisms can typically be inferred only indirectly, but rare fossil finds can provide surprising insights. Here, we report from the Eocene Messel Pit Fossil Site between Darmstadt and Frankfurt, Germany numerous pairs of the fossil carettochelyid turtle Allaeochelys crassesculpta that represent for the first time among fossil vertebrates couples that perished during copulation. Females of this taxon can be distinguished from males by their relatively shorter tails and development of plastral kinesis. The preservation of mating pairs has important taphonomic implications for the Messel Pit Fossil Site, as it is unlikely that the turtles would mate in poisonous surface waters. Instead, the turtles initiated copulation in habitable surface waters, but perished when their skin absorbed poisons while sinking into toxic layers. The mating pairs from Messel are therefore more consistent with a stratified, volcanic maar lake with inhabitable surface waters and a deadly abyss. PMID:22718955

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

2012-10-23

128

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

PubMed Central

The behaviour of fossil organisms can typically be inferred only indirectly, but rare fossil finds can provide surprising insights. Here, we report from the Eocene Messel Pit Fossil Site between Darmstadt and Frankfurt, Germany numerous pairs of the fossil carettochelyid turtle Allaeochelys crassesculpta that represent for the first time among fossil vertebrates couples that perished during copulation. Females of this taxon can be distinguished from males by their relatively shorter tails and development of plastral kinesis. The preservation of mating pairs has important taphonomic implications for the Messel Pit Fossil Site, as it is unlikely that the turtles would mate in poisonous surface waters. Instead, the turtles initiated copulation in habitable surface waters, but perished when their skin absorbed poisons while sinking into toxic layers. The mating pairs from Messel are therefore more consistent with a stratified, volcanic maar lake with inhabitable surface waters and a deadly abyss. PMID:22718955

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

2012-01-01

129

Differentiation between Neotropical rainforest, dry forest, and savannah ecosystems by their modern pollen spectra and implications for the fossil pollen record  

Microsoft Academic Search

Accurate differentiation between tropical forest and savannah ecosystems in the fossil pollen record is hampered by the combination of: i) poor taxonomic resolution in pollen identification, and ii) the high species diversity of many lowland tropical families, i.e. with many different growth forms living in numerous environmental settings. These barriers to interpreting the fossil record hinder our understanding of the

William D. Gosling; Francis E. Mayle; Nicholas J. Tate; Timothy J. Killeen

2009-01-01

130

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

Microsoft Academic Search

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

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

2002-01-01

131

On the development of probabilistic climate reconstructions based on fossil pollen records  

NASA Astrophysics Data System (ADS)

Past climate reconstructions based on proxy data help to understand natural climate variability. It is essential that palaeoenvironmental transfer functions between climate and proxy variables take in to account the stochastical nature of the climate system. Especially pollen based reconstructions are a complex issue, since pollen counts do not show direct relation to climatological parameters, e.g. due to plant competition and/or land cultivation. The idea is to assess the background knowledge from classical, more empirically based methods in order to develop statistical transfer functions between vegetation and climate. Two popular concepts, the indicator taxa approach (or MCR) as well as the biomisation (BIOME/PFT), are translated into a statistical framework in order to reconstruct January and July temperatures as well as annual precipitation during the Holocene (10,000yrs BP). This involves the problem of multivariate random vectors with non-normally distributed marginals, which has been adressed by using copulas. The methods are applied to fossil pollen records of laminated sediments from the Eifel region in Germany. On the one hand, the reconstructions indicate that pollen based reconstructions show larger uncertainty ranges than expected by several classical approaches. On the other hand, the indicator taxa approach is robust to the lack of modern analogues, which is an advantage in highly anthropogenically influenced areas such as the Mediterranean or Central Europe.

Schoelzel, C.; Hense, A.

2009-04-01

132

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

USGS Publications Warehouse

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

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

2005-01-01

133

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

PubMed

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

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

2014-10-01

134

El Nio 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 Nio - 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 Nio, 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 Nio 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.; Schne, Bernd R.

2011-08-01

135

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

NASA Astrophysics Data System (ADS)

Understanding compositional changes in vegetation over the common era provides insight about ecosystem dynamics in response to changing environments. Past vegetation reconstructions rely predominantly on fossil pollen data from sedimentary lake cores, which acts as a proxy record for the surrounding vegetation. Stratigraphic changes in these pollen records allow us to infer changes in composition and species distributions. Pollen records collected from a network of sites allow us to make inference about the spatio-temporal changes in vegetation over thousands of years. To reconstruct vegetation composition, we build a Bayesian model for the Upper Midwestern USA that links vegetation composition to fossil pollen data via a dispersal model. We estimate the relationship between vegetation and pollen for the settlement era using United States Public Land Survey data and a network of pollen records. Using parameter estimates from the settlement era, we use the fossil pollen proxy records to estimate species distributions and relative abundances over the last 2500 years. Resulting composition and abundance estimates will be used to improve the forecasting capabilities of ecosystem models.

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

2013-12-01

136

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

Microsoft Academic Search

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

Michael G. Newbrey; Allan C. Ashworth

2004-01-01

137

Finding Fossils  

NSDL National Science Digital Library

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

138

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

NASA Astrophysics Data System (ADS)

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

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

2002-12-01

139

Fossil Excavation  

NSDL National Science Digital Library

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

140

A systematic assessment of early African hominids.  

PubMed

A large sample of Pliocene fossil hominid remains has been recovered from the African sites of Hadar in Ethiopia and Laetolil in Tanzania. These collections, dating approximately between 2.9 and 3.8 million years ago, constitute the earliest substantial record of the family Hominidae. This article assesses the phylogenetic relationships of the newly discovered fossil hominids and provides a taxonomy consistent with that assessment. A new taxon, Australopithecus afarensis, has been created to accommodate these Pliocene hominid fossils. PMID:104384

Johanson, D C; White, T D

1979-01-26

141

Project EARTH-10-MF2: Form And Function in the Fossil Record: Using Exceptionally Preserved Skulls  

E-print Network

-Campanian) English Chalk and the lower Eocene (Ypresian) London Clay. These marine localities yield diverse bony fish-dimensional fossils, but the London Clay and English Chalk yield exquisite three-dimensional heads (see figure English Chalk (bott

Henderson, Gideon

142

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

Microsoft Academic Search

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

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

1973-01-01

143

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

144

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

PubMed Central

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

HYN, MATڊ; GAPARI?, ROK

2015-01-01

145

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

PubMed Central

Background We describe the first occurrence in the fossil record of an aquatic avian twig-nest with five eggs in situ (Early Miocene Tudela Formation, Ebro Basin, Spain). Extensive outcrops of this formation reveal autochthonous avian osteological and oological fossils that represent a single taxon identified as a basal phoenicopterid. Although the eggshell structure is definitively phoenicopterid, the characteristics of both the nest and the eggs are similar to those of modern grebes. These observations allow us to address the origin of the disparities between the sister taxa Podicipedidae and Phoenicopteridae crown clades, and traces the evolution of the nesting and reproductive environments for phoenicopteriforms. Methodology/Principal Findings Multi-disciplinary analyses performed on fossilized vegetation and eggshells from the eggs in the nest and its embedding sediments indicate that this new phoenicopterid thrived under a semi-arid climate in an oligohaline (seasonally mesohaline) shallow endorheic lacustine environment. High-end microcharacterizations including SEM, TEM, and EBSD techniques were pivotal to identifying these phoenicopterid eggshells. Anatomical comparisons of the fossil bones with those of Phoenicopteriformes and Podicipediformes crown clades and extinct palaelodids confirm that this avian fossil assemblage belongs to a new and basal phoenicopterid. Conclusions/Significance Although the Podicipediformes-Phoenicopteriformes sister group relationship is now well supported, flamingos and grebes exhibit feeding, reproductive, and nesting strategies that diverge significantly. Our multi-disciplinary study is the first to reveal that the phoenicopteriform reproductive behaviour, nesting ecology and nest characteristics derived from grebe-like type strategies to reach the extremely specialized conditions observed in modern flamingo crown groups. Furthermore, our study enables us to map ecological and reproductive characters on the Phoenicopteriformes evolutionary lineage. Our results demonstrate that the nesting paleoenvironments of flamingos were closely linked to the unique ecology of this locality, which is a direct result of special climatic (high evaporitic regime) and geological (fault system) conditions. PMID:23082136

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

2012-01-01

146

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

E-print Network

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

Benton, Michael

147

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

148

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

149

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

PubMed

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

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

2015-04-01

150

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

PubMed Central

The fossil record is the only source of information on the long-term dynamics of species assemblages. Here we assess the degree of ecological stability of the epifaunal pterioid bivalve assemblage (EPBA), which is part of the Middle Devonian Hamilton fauna of New Yorkthe type example of the pattern of coordinated stasis, in which long intervals of faunal persistence are terminated by turnover events induced by environmental change. Previous studies have used changes in abundance structure within specific biofacies as evidence for a lack of ecological stability of the Hamilton fauna. By comparing data on relative abundance, body size, and predation, indexed as the frequency of unsuccessful shell-crushing attacks, of the EPBA, we show that abundance structure varied through time, but body-size structure and predation pressure remained relatively stable. We suggest that the energetic set-up of the Hamilton fauna's food web was able to accommodate changes in species attributes, such as fluctuating prey abundances. Ecological redundancy in prey resources, adaptive foraging of shell-crushing predators (arising from predator behavioral or adaptive switching in prey selection in response to changing prey abundances), and allometric scaling of predator-prey interactions are discussed as potential stabilizing factors contributing to the persistence of the Hamilton fauna's EPBA. Our study underscores the value and importance of multiple lines of evidence in tests of ecological stability in the fossil record. PMID:23690981

Handley, John C.; Brett, Carlton E.

2013-01-01

151

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

NASA Astrophysics Data System (ADS)

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

Blank, Carrine E.

2009-03-01

152

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

E-print Network

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

Schne, Bernd R.

153

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

154

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

USGS Publications Warehouse

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

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

1998-01-01

155

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

E-print Network

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

Lieberman, Bruce S

2007-01-01

156

Late glacial climate estimates for southern Nevada the ostracode fossil record  

SciTech Connect

Climate change plays an important role in determining the 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)

1994-12-31

157

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

158

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

NASA Astrophysics Data System (ADS)

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

Saltr, Frdrik; Brook, Barry W.; Rodrguez-Rey, Marta; Cooper, Alan; Johnson, Christopher N.; Turney, Chris S. M.; Bradshaw, Corey J. A.

2015-03-01

159

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

E-print Network

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

A. Aparicio

1998-11-11

160

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

PubMed Central

The vast mammal diversity of the Neotropics is the result of a long evolutionary history. During most of the Cenozoic, South America was an island continent with an endemic mammalian fauna. This isolation ceased during the late Neogene after the formation of the Isthmus of Panama, resulting in an event known as the Great American Biotic Interchange (GABI). In this study, we investigate biogeographic patterns in South America, just before or when the first immigrants are recorded and we review the temporal and geographical distribution of fossil mammals during the GABI. We performed a dissimilarity analysis which grouped the faunal assemblages according to their age and their geographic distribution. Our data support the differentiation between tropical and temperate assemblages in South America during the middle and late Miocene. The GABI begins during the late Miocene (~107 Ma) and the putative oldest migrations are recorded in the temperate region, where the number of GABI participants rapidly increases after ~5 Ma and this trend continues during the Pleistocene. A sampling bias toward higher latitudes and younger records challenges the study of the temporal and geographic patterns of the GABI. PMID:25601879

Carrillo, Juan D.; Forasiepi, Anala; Jaramillo, Carlos; Snchez-Villagra, Marcelo R.

2015-01-01

161

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

PubMed

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

Carrillo, Juan D; Forasiepi, Anala; Jaramillo, Carlos; Snchez-Villagra, Marcelo R

2014-01-01

162

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

PubMed

Variation is the raw material for natural selection, but the factors shaping variation are still poorly understood. Genetic and developmental interactions can direct variation, but there has been little synthesis of these effects with the extrinsic factors that can shape biodiversity over large scales. The study of phenotypic integration and modularity has the capacity to unify these aspects of evolutionary study by estimating genetic and developmental interactions through the quantitative analysis of morphology, allowing for combined assessment of intrinsic and extrinsic effects. Data from the fossil record in particular are central to our understanding of phenotypic integration and modularity because they provide the only information on deep-time developmental and evolutionary dynamics, including trends in trait relationships and their role in shaping organismal diversity. Here, we demonstrate the important perspective on phenotypic integration provided by the fossil record with a study of Smilodon fatalis (saber-toothed cats) and Canis dirus (dire wolves). We quantified temporal trends in size, variance, phenotypic integration, and direct developmental integration (fluctuating asymmetry) through 27,000 y of Late Pleistocene climate change. Both S. fatalis and C. dirus showed a gradual decrease in magnitude of phenotypic integration and an increase in variance and the correlation between fluctuating asymmetry and overall integration through time, suggesting that developmental integration mediated morphological response to environmental change in the later populations of these species. These results are consistent with experimental studies and represent, to our knowledge, the first deep-time validation of the importance of developmental integration in stabilizing morphological evolution through periods of environmental change. PMID:25901310

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

2015-04-21

163

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

PubMed

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

Webber, Andrew J; Hunda, Brenda R

2007-06-01

164

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

PubMed

The Patagonian steppe-a massive rain-shadow on the lee side of the southern Andes-is assumed to have evolved ~15-12?Myr as a consequence of the southern Andean uplift. However, fossil evidence supporting this assumption is limited. Here we quantitatively estimate climatic conditions and plant richness for the interval ~10-6?Myr based on the study and bioclimatic analysis of terrestrially derived spore-pollen assemblages preserved in well-constrained Patagonian marine deposits. Our analyses indicate a mesothermal climate, with mean temperatures of the coldest quarter between 11.4?C and 16.9?C (presently ~3.5?C) and annual precipitation rarely below 661?mm (presently ~200?mm). Rarefied richness reveals a significantly more diverse flora during the late Miocene than today at the same latitude but comparable with that approximately 2,000?km further northeast at mid-latitudes on the Brazilian coast. We infer that the Patagonian desertification was not solely a consequence of the Andean uplift as previously insinuated. PMID:24675482

Palazzesi, L; Barreda, V D; Cuitio, J I; Guler, M V; Tellera, M C; Ventura Santos, R

2014-01-01

165

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

E-print Network

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

Bruce S. Lieberman; Adrian L. Melott

2007-08-22

166

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.

