Sample records for african fossil record

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

    PubMed Central

    Bibi, Faysal

    2011-01-01

    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

  2. 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.

  3. 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.

  4. 004118:a0001 Fossil Record

    E-print Network

    Benton, Michael

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

  5. The Fossil Record

    NSDL National Science Digital Library

    Lisa Wu

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

  6. The fossil record of cnidarian medusae

    Microsoft Academic Search

    Graham A. Young; James W. Hagadorn

    2010-01-01

    Fossils of cnidarian medusae are extremely rare, although reports of fossil “medusoids,” most of which do not represent medusae, are rather common. Our previous inability to distinguish these fossils has hampered attempts to investigate patterns and processes within the medusozoan fossil record. Here we describe criteria for the recognition of bona fide fossil medusae and use them to assess the

  7. Evolution and the Fossil Record

    NSDL National Science Digital Library

    Dale Springer

    2007-12-12

    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.

  8. The First Fossil Record of Caecilian Amphibians

    Microsoft Academic Search

    Richard Estes; MARVALEE H. WAKE

    1972-01-01

    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.

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

    E-print Network

    Heim, Noel A.

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

  10. The fossil record of the Peronosporomycetes (Oomycota).

    PubMed

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

    2011-01-01

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

  11. Evolution and the Fossil Record

    E-print Network

    Kammer, Thomas

    .) · Charles Darwin, 1859: The Origin of Species by Natural Selection. #12;Artificial Selection vs. Natural Anatomy of Fossilized organisms #12;Natural Selection · Natural selection, a creative force, is one Selection: Dog breeds produced by artificial selection #12;Natural Selection: Key Points · 3 facts lead

  12. 004144:a0001 Fossil Record: Quality

    E-print Network

    Benton, Michael

    of Darwin's On the Origin of Species by Means of Natural Selection provide benchmarks of major changes questioned, and doubts have arisen because of questions of quality. Charles Darwin hoped that, over time partnership with the study of modern organ- isms. See also: Darwin, Charles Robert; Fossil record; History

  13. Name: Section: GEOL 204: The Fossil Record

    E-print Network

    Holtz Jr., Thomas R.

    Mammals (First Floor) · Hall of Ice Age Mammals (First Floor) · Butterflies + Plants: Partners) Mass extinctions are an extremely significant phenomenon in the fossil record. Find a display discussing a major mass extinction (the easiest way to do this is in the Sant Ocean Hall, which deals

  14. SURVEY OF SOCIAL INSECTS IN THE FOSSIL RECORD*

    E-print Network

    Villemant, Claire

    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

  15. RESEARCH LETTERS 161 The Fossil Record of Cretaceous

    E-print Network

    Benton, Michael

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

  16. Spatial Bias in the Marine Fossil Record

    PubMed Central

    Vilhena, Daril A.; Smith, Andrew B.

    2013-01-01

    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

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

    E-print Network

    Villemant, Claire

    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

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

    E-print Network

    Benton, Michael

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

  19. Neoproterozoic glaciations and the fossil record

    NASA Astrophysics Data System (ADS)

    Xiao, Shuhai

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

  20. Aestivation in the fossil record: evidence from ichnology.

    PubMed

    Hembree, Daniel I

    2010-01-01

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

  1. First Fossil Lamprey: A Record from the Pennsylvanian of Illinois

    Microsoft Academic Search

    David Bardack; Rainer Zangerl

    1968-01-01

    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

  2. The earliest fossil record of the animals and its significance.

    PubMed

    Budd, Graham E

    2008-04-27

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

  3. Aestivation in the Fossil Record: Evidence from Ichnology

    Microsoft Academic Search

    Daniel I. Hembree

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

  4. How Good is the Fossil Record?

    ERIC Educational Resources Information Center

    Boucot, A. J.

    1983-01-01

    Suggests that earth scientists become active in the creationist debate by making sure that the religious concept creationism is not taught in schools and that well-based, informative material about organic evolution, earth's age, and nature of stratigraphic record are employed by science teachers. (Author/JN)

  5. Evidence for Evolution from the Vertebrate Fossil Record.

    ERIC Educational Resources Information Center

    Gingerich, Philip D.

    1983-01-01

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

  6. Teacher Overview to Stories from the Fossil Record

    NSDL National Science Digital Library

    This is the teacher resource site for the University of California Museum of Paleontology (UCMP) program "Stories from the Fossil Record". It provides information to aide instructors in implementing the program in a classroom setting. Included are lesson plans, handouts, related activities, and background references. Also included are pre- and post-lesson assessments.

  7. A fossil record of galaxy encounters.

    PubMed

    Elbaz, David; Cesarsky, Catherine J

    2003-04-11

    The cosmic infrared background (CIRB) is a record of a large fraction of the emission of light by stars and galaxies over time. The bulk of this emission has been resolved by the Infrared Space Observatory camera. The dominant contributors are bright starburst galaxies with redshift z approximately 0.8; that is, in the same redshift range as the active galactic nuclei responsible for the bulk of the x-ray background. At the longest wavelengths, sources of redshift z >/= 2 tend to dominate the CIRB. It appears that the majority of present-day stars have been formed in dusty starbursts triggered by galaxy-galaxy interactions and the buildup of large-scale structures. PMID:12690183

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

    E-print Network

    Gehring, William J.

    .sciencemag.org SCIENCE VOL 295 22 MARCH 2002 2193 and African fossils, and it therefore links them all as interbreeding members of the same wide-ranging species that gave rise to living humans. "This fossil is a crucial piece-author and paleoanthropologist Tim White of the University of California, Berkeley. "This African fossil is so similar to its

  9. Self-organized criticality, evolution and the fossil extinction record

    Microsoft Academic Search

    M. E. J. Newman

    1996-01-01

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

  10. An overview of the dinosaur fossil record from Chile

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

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

    E-print Network

    Benton, Michael

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

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

    E-print Network

    Benton, Michael

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

  13. The fossil record and macroevolutionary history of the beetles.

    PubMed

    Smith, Dena M; Marcot, Jonathan D

    2015-04-22

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

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

    Budd, Graham E

    2013-09-01

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

  16. At the Origin of Animals: The Revolutionary Cambrian Fossil Record

    PubMed Central

    Budd, Graham E

    2013-01-01

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

  17. The Paleogene fossil record of birds in Europe.

    PubMed

    Mayr, Gerald

    2005-11-01

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

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

    E-print Network

    Grotzinger, John P.

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

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

    E-print Network

    Plotnick, Roy E.

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

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

    Microsoft Academic Search

    E. N. Kurochkin; G. J. Dyke

    2011-01-01

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

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

    PubMed Central

    2014-01-01

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

  2. An assessment of the contribution of fossil cave deposits to the Quaternary paleontological record

    Microsoft Academic Search

    Christopher N. Jass; Christian O. George

    2010-01-01

    Mammal-bearing cave deposits are an important part of the Quaternary fossil record, but the exact nature of the contribution that caves make to the fossil record is a research area that is largely unexplored. To explore this issue, late Pleistocene species representation in cave versuses non-cave deposits was examined. Additionally, this study examined how fossiliferous cave deposits influence perceptions of

  3. Testing homogeneity with the fossil record of galaxies

    E-print Network

    Alan F. Heavens; Raul Jimenez; Roy Maartens

    2011-09-15

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

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

    PubMed

    Gilbert, Christopher C

    2013-05-01

    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

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

    NASA Astrophysics Data System (ADS)

    McGowan, Alistair

    2014-05-01

    Biodiversity recording activities have been greatly enhanced by the emergence of online schemes and smartphone applications for recording and sharing data about a wide variety of flora and fauna. As a palaeobiologist, one of the areas of research I have been heavily involved in is the question of whether the amount of rock available to sample acts as a bias on our estimates of biodiversity through time. Although great progress has been made on this question over the past ten years by a number of researchers, I still think palaeontology has not followed the lead offered by the 'citizen science' revolution in studies of extant biodiversity. By constructing clearly structured surveys with online data collection support, it should be possible to collect field data on the occurrence of fossils at the scale of individual exposures, which are needed to test competing hypotheses about these effects at relatively small spatial scales. Such data collection would be hard to justify for universities and museums with limited personnel but a co-ordinated citizen science programme would be capable of delivering such a programme. Data collection could be based on the MacKinnon's Lists method, used in rapid conservation assessment work. It relies on observers collecting lists of a fixed length (e.g. 10 species long) but what is important is that it focuses on getting observers to ignore sightings of the same species until that list is complete. This overcomes the problem of 'common taxa being commonly recorded' and encourages observers to seek out and identify the rarer taxa. This gives a targeted but finite task. Rather than removing fossils, participants would be encouraged to take photographs to share via a recording website. The success of iSpot, which allows users to upload photos of plants and animals for other users to help with identifications, offers a model for overcoming the problems of identifying fossils, which can often look nothing like the examples illustrated in guidebooks. The requirements for a web platform could be met by the use of the freely-available Indicia software developed by the UK Centre for Ecology and Hydrology for biodiversity recording. However, some trials with the software have found it would be suitable for recording fossil occurrences as well. The software allows users to plot collections on maps, upload and share photographs and make identifications of material. Within the UK, the British Geological Survey has made geological map data available via the iGeology smartphone app and the Geology of Britain website. Thus it is now possible for people with access to smartphones or the internet to know which geological units they are sampling from, which would previously have been difficult without access to paper copies of geological maps. Such a programme could make a significant contribution towards reviving palaeontology and geology as field-based natural history and create wider interest in basic geological and taxonomic skills and form the basis for work on geodiversity recording and exploring links between geodiversity and biodiversity.

  6. Characterisation of Bolivian savanna ecosystems by their modern pollen rain and implications for fossil pollen records

    Microsoft Academic Search

    Huw T. Jones; Francis E. Mayle; R. Toby Pennington; Timothy J. Killeen

    2011-01-01

    The majority of vegetation reconstructions from the Neotropics are derived from fossil pollen records extracted from lake sediments. However, the interpretation of these records is restricted by limited knowledge of the contemporary relationships between the vegetation and pollen rain of Neotropical ecosystems, especially for more open vegetation such as savannas. This research aims to improve the interpretation of these records

  7. A new species of Stigmatomyces from Baltic amber, the first fossil record of Laboulbeniomycetes.

    PubMed

    Rossi, Walter; Kotrba, Marion; Triebel, Dagmar

    2005-03-01

    A fossil ascomycete was found attached to the thorax of a stalk eyed fly (Diopsidae: Prosphyracephala succini) in a fragment of Baltic amber. The fungus is assigned to the extant genus Stigmatomyces and described as S. succini sp. nov. This find is the first fossil record of the order Laboulbeniales. At the same time it constitutes the oldest record of a parasitic fungus on an insect. The palaeohabitat is discussed with regard to the find. PMID:15912943

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

    Microsoft Academic Search

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

    2009-01-01

    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

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

    PubMed Central

    Camens, Aaron Bruce; Carey, Stephen Paul

    2013-01-01

    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

  10. Mass extinction events and the plant fossil record

    Microsoft Academic Search

    Jennifer C. McElwain; Surangi W. Punyasena

    2007-01-01

    Five mass extinction events have punctuated the geo- logical record of marine invertebrate life. They are characterized by faunal extinction rates and magnitudes that far exceed those observed elsewhere in the geo- logical record. Despite compelling evidence that these extinction events were probably driven by dramatic global environmental change, they were originally thought to have little macroecological or evolutionary consequence

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

    PubMed Central

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

    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.

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

    E-print Network

    Benton, Michael

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

  14. The celestial factor and the formula to explain or predict all extinctions of the fossil record

    Microsoft Academic Search

    Noort van den P; A. M. T. Elewa

    2012-01-01

    In reality there are various kinds of explanations for each type of extinction. This paper introduces a new theory to explain and to estimate the size and frequency of all extinctions over the entire period of 600 my of the fossil record. The central point was the search for a common pattern and even one common formula. The current explanation

  15. Insect-Damaged Fossil Leaves Record Food Web Response to Ancient Climate Change and Extinction

    Microsoft Academic Search

    P. Wilf

    2008-01-01

    Plants and herbivorous insects have dominated terrestrial ecosystems for over 300 million years. Uniquely in the fossil record, foliage with well-preserved insect damage offers abundant and diverse information both about producers and about ecological and sometimes taxonomic groups of consumers. These data are ideally suited to investigate food web response to environmental perturbations, and they represent an invaluable deep-time complement

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

    Microsoft Academic Search

    Kevin J. Peterson; Nicholas J. Butterfield

    2005-01-01

    Molecular clocks have the potential to shed light on the timing of early metazoan divergences, but differing algorithms and calibration points yield conspicuously discordant results. We argue here that competing molecular clock hypotheses should be testable in the fossil record, on the principle that fundamentally new grades of animal organization will have ecosystem-wide impacts. Using a set of seven nuclear-encoded

  17. First Quaternary Fossil Record of Caecilians from a Mexican Archaeological Site

    Microsoft Academic Search

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

    1999-01-01

    A single vertebra from an Early Formative period archaeological site in coastal Chiapas, México, is identified as belonging to the amphibian Dermophis mexicanus (Duméril and Bibron) 1841 (Amphibia: Gymnophiona: Caeciliidae). The vertebra was recovered from deposits dated to approximately 1200–1350 B.C. The specimen represents the first Quaternary fossil record for gymnophiones. Its presence suggests the possible role of the species

  18. FOSSIL RECORD OF THE ANDEAN RAT, Andinomys edax (RODENTIA: CRICETIDAE), IN ARGENTINA

    Microsoft Academic Search

    Pablo E. Ortiz; J. Pablo Jayat

    Andinomys edax (Rodentia, Cricetidae) has a broad distribution in the Central Andean region. The fossil record is restricted to only three localities from Lower-Middle Pleistocene in Bolivia to Upper Holocene in Argentina. Recent field work in northwestern Argentina produced five new paleontological localities: Las Juntas, Catamarca (13.4 - 12.95 kyr BP); Inca Cueva 4, Jujuy (11 - 9 kyr BP);

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

    E-print Network

    Newman, Mark

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

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

    E-print Network

    Henderson, Gideon

    Project EARTH-10-MF2: 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, London. Examples of exceptionally preserved, three-dimensional fish skulls from the Upper Cretaceous

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

    PubMed Central

    2014-01-01

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

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

    PubMed

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

    2012-01-01

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

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

    USGS Publications Warehouse

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

    2006-01-01

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

  4. Fossil invertebrates records in cave sediments and paleoenvironmental assessments: a study of four cave sites from Romanian Carpathians

    NASA Astrophysics Data System (ADS)

    Moldovan, O. T.; Constantin, S.; Panaiotu, C.; Roban, R. D.; Frenzel, P.; Miko, L.

    2015-06-01

    Fossil invertebrates from cave sediments have been recently described as a potential new proxy for paleoenvironment and used in cross-correlations with alternate proxy records from cave deposits. Here we present the results of a fossil invertebrates study in four caves from two climatically different regions of the Romanian Carpathians, to complement paleoenvironmental data previously reported. Oribatid mites and ostracods are the most common invertebrates in the studied cave sediments. Some of the identified taxa are new for science, and most of them are indicative for either warm/cold stages or dry/wetter oscillations. In two caves the fossil invertebrates records indicate rapid climate oscillations during times known for a relatively stable climate. By corroborating the fossil invertebrates' record with the information given by magnetic properties and sediment structures, complementary data on past vegetation, temperatures, and hydraulic regimes could be gathered. This paper analyses the potential of fossil invertebrate records as a paleoenvironmental proxy, potential problems and pitfalls.

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

    NASA Astrophysics Data System (ADS)

    Benton, Michael J.

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

  6. First Quaternary Fossil Record of Caecilians from a Mexican Archaeological Site

    NASA Astrophysics Data System (ADS)

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

    1999-07-01

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

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

    PubMed Central

    Guinot, Guillaume; Adnet, Sylvain; Cappetta, Henri

    2012-01-01

    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

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

    Microsoft Academic Search

    David Jablonski

    2005-01-01

    The origins of evolutionary innovations have been intensively studied, but relatively little is known about their large-scale ecological patterns. For post-Paleozoic benthic marine invertebrates, which have the richest and most densely sampled fossil record, order-level taxa tend to appear first in onshore, disturbed habitats, even in groups that are now exclusively deep- water (so that present-day distributions are not reliable

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

    Microsoft Academic Search

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

    1987-01-01

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

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

    PubMed

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

    2014-07-01

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

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

    E-print Network

    Benton, Michael

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

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

    PubMed Central

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

    2009-01-01

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

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

    PubMed

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

    2009-11-01

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

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

    PubMed Central

    Sánchez-Villagra, Marcelo R.

    2010-01-01

    The study of fossilized ontogenies in mammals is mostly restricted to postnatal and late stages of growth, but nevertheless can deliver great insights into life history and evolutionary mechanisms affecting all aspects of development. Fossils provide evidence of developmental plasticity determined by ecological factors, as when allometric relations are modified in species which invaded a new space with a very different selection regime. This is the case of dwarfing and gigantism evolution in islands. Skeletochronological studies are restricted to the examination of growth marks mostly in the cement and dentine of teeth and can provide absolute age estimates. These, together with dental replacement data considered in a phylogenetic context, provide life-history information such as maturation time and longevity. Palaeohistology and dental replacement data document the more or less gradual but also convergent evolution of mammalian growth features during early synapsid evolution. Adult phenotypes of extinct mammals can inform developmental processes by showing a combination of features or levels of integration unrecorded in living species. Some adult features such as vertebral number, easily recorded in fossils, provide indirect information about somitogenesis and hox-gene expression boundaries. Developmental palaeontology is relevant for the discourse of ecological developmental biology, an area of research where features of growth and variation are fundamental and accessible among fossil mammals. PMID:20071389

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

    Microsoft Academic Search

    Jakob DAMGAARD

    2008-01-01

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

  16. Large-scale heterogeneity of the fossil record: implications for Phanerozoic biodiversity studies.

    PubMed

    Smith, A B

    2001-03-29

    Patterns of origination, extinction and standing diversity through time have been inferred from tallies of taxa preserved in the fossil record. This approach assumes that sampling of the fossil record is effectively uniform over time. Although recent evidence suggests that our sampling of the available rock record has indeed been very thorough and effective, there is also overwhelming evidence that the rock record available for sampling is itself distorted by major systematic biases. Data on rock outcrop area compiled for post-Palaeozoic sediments from Western Europe at stage level are presented. These show a strongly cyclical pattern corresponding to first- and second-order sequence stratigraphical depositional cycles. Standing diversity increases over time and, at the coarsest scale, is decoupled from surface outcrop area. This increasing trend can therefore be considered a real pattern. Changes in standing diversity and origination rates over time-scales measured in tens of millions of years, however, are strongly correlated with surface outcrop area. Extinction peaks conform to a random-walk model, but larger peaks occur at just two positions with respect to second-order stratigraphical sequences, towards the culmination of stacked transgressive system tracts and close to system bases, precisely the positions where taxonomic last occurrences are predicted to cluster under a random distribution model. Many of the taxonomic patterns that have been described from the fossil record conform to a species-area effect. Whether this arises primarily from sampling bias, or from changing surface area of marine shelf seas through time and its effect on biodiversity, remains problematic. PMID:11316484

  17. Quantifying Uncertainty in Spatio-temporal Forest Composition Changes Inferred from Fossil Pollen Records

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Understanding past compositional changes in vegetation provides insight about ecosystem dynamics in response to changing environments. Past vegetation reconstructions rely predominantly on fossil pollen data from sedimentary lake cores, which acts as a proxy record for the surrounding vegetation. Stratigraphic changes in these pollen records allow us to infer changes in composition and species distributions. Pollen records collected from a network of sites allow us to make inference about the spatio-temporal changes in vegetation over thousands of years. However, the complexity of the relationship between pollen deposits and surrounding vegetation, as well as the spatially sparse set of fossil pollen sites are important sources of uncertainty. In addition, uncertainty arises from the carbon dating and age-depth modelling processes. To reconstruct vegetation composition including uncertainty for the Upper Midwestern USA, we build a Bayesian hierarchical model that links vegetation composition to fossil pollen data via a dispersal model. In the calibration phase, we estimate the relationship between vegetation and pollen for the settlement era using Public Land Survey data and a network of pollen records. In the prediction phase, parameter estimates obtained during the calibration phase are used to estimate latent species distributions and relative abundances over the last 2500 years. We account for additional uncertainty in the pollen records by: allowing expert palynologists to identify pre-settlement pollen samples to be included in our calibration data, and through the incorporation of age uncertainty obtained from the Bayesian age-depth model BACON in our prediction data. Resulting spatio-temporal composition and abundance estimates will be used to improve forecasting capabilities of ecosystem models.

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

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-06-01

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

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

    E-print Network

    Henderson, Gideon

    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

  1. Relationships and biogeography of the fossil and living African snakehead fishes (Percomorpha, Channidae, Parachanna)

    Microsoft Academic Search

    Alison M. Murray

    2012-01-01

    The ability to determine relationships of Cenozoic fossil fishes relies heavily on having osteological information from their extant relatives with which to compare the fossil remains. For many higher teleost fishes, these osteological data do not exist. For example, †Parachanna fayumensis, from Eocene and Oligocene deposits of Egypt, was placed in the Recent snakehead genus Parachanna, but in the absence

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

    NASA Astrophysics Data System (ADS)

    Davis, Margaret Bryan; Botkin, Daniel B.