Michael Savarese

167

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

Microsoft Academic Search

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

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

1994-01-01

168

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

169

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

170

A large extinct marabou stork in African Pliocene hominid sites, and a review of the fossil species of Leptoptilos  

Microsoft Academic Search

New fossils of the family Ciconiidae from Pliocene hominid localities in Chad and Ethiopia are described, and several are shown to belong to Leptoptilos falconeri, originally known from the late Pliocene of the Siwalik Hills of India. Compari? sons with all the hitherto known species of large Ciconiidae, and with an enlarged sample representing extant species, lead to a re?evaluation

ANTOINE LOUCHART; PATRICK VIGNAUD; ANDOSSA LIKIUS; MICHEL BRUNET; TIM D. WHITE

171

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

PubMed Central

Carcharocles megalodon (Megalodon) is the largest shark that ever lived. Based on its distribution, dental morphology, and associated fauna, it has been suggested that this species was a cosmopolitan apex predator that fed on marine mammals from the middle Miocene to the Pliocene (15.92.6 Ma). Prevailing theory suggests that the extinction of apex predators affects ecosystem dynamics. Accordingly, knowing the time of extinction of C. megalodon is a fundamental step towards understanding the effects of such an event in ancient communities. However, the time of extinction of this important species has never been quantitatively assessed. Here, we synthesize the most recent records of C. megalodon from the literature and scientific collections and infer the date of its extinction by making a novel use of the Optimal Linear Estimation (OLE) model. Our results suggest that C. megalodon went extinct around 2.6 Ma. Furthermore, when contrasting our results with known ecological and macroevolutionary trends in marine mammals, it became evident that the modern composition and function of modern gigantic filter-feeding whales was established after the extinction of C. megalodon. Consequently, the study of the time of extinction of C. megalodon provides the basis to improve our understanding of the responses of marine species to the removal of apex predators, presenting a deep-time perspective for the conservation of modern ecosystems. PMID:25338197

Pimiento, Catalina; Clements, Christopher F.

2014-01-01

172

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

173

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

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

174

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

PubMed

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

Overmann, Karenleigh; Coolidge, Frederick

2013-01-01

175

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

PubMed Central

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

Kano, Yasunori; Chiba, Satoshi; Kase, Tomoki

2002-01-01

176

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

177

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

178

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

179

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

PubMed

Sauria is the crown-group of Diapsida and is subdivided into Lepidosauromorpha and Archosauromorpha, comprising a high percentage of the diversity of living and fossil tetrapods. The split between lepidosauromorphs and archosauromorphs (the crocodile-lizard, or bird-lizard, divergence) is considered one of the key calibration points for molecular analyses of tetrapod phylogeny. Saurians have a very rich Mesozoic and Cenozoic fossil record, but their late Paleozoic (Permian) record is problematic. Several Permian specimens have been referred to Sauria, but the phylogenetic affinity of some of these records remains questionable. We reexamine and review all of these specimens here, providing new data on early saurian evolution including osteohistology, and present a new morphological phylogenetic dataset. We support previous studies that find that no valid Permian record for Lepidosauromorpha, and we also reject some of the previous referrals of Permian specimens to Archosauromorpha. The most informative Permian archosauromorph is Protorosaurus speneri from the middle Late Permian of Western Europe. A historically problematic specimen from the Late Permian of Tanzania is redescribed and reidentified as a new genus and species of basal archosauromorph: Aenigmastropheus parringtoni. The supposed protorosaur Eorasaurus olsoni from the Late Permian of Russia is recovered among Archosauriformes and may be the oldest known member of the group but the phylogenetic support for this position is low. The assignment of Archosaurus rossicus from the latest Permian of Russia to the archosauromorph clade Proterosuchidae is supported. Our revision suggests a minimum fossil calibration date for the crocodile-lizard split of 254.7 Ma. The occurrences of basal archosauromorphs in the northern (30N) and southern (55S) parts of Pangea imply a wider paleobiogeographic distribution for the group during the Late Permian than previously appreciated. Early archosauromorph growth strategies appear to be more diverse than previously suggested based on new data on the osteohistology of Aenigmastropheus. PMID:24586565

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

2014-01-01

180

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

PubMed Central

Sauria is the crown-group of Diapsida and is subdivided into Lepidosauromorpha and Archosauromorpha, comprising a high percentage of the diversity of living and fossil tetrapods. The split between lepidosauromorphs and archosauromorphs (the crocodile-lizard, or bird-lizard, divergence) is considered one of the key calibration points for molecular analyses of tetrapod phylogeny. Saurians have a very rich Mesozoic and Cenozoic fossil record, but their late Paleozoic (Permian) record is problematic. Several Permian specimens have been referred to Sauria, but the phylogenetic affinity of some of these records remains questionable. We reexamine and review all of these specimens here, providing new data on early saurian evolution including osteohistology, and present a new morphological phylogenetic dataset. We support previous studies that find that no valid Permian record for Lepidosauromorpha, and we also reject some of the previous referrals of Permian specimens to Archosauromorpha. The most informative Permian archosauromorph is Protorosaurus speneri from the middle Late Permian of Western Europe. A historically problematic specimen from the Late Permian of Tanzania is redescribed and reidentified as a new genus and species of basal archosauromorph: Aenigmastropheus parringtoni. The supposed protorosaur Eorasaurus olsoni from the Late Permian of Russia is recovered among Archosauriformes and may be the oldest known member of the group but the phylogenetic support for this position is low. The assignment of Archosaurus rossicus from the latest Permian of Russia to the archosauromorph clade Proterosuchidae is supported. Our revision suggests a minimum fossil calibration date for the crocodile-lizard split of 254.7 Ma. The occurrences of basal archosauromorphs in the northern (30N) and southern (55S) parts of Pangea imply a wider paleobiogeographic distribution for the group during the Late Permian than previously appreciated. Early archosauromorph growth strategies appear to be more diverse than previously suggested based on new data on the osteohistology of Aenigmastropheus. PMID:24586565

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

2014-01-01

181

The Strontium Isotope Composition of Fossil Hackberry Seed Carbonate and Tooth Enamel as a Potential Record of Soil Erosion  

Microsoft Academic Search

The Edwards Plateau in central Texas has experienced significant soil erosion since the Last Glacial Maximum. In contrast to the thin soils that mantle the Cretaceous limestone bedrock of the modern Edwards Plateau, Quaternary fossils of burrowing mammals contained within several central Texas cave deposits suggest soil cover was much thicker in the latest Pleistocene and early Holocene. As the

M. J. Cooke; L. A. Stern; J. L. Banner

2001-01-01

182

The Strontium Isotope Composition of Fossil Hackberry Seed Carbonate and Tooth Enamel as a Potential Record of Soil Erosion  

NASA Astrophysics Data System (ADS)

The Edwards Plateau in central Texas has experienced significant soil erosion since the Last Glacial Maximum. In contrast to the thin soils that mantle the Cretaceous limestone bedrock of the modern Edwards Plateau, Quaternary fossils of burrowing mammals contained within several central Texas cave deposits suggest soil cover was much thicker in the latest Pleistocene and early Holocene. As the landscape is denuded, the Cretaceous limestone bedrock is exhumed and becomes a more important source of exchangeable Sr to the soils. Therefore, the Sr isotope composition of the soil and organisms deriving nutrients from the soil, such as plants and herbivores, should become more like the Sr isotope composition of the bedrock as erosion continues. Because the marine limestone bedrock has a lower 87Sr/86Sr value than the soil, the exchangeable soil Sr should evolve to lower 87Sr/86Sr values through time resulting in a decrease in the 87Sr/86Sr of plants and animals deriving nutrients from the soil. In order to test this hypothesis, terrestrial fossils from an extensively dated Quaternary deposit within Hall's Cave, Kerr County, Texas were analyzed by TIMS for 87Sr/86Sr. The materials analyzed include aragonitic fossil hackberry seeds and rodent tooth enamel. Results indicate an overall decrease in the 87Sr/86Sr of fossil hackberry seed aragonite and rodent tooth enamel over the last 16,000 years, with the highest rate of decrease in the 87Sr/86Sr of fossil hackberry seeds (0.70982 to 0.70841) occurring between approximately 16,000 and 10,000 Y.B.P. This decrease in the 87Sr/86Sr is interpreted as evidence for an increase in the proportion of bedrock-derived Sr to the soils, corresponding to a general decrease in soil thickness. An increase in aridity or an increase in the seasonality of precipitation during this time could account for the post-glacial soil erosion in central Texas. This study suggests that the 87Sr/86Sr of fossils may be a useful proxy for paleo soil depth. Additionally, when applied to central Texas cave fossils, this technique may be able to provide a better understanding of the geomorphic and environmental history of the Edwards Plateau.

Cooke, M. J.; Stern, L. A.; Banner, J. L.

2001-12-01

183

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

NASA Astrophysics Data System (ADS)

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

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

184

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

PubMed Central

A new fossil leaf impression of Alphonsea Hk. f. & T. of the family Annonaceae is described from the Late Oligocene sediments of Makum Coalfield, Assam, India. This is the first authentic record of the fossil of Alphonsea from the Tertiary rocks of South Asia. The Late Oligocene was the time of the last significant globally warm climate and the fossil locality was at 1015N palaeolatitude. The known palaeoflora and sedimentological studies indicate a fluvio-marine deltaic environment with a mosaic of mangrove, fluvial, mire and lacustrine depositional environments. During the depositional period the suturing between the Indian and Eurasian plates was not complete to facilitate the plant migration. The suturing was over by the end of the Late Oligocene/beginning of Early Miocene resulting in the migration of the genus to Southeast Asia where it is growing profusely at present. The present study is in congruence with the earlier published palaeofloral and molecular phylogenetic data. The study also suggests that the Indian plate was not only a biotic ferry during its northward voyage from Gondwana to Asia but also a place for the origin of several plant taxa. PMID:23349701

Srivastava, Gaurav; Mehrotra, Rakesh C.

2013-01-01

185

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

PubMed

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

Srivastava, Gaurav; Mehrotra, Rakesh C

2013-01-01

186

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

187

Fossil Fondue  

NSDL National Science Digital Library

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

2014-09-18

188

Fossil primates 1 Fossil primates  

E-print Network

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

Delson, Eric

189

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.

190

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

PubMed Central

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

2012-01-01

191

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

NASA Astrophysics Data System (ADS)

Identifying the adaptation of hunter-gatherer communities to particular situations that provided natural resources is a major concern for multidisciplinary team studying archaeological contexts. This challenge is illustrated in the desertic El Kowm basin in central Syria by data from Hummal and El Kowm Paleolithic sites. The sites form prominent mounds at artesian springs resulting from recurrent episodes of lacustrine, limnic and aeolian sedimentation in pseudo-karstic depressions. The few meter sequences provide semi-continuous succession of archaeological levels from the Oldest Palaeolithic (Oldowan) to the early Neolithic period. This long term continuity of occupation is partly due to attracting conditions due to the profusion of water from epithermal artesian wells during periods of high water recharge. In addition, we document here the unique potential of this endoreic basin to have accumulated singular fossil combustible of high energy value during particular environmental episodes. The latter are represented by the recurrence of distinctive black organogenic facies showing a contrasting micro stratification formed of interlayered grey calcareous silty clay, dark brown organic rich clay and dull orange clay. Spatial excavation has shown the unique preservation of Palaeolithic occupation surfaces in association to the microstratified facies. High resolution sampling and multi-proxy analysis have allowed explaining the formation of the microstratified facies from rapid changes of environmental conditions in response to contrasting fluctuations of atmospheric dust loading, precipitation events, rainwater quality and evapotranspiration. Organogenic microfacies formed at different time periods share common compositional assemblage and structural behaviour: occurrence of exotic fine sand-sized debris formed of metal-rich carbonaceous components with polymer, fine charcoal, vitrous carbon, carbon fibres, and exotic rock clasts with a metal-rich carbonaceous coating; highly stable microstructure and low wettability. Based on their analytical properties, the carbonaceous polymorphs and the associated mineral components are shown to deriving from fossil combustible of stratospheric origin. The comparison with modern analogues (cf. Courty et al., 2012) has provided keys to explaining the organogenic microfacies from accumulation episodes of exotic stratospheric aerosols in response to serial meteor explosion at high altitude. Geogenic markers and microfacies pattern show four situations: (1) nearly intact ancient surfaces with pulverized carbonaceous composite debris that trace the local effects of meteor explosion ; (2) secondary concentrations expressing accumulation of stratospheric aerosols from the heavy rainfall events subsequent to the meteor explosions; (3) relictual concentrations resulting from selective accumulation of the most resistant components by chemical and physical erosion along to the fossilization; (4) human-controlled concentrations of the unusual debris indicating intentional collect, use and transformation of the singular fossil combustible and related materials. Ancient humans are thus suggested to have regularly exploited the local sources of the singular fossil combustible that formed during episodes of serial cosmic explosions. The direct effect of increased atmospheric dust loading on precipitation regime explains the apparent synchrony between occupation phases and local climate changes. These are simply two distinctive responses to a common cause. Courty, Benot and Vaillant (2012). Possible interaction of meteor explosion with stratospheric aerosols on cloud nucleation based on 2011 observations. Geophysical Research Abstracts Vol. 14, EGU2012.

Courty, M.-A.; Le Tensorer, J.-M.; Boda, E.; Muhesen, S.; Alsakhel, E.; Wegmller, F.

2012-04-01

192

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

193

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

NASA Astrophysics Data System (ADS)

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

Wake, Thomas A.; Roeder, Mark A.

2009-11-01

194

"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

195

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

NASA Astrophysics Data System (ADS)

The reconstruction and structure of the European Holocene "wildwood" has been the focus of considerable academic debate. The ability of palaeoecological data and particularly pollen analysis to accurately reflect the density of wildwood canopy has also been widely discussed. Fossil insects, as a proxy for vegetation and landscape structure, provide a potential approach to address this argument. Here, we present a review and re-analysis of 36 early and mid-Holocene (9500-2000 cal BC) sub-fossil beetle assemblages from Britain, examining percentage values of tree, open ground and dung beetles as well as tree host data to gain an insight into vegetation structure, the role of grazing animals in driving such structure and establish independently the importance of different types of trees and associated shading in the early Holocene "wildwood". Open indicator beetle species are persistently present over the entire review period, although they fluctuate in importance. During the early Holocene (9500-6000 cal BC), these indicators are initially high, at levels which are not dissimilar to modern data from pasture woodland. However, during the latter stages of this and the next period, 6000-4000 cal BC, open ground and pasture indicators decline and are generally low compared with previously. Alongside this pattern, we see woodland indicators generally increase in importance, although there are significant local fluctuations. Levels of dung beetles are mostly low over these periods, with some exceptions to this pattern, especially towards the end of the Mesolithic and in floodplain areas. Host data associated with the fossil beetles indicate that trees associated with lighter canopy conditions such as oak, pine, hazel and birch are indeed important components of the tree canopy during the earlier Holocene (c. 9500-6000 cal BC), in accordance with much of the current pollen literature. Beetles associated with more shade-tolerant trees (such as lime and elm) become more frequent in the middle Holocene (6000-4000 cal BC) suggesting that at this stage the woodland canopy was less open than previously, although open ground and pasture areas appear to have persisted in some locations. The onset of agriculture (4000-2000 cal BC) coincides with significant fluctuations in woodland composition and taxa. This is presumably as a result of human impact, although here there are significant regional variations. There are also increases in the amounts of open ground represented and especially in the levels of dung beetles present in faunas, suggesting there is a direct relationship between the activities of grazing animals and the development of more open areas. One of the most striking aspects of this review is the variable nature of the landscape suggested by the palaeoecological data, particularly but not exclusively with the onset of agriculture: some earlier sites indicate high variability between levels of tree-associated species on the one hand and the open ground beetle fauna on the other, indicating that in some locations, open areas were of local significance and can be regarded as important features of the Holocene landscape. The role of grazing animals in creating these areas of openness was apparently minimal until the onset of the Neolithic.