    1985-05-01

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

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

    PubMed

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

    2011-08-16

    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

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

    PubMed Central

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

    2011-01-01

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

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

    PubMed Central

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

    1999-01-01

    We have developed a model based on the analyses of modern and Pleistocene eggshells and mammalian bones which can be used to understand the preservation of amino acids and other important biomolecules such as DNA in fossil specimens. The model is based on the following series of diagenetic reactions and processes involving amino acids: the hydrolysis of proteins and the subsequent loss of hydrolysis products from the fossil matrix with increasing geologic age; the racemization of amino acids which produces totally racemized amino acids in 10(5)-10(6) years in most environments on the Earth; the introduction of contaminants into the fossil that lowers the enantiomeric (D:L) ratios produced via racemization; and the condensation reactions between amino acids, as well as other compounds with primary amino groups, and sugars which yield humic acid-like polymers. This model was used to evaluate whether useful amino acid and DNA sequence information is preserved in a variety of human, amber-entombed insect and dinosaur specimens. Most skeletal remains of evolutionary interest with respect to the origin of modern humans are unlikely to preserve useful biomolecular information although those from high latitude sites may be an exception. Amber-entombed insects contain well-preserved unracemized amino acids, apparently because of the anhydrous nature of the amber matrix, and thus may contain DNA fragments which have retained meaningful genetic information. Dinosaur specimens contain mainly exogenous amino acids, although traces of endogenous amino acids may be present in some cases. Future ancient biomolecule research which takes advantage of new methologies involving, for example, humic acid cleaving reagents and microchip-based DNA-protein detection and sequencing, along with investigations of very slow biomolecule diagenetic reactions such as the racemization of isoleucine at the beta-carbon, will lead to further enhancements of our understanding of biomolecule preservation in the fossil record. PMID:10091249

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

    PubMed

    Hipsley, Christy A; Müller, Johannes

    2014-03-01

    Rhineurid amphisbaenians are represented by a rich Cenozoic fossil record in North America, but today conisist of a single living species restricted to the Florida Peninsula. Such relict endemism may be the result of phylogenetic niche conservatism (PNC), the retention of ancestral traits preventing expansion into new environments. Most tests of PNC derive ancestral niche preferences from species' extant ecologies, while ignoring valuable paleontological information. To test if PNC contributes to the restricted distribution of modern Rhineura floridana, we compare the species' current environmental preferences (temperature, precipitation and soil) to paleoenvironmental data from the rhineurid fossil record. We find no evidence of PNC in modern R. floridana, as it also occurred in Florida during drier glacial periods. Ancient rhineurids also exhibit tolerance to changing climates, having undergone a shift from subtropical-humid to semi-arid savanna conditions during the Eocene-Oligocene transition. However, rhineurids nearly disappear from North America after the middle Miocene, potentially due to the onset of prolonged freezing temperatures following the mid-Miocene Climatic Optimum. This physiological limit of environmental tolerances could be interpreted as PNC for the entire family, but also characterizes much of Amphisbaenia, emphasizing the relevance of the temporal as well as phylogenetic scale at which PNC is investigated. PMID:24482295

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

    PubMed Central

    Kidwell, Susan M.

    2015-01-01

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

  8. Changes to the Fossil Record of Insects through Fifteen Years of Discovery

    PubMed Central

    Nicholson, David B.; Mayhew, Peter J.; Ross, Andrew J.

    2015-01-01

    The first and last occurrences of hexapod families in the fossil record are compiled from publications up to end-2009. The major features of these data are compared with those of previous datasets (1993 and 1994). About a third of families (>400) are new to the fossil record since 1994, over half of the earlier, existing families have experienced changes in their known stratigraphic range and only about ten percent have unchanged ranges. Despite these significant additions to knowledge, the broad pattern of described richness through time remains similar, with described richness increasing steadily through geological history and a shift in dominant taxa, from Palaeoptera and Polyneoptera to Paraneoptera and Holometabola, after the Palaeozoic. However, after detrending, described richness is not well correlated with the earlier datasets, indicating significant changes in shorter-term patterns. There is reduced Palaeozoic richness, peaking at a different time, and a less pronounced Permian decline. A pronounced Triassic peak and decline is shown, and the plateau from the mid Early Cretaceous to the end of the period remains, albeit at substantially higher richness compared to earlier datasets. Origination and extinction rates are broadly similar to before, with a broad decline in both through time but episodic peaks, including end-Permian turnover. Origination more consistently exceeds extinction compared to previous datasets and exceptions are mainly in the Palaeozoic. These changes suggest that some inferences about causal mechanisms in insect macroevolution are likely to differ as well. PMID:26176667

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

    PubMed

    Kidwell, Susan M

    2015-04-21

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

  10. Changes to the Fossil Record of Insects through Fifteen Years of Discovery.

    PubMed

    Nicholson, David B; Mayhew, Peter J; Ross, Andrew J

    2015-01-01

    The first and last occurrences of hexapod families in the fossil record are compiled from publications up to end-2009. The major features of these data are compared with those of previous datasets (1993 and 1994). About a third of families (>400) are new to the fossil record since 1994, over half of the earlier, existing families have experienced changes in their known stratigraphic range and only about ten percent have unchanged ranges. Despite these significant additions to knowledge, the broad pattern of described richness through time remains similar, with described richness increasing steadily through geological history and a shift in dominant taxa, from Palaeoptera and Polyneoptera to Paraneoptera and Holometabola, after the Palaeozoic. However, after detrending, described richness is not well correlated with the earlier datasets, indicating significant changes in shorter-term patterns. There is reduced Palaeozoic richness, peaking at a different time, and a less pronounced Permian decline. A pronounced Triassic peak and decline is shown, and the plateau from the mid Early Cretaceous to the end of the period remains, albeit at substantially higher richness compared to earlier datasets. Origination and extinction rates are broadly similar to before, with a broad decline in both through time but episodic peaks, including end-Permian turnover. Origination more consistently exceeds extinction compared to previous datasets and exceptions are mainly in the Palaeozoic. These changes suggest that some inferences about causal mechanisms in insect macroevolution are likely to differ as well. PMID:26176667

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

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

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

  12. 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.

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

    PubMed

    Retallack, G J

    2001-05-17

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

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

    PubMed

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

    2012-06-01

    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

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

    PubMed Central

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

    2012-01-01

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

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

    PubMed

    Wilf, P

    2008-01-01

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

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

    PubMed

    Yamada, Toshihiro; Yamada, Mariko; Tsukagoshi, Minoru

    2014-03-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

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

    PubMed

    Peterson, Kevin J; Butterfield, Nicholas J

    2005-07-01

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

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

    PubMed Central

    Peterson, Kevin J.; Butterfield, Nicholas J.

    2005-01-01

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

  1. The taphonomy of unmineralised Palaeozoic fossils preserved as siliciclastic moulds and casts, and their utility in assessing the interaction between environmental change and the fossil record

    NASA Astrophysics Data System (ADS)

    MacGabhann, Breandán; Schiffbauer, James; Hagadorn, James; Van Roy, Peter; Lynch, Edward; Morrsion, Liam; Murray, John

    2015-04-01

    The enhanced preservation potential of biomineralised tissues in fossil organisms is a key factor in their utility in the investigation of palaeoenvironmental change on fossil ecosystems. By contrast, the considerably lower preservation potential of entirely unmineralised organisms severely reduces the utility of their temporal and spatial distribution in such analyses. However, understanding the taphonomic processes which lead to the preservation of such soft-bodied fossils may be an under-appreciated source of information, particularly in the case of specimens preserved as moulds and casts in coarser siliciclastic sediments. This information potential is well demonstrated by fossil eldonids, a Cambrian to Devonian clade of unmineralised asymmetrical discoidal basal or stem deuterostomes, with an apparently conservative biology and no clear palaeoenvironmental or biogeographical controls on their distribution. We investigated the taphonomic processes involved in the preservation of fossil eldonids as moulds and casts on bedding surfaces and within event beds from sandstones of the Ordovician Tafilalt lagerstätte in south-eastern Morocco, and from siltstones of the Devonian West Falls Group of New York, USA. Laser Raman microspectroscopy, SEM BSE imaging and EDS elemental mapping of fossil specimens reveals that moulded biological surfaces are coated by a fossil surface veneer primarily consisting of mixed iron oxides and oxyhydroxides (including pseudomorphs after pyrite), and aluminosilicate clay minerals. Moreover, comparison to fossil eldonids preserved as carbonaceous compressions in the Burgess Shale reveals that the biological structures preserved in the Tafilalt and New York specimens - the dorsal surface and a coiled sac containing the digestive tract - represent only specific portions of the anatomy of the complete animal. We suggest that the preserved remains were the only parts of these eldonid organisms composed primarily of complex organic biopolymers, and that these tissues were preferentially fossilised by the formation of an early diagenic mould directly on the organic surfaces. Excess divalent iron ions, produced during decay of more labile tissues by means of bacterial iron reduction, would have adsorbed to anionic functional groups in the biopolymeric tissues. This would have provided a ready substrate for the formation and growth of such an early diagenic mineralised mould, including aluminosilicate minerals produced via reaction with seawater silica and metal ions, and iron sulphide minerals produced via reaction with hydrogen sulphide and free sulphur produced from seawater sulphate through bacterial sulphate reduction associated with further decay. Subsequent weathering would have oxidised such iron sulphides to oxides and oxyhydroxides. This taphonomic model supports the lack of utility of the eldonid palaeobiological record in analysing environmental influence on biological communities, due to the lack of preservation of key anatomical components. However, it also suggests that the very occurrence of fossils preserved in this style is dependent on extrinsic palaeoenvironmental factors - including pH, Eh, and the concentration of other ions in the contemporaneous seawater. Analyses of the distribution of fossils preserved in this style may therefore provide information on ambient conditions which may have affected the distribution of contemporaneous mineralised fossils, potentially allowing a more complete analysis of the effects of palaeoenvironmental change on fossil ecosystems.

  2. Changes in ENSO and Interdecadal Climate Variability in the Holocene Recorded in Fossil Corals

    NASA Astrophysics Data System (ADS)

    Tudhope, S.; Battisti, D.; Brown, J.; Burr, G.; Chilcott, C.; Collins, M.; Ellam, R.; Pandolfi, J.; Shimmield, G.; Shimmield, T.; Timmermann, A.

    2005-12-01

    Annually-banded corals living on the north coast of Papua New Guinea record changes in SST and salinity in the stable isotopic and trace element composition of their skeletons. Previously, we exploited these attributes and the presence of abundant fossil corals to investigate changes in ENSO over the last glacial-interglacial cycle. Here we focus on more detailed analysis of the Holocene interval based on a total of about 400 years of new, near-monthly-resolved, isotopic and trace element coral data from the interval from about 9,500 to 6,500 years BP. Our findings include: INTERANNUAL ENSO VARIABILITY: The amplitude of ENSO-related variability in skeletal ?18O is reduced to about 30% of Modern and late Holocene values in corals from 9.1-9.4 ka through to 6.5 ka. These results support previous inferences of weakened ENSO variability in the early-mid-Holocene. MEAN CONDITIONS: Based on a combination of trace element and ?18O analysis, our initial results suggest that SST was similar to present at around 9.1-9.4 ka. Mean salinity, however, appears to have been higher in the earlier period, similar to what is experienced today during El Niño events. These observations contrast with some previous suggestions of general La Niña-like conditions in the early Holocene based on eastern equatorial Pacific data. INTERDECADAL VARIABILITY: Interdecadal variability in skeletal ?18O of modern corals from the region appears to record salinity changes associated with the Pacific Decadal Oscillation. In our fossil corals, we find that the amplitude of this interdecadal variability is reduced in the early-mid-Holocene, when interannual ENSO-related variability is also weak. These observations lend some support to the suggestion that much of the modern-day PDO variability is related to ENSO, and, therefore, is not a separate mode of climate variability.

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

    PubMed

    Huntley, John Warren; Kowalewski, Michal

    2007-09-18

    The importance of ecological interactions in driving the evolution of animals has been the focus of intense debate among paleontologists, evolutionary biologists, and macroecologists. To test whether the intensity of such interactions covaries with the secular evolutionary trend in global biodiversity, we compiled a species-level database of predation intensity, as measured by the frequency of common predation traces (drillings and repair scars ranging in age from Ediacaran to Holocene). The results indicate that the frequency of predation traces increased notably by the Ordovician, and not in the mid-Paleozoic as suggested by multiple previous studies. Importantly, these estimates of predation intensity and global diversity of marine metazoans correlate throughout the Phanerozoic fossil record regardless of corrections and methods applied. This concordance may represent (i) an ecological signal: long-term coupling of diversity and predation; (ii) a diversity-driven diffusion of predatory behaviors: an increased probability of more complex predatory strategies to appear at higher diversity levels; or (iii) a spurious concordance in signal capture: an artifact where rare species and less-frequent (e.g., trace-producing) predatory behaviors are both more detectable at times when sampling improves. The coupling of predation and diversity records suggests that macroevolutionary and macroecological patterns share common causative mechanisms that may reflect either historical processes or sampling artifacts. PMID:17855566

  4. The Ediacaran emergence of bilaterians: congruence between the genetic and the geological fossil records.

    PubMed

    Peterson, Kevin J; Cotton, James A; Gehling, James G; Pisani, Davide

    2008-04-27

    Unravelling the timing of the metazoan radiation is crucial for elucidating the macroevolutionary processes associated with the Cambrian explosion. Because estimates of metazoan divergence times derived from molecular clocks range from quite shallow (Ediacaran) to very deep (Mesoproterozoic), it has been difficult to ascertain whether there is concordance or quite dramatic discordance between the genetic and geological fossil records. Here, we show using a range of molecular clock methods that the major pulse of metazoan divergence times was during the Ediacaran, which is consistent with a synoptic reading of the Ediacaran macrobiota. These estimates are robust to changes in priors, and are returned with or without the inclusion of a palaeontologically derived maximal calibration point. Therefore, the two historical records of life both suggest that although the cradle of Metazoa lies in the Cryogenian, and despite the explosion of ecology that occurs in the Cambrian, it is the emergence of bilaterian taxa in the Ediacaran that sets the tempo and mode of macroevolution for the remainder of geological time. PMID:18192191

  5. Atlantic Multidecadal Oscillation recorded in fossil corals during the last Interglacial

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    The Atlantic Multidecadal Oscillation (AMO) is a mode of sea surface temperature variability occurring in the North Atlantic Ocean, whose warm phase correlates strongly with Atlantic hurricane activity. While support for this mode originates in historical observations and models, controversy exists with regard to the attribution of sea surface temperature change to natural or anthropogenic forcing. Previously, we showed that long-lived colonies of the massive Caribbean coral Siderastrea siderea (Ellis & Solander, 1786) on the Yucatan Peninsula capture AMO-like variability in their annual growth bands (Vásquez-Bedoya et al., 2012) allowing us to extend the record of Atlantic multidecadal variability back to 1775 AD. Here we report an analysis of skeletal growth bands of a fossil coral of the same species, dated by U-series (122.24±0.19 kyr) to the Last Interglacial (LIG). MultiTaper spectral analysis of the LIG coral record reveals significant concentrations of power (99% confidence level) at intervals centered at 45-67 and 50-67 years respectively, consistent with the AMO spectrum, which is centered in intervals of 60-70 years. Thus our analysis provides the first evidence of AMO mode during the LIG and supports the hypotheses of a persistent, naturally-forced multidecadal mode of SST variability in the North Atlantic.

  6. 14.8 Marine Sediment Records of African Climate Change: Progress and Puzzles

    E-print Network

    deMenocal, Peter B.

    witnessed some of the most sweeping changes in terrestrial climate and vegetation during the Cenozoic14.8 Marine Sediment Records of African Climate Change: Progress and Puzzles PB deMenocal, Lamont. 14.8.1 Introduction 99 14.8.2 Marine Sediments as Recorders of Terrestrial Climate Change 100 14

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

    Microsoft Academic Search

    Christina L. Belanger

    2012-01-01

    Modern climate change has a strong potential to shift earth systems and biological communities into novel states that have no present-day analog, leaving ecologists with no observational basis to predict the likely biotic effects. Fossil records contain long time-series of past environmental changes outside the range of modern observation, which are vital for predicting future ecological responses, and are capable

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

    E-print Network

    Benton, Michael

    Finding the tree of life: matching phylogenetic trees to the fossil record through the 20th century.benton@bristol.ac.uk) Phylogenies, or evolutionary trees, are fundamental to biology. Systematists have laboured since the time of Darwin to discover the tree of life. Recent developments in systematics, such as cladistics and mol

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

    Microsoft Academic Search

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

    2009-01-01

    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

  10. Using ghost lineages to identify diversification events in the fossil record.

    PubMed

    Cavin, Lionel; Forey, Peter L

    2007-04-22

    Observed rises in taxic diversity could reflect bias of the fossil record or a genuine diversification. Here we outline a new method that attempts to differentiate between these two possible explanations. The method is based on the calculations of average ghost lineage duration through successive intervals of time. Biases due to variation in preservational conditions affect taxa independently from their position in the tree of life. A genuine radiation event will affect some parts of the tree of life more than others. During periods of rapid diversification, there will be a high proportion of new taxa showing short ghost lineages and therefore the average ghost lineage duration will drop as diversity rises, allowing us to distinguish such events from preservational bias during which ghost lineage duration remains unchanged. We test the method on Aptian-Maastrichtian (Cretaceous) ray-finned fish diversity. The result shows that a peak of diversity in the Cenomanian is associated with a drop in average ghost lineage duration, indicating that a genuine biological radiation occurred at that time. PMID:17284405

  11. 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.

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

    Microsoft Academic Search

    Michael G. Newbrey; Allan C. Ashworth

    2004-01-01

    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

  13. Fossil spiders.

    PubMed

    Selden, Paul A; Penney, David

    2010-02-01

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

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

    PubMed Central

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

    2011-01-01

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

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

    SciTech Connect

    Nicholson, S.E.

    1997-11-01

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

  16. Consistency of Age Reporting on Death Certificates and Social Security Records among Elderly African Americans

    Microsoft Academic Search

    Irma T. Elo; Samuel H. Preston; Ira Rosenwaike; Mark Hill; Timothy P. Cheney

    1996-01-01

    This paper investigates the quality of age data among African Americans in two sets of government documents extensively used to study health and mortality among the elderly in the United States, namely vital statistics and Medicare\\/Social Security data. The analyses reveal significant inconsistencies in age reporting in the two sources. A linkage of records to a third data source, the

  17. Nineteenth Century US African-American and White Female Statures: Insight from US Prison Records

    Microsoft Academic Search

    Scott A. Carson

    2010-01-01

    Using a new source of 19th century state prison records, this study contrasts the biological living conditions of comparable US African-American and white female statures during economic development. Black and white female statures varied regionally, and white Southeastern and black Southwestern females reached the tallest statures. White females were consistently taller than black females. Black and white female statures also

  18. Modelling an alkenone-like proxy record in the NW African upwelling

    Microsoft Academic Search

    X. Giraud

    2006-01-01

    A regional biogeochemical model is applied to the NW African coastal upwelling between 19° N and 27° N to investigate how a water temperature proxy, alkenones, are produced at the sea surface and recorded in the slope sediments. The biogeochemical model has two phytoplankton groups: an alkenone producer group, considered to be coccolithophores, and a group comprising other phytoplankton. The

  19. Eocene to Miocene Southern Ocean Circulation: Neodymium Records from Fossil Fish Teeth

    NASA Astrophysics Data System (ADS)

    Scher, H. D.; Martin, E. E.

    2003-04-01

    The Eocene to Miocene was a period of dramatic changes to ocean circulation, which have been linked to major shifts in global climate. Evolution of the Southern Ocean had a powerful influence over patterns of ocean circulation during this time. Pre-Miocene seawater Nd isotope records, proxies for water mass used to reconstruct paleocean circulation, are poorly represented in the Southern Ocean. Here we supplement the small, but growing, Nd isotope database with two long-term Nd records from fossil fish teeth in ODP sites 689 (Maud Rise, 2080 m) and 1090 (Aghulas Ridge, 3702 m), both located in the Southern Ocean. ?{Nd} values from site 689 range from -8 at 35 Ma to -9.1 at 20 Ma. The intermediate water mass at this site was at least 1 ?{Nd} lower than the deep water mass at site 1090 throughout the late Eocene to early Miocene with the exception of a brief interval at ˜26 Ma, when increasing values at site 689 overlap with decreasing values at site 1090. Site 1090 ?{Nd} values are dominated by a decreasing trend during the Oligocene when ?{Nd} values of -6.5 at 28.5 Ma decrease to -8.5 by 22 Ma. This long-term trend is punctuated by a rapid negative oscillation of 2 ?{Nd} at ˜26 Ma and a rapid positive oscillation of 1 ?{Nd} at ˜23 Ma. ?{Nd} values at site 1090 then increase by 1 ?{Nd} during the early to mid-Miocene. Together sites 689 and 1090 illustrate an ?{Nd} depth profile that becomes more radiogenic with depth, which is opposite to the present-day Atlantic, Indian, and Pacific oceans. This gradient persists through the late Eocene to Miocene except at ˜26 Ma when the difference in ?{Nd} between the two sites diminishes to .4, suggesting a water mass between -8.1 and -8.5 ?{Nd} at both sites. Tethyan waters have been characterized as having ?{Nd} in this range during the Oligocene/Miocene. A brief pulse of Warm Saline Bottom Water emanating from the Tethyan region may be responsible for rapid oscillations in Southern Ocean Nd records. The coincidence of these oscillations with the Late Oligocene Warming event (˜26 Ma) recognized in global ?18O records (including site 689) supports this interpretation. The only known potential source of radiogenic water necessary to bring ?{Nd} values at site 1090 as high as -6.5 were Pacific source waters which ranged from -6.5 to -4 in the Oligocene/Miocene. We believe that site 1090 Nd isotopes provide evidence for transport of Pacific seawater through the Drake Passage by at least 28.5 Ma. Nonradiogenic ?{Nd} values at site 689 are consistent with the presence of an intermediate to deep water mass sourced near Antarctica.

  20. Trace Metals as Biomarkers for Eumelanin Pigment in the Fossil Record

    Microsoft Academic Search

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

    2011-01-01

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

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

    PubMed Central

    HYŽNÝ, MATÚŠ; GAŠPARI?, ROK

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

    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.

  3. Two Years of Plankton Tows in a Seasonal Upwelling Region: Foraminiferal Abundances and Implications for the Fossil Record

    NASA Astrophysics Data System (ADS)

    Davis, C. V.; Hill, T. M.; Jahncke, J.

    2014-12-01

    Planktic foraminifera have a long history of use as paleoceaographic proxies due to their environmental sensitivity, cosmopolitan distribution and extensive fossil record. The seasonal, spatial and water mass affinities of foraminifera species have implications for the interpretation of fossil assemblages and the interpretation of shell geochemistry. Two years (2012-2014) of shallow (<200 m) plankton tows, taken along the continental shelf inside the California Current system, offer new insights into the spatial and seasonal dynamics of planktic foraminifera in an upwelling regime. Tows along with intensive hydrologic monitoring by CTD casts and discrete bottle sampling (temperature, salinity, oxygen, thermocline depth, carbonate saturation state) have spanned two complete seasonal upwelling-relaxation cycles. We present the results from these tows as well as preliminary models linking environmental drivers and foraminifera assemblages in this highly dynamic environment. Species abundances appear to be highly seasonal, in keeping with water column structure, with a seasonal upwelling to relaxation trade off between the non-spinose foraminifers Neogloboquadrina pachyderma and Neogloboquadrina incompta. We focus on the implications of species seasonality and hydrologic affinities to the interpretation of the fossil record in upwelling regions.