Whitehouse, Nicki J.; Smith, David

2010-02-01

196

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

197

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

PubMed

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

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

2012-09-01

198

"It's Alive!" Fossil Activity  

NSDL National Science Digital Library

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

Peg Yacobucci

199

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

USGS Publications Warehouse

In North America, terrestrial records of biodiversity and climate change that span Marine Oxygen Isotope Stage (MIS) 5 are rare. Where found, they provide insight into how the coupling of the oceanatmosphere system is manifested in biotic and environmental records and how the biosphere responds to climate change. In 20102011, construction at Ziegler Reservoir near Snowmass Village, Colorado (USA) revealed a nearly continuous, lacustrine/wetland sedimentary sequence that preserved evidence of past plant communities between ~ 140 and 55 ka, including all of MIS 5. At an elevation of 2705 m, the Ziegler Reservoir fossil site also contained thousands of well-preserved bones of late Pleistocene megafauna, including mastodons, mammoths, ground sloths, horses, camels, deer, bison, black bear, coyotes, and bighorn sheep. In addition, the site contained more than 26,000 bones from at least 30 species of small animals including salamanders, otters, muskrats, minks, rabbits, beavers, frogs, lizards, snakes, fish, and birds. The combination of macro- and micro-vertebrates, invertebrates, terrestrial and aquatic plant macrofossils, a detailed pollen record, and a robust, directly dated stratigraphic framework shows that high-elevation ecosystems in the Rocky Mountains of Colorado are climatically sensitive and varied dramatically throughout MIS 5.

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

2014-01-01

200

A high-elevation, multi-proxy biotic and environmental record of MIS 64 from the Ziegler Reservoir fossil site, Snowmass Village, Colorado, USA  

SciTech Connect

In North America, terrestrial records of biodiversity and climate change that span Marine Oxygen Isotope Stage (MIS) 5 are rare. Where found, they provide insight into how the coupling of the oceanatmosphere system is manifested in biotic and environmental records and how the biosphere responds to climate change. In 20102011, construction at Ziegler Reservoir near Snowmass Village, Colorado (USA) revealed a nearly continuous, lacustrine/wetland sedimentary sequence that preserved evidence of past plant communities between ~140 and 55 ka, including all of MIS 5. At an elevation of 2705 m, the Ziegler Reservoir fossil site also contained thousands of well-preserved bones of late Pleistocene megafauna, including mastodons, mammoths, ground sloths, horses, camels, deer, bison, black bear, coyotes, and bighorn sheep. In addition, the site contained more than 26,000 bones from at least 30 species of small animals including salamanders, otters, muskrats, minks, rabbits, beavers, frogs, lizards, snakes, fish, and birds. The combination of macro- and micro-vertebrates, invertebrates, terrestrial and aquatic plant macrofossils, a detailed pollen record, and a robust, directly dated stratigraphic framework shows that high-elevation ecosystems in the Rocky Mountains of Colorado are climatically sensitive and varied dramatically throughout MIS 5

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

2014-10-01

201

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

PubMed Central

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

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

2014-01-01

202

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

PubMed

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

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

2014-01-01

203

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

204

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

205

Continental environment variations (climate, erosion) recorded by Marine quaternary sediments of the northwestern and eastern African margins  

NASA Astrophysics Data System (ADS)

Samples collected from 4 sites on the northwestern and eastern African margins were used to test the reliability of marine sedimentary record of continental environmental variations, during the last Glacial and Interglacial climatic cycle. On the northwestern margin which is passive and stable (between Cape Verde and Cape Blanc), climatic variations are marked by parameters such as sedimentary facies, sedimentary dynamics, sedimentation rates or faunal assemblages. These parameters are controlled by climatic changes that modify continental environments (erosion conditions, rate of terrigenous supplies) and marine environments as well (sea-level, currents and biogenic sediment productivity). On the opposite, in the Gulf of Aden, 3 sites show the extent to which tectonics may affect the record of environment modifications due to climatic changes. In the East of the Gulf, on the Sukra margin that is passive but with young and still active structures, the continental slope is uneven with tectonic basins acting as sediment traps. Here, several parameters like sedimentation rates become unreliable for they no longer reflect the importance of terrigenous inputs nor that of primary productivity. Further to the West, the deep narrow trough of Alula Fartak and the epicontinental domain belonging to the Assal rift (Ghubbet el Kharab), are part of highly active tectonic and volcanic margins. Continental environment variations cease to be recorded through sedimentological parameters which are closely related to morpho-structural and volcanic factors.

Faugres, J. C.; Pujol, Cl.

206

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

NASA Astrophysics Data System (ADS)

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

Prez, Claudio; Bianchi, Mara Martha; Gassmann, Marisa; Pisso, Ignacio

2014-05-01

207

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.

208

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.

2012-06-26

209

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

PubMed Central

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

Stehlk, Jaroslav L.; Jindra, Zden?k

2011-01-01

210

A High-Resolution Late Holocene Record of Rainfall From Lake Edward, Equatorial Africa: Linkages Between the African and Indian Monsoons  

NASA Astrophysics Data System (ADS)

High-resolution analyses of the chemical composition of calcite and the biogenic silica content of sediments from piston cores spanning the past 3,500 years from Lake Edward, Uganda-Congo, document multidecadal to millennial-scale climate variability in the heart of equatorial Africa. Major drought events in the Lake Edward record occur at about 500, 850, 1500, ~2000, and 2700 cal yr BP, in addition to numerous other events of lesser magnitude/duration. Comparison of our record to other Holocene records of African lake levels suggests that most of these intervals of drought affected most of equatorial East Africa. However, wet conditions at about 500 cal yrs BP at sites to the east of Lake Edward could indicate spatial heterogeneity within the African continent during the "Little Ice Age", which could have resulted from complex interactions between the African (Atlantic) and Indian Ocean monsoons. Spectral analysis of our drought record, sampled at a 3-year step, shows evidence for numerous multidecadal to century-scale drought periods in the region. The periodicities observed do not appear linked to solar forcing; rather, periods of ~125, ~70, ~28, and ~18 years apparent in our record as well as other records from the Indian Ocean basin may arise from climate variability internal to the tropical oceans, in particular the Indo-Pacific. Lastly, the Lake Edward record suggests that the climate of equatorial Africa has been unusually stable and generally wet for the past ca. 100 years. This stability appears unusual in light of the considerable climate variability suggested by our record for the past several millennia, a finding with clear implications for East African societies.

Russell, J. M.; Johnson, T. C.

2005-12-01

211

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

PubMed Central

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

2011-01-01

212

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

213

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

214

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.

Iowa Public Television. Explore More Project

2004-01-01

215

Fossil humans 1 Fossil humans  

E-print Network

, and close extinct rel- atives) recognizes the family Hylobatidae for the gib- bons and Hominidae for humansFossil humans 1 Fossil humans All prehistoric skeletal remains of humans which are archeologically, anatomically modern humans. In this sense, the term "humans" is used broadly to mean all primates related

Delson, Eric

216

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

NASA Astrophysics Data System (ADS)

Fossiliferous middle Pleistocene sediments of the Tarija basin of southern Bolivia contain a classic Ensenadan land-mammal fauna. New carbon isotopic data reported here for 50 specimens of the grazing mammals Equus (horse) and Cuvieronius (mastodon), documented from eight stratigraphic levels at Tarija, vary significantly in the ?13C values of their teeth. The pattern of variation appears to reflect the proportion of C3 and C4 grasses eaten during colder (more C3) and warmer (more C4) times. Within age limits set by associated magnetostratigraphy, the cold periods can be correlated with particular even-numbered stages in the marine oxygen-isotope record, and the warm periods can be correlated with odd-numbered stages. The oldest fossil teeth analyzed from the Tarija section can thereby be assigned to stage 29, and the youngest to stages 17 or 15, that is; the teeth range in age from about 1.1 myr to as young as 0.7 myr. Based on correlation of the upper part of the Tarija beds to the isotopic stages, the upper limit of the Ensenadan land-mammal age is between 0.7 and 0.6 myr, which is younger than stated in most previous studies.

MacFadden, Bruce J.

2000-07-01

217

Late Quaternary hillslope evolution recorded in eastern South African colluvial badlands  

Microsoft Academic Search

Infrared stimulated luminescence (IRSL) ages have been obtained from a sequence of sandy colluvial deposits in northern KwaZuluNatal. Comparison of the IRSL ages on sand-sized, potassium-rich feldspars, with radiocarbon dates on A-horizon organic matter from buried palaeosols within the colluvial succession shows good agreement between the dating techniques. When compared with palaeoenvironmental records, the data suggest that the colluvium accumulated

M. L. Clarke; J. C. Vogel; G. A. Botha; A. G. Wintle

2003-01-01

218

Restoring Fossil Creek  

NSDL National Science Digital Library

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

Carri J. LeRoy

2004-07-01

219

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.

220

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

NASA Astrophysics Data System (ADS)

Soil erosion threatens the food security of 2.6 billion people worldwide. The situation is particularly dire in East and Sub-Saharan Africa where per capita food production has declined over the past 45 years. Erosion and the resultant loss of fertile soil is a key socio-economic and ecological problem in Kenya, affecting all sectors of its economy and damaging marine and terrestrial ecosystems. The temporal pattern of soil erosion is almost unknown and currently only sparse and rather anecdotal information exists. To aid in filling this gap of knowledge, we present a 300-year long Barium record from two Kenyan coral colonies (Porites sp., 315'S, 409' E; Malindi Marine National Park) that documents a dynamic history of soil erosion in the Sabaki river drainage basin. To reconstruct Sabaki River sediment flux to the Malindi coral reef Ba/Ca ratios were measured in the skeleton of two Porites colonies (Mal 96-1 and Mal 95-3). Well-developed annual bands allow us to develop annually precise chronologies. Ba/Ca ratios were measured in core Mal 96-1 at continuous 40 ?m intervals (~400 to 500 samples yr-1) using laser-ablation inductively coupled plasma mass spectrometry (LA- ICP-MS). To test for reproducibility and accuracy of the Mal 96-1 Ba/Ca profile, coral core Mal 95-3 was analyzed at lower resolution (1 to 12 samples yr-1) using discrete micro-drill sampling and isotope dilution ICP-MS. The close similarity between both coral Ba/Ca profiles, in absolute values as well as general pattern, underscores the accuracy of the LA-ICP-MS technique and adds confidence to our interpretation of the 300 year long Mal 96-1 Ba/Ca profile. The Ba/Ca coral proxy record shows that while the sediment flux from the Sabaki River is nearly constant between 1700 and 1900, a continuous rise in sediment flux is observed since 1900, reflecting steadily increasing demographic pressure on land use. The peak in suspended sediment load and hence soil erosion recorded at the Malindi reef occurred between 1974 and 1980 where there is a five to tenfold increase relative to natural levels. This is attributed to the combined effects of dramatically increasing population, unregulated land use, deforestation and severe droughts in the early 1970s. It is concluded that despite laudable attempts to instigate soil conservation measures, it is unlikely that in Kenya there will be a sustainable reduction in soil erosion without a significant improvement in socio-economic conditions.

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

2006-12-01

221

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

NASA Astrophysics Data System (ADS)

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

Ehrmann, Werner; Seidel, Martin; Schmiedl, Gerhard

2013-08-01

222

Darwin's Enigma: The Fossil Record.  

ERIC Educational Resources Information Center

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

Sunderland, Luther D.

223

Evolution and the Fossil Record  

E-print Network

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

Kammer, Thomas

224

Evolution and the Fossil Record  

E-print Network

.) · Charles Darwin, 1859: The Origin of Species by Natural Selection. #12;Artificial Selection vs. Natural population growth #12;Charles Darwin in 1837, age 28, after voyage of the Beagle #12;Age 40 Age 45 #12;Darwin in 1879, age 70. #12;#12;#12;One of the most famous books of science. #12;Darwin's home, Down House

Kammer, Thomas

225

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

PubMed

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

Tripp, Erin A; McDade, Lucinda A

2014-09-01

226

Tropical tales of polar ice: evidence of Last Interglacial polar ice sheet retreat recorded by fossil reefs of the granitic Seychelles islands  

NASA Astrophysics Data System (ADS)

In the search for a record of eustatic sea level change on glacial-interglacial timescales, the Seychelles ranks as one of the best places on the planet to study. Owing to its location with respect to the former margins of Northern Hemisphere ice sheets that wax and wane on orbital cycles, the local-or relative-sea level history is predicted to lie within a few meters of the globally averaged eustatic signal during the Last Interglacial period. We have surveyed and dated Last Interglacial fossil corals to ascertain peak sea level and hence infer maximum retreat of polar ice sheets during this time interval. We observe a pattern of gradually rising sea level in the Seychelles between ?129 and 125 thousand years ago (ka), with peak eustatic sea level attained after 125ka at 7.61.7mhigher than present. After accounting for thermal expansion and loss of mountain glaciers, this sea-level budget would require ?5-8mof polar ice sheet contribution, relative to today's volume, of which only ?2mcame from the Greenland ice sheet. This result clearly identifies the Antarctic ice sheet as a significant source of melt water, most likely derived from one of the unstable, marine-based sectors in the West and/or East Antarctic ice sheet. Furthermore, the establishment of a+5.91.7m eustatic sea level position by 128.60.8ka would require that partial AIS collapse was coincident with the onset of the sea level highstand.

Dutton, Andrea; Webster, Jody M.; Zwartz, Dan; Lambeck, Kurt; Wohlfarth, Barbara

2015-01-01

227

Electroencephalographic and polygraphic features of 24-hour recordings in sleeping sickness and healthy African subjects.  

PubMed

Electroencephalographic (EEG) and polygraphic features were analysed in six healthy control subjects and eight patients suffering from sleeping sickness meningoencephalitis in order to determine possible functional relationships. One patient was disqualified because of intermittent metabolic disease. Twenty-four h polygraphic recordings-EEG, electrooculography (EOG), electromyography (EMG), nasal and buccal air flow, chest respiratory movements-were performed continuously both on paper and on cassette tapes. Tapes were played back on paper (paper speed: 15 mm/s). Traces were analyzed for normal and pathologic features, and transient activation phases and paroxysmal hypnopompic hypersynchrony events were counted. During wakefulness, slow theta and delta waves occurred in four patients, but alpha reactivity was present. During sleep, normal features were seen. However, transient activation phases were decreased in the patients. During slow-wave sleep, four patients presented predominantly monophasic frontal delta bursts along with paroxysmal hypnopompic hypersynchrony events. In conclusion, in sleeping sickness patients, although dampened, the waking process remains responsive and slows down only during the late stage of meningoencephalitis. PMID:8858496

Tapie, P; Buguet, A; Tabaraud, F; Bogui, P; Doua, F; Bert, J

1996-07-01

228

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.

229

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.

Jon Garbisch

230

Fossil Identification  

NSDL National Science Digital Library

This activity asks students to identify examples of types of fossils amongst the exhibits at the Museum of the Earth at the Paleontological Research Institution in Ithaca, New York. Students will build on their understanding of the history of life, paleontology, taphonomy, ichnology, and paleoecologyespecially reefs.