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

    SciTech Connect

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

    1995-12-31

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

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

    PubMed

    Cloutier, R

    2010-06-01

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

  6. Authigenic sericite record of a fossil geothermal system: the Offenburg trough, central Black Forest, Germany

    Microsoft Academic Search

    Olaf Brockamp; Norbert Clauer; Michael Zuther

    2003-01-01

    A fossil geothermal area is hosted by the Carboniferous, Permian and Bunter sandstones of the Offenburg intramontane trough in the central Black Forest. The hydrothermal alteration is identified on the basis of newly formed sericites, which appear as pseudomorphs after feldspar and filling of pore spaces. According to K–Ar dating of sericite, serititization occurred about 145 Ma ago (Jurassic). On the

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

    E-print Network

    Benton, Michael

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

  8. The Olorgesailie Drilling Project (ODP): a high-resolution drill core record from a hominin site in the East African Rift Valley

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    PubMed

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

    2012-01-01

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

  10. The bubble fossil record: insight into boiling nucleation using nanofluid pool-boiling

    Microsoft Academic Search

    David Huitink; Elvis Efren Dominguez Ontiveros; Yassin Hassan

    2011-01-01

    Subcooled pool boiling of Al2O3\\/water nanofluid (0.1 vol%) was investigated. Scanning electron microscopy and energy dispersive X-ray spectroscopy were used\\u000a to observe surface features of the wire heater where nanoparticles had deposited. A layer of aggregated alumina particles\\u000a collected on the heated surface, where evidence of fluid shear associated with bubble nucleation and departure was “fossilized”\\u000a in the fluidized nano-porous

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

    Microsoft Academic Search

    Jan A. van Dam

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

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

    PubMed

    Belanger, Christina L

    2012-01-01

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

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

    PubMed

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

    2015-04-01

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

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

    PubMed Central

    Boyce, C. Kevin; Zwieniecki, Maciej A.

    2012-01-01

    Declining CO2 over the Cretaceous has been suggested as an evolutionary driver of the high leaf vein densities (7–28 mm mm?2) that are unique to the angiosperms throughout all of Earth history. Photosynthetic modeling indicated the link between high vein density and productivity documented in the modern low-CO2 regime would be lost as CO2 concentrations increased but also implied that plants with very low vein densities (less than 3 mm mm?2) should experience substantial disadvantages with high CO2. Thus, the hypothesized relationship between CO2 and plant evolution can be tested through analysis of the concurrent histories of alternative lineages, because an extrinsic driver like atmospheric CO2 should affect all plants and not just the flowering plants. No such relationship is seen. Regardless of CO2 concentrations, low vein densities are equally common among nonangiosperms throughout history and common enough to include forest canopies and not just obligate shade species that will always be of limited productivity. Modeling results can be reconciled with the fossil record if maximum assimilation rates of nonflowering plants are capped well below those of flowering plants, capturing biochemical and physiological differences that would be consistent with extant plants but previously unrecognized in the fossil record. Although previous photosynthetic modeling suggested that productivity would double or triple with each Phanerozoic transition from low to high CO2, productivity changes are likely to have been limited before a substantial increase accompanying the evolution of flowering plants. PMID:22689947

  15. Revisiting the origin and diversification of vascular plants through a comprehensive Bayesian analysis of the fossil record.

    PubMed

    Silvestro, Daniele; Cascales-Miñana, Borja; Bacon, Christine D; Antonelli, Alexandre

    2015-07-01

    Plants have a long evolutionary history, during which mass extinction events dramatically affected Earth's ecosystems and its biodiversity. The fossil record can shed light on the diversification dynamics of plant life and reveal how changes in the origination-extinction balance have contributed to shaping the current flora. We use a novel Bayesian approach to estimate origination and extinction rates in plants throughout their history. We focus on the effect of the 'Big Five' mass extinctions and on estimating the timing of origin of vascular plants, seed plants and angiosperms. Our analyses show that plant diversification is characterized by several shifts in origination and extinction rates, often matching the most important geological boundaries. The estimated origin of major plant clades predates the oldest macrofossils when considering the uncertainties associated with the fossil record and the preservation process. Our findings show that the commonly recognized mass extinctions have affected each plant group differently and that phases of high extinction often coincided with major floral turnovers. For instance, after the Cretaceous-Paleogene boundary we infer negligible shifts in diversification of nonflowering seed plants, but find significantly decreased extinction in spore-bearing plants and increased origination rates in angiosperms, contributing to their current ecological and evolutionary dominance. PMID:25619401

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

    NASA Astrophysics Data System (ADS)

    Mente?, Merve; Özkar Öngen, ?zver

    2015-04-01

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

  17. Vegetation response to climate change in Alaska: examples from the fossil record

    USGS Publications Warehouse

    Ager, Thomas A.

    2007-01-01

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

  18. The baryon halo of the milky way: A fossil record of its formation

    PubMed

    Bland-Hawthorn; Freeman

    2000-01-01

    Astronomers believe that the baryon (stellar) halo of the Milky Way retains a fossil imprint of how it was formed. But a vast literature shows that the struggle to interpret the observations within a consistent framework continues. The evidence indicates that the halo has built up through a process of accretion and merging over billions of years, which is still going on at a low level. Future satellite missions to derive three-dimensional space motions and heavy element (metal) abundances for a billion stars will disentangle the existing web and elucidate how galaxies like our own came into existence. PMID:10615053

  19. The bubble fossil record: insight into boiling nucleation using nanofluid pool-boiling

    NASA Astrophysics Data System (ADS)

    Huitink, David; Ontiveros, Elvis Efren Dominguez; Hassan, Yassin

    2012-02-01

    Subcooled pool boiling of Al2O3/water nanofluid (0.1 vol%) was investigated. Scanning electron microscopy and energy dispersive X-ray spectroscopy were used to observe surface features of the wire heater where nanoparticles had deposited. A layer of aggregated alumina particles collected on the heated surface, where evidence of fluid shear associated with bubble nucleation and departure was "fossilized" in the fluidized nano-porous surface coating. These structures contain evidence of the fluid forces present in the microlayer prior to departure and provide a unique understanding of boiling phenomena. A unique mode of heat transfer was identified in nanofluid pool boiling.

  20. Co-occurrence of pliopithecoid and hominoid primates in the fossil record: An ecometric analysis.

    PubMed

    Sukselainen, Leena; Fortelius, Mikael; Harrison, Terry

    2015-07-01

    Both pliopithecoid and hominoid primates were widely distributed throughout Eurasia during the Miocene but are known to have coexisted at only a few localities. It has been speculated that their different habitat preferences permitted only minimal overlap under special environmental conditions. Here we study the context for pliopithecoid and hominoid co-occurrence by assessing taxonomically-based palaeoecological diversity of associated fossil mammals and by direct ecometric analysis based on hypsodonty of mammalian herbivores. Our results show that pliopithecoids persistently inhabited more humid environments compared to the other primate groups studied, suggesting an inability to adapt to changing environmental conditions. The opportunity for hominoids and pliopithecoids to co-occur appears to have been restricted by niche conservatism in the latter group. Our study also indicates that direct ecometric analysis gives a better separation of the ecological preferences of these primate clades than do analyses of taxonomically-based community structure. PMID:25980796

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

    SciTech Connect

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

    1995-10-01

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

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

    PubMed Central

    Carrillo, Juan D.; Forasiepi, Analía; Jaramillo, Carlos; Sánchez-Villagra, Marcelo R.

    2015-01-01

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

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

    E-print Network

    Bruce S. Lieberman; Adrian L. Melott

    2007-08-22

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

  4. When did Carcharocles megalodon become extinct? A new analysis of the fossil record.

    PubMed

    Pimiento, Catalina; Clements, Christopher F

    2014-01-01

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

  5. Modelling an alkenone-like proxy record in the NW African upwelling

    NASA Astrophysics Data System (ADS)

    Giraud, X.

    2006-01-01

    A regional biogeochemical model is applied to the NW African coastal upwelling between 19° N and 27° N to investigate how a water temperature proxy is produced at the sea surface and recorded in the slope sediments. The biological model has two phytoplankton groups, to distinguish an alkenone producer group (considered as coccolithophores) from other phytoplankton. The Regional Ocean Modelling System (ROMS) is used to simulate the ocean circulation, and takes advantage of the Adaptive Grid Refinement in Fortran (AGRIF) package to set up an embedded griding system. The results show that the alkenone-like temperature records in the sediments are between 1.1 and 2.1°C colder compared to the annual mean SSTs. Despite the seasonality of the coccolithophorid production, this temperature difference is not mainly due to a seasonal bias, nor to the lateral advection of phytoplankton and phytodetritus from the cold water domain to most offshore locations, but to the production depth of the coccolithophores. If core-top sediment alkenone-derived temperatures are effectively recording the annual mean SSTs, the quantitative alkenone production in the water column must be inhomogeneous among the coccolithophore population and depend on physiological factors (growth rate, nutrient stress).

  6. Modelling an alkenone-like proxy record in the NW African upwelling

    NASA Astrophysics Data System (ADS)

    Giraud, X.

    2006-06-01

    A regional biogeochemical model is applied to the NW African coastal upwelling between 19° N and 27° N to investigate how a water temperature proxy, alkenones, are produced at the sea surface and recorded in the slope sediments. The biogeochemical model has two phytoplankton groups: an alkenone producer group, considered to be coccolithophores, and a group comprising other phytoplankton. The Regional Ocean Modelling System (ROMS) is used to simulate the ocean circulation and takes advantage of the Adaptive Grid Refinement in Fortran (AGRIF) package to set up an embedded griding system. In the simulations the alkenone temperature records in the sediments are between 1.1 and 2.3°C colder than the annual mean SSTs. Despite the seasonality of the coccolithophore production, this temperature difference is not mainly due to a seasonal bias, nor to the lateral advection of phytoplankton and phytodetritus seaward from the cold near-shore waters, but to the production depth of the coccolithophores. If coretop alkenone temperatures are effectively recording the annual mean SSTs, the amount of alkenone produced must vary among the coccolithophores in the water column and depend on physiological factors (e.g. growth rate, nutrient stress).

  7. Southern East African climate recorded in laminated sediments of Lake Malawi

    NASA Astrophysics Data System (ADS)

    Brown, E. T.; Katsev, S.

    2012-12-01

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

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

    USGS Publications Warehouse

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

    1996-01-01

    Recent trails formed by soldier fly larvae (Diptera: Stratiomyidae) were examined in a shallow pond in the floodplain of a braided river in Jujuy Province, northwestern Argentina. Collected specimens were identified as Stratiomys convexa van der Wulp. Simple, irregularly meandering trails were produced across the surface of a muddy-silty substrate. Since soldier fly larvae extend their caudal respiratory tube to the water-air interface, they are restricted to extremely shallow water. The presence of benthic algal remains within the mouthparts of the larvae suggests a feeding habit of algal grazing. If preserved, these trails would be included in the ichnogenus Helminthopsis, a common element in ancient freshwater ichnofaunas. Helminthopsis preserved in pond and lacustrine margin deposits younger than Late Jurassic is regarded as one possible trace fossil analogue of the trails documented herein. Additionally, it is suggested that larvae of many aquatic Diptera with similar ecologic restrictions are potential tracemakers of Helminthopsis and other simple trails in these environments, particularly in post-Paleozoic deposits. Studies of modern shallow aquatic habitats and reexamination of the ichnologic record stress the importance of fly larvae as tracemakers in lake margin and pond ecosystems. Ecologic requirements of soldier fly larvae make them inappropriate analogues of Helminthopsis tracemakers in deeper water, lacustrine settings. ?? 1996 OPA (Overseas Publishers Association) Amsterdam B.V. Published in The Netherlands by Harwood Academic Publishers GmbH.

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

    NASA Astrophysics Data System (ADS)

    Stegner, Mary Allison

    2015-05-01

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

  10. Paleovegetation changes recorded by n-alkyl lipids bound in macromolecules of plant fossils and kerogens from the Cretaceous sediments in Japan

    NASA Astrophysics Data System (ADS)

    Miyata, Y.; Sawada, K.; Nakamura, H.; Takashima, R.; Takahashi, M.

    2014-12-01

    Resistant macromolecules composing living plant tissues tend to be preserved through degradation and diagenesis, hence constituate major parts of sedimentary plant-derived organic matter (kerogen), and their monomer compositions vary widely among different plant taxa, organs and growth stages. Thus, analysis of such macromolecule may serve as new technique for paleobotanical evaluation distinctive from classical paleobotnical studies depends on morphological preservation of fossils. In the present study, we analyzed plant fossils and kerogens in sediments from the Cretaceous strata in Japan to examine chemotaxonomic characteristics of fossil macromolecules and to reconstruct paleovegetation change by kerogen analysis. The kerogens were separated from the powdered sediments of Cretaceous Yezo Group, Hokkaido, Japan. All kerogens have been confirmed to be mostly originated from land plant tissues by microscopic observation. Mummified angiosperm and gymnosperm fossil leaves were separated from carbonaceous sandstone of the Cretaceous Ashizawa Formation, Futaba Group. The kerogens and plant fossils were extracted with methanol and dichloromethane, and were subsequently refluxed under 110°C to remove free compounds completely. The residues are hydrolyzed by KOH/methanol under 110°C. These released compounds are analyzed by GC-MS. As main hydrolyzed products (ester-bound molecular units) from all kerogens, C10-C28 n-alkanoic acids and C10-C30 n-alkanols were detected. Recent studies on the hydrolysis products of plant tissues suggested the long chain (>C20) n-alkanols were predominantly abundant in deciduous broadleaved angiosperms. Correspondingly, the stratigraphic variation of the ratios of long chain (>C20) n-alkanols to fatty acids was concordant with the variation of angiosperm/gymnosperm ratios recorded by land plant-derived terpenoid biomarkers. In addition, we found that the long chain n-alkanols/fatty acids ratio in the angiosperm fossil leaf was significantly higher than that of conifer fossil leaf from Ashizawa coal bed. From these results, we propose that the proportions of long chain n-alkanols released from terrigenous kerogens are applicable for paleovegetation reconstruction.

  11. 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)

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

    2010-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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.

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

    PubMed Central

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

    2010-01-01

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

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

    SciTech Connect

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

    1992-11-01

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

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

    PubMed

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Beauvais, Anicet; Chardon, Dominique

    2013-04-01

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

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

    Microsoft Academic Search

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

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

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

    Microsoft Academic Search

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

    2001-01-01

    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

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

    Microsoft Academic Search

    Nicki J. Whitehouse; David Smith

    2010-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

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

    PubMed Central

    Srivastava, Gaurav; Mehrotra, Rakesh C.

    2013-01-01

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

  3. Fossil primates 1 Fossil primates

    E-print Network

    Delson, Eric

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

  4. Analysis of hospital records in four African countries, 1975-1990, with emphasis on infectious diseases.

    PubMed

    Petit, P L; van Ginneken, J K

    1995-08-01

    Detailed standardized annual reports are analysed for 17 rural hospitals in four African countries, with admission figures of 1.2 million patients (excluding deliveries) and more than 67,000 deaths over a period of 16 years. The countries involved are Zambia, Tanzania, Kenya and Ghana. Figures on admission, causes of death and clinical case fatality rates are presented per country and per 4-year calendar period for the most important infectious diseases. The number of admissions increased substantially in 3 of the 4 countries (50-77%) between 1976 and 1990, but admission rates (per 1,000 population per year) by much less (6-25%), indicating that a large part of the increase in the volume of services was due to population growth. The number of infectious disease admissions in Ghana, however, decreased by 12% and even more in terms of admission rates (by 42%). About 75% of all admissions in children below 15 years of age were due to infections and infection related diseases; for adults this figure was 31%. Malaria is the single most important infectious disease both in terms of admissions and as a cause of death; it has increased substantially in three of the four countries. Bacterial infections, in particular pneumonia, gastroenteritis, meningitis and tuberculosis, are also important diseases in terms of admissions and deaths. On the whole they have remained at more or less the same level in 1975-1990 in terms of both admissions and deaths. Immunizable diseases and measles, once important as causes of admissions and deaths, have declined in all countries. Case fatality rates vary substantially by type of disease. They are very high for tetanus (36.7-68.8%) and meningitis (14.7-43%), and low for malaria (0.6-4.6%). However, they vary considerably in the four countries included in the study and are usually lower in children than in adults. A need for detailed studies with good "standardized" hospital records is emphasized. Representative data are needed from all hospitals in a given catchment area, with defined diagnoses for diseases and details regarding age and sex. This kind of information is highly desirable for planning and operation of curative and preventive medical care in developing countries. PMID:7636917

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

    NASA Astrophysics Data System (ADS)

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

    2005-10-01

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

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

    Microsoft Academic Search

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

    2002-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

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

    PubMed Central

    Petrulevi?ius, Julián F.; Popov, Yuri A.

    2014-01-01

    Abstract A new genus and species of Discocephalini, Acanthocephalonotum martinsnetoi gen. n. et sp. n. is described from Río Pichileufú, middle Eocene of Patagonia, Argentina at palaeolatitude ~ 46°S. The new species is the first fossil representative of the Discocephalinae. This taxon is extant in equatorial to subtropical America, and some species reach warm temperate latitudes (Buenos Aires province). The new genus is distinguished from the other genera of Discocephalini by the combination of these characters: interocular width greater than head length; head massive and quadrangular with the anterior margin almost straight; juga touching each other; labrum thick and curved; triangular ante-ocular process extending beyond the eye; broad spine-like antero-lateral process of the pronotum; pronotum explanate and bean shaped; scutellum triangular with a circular tongue reaching the anterior side of abdominal segment 7; and wings well developed with membrane just surpassing end of abdomen. PMID:25061387

  9. 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)

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

    2011-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2002-11-01

    A reconstruction of the tectonic evolution of the northern African margin in Tunisia since the Late Permian combining paleostress, tectonic stratigraphic and sedimentary approaches allows the characterization of several major periods corresponding to consistent stress patterns. The extension lasting from the Late Permian to the Middle Triassic is contemporaneous of the rifting related to the break up of Pangea. During Liassic times, regional extensional tectonics originated the dislocation of the initial continental platform. In northern Tunisia, the evolution of the Liassic NE-SW rifting led during Dogger times to the North African passive continental margin, whereas in southern Tunisia, a N-S extension, associated with E-W trending subsiding basins, lasted from the Jurassic until the Early Cretaceous. After an Upper Aptian-Early Albian transpressional event, NE-SW to ENE-WSW trending extensions prevailed during Late Cretaceous in relationship with the general tectonic evolution of the northeastern African plate. The inversions started in the Late Maastrichtian-Paleocene in northern Tunisia, probably as a consequence of the Africa-Eurasia convergence. Two major NW-SE trending compressions occurred in the Late Eocene and in the Middle-Late Miocene alternating with extensional periods in the Eocene, Oligocene, Early-Middle Miocene and Pliocene. The latter compressional event led to the complete inversion of the basins of the northwestern African plate, originating the Maghrebide chain. Such a study, supported by a high density of paleostress data and including complementary structural and stratigraphic approaches, provides a reliable way of determining the regional tectonic evolution.

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

    NASA Astrophysics Data System (ADS)

    Whitehouse, Nicki J.; Smith, David

    2010-02-01

    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.

  12. Fossil mammals and paleoenvironments in the Omo-Turkana Basin.

    PubMed

    Bobe, René

    2011-01-01

    Although best known for its fossil hominins, the Omo-Turkana Basin of Kenya and Ethiopia is the source of one of the best records of vertebrate evolution from the Late Cenozoic of Africa. Located near the heart of the East African Rift Valley, the basin serves as an important frame of reference for the continent. The fossil record from this region plays a key role in our efforts to understand the environmental and ecological context of human evolution in Africa. The Omo-Turkana faunal data shed light on key questions of human evolution: What kinds of environments did early humans inhabit? How did these environments change over time? What is the relationship between faunal change in East Africa and broader patterns of climatic change? PMID:22170694

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

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Wierzchos, Jacek; Ascaso, Carmen

    2002-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  16. Fossil Fuels.

    ERIC Educational Resources Information Center

    Crank, Ron

    This instructional unit is one of 10 developed by students on various energy-related areas that deals specifically with fossil fuels. Some topics covered are historic facts, development of fuels, history of oil production, current and future trends of the oil industry, refining fossil fuels, and environmental problems. Material in each unit may…

  17. Fossil Fuels

    NSDL National Science Digital Library

    Iowa Public Television. Explore More Project

    2004-01-01

    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.

  18. The Nuclear Orbital Distribution in Galaxies as Fossil Record of Black Hole Formation from Integral-Field Spectroscopy

    E-print Network

    Michele Cappellari; Richard McDermid

    2005-10-14

    In the past decade, most effort in the study of supermassive black holes (BHs) has been devoted to measuring their masses. This lead to the finding of the tight M_BH-sigma relation, which indicates the existence of strong links between the formation of the BH and of their host spheroids. Many scenarios have been proposed to explain this relation, and all agree on the key role of BHs' growth and feedback in shaping their host galaxies. However the currently available observational constraints, essentially BH masses and galaxy photometry, are not sufficient to conclusively select among the alternatives. A crucial piece of information of the black hole formation is recorded in the orbital distribution of the stars, which can only be extracted from high-resolution integral-field (IF) stellar kinematics. The introduction of IF spectrographs with adaptive optics on large telescopes opens a new era in the study of BHs by finally allowing this key element to be uncovered. This information will be complementary to what will be provided by the LISA gravitational wave satellite, which can directly detect coalescing BHs. Here an example is presented for the recovery of the orbital distribution in the center of the giant elliptical galaxy M87, which has a well resolved BH sphere of influence, using SAURON IF kinematics.

  19. Fossil Evidence of Bipedalism

    NSDL National Science Digital Library

    2010-03-10

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

  20. An expansion of age constraints for microbial clades that lack a conventional fossil record using phylogenomic dating.

    PubMed

    Blank, Carrine E

    2011-10-01

    Most microbial taxa lack a conventional microfossil or biomarker record, and so we currently have little information regarding how old most microbial clades and their associated traits are. Building on the previously published oxygen age constraint, two new age constraints are proposed based on the ability of microbial clades to metabolize chitin and aromatic compounds derived from lignin. Using the archaeal domain of life as a test case, phylogenetic analyses, along with published metabolic and genetic data, showed that members of the Halobacteriales and Thermococcales are able to metabolize chitin. Ancestral state reconstruction combined with phylogenetic analysis of the genes underlying chitin degradation predicted that the ancestors of these two groups were also likely able to metabolize chitin or chitin-related compounds. These two clades were therefore assigned a maximum age of 1.0 Ga (when chitin likely first appeared). Similar analyses also predicted that the ancestor to the Sulfolobus solfataricus-Sulfolobus islandicus clade was able to metabolize phenol using catechol dioxygenase, so this clade was assigned a maximum age of 475 Ma. Inferred ages of archaeal clades using relaxed molecular clocks with the new age constraints were consistent with those inferred with the oxygen age constraints. This work expands our current toolkit to include Paleoproterozoic, Neoproterozoic, and Paleozoic age constraints, and should aid in our ability to phylogenetically reconstruct the antiquity of a wide array of microbial clades and their associated morphological and biogeochemical traits, spanning deep geologic time. Such hypotheses-although built upon evolutionary inferences-are fundamentally testable. PMID:22105429

  1. Restoring Fossil Creek

    NSDL National Science Digital Library

    Carri J. LeRoy

    2004-07-01

    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.