Connie Soja, Colgate University, csoja@colgate.edu

231

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

232

Diversity and ecology of tropical African fungal spores from a 25,000-year palaeoenvironmental record in southeastern Kenya  

Microsoft Academic Search

Fossil fungal spores and other non-pollen palynomorphs (NPPs) are powerful environmental proxies in European palaeoecological and archaeological contexts. However, their application on other continents, and particularly in the tropics, is hampered by uncertain equivalence with morphologically similar taxa in Europe, and incomplete knowledge of their ecology in the new local contexts. Here we use fossil NPP assemblages in a 25,000-year

Bas van Geel; Vanessa Gelorini; Anna Lyaruu; Andr Aptroot; Stephen Rucina; Rob Marchant; Jaap S. Sinninghe Damst; Dirk Verschuren

2011-01-01

233

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

234

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

PubMed

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

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

2008-12-01

235

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

PubMed Central

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

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

2008-01-01

236

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

NASA Astrophysics Data System (ADS)

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

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

2005-02-01

237

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.

238

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

Microsoft Academic Search

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

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

2005-01-01

239

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

Microsoft Academic Search

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

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

2005-01-01

240

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

PubMed

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

Herendeen, P S; Jacobs, B F

2000-09-01

241

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

NASA Astrophysics Data System (ADS)

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

Gerbault, Muriel; Ganne, Jerome; Block, Sylvain

2014-05-01

242

Describing Fossils  

NSDL National Science Digital Library

Students are given a description of a fossil brachiopod, from the literature, along with a one-page handout describing the basic morphology of brachiopods. Students work independently to make a scale drawing of the fossil described (brachial valve, pedicle valve, anterior view, lateral view). They have access to textbooks (Moore, Laliker & Fisher; Clarkson), the Treatise volume, and the internet to get information on morphological terms. This takes about an hour, after which I display all of the diagrams on the wall along with the photographs from the paper from which the description was extracted. We discuss some of the differences and where problems arose in interpreting the description. I emphasize the importance of an accurate drawing or photograph to accompany a description. Students are then given a different brachiopod specimen and asked to produce a written description (pedicle-valve, brachial valve, anterior view, lateral view) of their fossil similar to the one that they readi.e. using all of the appropriate terms. They are told that other students will be trying to match their description to their specimen. I collect all of the descriptions, edit them (remove portions that use incorrect terminology or inappropriate), and produce a handout of all of the descriptions. At the next class, students are given the descriptions and asked to match descriptions to specimens. They do this independently outside of class. The specimens are made available in the lab room for several days. I add a couple of 'extra' specimens (without description) so that it is not a process of elimination.

Judy Massare

243

The largest fossil rodent  

PubMed Central

The discovery of an exceptionally well-preserved skull permits the description of the new South American fossil species of the rodent, Josephoartigasia monesi sp. nov. (family: Dinomyidae; Rodentia: Hystricognathi: Caviomorpha). This species with estimated body mass of nearly 1000?kg is the largest yet recorded. The skull sheds new light on the anatomy of the extinct giant rodents of the Dinomyidae, which are known mostly from isolated teeth and incomplete mandible remains. The fossil derives from San Jos Formation, Uruguay, usually assigned to the PliocenePleistocene (42?Myr ago), and the proposed palaeoenvironment where this rodent lived was characterized as an estuarine or deltaic system with forest communities. PMID:18198140

Rinderknecht, Andrs; Blanco, R. Ernesto

2008-01-01

244

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. PMID:20368427

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

2010-01-01

245

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

PubMed Central

Background The family Phyllanthaceae has a predominantly pantropical distribution. Of its several genera, Bridelia Willd. is of a special interest because it has disjunct equally distributed species in Africa and tropical Asia i.e. 1820 species in Africa-Madagascar (all endemic) and 18 species in tropical Asia (some shared with Australia). On the basis of molecular phylogenetic study on Bridelia, it has been suggested that the genus evolved in Southeast Asia around 335 Ma, while speciation and migration to other parts of the world occurred at 102 Ma. Fossil records of Bridelia are equally important to support the molecular phylogenetic studies and plate tectonic models. Results We describe a new fossil leaf of Bridelia from the late Oligocene (Chattian, 28.423 Ma) sediments of Assam, India. The detailed venation pattern of the fossil suggests its affinities with the extant B. ovata, B. retusa and B. stipularis. Based on the present fossil evidence and the known fossil records of Bridelia from the Tertiary sediments of Nepal and India, we infer that the genus evolved in India during the late Oligocene (Chattian, 28.423 Ma) and speciation occurred during the Miocene. The stem lineage of the genus migrated to Africa via Iranian route and again speciosed in Africa-Madagascar during the late Neogene resulting in the emergence of African endemic clades. Similarly, the genus also migrated to Southeast Asia via Myanmar after the complete suturing of Indian and Eurasian plates. The emergence and speciation of the genus in Asia and Africa is the result of climate change during the Cenozoic. Conclusions On the basis of present and known fossil records of Bridelia, we have concluded that the genus evolved during the late Oligocene in northeast India. During the Neogene, the genus diversified and migrated to Southeast Asia via Myanmar and Africa via Iranian Route. PMID:25353345

Srivastava, Gaurav; Mehrotra, R.C.

2014-01-01

246

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

PubMed

The platyrrhine primates, or New World monkeys, are immigrant mammals whose fossil record comes from Tertiary and Quaternary sediments of South America and the Caribbean Greater Antilles. The time and place of platyrrhine origins are some of the most controversial issues in primate palaeontology, although an African Palaeogene ancestry has been presumed by most primatologists. Until now, the oldest fossil records of New World monkeys have come from Salla, Bolivia, and date to approximately 26million years ago, or the Late Oligocene epoch. Here we report the discovery of new primates from the ?Late Eocene epoch of Amazonian Peru, which extends the fossil record of primates in South America back approximately 10million years. The new specimens are important for understanding the origin and early evolution of modern platyrrhine primates because they bear little resemblance to any extinct or living South American primate, but they do bear striking resemblances to Eocene African anthropoids, and our phylogenetic analysis suggests a relationship with African taxa. The discovery of these new primates brings the first appearance datum of caviomorph rodents and primates in South America back into close correspondence, but raises new questions about the timing and means of arrival of these two mammalian groups. PMID:25652825

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

2015-04-23

247

A Fossil Thermometer  

NSDL National Science Digital Library

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

Smithsonian Institution

248

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. PMID:6780500

Lewis, O J

1980-01-01

249

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

NASA Astrophysics Data System (ADS)

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

Mayr, Gerald; De Pietri, Vanesa L.

2014-02-01

250

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

PubMed

The recent identification of hoatzins (Opisthocomiformes) in the Miocene of Africa showed part of the evolution of these birds, which are now only found in South America, to have taken place outside the Neotropic region. Here, we describe a new fossil species from the late Eocene of France, which constitutes the earliest fossil record of hoatzins and the first one from the Northern Hemisphere. Protoazin parisiensis gen. et sp. nov. is more closely related to South American Opisthocomiformes than the African taxon Namibiavis and substantiates an Old World origin of hoatzins, as well as a relictual distribution of the single extant species. Although recognition of hoatzins in Europe may challenge their presumed transatlantic dispersal, there are still no North American fossils in support of an alternative, Northern Hemispheric, dispersal route. In addition to Opisthocomiformes, other avian taxa are known from the Cenozoic of Europe, the extant representatives of which are only found in South America. Recognition of hoatzins in the early Cenozoic of Europe is of particular significance because Opisthocomiformes have a fossil record in sub-Saharan Africa, which supports the hypothesis that extinction of at least some of these "South American" groups outside the Neotropic region was not primarily due to climatic factors. PMID:24441712

Mayr, Gerald; De Pietri, Vanesa L

2014-02-01

251

Are the oldest 'fossils', fossils  

NASA Technical Reports Server (NTRS)

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

Schopf, J. W.

1976-01-01

252

Will My Fossil Float?  

ERIC Educational Resources Information Center

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

Riesser, Sharon; Airey, Linda

1993-01-01

253

Creature Features - Showcase of Living Fossils  

NSDL National Science Digital Library

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

David Sunderlin

254

What Is a Fossil?  

NSDL National Science Digital Library

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

255

African Art, African Voices  

NSDL National Science Digital Library

This website created by the Philadelphia Museum of Art complements an exhibition that "surveys the artistic achievements of just a few of the many cultures of sub-Saharan Africa" organized by the Seattle Art Museum, using artifacts from its African collections. The largest section of the Web site, African Voices, features interviews with African artists, art historians and others, focusing on particular aspects of African cultures. For example, Hannah Kema Foday, a Mende woman from Segbwema, southwestern Sierra Leone, now living in New York city, speaks about Sowei masks and initiation for girls into womanhood. The other two sections - African Art in Motion and Contemporary African Art, show the expressive use of figures in African sculpture and the work of modern African artists, living in Africa and all over the world, respectively.

256

Fossils, Rocks, and Time  

NSDL National Science Digital Library

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

Lucy E. Edwards

1997-06-26

257

Deductions from Fossil Preservtion  

NSDL National Science Digital Library

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

Steven Stanley

258

Supermassive Black Holes at Work: ``Fossil Records'' of Outbursts from Supermassive Black Holes and the Effects of Outbursts on the Evolution of Gas Rich Galaxies, Groups, and Galaxy Clusters  

NASA Astrophysics Data System (ADS)

Supermassive black holes (SMBHs) play key roles in galaxy and cluster evolution. This is most clearly seen in the ``fossil record'' that is imprinted in the gas rich atmospheres of early type galaxies, groups, and clusters by powerful SMBH outbursts. From detailed X-ray studies of clusters and groups, we present the properties of typical SMBH outbursts, their evolution, and the energy partition between shocks and the enthalpy of the gas cavities inflated by the SMBHs focussing on M87. The interplay between gas cooling and SMBH outbursts can be traced over cosmological time. We discuss several galaxies where SMBH outbursts at very early epochs have truncated star formation and altered the ``normal'' evolution of the stellar component of galaxy bulges. We conclude by describing a future mission that would allow us to understand the evolution of SMBHs and their host galaxies from high redshifts to the present.

Forman, William R.; Churazov, Eugene; Jones, Christine; Heinz, Sebastian; Bogdan, Akos

2015-01-01

259

Fossil Papio Cranium From !Ncumtsa (Koanaka) Hills, Western Ngamiland, Botswana  

E-print Network

Fossil Papio Cranium From !Ncumtsa (Koanaka) Hills, Western Ngamiland, Botswana Blythe A. Williams cercopithecoid; baboon; Kalahari; Pleistocene ABSTRACT Three fossils, a cranium of Papio, a cer- copithecid crania of Papio are extremely rare in the fossil record outside of South Africa and because

260

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

261

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

PubMed

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

Gilmore, Cassandra C

2013-06-01

262

Pollen percentage thresholds of Abies alba based on 13-year annual records of pollen deposition in modified Tauber traps: perspectives of application to fossil situations  

E-print Network

Pollen percentage thresholds of Abies alba based on 13-year annual records of pollen deposition Keywords: Abies alba pollen accumulation rate modified Tauber trap pollen threshold value Central Mts (Czech Republic). The study aims: to estimate pollen thresholds for fir presence

Bern, Universitt

263

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

NASA Astrophysics Data System (ADS)

Here we present a detailed radiocarbon-dated 936 cm long pollen record from Lake Billyakh (6517'N, 12647'E; 340 m a.s.l.) situated in the western part of the Verkhoyansk Mountains, about 140 km south of the Arctic Circle. A set of 53 surface pollen samples representing tundra, cold deciduous forest and taiga was collected in northern and central Yakutia communities to verify the accuracy of the quantitative biome reconstruction method and to obtain a more precise attribution of the identified pollen taxa to the main regional biomes. The adjusted method is then applied to the pollen record from Lake Billyakh to gain a reconstruction of vegetation and environments since about 50.7 kyr BP. The results of the pollen analysis and pollen-based biome reconstruction suggest that herbaceous tundra and steppe communities dominated the area from 50.7 to 13.5 kyr BP. Relatively low pollen concentrations and high percentages of herbaceous pollen taxa (mainly Cyperaceae, Poaceae and Artemisia) likely indicate a reduced vegetation cover and/or lower pollen production. On the other hand, extremely low percentages of drought-tolerant taxa, such as Chenopodiaceae and Ephedra, and the constant presence of various mesophyllous herbaceous ( Thalictrum, Rosaceae, Asteraceae) and shrubby taxa ( Betula sect. Nanae/Fruticosae, Duschekia fruticosa, Salix) in the pollen assemblages prevent an interpretation of the last glacial environments around Lake Billyakh as extremely arid. The lowest pollen percentages of woody taxa and the highest values of Artemisia pollen attest that the 31-15 kyr BP period as the driest and coldest interval of the entire record. A relative high content of taxa representing shrub tundra communities and the presence of larch pollen recorded prior to 31 kyr and after 13.5 kyr BP likely indicate interstadial climate amelioration associated with the middle and latest parts of the last glacial. An increase in pollen percentages of herbaceous taxa around 12 kyr BP suggests broader distribution of drier communities in response to the colder and drier than present climate of the Younger Dryas (YD). The onset of the Holocene is marked in the pollen record by the highest values of shrub taxa, mainly B. sect. Nanae/Fruticosae. Pollen percentages of arboreal taxa increase gradually and reach maximum values after 7 kyr BP. The latter maximum mainly reflects the spread of Pinus sylvestris in central Yakutia as a response to the mid-Holocene climatic optimum. The quasi-continuous presence of larch, shrubby birch and alder pollen throughout the whole record is the most striking feature of the pollen record. Noticeable variations in larch pollen percentages point to multiple short-term warming episodes, which might be synchronous with the Dansgaard-Oeschger cycles in the North Atlantic records. The Lake Billyakh pollen record suggests that larch possibly survived during the last 50 kyr BP in locally favourable environments in the study region.

Mller, Stefanie; Tarasov, Pavel E.; Andreev, Andrei A.; Ttken, Thomas; Gartz, Steffi; Diekmann, Bernhard

2010-08-01

264

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

265

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

Microsoft Academic Search

Here we present a detailed radiocarbon-dated 936cm long pollen record from Lake Billyakh (6517?N, 12647?E; 340m a.s.l.) situated in the western part of the Verkhoyansk Mountains, about 140 km south of the Arctic Circle. A set of 53 surface pollen samples representing tundra, cold deciduous forest and taiga was collected in northern and central Yakutia communities to verify the accuracy

Stefanie Mller; Pavel E. Tarasov; Andrei A. Andreev; Thomas Ttken; Steffi Gartz; Bernhard Diekmann

2010-01-01

266

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

267

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

PubMed Central

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

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

2014-01-01

268

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

PubMed

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

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

2014-01-01

269

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

270

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

E-print Network

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

M. Omerbashich

2007-06-09

271

Hominid Fossil Record Geology 230: Fossils and Evolution  

E-print Network

of Homo erectus from China #12;Skeleton of Homo erectus, Nariokotome boy from Kenya #12;H. erectus skull of Nariokotome boy #12;The face of Homo erectus #12;Homo erectus from Indonesia, Java Man #12;Homo erectus using. #12;Neandertal night life around the fire. #12;A more modern view of Neandertals with naked skin like

Kammer, Thomas

272

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

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

273

Transitional Tetrapod Fossil  

NSDL National Science Digital Library

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

WGBH Educational Foundation

2007-11-01

274

Genomic Fossils Calibrate the Long-Term Evolution of Hepadnaviruses  

E-print Network

Because most extant viruses mutate rapidly and lack a true fossil record, their deep evolution and long for their replication, many other viruses replicate in the nucleus of their host's cells and are therefore prone-term vertical inheritance. Such endogenous viruses are highly valuable as they provide a molecular fossil record

Feschotte, Cedric

275

Picture Matching Fossils  

NSDL National Science Digital Library

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

Elizabeth Rhenberg

276

Follow a Fossil  

NSDL National Science Digital Library

The Follow a Fossil Web site is presented by the Denver Museum of Nature and Science. It documents the prospecting, evacuation, preparation, curation, research, and exhibiting of vertebrate, invertebrate, and plant fossils. The site is simple and effective, giving a good introduction to the process of finding and using fossils for learning about the past.