  2. Toward a Late Quaternary tephrostratigraphic framework for East African palaeoenvironmental records

    NASA Astrophysics Data System (ADS)

    Lane, Christine; Martin-Jones, Catherine; Johnson, Thomas; Lamb, Henry; Pearce, Nick; Scholz, Christopher; Smith, Victoria; Verschuren, Dirk

    2015-04-01

    Understanding the spatial and temporal variability of climate forcing and environmental response across a continent as climatically diverse as Africa relies upon comparison of data from widespread palaeoenvironmental archives. Accurate, precise and independent chronologies for such records are essential; however this remains a challenge in many environments, often preventing the valid comparison of detailed palaeo-proxy records. Many studies have now shown that volcanic ash (tephra) can be detected in terrestrial and marine sediments thousands of kilometres from their source, often as microscopic or "cryptic" layers. As well as offering opportunities for both direct (e.g. by 40Ar/39Ar methods) and indirect (e.g. by associated 14C dates) dating of the sediment sequence, tephra layers can provide stratigraphic tie-lines between archives, facilitating precise correlations at single moments in time. Furthermore, where two or more tephra layers are co-located in multiple records, rates of change can be compared within a period of equivalent duration, even in the absence of absolute age estimates. Investigations into the presence of visible and non-visible (crypto-) tephra layers within lacustrine palaeoenvironmental records of the last ~150 ka BP from across East Africa are revealing the potential for this approach to (i) correlate palaeoclimate archives from across and beyond tropical Africa within a regional tephrostratigraphic framework; (ii) provide age constraints for individual core chronologies, in particular beyond the limits of radiocarbon dating; and (iii) increase our knowledge of the history of Late Quaternary explosive volcanism in East Africa.

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

    PubMed

    Woodborne, Stephan; Hall, Grant; Robertson, Iain; Patrut, Adrian; Rouault, Mathieu; Loader, Neil J; Hofmeyr, Michele

    2015-01-01

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

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  6. Science Sampler: Fossil detectives

    NSDL National Science Digital Library

    Virginia Bourdeau

    2006-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-01-01

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

  8. Book reviews Just looking at fossils

    E-print Network

    Tullberg, Birgitta

    Book reviews Just looking at fossils A review by F. Boero Evolutionary Patterns. Growth, Form and Tempo in the Fossil Record. J. B. Jackson, S. Lidgard, F. McKinney (Eds), 2001. University of Chicago on human evolution based on fossils is one example of this pattern. There are groups of organisms, however

  9. Evolution and the Fossil Record

    E-print Network

    Kammer, Thomas

    Within #12;Natural Selection · Natural selection, a creative force, is one of the prime mechanisms of evolutionary change. (The other mechanism, a destructive force, is mass extinction.) · Charles Darwin, 1859: The Origin of Species by Natural Selection. #12;Artificial Selection vs. Natural Selection: Dog breeds

  10. The Fossil Record of Gibbons

    Microsoft Academic Search

    Nina G. Jablonski; George Chaplin

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

  11. Hunting Invertebrate Fossils in the Classroom

    NSDL National Science Digital Library

    Jon Garbisch

    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.

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

    Microsoft Academic Search

    Frank P. Cuozzo

    2008-01-01

    Patterns of extant primate dental variation provide important data for interpreting taxonomic boundaries in fossil forms.\\u000a Here I use dental data from several well-known living primates (as well as data from selected Eocene forms) to evaluate dental\\u000a variation in Middle Eocene Omomys, the first North American fossil primate identified by paleontologists. Measurements were collected from a sample of 148\\u000a omomyid

  13. Fossil Identification

    NSDL National Science Digital Library

    Connie Soja, Colgate University, csoja@colgate.edu

    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 paleoecologyâespecially reefs.

  14. Remarkable Fossils

    Microsoft Academic Search

    Thomas Wm. Cowan

    1874-01-01

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

  15. Impact of sea-level change on the paleo Primary Productivity record in the NW African coastal upwelling area

    NASA Astrophysics Data System (ADS)

    Giraud, X.; Paul, A.

    2009-04-01

    A sea level decrease of 120 m at the Last Glacial Maximum (LGM) drastically modifies the shelf morphology of the North West African coastal upwelling area. Using a regional coupled circulation-ecosystem model subject to a set of boundary conditions that reflect Present Day (PD) and LGM conditions, we aim to quantify how changes in shelf morphology, as well as changes in sub-surface nutrient concentrations or local climatic conditions, influence the biological productivity and its record in the sediments. The oceanic circulation is simulated by the Regional Ocean Modelling System (ROMS), taking advantage of the AGRIF (Adaptive Grid Refinement in Fortran) technique to set-up an embedded grid structure. A high-resolution grid (1/10°) is centred on our study area, and is nested in a larger, coarser grid (1/2°) over the Atlantic domain. Boundary and initial conditions for PD and LGM are provided by global simulations performed with the University of Victoria Earth System-Climate Model (UVic ESCM). We used NPZD (Nutrient, Phytoplankton, Zooplankton and Detritus) biogeochemical models. We have identified the following issues in interpreting a sedimentary record at a fixed core location as an indicator of the total upwelling productivity: - Changes in the shelf morphology due to sea-level change appeared to have an impact on the productivity of the upwelling itself, but also to displace the high-productivity zone. - Comparing the Primary Production (PP) between PD and LGM at a given geographical location, or comparing the zonal mean of the PP, can show opposite results. The comparison at geographical locations assumes a direct connection between the production in the surface ocean and the underlying sediments. The comparison of the zonal mean of PP or sediment flux assumes that lateral advection of particulates and sediment transport are significant processes in producing the sedimentary signal at a given location. We illustrate the various situations, with or without lateral integration of the PP, by a comparison of sedimentary data with the different modelling scenarios. While core data north of 23°N show an increase of organic carbon flux to the sediments at LGM compared to PD, our standard LGM simulation yielded a decrease. We attribute this decrease to the nutrient depletion of subsurface waters. Model results showed an increase in PP in an experiment where the wind stress was doubled over the NW Africa area. All simulations showed the same decoupling between PP at a geographical location and zonal mean PP.

  16. 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

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

    2005-01-01

    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

  17. 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

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

    2005-01-01

    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

  18. Searching for Scaling With Magnitude of Signals in the Early Portion of P Waveforms Recorded in South African Mines

    NASA Astrophysics Data System (ADS)

    Lewis, M. A.; Ben-Zion, Y.; Boettcher, M.

    2006-12-01

    The process of earthquake rupture may follow a cascade process where the eventual event size is determined by the (evolving, generally heterogeneous) stress-strength conditions on the fault. Some studies, however, reported scaling of signals in the early P waveforms with the final event magnitude, which may be related to the nucleation process. In this study we use a large seismic data set of near-source stations to investigate if any such scaling can be observed with a variety of proposed techniques. Umeda (1990) and Ellsworth and Beroza (1995) suggested that P waveforms are characterized by an initial phase of low amplitude followed by strong motion of the main event, and that the time between these two scales with the final magnitude. Iio (1995) measured the time difference between the very first onset and the projected onset if the P wave was a ramp function, and suggested that this scales with the final event size. A second set of methods, following Nakamura (1988), Allen and Kanamori (2003) and Kanamori (2004), look at how the frequency content of the waveform in the first few seconds changes with final event magnitude. Using high sampling rate data recorded within South African mines, we search systematically for the Ellsworth/Beroza-type nucleation, Iio-type nucleation, and Nakamura-type period in the early P waveforms. With hypocentral distances as low as ~400m and low seismic attenuation, any scaling with magnitude or nucleation phases that might exist have a good chance of being recoded at the stations. From an initial study of 64 events, ranging between approximately magnitude -1.5 and 2.5, at 26 stations, we find that candidates for Ellsworth/Beroza-type nucleation phases exists for only ~30% of the waveforms. This phase and the Iio-type phase do not appear to scale with the final event size in the examined data. Measurements of the Nakamura-type period in the first few seconds show overall scaling with the final event magnitude, albeit with a large scatter.

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

    E-print Network

    Kirchner, James W.

    Correlations in fossil extinction and origination rates through geological time James W. Kirchner1, implying that the fossil record may be controlled by self-organized criticality or other scale-free internal dynamics of the biosphere. Here we directly test for correlations in the fossil record

  20. Describing Fossils

    NSDL National Science Digital Library

    Judy Massare

    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 readâi.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.

  1. The largest fossil rodent

    PubMed Central

    Rinderknecht, Andrés; Blanco, R. Ernesto

    2008-01-01

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

  2. Cretaceous African life captured in amber

    PubMed Central

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

    2010-01-01

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

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

    PubMed Central

    Srivastava, Gaurav; Mehrotra, R.C.

    2014-01-01

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

  4. Impact of sea-level change on the paleo Primary Productivity record in the NW African coastal upwelling area

    Microsoft Academic Search

    X. Giraud; A. Paul

    2009-01-01

    A sea level decrease of 120 m at the Last Glacial Maximum (LGM) drastically modifies the shelf morphology of the North West African coastal upwelling area. Using a regional coupled circulation-ecosystem model subject to a set of boundary conditions that reflect Present Day (PD) and LGM conditions, we aim to quantify how changes in shelf morphology, as well as changes

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

    PubMed

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

    2015-04-23

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    PubMed Central

    Lewis, O J

    1980-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Mayr, Gerald; De Pietri, Vanesa L.

    2014-02-01

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

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

    PubMed

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

    2009-09-29

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

  10. ? 18O of carbonate, quartz and phosphate from belemnite guards: implications for the isotopic record of old fossils and the isotopic composition of ancient seawater

    NASA Astrophysics Data System (ADS)

    Longinelli, Antonio; Iacumin, Paola; Ramigni, Michele

    2002-10-01

    Belemnite guards of Cretaceous and Jurassic age were found to contain varying amounts of quartz deposited both on the external surface and inside the rostrum. The oxygen isotopic composition of coexisting carbonate, quartz and phosphate from the same rostrum was measured according to well-established techniques. None of these compounds showed isotopic values in equilibrium with one another. Assuming ? 18O values of the diagenetic water within the range of meteoric waters, the ? 18O(SiO 2) yield temperatures in agreement with the apparent secondary origin of this phase. The ? 18O(CO 32-) range, with a certain continuity, between -10.8 and +0.97 PDB-1 with most of the intermediate values being within the range of the carbonate isotopic values of Mesozoic fossils. The most positive isotopic results obtained from phosphate are close to +23/+24‰ (V-SMOW). They can hardly be related to a secondary origin of the phosphate, or to the presence of diagenetic effects, since these results are among the most positive ever measured on phosphate. As far as we know there is no widespread diagenetic process determining an 18O enrichment of phosphate. The very low concentration of phosphate did not allow the determination of its mineralogical composition. All the available ? 18O(PO 43-) values from belemnite and non-belemnite fossils of marine origin of Tertiary and Mesozoic age are reported along with the newly measured belemnites. The following conclusions may be drawn from the data reported: (1) the pristine oxygen isotope composition of fossil marine organisms (either carbonate or phosphate) may easily undergo fairly large changes because of oxygen isotope exchange processes with diagenetic water; this process is apparent even in the case of geologically recent fossils; (2) the ? 18O(PO 43-) of belemnite rostra seems to be, at least in the case of the most positive results, in isotopic equilibrium with environmental water because of the similarity between the results from Cretaceous belemnites and the results from Cretaceous and Lower Tertiary pelecypods and fish teeth; 3) if so, the only feasible interpretation that can be suggested for the 18O enriched data is the possibility of a relatively large variation of the oxygen isotopic composition of ocean paleowater from Jurassic to recent time.