277

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.

Jessica Fries-Gaither

278

Face-to-Fossil  

NSDL National Science Digital Library

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

279

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

E-print Network

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

Jernvall, Jukka

280

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

PubMed

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

Bilton, David T

2014-01-01

281

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 Damst, Jaap S.; Ossebaar, Jort; Schouten, Stefan; Verschuren, Dirk

2012-09-01

282

An Indoor Fossil/Archeological Dig  

NSDL National Science Digital Library

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

2011-06-24

283

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.

284

Size, shape, and asymmetry in fossil hominins: The status of the LB1 cranium based on 3D morphometric analyses  

E-print Network

Size, shape, and asymmetry in fossil hominins: The status of the LB1 cranium based on 3D that LB1 best fits predictions for a small specimen of fossil Homo but not for a small modern human extant African ape species. Compared to other fossil specimens, the degree of asymmetry in LB1

Baab, Karen L.

285

Fossilized bioelectric wire - the trace fossil Trichichnus  

NASA Astrophysics Data System (ADS)

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

K?dzierski, M.; Uchman, A.; Sawlowicz, Z.; Briguglio, A.

2014-12-01

286

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

PubMed Central

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

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

2014-01-01

287

Fossil Mapping of Utah  

NSDL National Science Digital Library

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

Ramsey

2009-11-18

288

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

PubMed Central

Background Within the subfamily Murinae, African murines represent 25% of species biodiversity, making this group ideal for detailed studies of the patterns and timing of diversification of the African endemic fauna and its relationships with Asia. Here we report the results of phylogenetic analyses of the endemic African murines through a broad sampling of murine diversity from all their distribution area, based on the mitochondrial cytochrome b gene and the two nuclear gene fragments (IRBP exon 1 and GHR). Results A combined analysis of one mitochondrial and two nuclear gene sequences consistently identified and robustly supported ten primary lineages within Murinae. We propose to formalize a new tribal arrangement within the Murinae that reflects this phylogeny. The diverse African murine assemblage includes members of five of the ten tribes and clearly derives from multiple faunal exchanges between Africa and Eurasia. Molecular dating analyses using a relaxed Bayesian molecular clock put the first colonization of Africa around 11 Mya, which is consistent with the fossil record. The main period of African murine diversification occurred later following disruption of the migration route between Africa and Asia about 79 Mya. A second period of interchange, dating to around 56.5 Mya, saw the arrival in Africa of Mus (leading to the speciose endemic Nannomys), and explains the appearance of several distinctive African lineages in the late Miocene and Pliocene fossil record of Eurasia. Conclusion Our molecular survey of Murinae, which includes the most complete sampling so far of African taxa, indicates that there were at least four separate radiations within the African region, as well as several phases of dispersal between Asia and Africa during the last 12 My. We also reconstruct the phylogenetic structure of the Murinae, and propose a new classification at tribal level for this traditionally problematic group. PMID:18616808

2008-01-01

289

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

290

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.

291

Plantae: Fossil Record and First Appearances  

NSDL National Science Digital Library

This University of California Berkeley Museum of Paleontology site provides an interactive geologic timescale that illustrates the temporal distribution of several important plant groups. First appearances of major plant groups are plotted on a colorful timescale and each group is linked to references, text, images, and further information. Key Cretaceous plant groups featured include Anthocerotophyta, Anthophyta and Gnetales. The site might be a useful resource for constructing introductory level lectures concerned with paleobotany and paleoecology of the Cretaceous Period.

Speer Brian

292

The Fossil Record of the Peronosporomycetes (Oomycota)  

E-print Network

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

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

2011-01-01

293

Evidence of Evolution the fossil record  

E-print Network

-line present loss of anal and dorsal fins enlarged and flattened head, mobile neck elongated humerus expanded still had teeth, unfused pelvis, shorter fingers, fully opposable big toe for perching, broad breastbone

Dever, Jennifer A.

294

THE FOSSIL RECORD OF PREDATION IN DINOSAURS  

Microsoft Academic Search

Predatory theropod dinosaurs can usually be identified as such by features of their jaws, teeth, and postcrania, but different clades of these reptiles differed in their adaptations for prey handling. Inferences about theropod diets and hunting behavior based on functional morphology are sometimes supported by evidence from taphonomic associations with likely prey species, bite marks, gut contents, coprolites, and trackways.

JAMES O. FARLOW; THOMAS R. HOLTZ

295

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.

Elizabeth Heise

296

GEOL 204: The Fossil Record Team Project  

E-print Network

. Your teams should be formed by the end of the Discussion Section meeting on Mar. 4. STEP TWO; the Cambrian Explosion; the Colonization of Land by Plants; the Colonization of Land by Vertebrates; Dinosaur; the Origin of Humans; "Out-of-Africa"; Peopling of the New World; the Quaternary Extinctions Outside

Holtz Jr., Thomas R.

297

Fossil Record of Precambrian Life on Land  

NASA Technical Reports Server (NTRS)

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

Knauth, Paul

2000-01-01

298

Globular cluster formation - The fossil record  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

299

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

E-print Network

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

Olsen, Paul E.

300

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.

Chicago Children's Museum

2011-01-01

301

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.

Anthony Martin

302

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 mud (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.

2012-12-27

303

Make a Model Fossil  

NSDL National Science Digital Library

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

304

Polychaete chaetae: Function, fossils, and phylogeny  

Microsoft Academic Search

Synopsis In this article we review the phylogenetic distribution of major chaetal types within the Polychaeta, discuss what has been demonstrated about chaetal function in modern worms, and examine what is known about the evolution of chaete through the fossil record. We conclude with specific cautions about how chaetae are treated in phylogenetic analyses and make suggestions about how they

Rachel A. Merz; Sarah A. Woodin

2006-01-01

305

Mycorrhization of fossil and living plants  

Microsoft Academic Search

The widespread mycorrhization together with the fossil record indicate that plants and fungi have evolved in mycorrhizal relationship since the colonization of land by early plants. In living plants most mycorrhizal symbioses are mutualistic associations in which fungus and plant exchange metabolites and nutrients required for their growth and survival. They concern either the gametophyte and\\/or the sporophyte of most

Christine Strullu-Derrien; Dsir-Georges Strullu

2007-01-01

306

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

307

Fossil Identification Project  

NSDL National Science Digital Library

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

Melissa Lobegeier

308

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

PubMed Central

Background The Rhinopomatidae, traditionally considered to be one of the most ancient chiropteran clades, remains one of the least known groups of Rhinolophoidea. No relevant fossil record is available for this family. Whereas there have been extensive radiations in related families Rhinolophidae and Hipposideridae, there are only a few species in the Rhinopomatidae and their phylogenetic relationship and status are not fully understood. Results Here we present (a) a phylogenetic analysis based on a partial cytochrome b sequence, (b) new fossils from the Upper Miocene site Elaiochoria 2 (Chalkidiki, Greece), which represents the first appearance datum of the family based on the fossil record, and (c) discussion of the phylogeographic patterns in both molecular and morphological traits. We found deep divergences in the Rhinopoma hardwickii lineage, suggesting that the allopatric populations in (i) Iran and (ii) North Africa and the Middle East should have separate species status. The latter species (R. cystops) exhibits a shallow pattern of isolation by distance (separating the Middle East and the African populations) that contrasts with the pattern of geographic variation in the morphometrical traits. A deep genetic gap was also found in Rhinopoma muscatellum (Iran vs. Yemen). We found only minute genetic distance between R. microphyllum from the Levant and India, which fails to support the sub/species distinctness of the Indian form (R. microphyllum kinneari). Conclusion The mtDNA survey provided phylogenetic tree of the family Rhinopomatidae for the first time and revealed an unexpected diversification of the group both within R. hardwickii and R. muscatellum morphospecies. The paleobiogeographic scenario compiled in respect to molecular clock data suggests that the family originated in the region south of the Eocene Western Tethyan seaway or in India, and extended its range during the Early Miocene. The fossil record suggests a Miocene spread into the Mediterranean region, followed by a post-Miocene retreat. Morphological analysis compared with genetic data indicates considerable phenotypic plasticity in this group. PMID:17868440

Hulva, Pavel; Hor?ek, Ivan; Benda, Petr

2007-01-01

309

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

310

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.

311

Fossil Systematic Description Project  

NSDL National Science Digital Library

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

Samantha Hopkins

312

Dinosaur Trace Fossils  

NSDL National Science Digital Library

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

Martin, Anthony J.

313

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 fossil playing cards from newspapers stacked in chronological order. Learners identify the age of the card based on the evidence (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

314

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

315

The Great Fossil Find  

NSDL National Science Digital Library

On an imaginary fossil hunt, learners "find" (remove from envelope) paper "fossils" of some unknown creature, only 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." Use this as an introduction to the nature of science inquiry -- scientists don't always have all the information, scientists must form interpretations of the information, scientists must work together to come to consensus about interpretations.

Steve Rendak

1999-01-01

316

Fossil Simulation in the Classroom  

ERIC Educational Resources Information Center

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

Hoehn, Robert G.

1977-01-01

317

Two Eocene fossil fruits from the Changchang Basin of Hainan Island, China  

Microsoft Academic Search

Two types of fossil fruit, one belonging to Palaeocarya sp. (Juglandaceae) and the other to Acer cf. A. miofranchetii Hu et Chaney (Aceraceae), are found in the Eocene coal-bearing series from the Changchang Basin of Hainan Island, China. This is the first fossil record of Palaeocarya and Acer in a tropical area of China. These fossils provide evidence for an

Jianhua Jin

2009-01-01

318

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

E-print Network

vol. 163, no. 2 the american naturalist february 2004 Exploring Developmental Modes in a Fossil to explore postem- bryonic development within the fossil record of arthropod evolution. In contrast to most. Given the considerable range in seg- ment numbers observed in fossil and ex- tant arthropods

319

Journal of the Geological Society, London, Vol. 170, 2013, pp. 291300. doi: 10.1144/jgs2012-025. The fossil record provides our best resource to study evolutionary  

E-print Network

and the number of fossil collections through the Cenozoic of New Zealand. In this study we assess sampling bias temporal and geographical scale allows the compi- lation of accurate data on sampled palaeodiversity The Triassic System of England and Wales represents largely ter- restrial rocks, with marine formations only

Benton, Michael

320

Fossil turbulence revisited  

E-print Network

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

Carl H. Gibson

1999-04-27

321

Fossil Fuels: Capstone  

NSDL National Science Digital Library

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

John Pratte

322

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.

2014-04-14

323

Pliocene northeast African vegetation change  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

324

Stroke and African Americans  

MedlinePLUS

... Population Profiles > Black/African American > Stroke Stroke and African Americans African American adults are twice as likely to have a ... persons 18 years of age and over, 2011 African American White African American/ White Ratio Men and Women ...

325

Fossil Halls: Cladistics  

NSDL National Science Digital Library

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

326

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

327

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 2630, 2009.

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

2010-01-01

328

Therapod Fossil Hunt Dispatch  

NSDL National Science Digital Library

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

329

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.

Inc. Black Hills Institute of Geological Research

330

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-Mart; Jos Angel Martn-Gago; Ricardo Amils

2010-01-01

331

Old fossilsyoung species: evolutionary history of an endemic gastropod assemblage in Lake Malawi  

PubMed Central

Studies on environmental changes provide important insights into modes of speciation, into the (adaptive) reoccupation of ecological niches and into species turnover. Against this background, we here examine the history of the gastropod genus Lanistes in the African Rift Lake Malawi, guided by four general evolutionary scenarios, and compare it with patterns reported from other endemic Malawian rift taxa. Based on an integrated approach using a mitochondrial DNA phylogeny and a trait-specific molecular clock in combination with insights from the fossil record and palaeoenvironmental data, we demonstrate that the accumulation of extant molecular diversity in the endemic group did not start before approximately 600?000 years ago from a single lineage. Fossils of the genus from the Malawi Rift, however, are over one million years older. We argue that severe drops in the lake level of Lake Malawi in the Pleistocene offer a potential explanation for this pattern. Our results also challenge previously established phylogenetic relationships within the genus by revealing parallel evolution and providing evidence that the endemic Lanistes species are not restricted to the lake proper but are present throughout the Malawi Rift. PMID:19439440

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

2009-01-01

332

Fossil Biodiversity: Red Noise Plus Signal  

E-print Network

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

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

2006-01-01

333

Fossil Biodiversity: Red Noise Plus Signal  

E-print Network

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

Adrian L. Melott; Bruce S. Lieberman

2006-06-14

334

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.

Indiana University. Bloomington. Archives of African American Music and Culture.

1998-01-01

335

African Studies  

NSDL National Science Digital Library

The African Studies WWW server contains information on programs and resources at the University of Pennsylvania, in Africa, the U.S. and elsewhere. The web site is supported by the African Studies Center, part of a four-school consortium, including Bryn Mawr, Haverford, and Swarthmore Colleges and the University of Pennsylvania.

336

Laser-Raman imagery of Earth's earliest fossils  

NASA Astrophysics Data System (ADS)

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

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

2002-03-01

337

Puzzling distribution of the fossil and living genus Hiatella (Bivalvia)  

Microsoft Academic Search

The bivalve Hiatella has been present for the last 150Ma and is consistently linked to cool-temperate and polar regions. Its origin can be traced back to at least the Jurassic, with earliest known records being temperate forms that occurred on the northern side of the Tethys. The subsequent fossil record suggests two possible alternative migration routes. The more plausible one

Sandra Gordillo

2001-01-01

338

Triassic Leech Cocoon From Antarctica Contains Fossil Bell Animal  

E-print Network

Our understanding of the evolution of life on Earth is limited by the imperfection of the fossil record. One reason for this imperfect record is that organisms without hard parts, such as bones, shells, and wood, have a very low potential to enter...

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

2012-01-01

339

Organic preservation of fossil musculature with ultracellular detail  

PubMed Central

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

McNamara, Maria; Orr, Patrick J.; Kearns, Stuart L.; Alcal, Luis; Anadn, Pere; Pealver-Moll, Enrique

2010-01-01

340

Organic preservation of fossil musculature with ultracellular detail.  

PubMed

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

McNamara, Maria; Orr, Patrick J; Kearns, Stuart L; Alcal, Luis; Anadn, Pere; Pealver-Moll, Enrique

2010-02-01

341

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.

342

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.

Max Reams

343

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

344

A report on biocompounds from palm fossil of India  

PubMed Central

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

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

2014-01-01

345

Fossilization Processes in Thermal Springs  

NASA Technical Reports Server (NTRS)

To create a comparative framework for the study of ancient examples, we have been carrying out parallel studies of the microbial biosedimentology, taphonomy and geochemistry of modem and sub-Recent thermal spring deposits. One goal of the research is the development of integrated litho- and taphofacies models for siliceous and travertline sinters. Thermal springs are regarded as important environments for the origin and early evolution of life on Earth, and we seek to utilize information from the fossil record to reconstruct the evolution of high temperature ecosystems. Microbial contributions to the fabric of thermal spring sinters occur when population growth rates keep pace with, or exceed rates of inorganic precipitation, allowing for the development of continuous biofilms or mats. In siliceous thermal springs, microorganisms are typically entombed while viable. Modes of preservation reflect the balance between rates of organic matter degradation, silica precipitation and secondary infilling. Subaerial sinters are initially quite porous and permeable and at temperatures higher than about 20 C, organic materials are usually degraded prior to secondary infilling of sinter frameworks. Thus, organically-preserved microfossils are rare and fossil information consists of characteristic biofabrics formed by the encrustation and underplating of microbial mat surfaces. This probably accounts for the typically low total organic carbon values observed in thermal spring deposits. In mid-temperature, (approx. 35 - 59 C) ponds and outflows, the surface morphology of tufted Phormidium mats is preserved through mat underplating by thin siliceous: crusts. Microbial taxes lead to clumping of ceils and/or preferred filament orientations that together define higher order composite fabrics in thermal spring stromatolites (e.g. network, coniform, and palisade). At lower temperatures (less than 35 C), Calothrix mats cover shallow terracette pools forming flat carpets or pustular surfaces that produce palisade and "shrub" fabrics, respectively. At finer scales, composite fabrics are seen to consist distinctive associations of microstructures formed by the encrustation of individual cells and filaments. Composite fabrics survive the diagenetic transitions from primary opaline silica to quartz and are known from subaerial thermal spring deposits as old as Lower Carboniferous. However, fossil microorganisms tend to be rare in older deposits, and are usually preserved only where cells or sheaths have been stained by iron oxides. In subaqueous mineralizing springs at lower temperatures, early infilling leads to a more rapid and complete reduction in porosity and permeability. This process, along with the slower rates of microbial degradation at lower temperatures, creates a more favorable situation for organic matter preservation. Application of this taphonomic model to the Rhynie Chert, previously interpreted as subaerial, suggest it was probably deposited in a subaqueous spring setting at lower temperatures.

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

1995-01-01

346

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

347

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

348

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.

2014-01-28

349

YZC Animal of the Month, September 2012 African Elephant  

E-print Network

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

350

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

PubMed Central

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

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

2012-01-01

351

Triassic leech cocoon from Antarctica contains fossil bell animal  

PubMed Central

Our understanding of the evolution of life on Earth is limited by the imperfection of the fossil record. One reason for this imperfect record is that organisms without hard parts, such as bones, shells, and wood, have a very low potential to enter the fossil record. Occasionally, however, exceptional fossil deposits that preserve soft-bodied organisms provide a rare glimpse of the true biodiversity during past periods of Earth history. We here present an extraordinary find of a fossil ciliate that is encased inside the wall layer of a more than 200 Ma leech cocoon from Antarctica. The microfossil consists of a helically contractile stalk that attaches to a main body with a peristomial feeding apparatus and a large C-shaped macronucleus. It agrees in every aspect with the living bell animals, such as Vorticella. Vorticellids and similar peritrichs are vital constituents of aquatic ecosystems worldwide, but so far have lacked any fossil record. This discovery offers a glimpse of ancient soft-bodied protozoan biotas, and also highlights the potential of clitellate cocoons as microscopic conservation traps comparable to amber. PMID:23213234

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

2012-01-01

352

Cycles in fossil diversity  

SciTech Connect

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

Rohde, Robert A.; Muller, Richard A.

2004-10-20

353

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.

Rick Crosslin

2004-01-01

354

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.

355

Cancer and African Americans  

MedlinePLUS

... Population Profiles > Black/African American > Cancer Cancer and African Americans African Americans have the highest mortality rate of ... 8MB] At a glance Top Cancer Sites for African Americans (2006-2010) Cancer Incidence Rates per 100,000 ...

356

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

ERIC Educational Resources Information Center

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

Riddick, William P.

2013-01-01

357

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

Microsoft Academic Search

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

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

358

Unearthing Important Fossils  

NSDL National Science Digital Library

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

Payne, Laura X.

359

Fossil Microorganisms in Archaean  

NASA Technical Reports Server (NTRS)

Ancient Archean and Proterozoic rocks are the model objects for investigation of rocks comprising astromaterials. The first of Archean fossil microorganisms from Baltic shield have been reported at the last SPIE Conference in 2005. Since this confeence biomorphic structures have been revealed in Archean rocks of Karelia. It was determined that there are 3 types of such bion structures: 1. structures found in situ, in other words microorganisms even-aged with rock matrix, that is real Archean fossils biomorphic structures, that is to say forms inhabited early formed rocks, and 3. younger than Archean-Protherozoic minerali microorganisms, that is later contamination. We made attempt to differentiate these 3 types of findings and tried to understand of burial of microorganisms. The structures belongs (from our point of view) to the first type, or real Archean, forms were under examination. Practical investigation of ancient microorganisms from Green-Stone-Belt of Northern Karelia turns to be very perspective. It shows that even in such ancient time as Archean ancient diverse world existed. Moreover probably such relatively highly organized cyanobacteria and perhaps eukaryotic formes existed in Archean world.

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

2006-01-01

360

Fossils 2: Uncovering the Facts  

NSDL National Science Digital Library

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

361

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

NASA Astrophysics Data System (ADS)

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

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

1997-09-01

362

Fossil turbulence and fossil turbulence waves can be dangerous  

E-print Network

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

Carl H Gibson

2012-11-25

363

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

364

Carbon cycling within an East African lake revealed by the carbon isotope composition of diatom silica: a 25-ka record from Lake Challa, Mt. Kilimanjaro  

NASA Astrophysics Data System (ADS)

The carbon cycle of a lake is a balance between supply from the atmosphere and catchment, and the net demand exerted by primary producers, minus losses back to the atmosphere and to sediment storage. Evaluating the sum of these processes and reconstructing them from sediment records of lake history requires a range of methods and a multi-proxy approach. One promising technique is to explore the carbon-isotope composition (?13Cdiatom) of organic matter incorporated within the silica frustules of diatom algae. Here we present a 25,000-year record of ?13Cdiatom from the sediments of crater Lake Challa on the eastern flank of Mt. Kilimanjaro, and along with other proxy data we make inferences about the three major phases in the history of the lake's carbon cycle. From 25ka to 15.8kayearsBP, ?13Cdiatom is positively correlated with the ?13C of bulk sediment organic matter (?13Cbulk), indicating that high diatom productivity, as recorded by high % biogenic silica at this time, was preferentially removing 12C and enriching the ?13C of lake-water dissolved inorganic carbon. From 15.8 to 5.5ka the correlation between ?13Cdiatom and ?13Cbulk breaks down, suggesting carbon supply to the lake satisfied or exceeded the demand from productivity. From 5.5kaBP the positive correlation resumes, indicating an increase in the internal demand for carbon relative to external supply. Diatom frustule-bound carbon isotopes offer an original tool in examining long-term fluctuations in a lake's carbon budget and how the balance between supply and demand has changed through time.

Barker, Philip A.; Hurrell, Elizabeth R.; Leng, Melanie J.; Plessen, Birgit; Wolff, Christian; Conley, Daniel J.; Keppens, Eddy; Milne, Isla; Cumming, Brian F.; Laird, Kathleen R.; Kendrick, Chris P.; Wynn, Peter M.; Verschuren, Dirk

2013-04-01

365

Fluid inclusions in high-pressure granulites of the Pan-African belt in Tanzania (Uluguru Mts): a record of prograde to retrograde fluid evolution  

NASA Astrophysics Data System (ADS)

The high-pressure granulites of the Uluguru Mountains are part of the Pan-African belt of Tanzania, the metamorphic evolution of which is characterized by an anticlockwise P-T path. Mineral assemblages that represent distinct metamorphic stages are selected for fluid inclusion studies in order to deduce the fluid evolution in metapelites and pyroxene granulites from the prograde to the retrograde stage. Fluid inclusion data improve the petrologically derived P-T path and confirm the anticlockwise evolution. Fluid inclusions in quartz enclosed in garnet porphyroblasts in metapelites preserve prograde fluids of CO2-N2 composition and later-trapped pure CO2. During isochoric heating at temperatures near the peak of metamorphism, deformation and recrystallization led to fluid homogenization yielding N2-poor CO2 composition in the metapelites. Near-peak CO2-N2 fluid inclusions in quartz of metapelites and CO2 inclusions in garnet-pyroxene granulites are characterized by perfect negative crystal shape. Garnet formed in veins and as coronas around orthopyroxene represent the near-isochoric/isobaric cooling stage which is characterized by high-density CO2-rich fluid inclusions. Up to 15mol% N2 in some primary CO2 inclusions in corona garnet indicate small-scale fluid heterogeneity during the static garnet growth. The fact that high-density fluid inclusions are preserved, suggests a shallow dP/dT slope of the uplift path. Nevertheless, some fluid inclusions decrepitated or re-equilibrated and low-density CO2 inclusions were trapped in the garnet-pyroxene granulite while N2-CH4 inclusions formed in the metapelites. Different fluid compositions in metapelite and metabasite argue for an internal control of the fluid composition by phase equilibria. In shear zones where the pyroxene granulite was transformed into scapolite-biotite schist, CO2-N2 and low-density N2-CH4 fluid inclusions indicate several stages of tectonic activity and suggest fluid influx from the nearby metapelites. High- and low-salinity aqueous inclusions observed beside CO2 inclusions in garnet-pyroxene granulites, in vein quartz and shear zones could be of high-grade origin but are mainly re-equilibrated or re-trapped along healed microfractures during lower-grade stages.

Herms, Petra; Schenk, Volker

366

Fossil-Based Hydrogen Production  

E-print Network

Fossil-Based Hydrogen Production Distributed Natural Gas WithCarbonSequestration Biomass Hydro Wind Solar Coal Nuclear Natural Gas Oil Arlene AndersonArlene Anderson #12;Barriers Fossil-Based Hydrogen Production · Capital Costs · O&M · Separation Technology · Control and Safety · Feedstock and Water Issues

367

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.

368

Phenotypic Evolution in Fossil Species: Pattern and Process  

NASA Astrophysics Data System (ADS)

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

Hunt, Gene; Rabosky, Daniel L.

2014-05-01

369

African Union  

NSDL National Science Digital Library

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

370

Ediacaran Fossils: Metazoan Origins in the  

E-print Network

Ediacaran Fossils: Metazoan Origins in the Proterozoic Geology 331, Paleontology #12;#12;The in sandstone. How were they preserved? #12;A fossil sea pen from the Ediacaran of Australia. Ediacaran fossils

Kammer, Thomas

371

Improved age control on early Homo fossils from the upper Burgi Member at Koobi Fora, Kenya  

E-print Network

the evolutionary origin, radiation and dispersal of the genus Homo, it is crucial to be able to place substantial fossil record of the genus Homo is first found. Here we combine magnetostratigraphy and strontiumImproved age control on early Homo fossils from the upper Burgi Member at Koobi Fora, Kenya

Utrecht, Universiteit

372

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

373

Vertebrate fossils and trace fossils in Upper Jurassic-Lower cretaceous red beds in the Atacama region, Chile  

NASA Astrophysics Data System (ADS)

Pterosaur, dinosaur, and crocodile bones are recorded here for the first time in Upper Jurassic-Lower Cretaceous red beds in the Atacama region east of Copiap, Chile. Trace fossils produced by vertebrate animals include the footprints of theropod dinosaurs and the depressions of sandstone laminae interpreted as burrows and foot impressions. The fossils occur in the 1500-meter-thick Quebrada Monardes Formation, which consists predominantly of the aeolian and alluvial deposits of a semi-arid terrestrial environment. Vertebrate fossils are very rare in Chile. Dinosaur bones and footprints have previously been recorded at only seven locations, and pterosaur remains at only one location. The newly discovered dinosaur bones are the oldest to be described in Chile.

Bell, C. M.; Surez, M.

374

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

375

Fossil fuel furnace reactor  

DOEpatents

A fossil fuel furnace reactor is provided for simulating a continuous processing plant with a batch reactor. An internal reaction vessel contains a batch of shale oil, with the vessel having a relatively thin wall thickness for a heat transfer rate effective to simulate a process temperature history in the selected continuous processing plant. A heater jacket is disposed about the reactor vessel and defines a number of independent controllable temperature zones axially spaced along the reaction vessel. Each temperature zone can be energized to simulate a time-temperature history of process material through the continuous plant. A pressure vessel contains both the heater jacket and the reaction vessel at an operating pressure functionally selected to simulate the continuous processing plant. The process yield from the oil shale may be used as feedback information to software simulating operation of the continuous plant to provide operating parameters, i.e., temperature profiles, ambient atmosphere, operating pressure, material feed rates, etc., for simulation in the batch reactor.

Parkinson, William J. (Los Alamos, NM)

1987-01-01

376

Submarine hydrothermal fossils confirmed  

NASA Astrophysics Data System (ADS)

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

Bell, Peter M.

377

Using more than the oldest fossils: dating osmundaceae with three bayesian clock approaches.  

PubMed

A major concern in molecular clock dating is how to use information from the fossil record to calibrate genetic distances from DNA sequences. Here we apply three Bayesian dating methods that differ in how calibration is achieved-"node dating" (ND) in BEAST, "total evidence" (TE) dating in MrBayes, and the "fossilized birth-death" (FBD) in FDPPDiv-to infer divergence times in the royal ferns. Osmundaceae have 16-17 species in four genera, two mainly in the Northern Hemisphere and two in South Africa and Australasia; they are the sister clade to the remaining leptosporangiate ferns. Their fossil record consists of at least 150 species in ?17 genera. For ND, we used the five oldest fossils, whereas for TE and FBD dating, which do not require forcing fossils to nodes and thus can use more fossils, we included up to 36 rhizomes and frond compression/impression fossils, which for TE dating were scored for 33 morphological characters. We also subsampled 10%, 25%, and 50% of the 36 fossils to assess model sensitivity. FBD-derived divergence ages were generally greater than those inferred from ND; two of seven TE-derived ages agreed with FBD-obtained ages, the others were much younger or much older than ND or FBD ages. We prefer the FBD-derived ages because they best fit the Osmundales fossil record (including Triassic fossils not used in our study). Under the preferred model, the clade encompassing extant Osmundaceae (and many fossils) dates to the latest Paleozoic to Early Triassic; divergences of the extant species occurred during the Neogene. Under the assumption of constant speciation and extinction rates, the FBD approach yielded speciation and extinction rates that overlapped those obtained from just neontological data. However, FBD estimates of speciation and extinction are sensitive to violations in the assumption of continuous fossil sampling; therefore, these estimates should be treated with caution. PMID:25503771

Grimm, Guido W; Kapli, Paschalia; Bomfleur, Benjamin; McLoughlin, Stephen; Renner, Susanne S

2015-05-01

378

Obesity and African Americans  

MedlinePLUS

... Population Profiles > Black/African American > Obesity Obesity and African Americans African American women have the highest rates of being overweight ... in the U.S. About four out of five African American women are overweight or obese. In 2011, African ...

379

FOSSIL2 energy policy model documentation: FOSSIL2 documentation  

SciTech Connect

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

None

1980-10-01

380

Integrating fossils with molecular phylogenies improves inference of trait evolution.  

PubMed

Comparative biologists often attempt to draw inferences about tempo and mode in evolution by comparing the fit of evolutionary models to phylogenetic comparative data consisting of a molecular phylogeny with branch lengths and trait measurements from extant taxa. These kinds of approaches ignore historical evidence for evolutionary pattern and process contained in the fossil record. In this article, we show through simulation that incorporation of fossil information dramatically improves our ability to distinguish among models of quantitative trait evolution using comparative data. We further suggest a novel Bayesian approach that allows fossil information to be integrated even when explicit phylogenetic hypotheses are lacking for extinct representatives of extant clades. By applying this approach to a comparative dataset comprising body sizes for caniform carnivorans, we show that incorporation of fossil information not only improves ancestral state estimates relative to those derived from extant taxa alone, but also results in preference of a model of evolution with trend toward large body size over alternative models such as Brownian motion or Ornstein-Uhlenbeck processes. Our approach highlights the importance of considering fossil information when making macroevolutionary inference, and provides a way to integrate the kind of sparse fossil information that is available to most evolutionary biologists. PMID:23206147

Slater, Graham J; Harmon, Luke J; Alfaro, Michael E

2012-12-01

381

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

382

Taxonomy and fossils: a critical appraisal.  

PubMed Central

Many compendia at the species, genus and family levels document the fossil record, but these are not standardized, nor usually critical in content, and few are available on the World Wide Web. The sampling of the available record is good for organisms with fossilizable parts, but preservational constraints on the entire morphology, life history and geographical distribution lead to difficulties in recognizing and naming species. We recommend abandoning some of the palaeontological species concepts such as chronospecies and stratospecies, and we advocate species recognition based on unique combinations of characters. The compilation of species lists is extremely time consuming, and given the inherent problems we suggest that compilation of generic lists is a more achievable goal because genera are recognized by definitive morphological characters. In calculating taxon duration, care must be taken to distinguish between mono-, para- and polyphyletic groups, the first being the only reliable unit for use in calculating diversity curves. We support the inclusion of fossils into classifications based on Recent organisms, but we recognize some of the problems this may pose for standard Linnaean classifications. Web-based taxonomy is the way forward, having the advantages of speed and currency of information dissemination, universal access with links to primary literature and increasingly sophisticated imagery. These advantages over conventional outlets will only be realized with careful Web design and a commitment to maintenance. PMID:15253350

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

2004-01-01

383

Dating Fossil Pollen: A Simulation.  

ERIC Educational Resources Information Center

Describes a hands-on simulation in which students determine the age of "fossil" pollen samples based on the pollen types present when examined microscopically. Provides instructions for the preparation of pollen slides. (MDH)

Sheridan, Philip

1992-01-01

384

African Americans and Smoking  

MedlinePLUS

... ENews Home > Stop Smoking > About Smoking > Facts & Figures African Americans Smoking among African Americans is a serious problem ... about the same amount. 2 Smoking Rates Among African Americans In 2008, about 5.6 million, or 21. ...

385

Diabetes in African Americans  

MedlinePLUS

... and Titles : Diabetes in African Americans Diabetes in African Americans 4 Steps to Manage Your Diabetes for Life ... to Prevent Type 2 Diabetes Tips to help African Americans at risk for type 2 diabetes move more ...

386

The legacy of fossil fuels.  

PubMed

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

Armaroli, Nicola; Balzani, Vincenzo

2011-03-01

387

CHAPTER FOUR Global and African Regional Climate  

E-print Network

age (Zachos et al., 2001). Deep-sea oxygen isotope records record global cooling of up to 8C revolutions in climate research that have dramatically altered our perception of global and African climate dynamical predictions, leading to new perspectives on the nature of Cenozoic climate change. Third, the role

deMenocal, Peter B.

388

Degradation of the upper pulvinus in modern and fossil leaves of Cercis (Fabaceae).  

PubMed

Identification of fossil leaf impressions as Cercis has been questioned based upon the presence or absence of a pulvinus at the base of the lamina (upper pulvinus). In the present study, leaves of Cercis canadensis were examined before and after abscission to explore the degradation processes that could occur prior to fossilization, and the North American record for fossil foliage of Cercis was revised accordingly. Results for C. canadensis indicate that: (1) the pulvinus consists largely of tissues with nonlignified cells (a wide cortex, a nonlignified fiber sheath, phloem, and pith) that degrade rapidly after leaf abscission, (2) the lignified xylem tissue that remains in the pulvinus after degradation is in brittle strands, (3) the pulvinus degrades at a faster rate than the lamina or the petiole, and (4) the degraded pulvinus cushion leaves a semicircular pattern on the lamina. From examination of fossils as well as extant species, we: (1) demonstrated that in fossils, the upper pulvinus can show a greater degree of degradation than the adjoining petiole or lamina tissue, suggesting the degradation of upper pulvinus tissue is similar in modern vs. fossil specimens, (2) defined numerous other laminar characters that can be used in conjunction with, or in the absence of, an upper pulvinus to confirm the presence of Cercis in the fossil record, and (3) showed from those criteria that the earliest known North American fossil leaf record for Cercis, from a specimen newly reported in the present study, is from the middle Miocene Succor Creek flora of Oregon. PMID:21684911

Owens, S; Fields, P; Ewers, F

1998-02-01

389

How do we recognize and use fossils in outcrop?  

NSDL National Science Digital Library

Getting students to "put on paleontologists' hats" before their first fossil-hunting field trip allows for a more enriching field experience. Rather than handing out an instructor-prepared field guide (that few students read, anyway), the students essentially work up their own geologic/paleontologic interpretation of a site, using a custom toolkit they develop through classroom and homework exercises. The activity begins with a worksheet that can be completed in groups during class (recommended) or as homework. Students are asked to imagine scenarios of fossil preservation, suggest factors that influence the completeness of the fossil record, and think of ways that fossil assemblages can give clues to the stratigraphic position and paleoenvironment of a rock formation. The instructor is involved as a guide, introducing concepts and terminology as needed. Students will also discuss with help from a textbook, specimens, or slide presentation - how the characteristics of major fossil groups might be used to identify a fossil in outcrop (for example, the coil of a gastropod, the pinnules of a crinoid). Next, each student is assigned to be an expert on one taxon or faunal group that they will encounter on the trip. This requires reading a fossil identification guide or instructor-prepared handout. They will make an "expert's notecard" to bring along on the field trip, and will be expected to find and present examples of their fossil(s) on the field trip. The taxonomic level or groups assigned will vary depending on the fossil assemblage and the class size. The activity culminates with the field experience, during which students keep a detailed field notebook (bringing along their in-class worksheets for reference). In the field, students will identify modes of preservation, assist one another as "experts" in fossil identification, and discuss the paleoecological and paleoenvironmental setting of the geologic section. After the field trip, the class compiles a faunal list for the site. Each student writes up an interpretation based on their individual observations and those made as a class. This set of activities can be streamlined if, for instance, the field trip is only a small unit of a general geology course. Rather than using open-ended discussion questions on the preliminary worksheet, the instructor can assign reading or give a lecture that covers modes of preservation and other concepts that students will use to complete the worksheet. The goal remains, however, for students to think about what they will observe at the outcrop BEFORE they are on the rocks.

Hilary Lackey

390

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

NASA Astrophysics Data System (ADS)

Although the age and location is disputed, the rise of the first closed-canopy forest is likely linked with the expansion of angiosperms in the late Cretacous or early Cenozoic. The carbon isotope 'canopy effect' reflects the extent of canopy closure, and is well documented in ?13C values of the leaves and leaf lipids in modern forests. To test the extent of canopy closure among the oldest documented angiosperm tropical forests, we analyzed isotopic characteristics of leaf fossils and leaf waxes from the Guaduas and Cerrejn Formations. The Guaduas Fm. (Maastrichtian) contains some of the earliest angiosperm fossils in the Neotropics, and both leaf morphology and pollen records at this site suggest an open-canopy structure. The Cerrejn Fm. (Paleocene) contains what are believed to be the first recorded fossil leaves from a closed-canopy forest. We analyzed the bulk carbon isotope content (?13Cleaf) of 199 fossil leaves, as well as the n-alkane concentration and chain-length distribution, and ?13C of alkanes (?13Clipid) of 73 fossil leaves and adjacent sediment samples. Fossil leaves are dominated by eudicots and include ten modern plant families (Apocynaceae, Bombaceae, Euphorbaceae, Fabaceae, Lauraceae, Malvaceae, Meliaceae, Menispermaceae, Moraceae, Sapotaceae). We interpreted extent of canopy coverage based on the range of ?13Cleaf values. The narrow range of ?13C values in leaves from the Guaduas Fm (2.7) is consistent with an open canopy. A significantly wider range in values (6.3) suggests a closed-canopy signature for site 0315 of the Cerrejn Fm,. In contrast, at Site 0318, a lacustrine deposit, leaves had a narrow range (3.3) in ?13C values, and this is not consistent with a closed-canopy, but is consistent with leaf assemblages from a forest edge. Leaves that accumulate in lake sediments tend to be biased toward plants living at the lake edge, which do not experience closed-canopy conditions, and do not express the isotopic characteristics associated with canopy effect. A biomass flux-weighted model of alkane chain-length distribution and ?13Cleaf indicate n-alkanes extracted from bulk rock are consistent with inputs integrated over time from plants represented by fossil leaves. In a modern rainforest, we found leaf lipid amounts markedly higher in the shaded and moist understory, consistent with studies that show alkanes proffer fungal protection. Shade tolerance is associated with higher plant orders and, consistent with this, literature data for modern plants from 30 plant orders shows alkane production in asterids and rosids is 2 to 3 times greater than in basal angiosperms or gymnosperms. The lower clades tend to contain greater amounts of terpenoids and novel benzylisoquinoline alkaloids, rather than alkanes. For our three fossil floras, alkane abundance is strongly influenced by depositional setting, with preservation best in the lacustrine setting. Within each site, abundance patterns are potentially influenced by both taxonomic affiliation and by canopy structure as measured by ?13Cleaf values, and such relationships shed light on the combined influences of plant evolution, canopy structure and the function of biochemical resources on the geochemical record of the first rainforests.

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

2013-12-01

391

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

NASA Astrophysics Data System (ADS)

Past limnological conditions of Lake Mbalang (719' N, 1344' E, altitude: 1130 m) and vegetation type were reconstructed from diatoms and sedimentary stable carbon isotope records (?13C) since 7200 cal yr BP. The data showed that before 3600 cal yr BP, the water column was dominantly stable except around 5000-5300 cal yr BP where diatoms evidenced a mixed upper water layer and ?13C data suggest more forested vegetation in the landscape. These stable conditions can be explained by a strong monsoon flux and relatively northern position of the ITCZ that entailed high or low rainfall well distributed over the year, allowing the development of mountainous forest taxa. The decreasing trend of the monsoon flux towards the mid-Holocene was affected by several abrupt centennial to millennial-scale weakening at 6700, 5800-6000, 5000-5300, 4500 and 3600 cal yr BP. However, their impact on the vegetation is not visible, probably because rainfall distribution was favourable to forest maintenance or extension. After 3600 cal yr BP, the water column became very mixed as a result of more intense NE trade winds (Harmattan) that led at ~3000 cal yr BP to the establishment of savannah in the vegetation landscape. At that time, rainfall was probably reduced following the southward shift of the ITCZ, and the distribution of yearly rainfall was not favourable anymore to forest development. A strong seasonality with a marked dry season was established, conditions that maintained the savannah vegetation until today. Diatom data suggest the lake did not dry up during the last 7200cal yr BP; however, a low lake level observed at 2400-2100 cal yr 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 yr BP, after which the lake rose to its present level.

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

2011-12-01

392

Ignoring Authentic African Literature Means Ignoring Africans  

ERIC Educational Resources Information Center

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

Romano, Carlin

2005-01-01

393

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. PMID:15503987

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

2004-01-01

394

Travels with the Fossil Hunters  

NASA Astrophysics Data System (ADS)

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

Whybrow, Peter J.

2000-04-01

395

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

PubMed Central

Background An extinct new family of Pentatomomorpha, Venicoridae Yao, Ren & Cai fam. nov., with 2 new genera and 2 new species (Venicoris solaris Yao, Ren & Rider gen. & sp. nov. and Clavaticoris zhengi Yao, Ren & Cai gen. & sp. nov.) are described from the Early Cretaceous Yixian Formation in Northeast China. Methodology/Principal Findings A cladistic analysis based on a combination of fossil and extant morphological characters clarified the phylogenetic status of the new family and has allowed the reconstruction of intersuperfamily and interfamily relationships within the Infraorder Pentatomomorpha. The fossil record and diversity of Pentatomomorpha during the Mesozoic is discussed. Conclusions/Significance Pentatomomorpha is a monophyletic group; Aradoidea and the Trichophora are sister groups; these fossils belong to new family, treated as the sister group of remainder of Trichophora; Pentatomoidea is a monophyletic group; Piesmatidae should be separated as a superfamily, Piesmatoidea. Origin time of Pentatomomorpha should be tracked back to the Middle or Early Triassic. PMID:22655038

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

2012-01-01

396

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.

397

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

398

Details of North African tectonics  

NSDL National Science Digital Library

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

Meghraoui et al.

399

Revision of the Proteaceae Macrofossil Record from Patagonia, Argentina  

E-print Network

Revision of the Proteaceae Macrofossil Record from Patagonia, Argentina Cynthia C. Gonzalez1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262 Key Based on Leaf Characters of Fossil Proteaceae from Patagonia in Argentina. Megafossil genera of Proteaceae recorded from Patagonia in- clude Lomatia, Embothrium, Orites

Wilf, Peter

400

Species longevity in North American fossil mammals.  

PubMed

Species longevity in the fossil record is related to many paleoecological variables and is important to macroevolutionary studies, yet there are very few reliable data on average species durations in Cenozoic fossil mammals. Many of the online databases (such as the Paleobiology Database) use only genera of North American Cenozoic mammals and there are severe problems because key groups (e.g. camels, oreodonts, pronghorns and proboscideans) have no reliable updated taxonomy, with many invalid genera and species and/or many undescribed genera and species. Most of the published datasets yield species duration estimates of approximately 2.3-4.3 Myr for larger mammals, with small mammals tending to have shorter species durations. My own compilation of all the valid species durations in families with updated taxonomy (39 families, containing 431 genera and 998 species, averaging 2.3 species per genus) yields a mean duration of 3.21 Myr for larger mammals. This breaks down to 4.10-4.39 Myr for artiodactyls, 3.14-3.31 Myr for perissodactyls and 2.63-2.95 Myr for carnivorous mammals (carnivorans plus creodonts). These averages are based on a much larger, more robust dataset than most previous estimates, so they should be more reliable for any studies that need species longevity to be accurately estimated. PMID:25236413

Prothero, Donald R

2014-08-01

401

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.

Rick Crosslin

2004-01-01

402

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.

403

FOSSIL2 energy policy model documentation: FOSSIL2 documentation  

SciTech Connect

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

None

1980-10-01

404

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

PubMed

Fossil record of Phanerozoic non-spicular sponges, beside of being important with respect to the lineage evolution per se, could provide valuable references for the investigation of Precambrian ancestral animal fossils. However, although modern phylogenomic studies resolve non-spicular demosponges as the sister group of the remaining spiculate demosponges, the fossil record of the former is extremely sparse or unexplored compared to that of the latter; the Middle Cambrian Vauxiidae Walcott 1920, is the only confirmed fossil taxon of non-spicular demosponges. Here, we describe carbonate materials from Devonian (Upper Givetian to Lower Frasnian) bioherms of northern France and Triassic (Anisian) microbialites of Poland that most likely represent fossil remnants of keratose demosponges. These putative fossils of keratose demosponges are preserved as automicritic clumps. They are morphologically distinguishable from microbial fabrics but similar to other spiculate sponge fossils, except that the skeletal elements consist of fibrous networks instead of assembled spicules. Consistent with the immunological behavior of sponges, these fibrous skeletons often form a rim at the edge of the automicritic aggregate, separating the inner part of the aggregate from foreign objects. To confirm the architecture of these fibrous networks, two fossil specimens and a modern thorectid sponge for comparison were processed for three-dimensional (3-D) reconstruction using serial grinding tomography. The resulting fossil reconstructions are three-dimensionally anastomosing, like modern keratose demosponges, but their irregular and nonhierarchical meshes indicate a likely verongid affinity, although a precise taxonomic conclusion cannot be made based on the skeletal architecture alone. This study is a preliminary effort, but an important start to identify fossil non-spicular demosponges in carbonates and to re-evaluate their fossilization potential. PMID:24763744

Luo, Cui; Reitner, Joachim

2014-06-01

405

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

NASA Astrophysics Data System (ADS)

Fossil record of Phanerozoic non-spicular sponges, beside of being important with respect to the lineage evolution per se, could provide valuable references for the investigation of Precambrian ancestral animal fossils. However, although modern phylogenomic studies resolve non-spicular demosponges as the sister group of the remaining spiculate demosponges, the fossil record of the former is extremely sparse or unexplored compared to that of the latter; the Middle Cambrian Vauxiidae Walcott 1920, is the only confirmed fossil taxon of non-spicular demosponges. Here, we describe carbonate materials from Devonian (Upper Givetian to Lower Frasnian) bioherms of northern France and Triassic (Anisian) microbialites of Poland that most likely represent fossil remnants of keratose demosponges. These putative fossils of keratose demosponges are preserved as automicritic clumps. They are morphologically distinguishable from microbial fabrics but similar to other spiculate sponge fossils, except that the skeletal elements consist of fibrous networks instead of assembled spicules. Consistent with the immunological behavior of sponges, these fibrous skeletons often form a rim at the edge of the automicritic aggregate, separating the inner part of the aggregate from foreign objects. To confirm the architecture of these fibrous networks, two fossil specimens and a modern thorectid sponge for comparison were processed for three-dimensional (3-D) reconstruction using serial grinding tomography. The resulting fossil reconstructions are three-dimensionally anastomosing, like modern keratose demosponges, but their irregular and nonhierarchical meshes indicate a likely verongid affinity, although a precise taxonomic conclusion cannot be made based on the skeletal architecture alone. This study is a preliminary effort, but an important start to identify fossil non-spicular demosponges in carbonates and to re-evaluate their fossilization potential.

Luo, Cui; Reitner, Joachim

2014-06-01

406

Fast Fossil Rotation of Neutron Star Cores  

NASA Astrophysics Data System (ADS)

It is argued that the superfluid core of a neutron star super-rotates relative to the crust, because stratification prevents the core from responding to the electromagnetic braking torque, until the relevant dissipative (viscous or Eddington-Sweet) timescale, which can exceed ~103 yr and is much longer than the Ekman timescale, has elapsed. Hence, in some young pulsars, the rotation of the core today is a fossil record of its rotation at birth, provided that magnetic crust-core coupling is inhibited, e.g., by buoyancy, field-line topology, or the presence of uncondensed neutral components in the superfluid. Persistent core super-rotation alters our picture of neutron stars in several ways, allowing for magnetic field generation by ongoing dynamo action and enhanced gravitational wave emission from hydrodynamic instabilities.

Melatos, A.

2012-12-01

407

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

408

African Voices  

NSDL National Science Digital Library

Released this month, African Voices, a Website from the Smithsonian, dynamically presents cross-sections of the history, culture, and art of Africa. The history section offers an interactive timeline providing text and some striking images to narrate Africa's history beginning with the first evidence of human ancestors and continuing through the ancient civilizations of the Nile on down to nineteenth-century colonialism and the present day. The cultural themes section features images and text on topics such as wealth and work in Africa, the Kongo Crossroads, and Global Africa. The Focus Gallery examines the carving artistry of Lamidi Fakeye, a fifth generation member of the celebrated Fakeye woodcarving family of Ila Orangun, Nigeria. A separate Learning Center Webpage offers a bibliography of further resources, including CDs and audiocassettes, and a listing of related Websites. Note: those with Apple computers might find the site easier to navigate if they disable Java in their preferences before visiting.

409

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.

410

Fossil Identification and Classification Lab  

NSDL National Science Digital Library

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

Ralph Willoughby

411

FOSSIL: A Robust Relational Learner  

Microsoft Academic Search

. The research reported in this paper describes Fossil, an ILPsystem that uses a search heuristic based on statistical correlation. Thisalgorithm implements a new method for learning useful concepts in thepresence of noise. In contrast to Foil's stopping criterion, which allowstheories to grow in complexity as the size of the training sets increases,we propose a new stopping criterion that is

Johannes Ffirnkranz

1994-01-01

412

Biomechanics in fossil plant biology  

Microsoft Academic Search

The use of biomechanics for the analysis of the formfunction 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

413

Rule Fossilization: A Tentative Model  

ERIC Educational Resources Information Center

A cybernetic model of factors involved in the fossilization of grammatical and lexical forms in learner grammars is offered. A distinction is made between affective and cognitive dimensions of a multidimensional channel of human communication; and the effect of expected and unexpected feedback on these two dimensions is discussed. (Author/POP)

Vigil, Neddy A.; Oller, John W.

1976-01-01

414

Synthetic soup ground trace fossils  

NSDL National Science Digital Library

This is a lab exercise where students make synthetic trace fossils (using fishing lures) that was presented as a scientific study: BIOGENIC SEDIMENTARY STRUCTURES PRODUCED BY WORMS IN SOUPY, SOFT MUDS: OBSERVATIONS FROM THE CHATTANOOGA SHALE (UPPER DEVONIAN) AND EXPERIMENTS, by VADEC LOBZA AND JURGEN SCHIEBER, JOURNAL OF SEDIMENTARY RESEARCH, VOL. 69, NO. 5, SEPTEMBER, 1999, P. 10411049

Clint Cowan

415

Theory of fossil magnetic field  

NASA Astrophysics Data System (ADS)

Theory of fossil magnetic field is based on the observations, analytical estimations and numerical simulations of magnetic flux evolution during star formation in the magnetized cores of molecular clouds. Basic goals, main features of the theory and manifestations of MHD effects in young stellar objects are discussed.

Dudorov, Alexander E.; Khaibrakhmanov, Sergey A.

2015-02-01

416

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.

417

Fossil Forests and Silicified Trunks  

Microsoft Academic Search

IN NATURE, vol. xix. p. 257, the discovery of fossil forests in the spring region of the Yellowstone River is referred to. I have visited the United States National Park, and its geysers, and observed exactly how silicified trunks in situ originate. All geologists suppose that this must have happened beneath water, and consequently Mr. Holmes supposes a constant alternation

Otto Kuntze

1879-01-01

418

Fossil/modern mole phylogeny  

NSDL National Science Digital Library

This study is introduced at the beginning of class, and runs throughout the quarter. Students are first given a paper describing a morphological phylogeny of modern moles. The first few weeks' labs teach the students basic phylogenetic methods and the aspects of skeletal morphology needed to understand the character descriptions. Students in groups of 2 or 3 are assigned a set of characters from a particular region of the skeleton (i.e. humerus, lower teeth, skull, etc.). Those groups are responsible for learning to distinguish those characters on a representative group of modern specimens (for which the character codings are already available in the paper they have) and then coding those characters for a number of fossil taxa. The fossils are either described in papers posted on the course website or are represented by specimens held in the instructor's research lab. Students are responsible for finding time to come in and work with the specimens. The next to last lab of the quarter is concerned with analyzing data within each group, for the class as a whole, for fossil taxa alone, and for fossil and modern taxa. Students then write up the results of their analyses for their term project due at the end of the quarter.

419

Risk for Human African Trypanosomiasis, Central Africa, 20002009  

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. PMID:22172322

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

2011-01-01

420

SURVIVAL AND MOVEMENTS OF AFRICAN PENGUINS, ESPECIALLY AFTER OILING.  

E-print Network

SURVIVAL AND MOVEMENTS OF AFRICAN PENGUINS, ESPECIALLY AFTER OILING. by Philip Anthony Whittington of first recorded breeding and the success of rehabilitating oiled African Penguins were investigated using re-sightings of flipper-banded birds. Seventeen penguin colonies between Algoa Bay and Lambert's Bay

de Villiers, Marienne

421

Review of script displays of African languages by current software  

Microsoft Academic Search

All recorded African languages that have a writing system have orthographies which use the Roman or Arabic scripts, with a few exceptions. While Unicode successfully handles the encoding of both these scripts, current software, in particular Web browsers, take little account of users wishing to operate in a minority script. Their use for displaying African languages has been limited by

Quintin Gee

2005-01-01

422

Molecular and Fossil Evidence on the Origin of Angiosperms  

NASA Astrophysics Data System (ADS)

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

Doyle, James A.

2012-05-01

423

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

E-print Network

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

Packard, Jane M.

424

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

425

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

426

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 conclusionthat cladogenesis is the predominant mode by which new planktic Foraminifera taxa become established at macroevolutionary time scalesdiffers markedly from the conclusion reached in a recent study based solely on fossil data. These disparate findings demonstrate that interpretations of macroevolutionary dynamics in the fossil record can be fundamentally altered in light of genetic evidence. PMID:23378632

Strotz, Luke C.; Allen, Andrew P.

2013-01-01

427

Schewel and Schipper 1 FOSSIL FREIGHT: HOW MUCH FOSSIL FUEL DOES IT TAKE TO MOVE FOSSIL1  

E-print Network

Schewel and Schipper 1 FOSSIL FREIGHT: HOW MUCH FOSSIL FUEL DOES IT TAKE TO MOVE FOSSIL1 FUEL?2 Laura Schewel 1 and Lee Schipper 2 3 (1) UC Berkeley, Energy and Resources Group4 (2) UC Berkeley author: LAURA.SCHEWEL@BERKELEY.EDU7 8 Word Count: 45339 Figures:1010 Tables: 411 12 Laura Schewel (laura.schewel

Kammen, Daniel M.

428

Replaying evolutionary transitions from the dental fossil record.  

PubMed

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

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

2014-08-01

429

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

430

Cell symbiosis theory - Status and implications for the fossil record  

NASA Technical Reports Server (NTRS)

Smith (1981) has presented three alternative models of the origin of eukaryotes. In the present investigation, alternative theories are discussed along with the status of serial endosymbiotic theory. It is pointed out that the usefulness of the serial endosymbiotic theory is attested by the great flourishing of productive scientific studies it has generated. Attention is given to the origin of mitochondria and plastids from free-living bacteria, the polyphyly of mitochondria, the origin of the nuclear membrane, the origin of undulipodia (cilia and other 9 + 2 organelles), the sequence of acquisition of organelles, large ribosomes, genome organization, animals and plants, and systematics and axonomy of the microorganisms.

Margulis, L.; Stolz, J. F.

1984-01-01

431

The Future of the Fossil Record David Jablonski  

E-print Network

experi- ments, sometimes richly replicated, as in regional extinction pulses, and sometimes confoundingly scales? The overall trend of plant and animal biodiversity--whether measured in terms of taxa, range by extinction events, and has had (in the oceans anyway) at least one prolonged episode of little net change

Boyce, C. Kevin

432

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

433

The fossil record of evolution: Data on diversification and extinction  

NASA Technical Reports Server (NTRS)

The two principle efforts include: (1) a compilation of a synoptic, mesoscale data base on times of origination and extinction of animal genera in the oceans over the last 600 million years of geologic time; and (2) an analysis of statistical patterns in these data that relate to the diversification of complex life and to the occurrence of mass extinctions, especially those that might be associated with extraterrestrial phenomena. The data base is unique in its taxonomic scope and detail and in its temporal resolution. It is a valuable resource for investigating evolutionary expansions and extinctions of complex life.

Sepkoski, J. John, Jr.

1990-01-01

434

The Fossil Record of Plant-Insect Dynamics  

NASA Astrophysics Data System (ADS)

Progress toward understanding the dynamics of ancient plant-insect associations has addressed major patterns in the ecology and evolution of herbivory and pollination. This advancement involves development of more analytical ways of describing plant-insect associational patterns in time and space and an assessment of the role that the environment and internal biological processes have in their control. Current issues include the deep origins of terrestrial herbivory, the spread of herbivory across late Paleozoic landscapes, recoveries from sudden major crises, reaction to and accommodation of protracted environmental perturbations, and the nature of herbivory and pollination before the appearance of angiosperms during the mid-Mesozoic. These and other exploratory research themes provide a more complete account of a great nexus of ecological activity that has been wedged between the two most diverse organismic groups on land for the past 410 million years.

Labandeira, Conrad C.; Currano, Ellen D.

2013-05-01

435

Climatic influences on species: Evidence from the fossil record  

USGS Publications Warehouse

The detailed Neogene and Quaternary paleoclimatic reconstructions now available provide a means to test how species respond to environmental change. Paleontologic studies of marine organisms show that climatic change causes evolution (via cladogenesis and anagenesis), ecophenotypic variation, migration, morphologic stasis and extinction. Evolution during climatic change is a rare event relative to the number of climatic cycles that have occurred, but climate-related environmental barriers, usually temperature, may play an important role in the isolation of populations during allopatric speciation.

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

1990-01-01

436

The Fossil Record of Star Formation from Galaxy Spectra  

E-print Network

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

Panter, Ben