  11. 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.

  12. Recordings

    Microsoft Academic Search

    Carole Pegg

    1999-01-01

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

  13. 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

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

    NASA Astrophysics Data System (ADS)

    Cohen, A. S.

    2014-12-01

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

  15. 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)

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

    2010-08-01

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

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

    PubMed Central

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

    2009-01-01

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

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

    PubMed

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

    2009-05-19

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

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

    NASA Astrophysics Data System (ADS)

    Elvevold, Synnøve; Engvik, Ane K.

    2013-10-01

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

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

    NASA Astrophysics Data System (ADS)

    Enzel, Yehouda; Kushnir, Yochanan; Quade, Jay

    2015-06-01

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

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

    E-print Network

    M. Omerbashich

    2007-06-09

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

  1. Theropod Fossil Hunt Dispatch

    NSDL National Science Digital Library

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

  2. Trace fossil preservation and the early evolution of animals

    Microsoft Academic Search

    Sören Jensen; Mary L. Droser; James G. Gehling

    2005-01-01

    The trace fossil record is an important element in discussions of the timing of appearance of bilaterian animals. A conservative approach does not extend this record beyond about 560–555 Ma. Crucial to the utility of trace fossils in detecting early benthic activity is the preservational potential of traces made close to the sediment–water interface. Our studies on the earliest Cambrian

  3. 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.

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

    E-print Network

    Jernvall, Jukka

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

  5. Summary statistics for fossil spider species taxonomy

    PubMed Central

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Boucot, A. J.

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

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

    E-print Network

    Baab, Karen L.

    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

  9. Plant Carbonate Fossils from the Ephemeral Pond Domain in South Texas/NE Mexico Yield a Record of Tropical Cyclone Activity: Oxygen Isotopes

    NASA Astrophysics Data System (ADS)

    Lawrence, J. R.; Maddocks, R.; Slowey, N. C.; Roark, E.

    2013-05-01

    Tropical cyclones produce rain with anomalously low oxygen isotope ratios. When dry ponds suddenly receive a large influx of this rainwater, algal plants known as "Charo" grow rapidly and produce desiccation resistant seeds covered by a carbonate coating. The oxygen isotopic composition of the carbonate reflects the presence of tropical cyclone water. A sediment core was taken in 2010 and pond waters were collected. Three tropical cyclones flooded the pond that year. The pond waters exhibited low isotope ratios that gradually rose as evaporation took place over the following days. Carbonate coated seeds "Charo" were separated from the top centimeter of the core. Two of the analyzed samples exhibited distinctly low isotope ratios indicating that the pond had been flooded with water from tropical cyclones at least twice. Additional isotopic analyses of carbonate coating from the seeds deeper in the core are in progress. The quantity of carbonate coating the seeds is more than adequate for obtaining lead 210 and carbon 14 dates. The main objective of our study is to produce a longterm record of tropical cyclone activity in the South Texas / Northeast Mexico region.

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

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

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

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

    PubMed

    Bilton, David T

    2014-01-01

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

  12. Calibrating the Tree of Life: fossils, molecules and evolutionary timescales

    PubMed Central

    Forest, Félix

    2009-01-01

    Background Molecular dating has gained ever-increasing interest since the molecular clock hypothesis was proposed in the 1960s. Molecular dating provides detailed temporal frameworks for divergence events in phylogenetic trees, allowing diverse evolutionary questions to be addressed. The key aspect of the molecular clock hypothesis, namely that differences in DNA or protein sequence between two species are proportional to the time elapsed since they diverged, was soon shown to be untenable. Other approaches were proposed to take into account rate heterogeneity among lineages, but the calibration process, by which relative times are transformed into absolute ages, has received little attention until recently. New methods have now been proposed to resolve potential sources of error associated with the calibration of phylogenetic trees, particularly those involving use of the fossil record. Scope and Conclusions The use of the fossil record as a source of independent information in the calibration process is the main focus of this paper; other sources of calibration information are also discussed. Particularly error-prone aspects of fossil calibration are identified, such as fossil dating, the phylogenetic placement of the fossil and the incompleteness of the fossil record. Methods proposed to tackle one or more of these potential error sources are discussed (e.g. fossil cross-validation, prior distribution of calibration points and confidence intervals on the fossil record). In conclusion, the fossil record remains the most reliable source of information for the calibration of phylogenetic trees, although associated assumptions and potential bias must be taken into account. PMID:19666901

  13. The oldest Asian record of Anthropoidea

    PubMed Central

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

    2008-01-01

    Undisputed anthropoids appear in the fossil record of Africa and Asia by the middle Eocene, about 45 Ma. Here, we report the discovery of an early Eocene eosimiid anthropoid primate from India, named Anthrasimias, that extends the Asian fossil record of anthropoids by 9–10 million years. A phylogenetic analysis of 75 taxa and 343 characters of the skull, postcranium, and dentition of Anthrasimias and living and fossil primates indicates the basal placement of Anthrasimias among eosimiids, confirms the anthropoid status of Eosimiidae, and suggests that crown haplorhines (tarsiers and monkeys) are the sister clade of Omomyoidea of the Eocene, not nested within an omomyoid clade. Co-occurence of Anthropoidea, Omomyoidea, and Adapoidea makes it evident that peninsular India was an important center for the diversification of primates of modern aspect (euprimates) in the early Eocene. Adaptive reconstructions indicate that early anthropoids were mouse–lemur-sized (?75 grams) and consumed a mixed diet of fruit and insects. Eosimiids bear little adaptive resemblance to later Eocene-early Oligocene African Anthropoidea. PMID:18685095

  14. [The fossil record of the Eurasian Neogene insectivores (Erinaceomorpha, Soricomorpha, Mammalia) : Part I \\/ L.W. van den Hoek Ostende, C.S. Doukas and J.W.F. Reumer (editors)]: Bulgaria

    Microsoft Academic Search

    B. Rzebik-Kowalska; V. V. Popov

    2005-01-01

    Introduction Research on Bulgarian fossil small mammals had a relatively late start and it was researchers from neighbouring countries who published the first few studies. The first fossil shrew, Crocidura sp., was mentioned by Jakubowski & Kraszewski (1972). It was found in the southeastern part of Bulgaria at Sarafovo, a locality of probably Pliocene age. A decade later, Rzebik-Kowalska (1982)

  15. Austrian phase on the northern African margin inferred from sequence stratigraphy and sedimentary records in southern Tunisia (Chotts and Djeffara areas)

    NASA Astrophysics Data System (ADS)

    Lazzez, Marzouk; Zouaghi, Taher; Ben Youssef, Mohamed

    2008-08-01

    A multidisciplinary study concerning Aptian and Albian deposits is reported from petroleum wells and the exposed section. The biostratigraphic and sedimentological analysis defined four sedimentary units. Well-logging signals' analysis allows us to refine the record resolution on Aptian series and reveals, in the Djeffara field, a transgressive system tract (TST) and a highstand system tract (HST). Exceptionally, the first sequence (S1) in the Mareth 1 well and the fifth sequence in the two wells Mareth 1 and Gourine 1 reveal the lower-stand system tract (LST). The unconformities characterized by the absence of Upper Aptian (Clansayesian) and Lower to Middle Albian deposits signed by a significant gamma-ray reduction. The Middle and Upper Albian is represented by only one deposit sequence (S6) in Mareth 1. Towards the south, in the Gourine well, two deposit sequences were identified (S6 and S7); to specify the Aptian and Albian evolution of the deposit sequences, a tentative correlation has been established between the Chotts and Djeffara areas. This correlation allows us to characterize the sedimentary unconformities related to the tectonics and eustatic events. The Chotts and the Djeffara deposition areas were developed, characterized by an irregular subsidence and separated by the Tebaga Medenine high area. The Aptian-Albian subsidence platform of southern Tunisia may be considered as a block diagram of environmental deposit with regressive and transgressive trends, showing the impact of tectonic deformations on the palaeogeographic evolution of southeastern Tunisia during the Austrian phase. This study also must be replaced within regional structural patterns that may explain both the sequential and sedimentological evolution of the area. Deformations regionally identified are integrated in the more general context of both Tethyan and Atlantic areas related to the drift of the African platform.

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

    E-print Network

    Olsen, Paul E.

    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

  17. The Proterozoic Fossil Record of Heterotrophic Eukaryotes

    Microsoft Academic Search

    Susannah M. Porter

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

  18. Fossil-energy program

    Microsoft Academic Search

    L. E. McNeese

    1982-01-01

    The increased utilization of coal and other fossil fuel alternatives as sources of clean energy is reported. The projects reported include: coal conversion development, chemical research and development, materials technology, component development and process evaluation, technical support to major liquefaction, process analysis and engineering evaluations, fossil energy environmental analysis, environmental control technology, coal preparation waste utilization, atmospheric fluidized bed coal

  19. Restoring Fossil Creek

    ERIC Educational Resources Information Center

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

    2004-01-01

    Fossil Creek had been dammed for the past 90 years, and plans were underway to restore the stream. The creek runs through Central Arizona and flows from the high plateaus to the desert, cutting through the same formations that form the Grand Canyon. This article discusses the Fossil Creek monitoring project. In this project, students and teachers…

  20. Becoming a Fossil

    NSDL National Science Digital Library

    2005-01-01

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

  1. Fossil fuels -- future fuels

    SciTech Connect

    NONE

    1998-03-01

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

  2. 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.

  3. Minerals and Fossils

    NSDL National Science Digital Library

    mineraltown.com

    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.

  4. Fossil Age Estimation Model

    NSDL National Science Digital Library

    Twin Cities Public Television, Inc.

    2006-01-01

    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.

  5. Fossil Simulation in the Classroom

    ERIC Educational Resources Information Center

    Hoehn, Robert G.

    1977-01-01

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

  6. Fossil evidence of the zygomycetous fungi.

    PubMed

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

    2013-06-01

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

  7. Rethinking Fossil Fuels

    NSDL National Science Digital Library

    James Hansen (NASA Goddard Institute for Space Studies; )

    2008-09-09

    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.

  8. Fossil-energy

    NASA Astrophysics Data System (ADS)

    1981-08-01

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

  9. Fossil Halls: Vertebrate Evolution

    NSDL National Science Digital Library

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

  10. 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?

  11. Advanced fossil energy utilization

    SciTech Connect

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

    2010-01-01

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

  12. Classification of Fossil Microplankton

    Microsoft Academic Search

    C. Downie; G. L. Williams; W. A. S. SARJEANT

    1961-01-01

    IT is becoming increasingly desirable that a definite decision be made as to whether the fossil organicshelled microplankton (dinoflagellates, hystrichospheres, and genera of presumed microplankton incertae sedis) should be classed, for nomenclatural purposes, in the animal or in the plant kingdom. The dinoflagellates, a group of unicellular organisms some of which contain chlorophyll, are clearly algae, while others contain no

  13. Fossil Biodiversity: Red Noise Plus Signal

    E-print Network

    Adrian L. Melott; Bruce S. Lieberman

    2006-06-14

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

  14. Plio-pleistocene African climate

    Microsoft Academic Search

    P. B. deMenocal

    1995-01-01

    Marine records of African climate variability document a shift toward more arid conditions after 2.8 million years ago (Ma), evidently resulting from remote forcing by cold North Atlantic sea-surface temperatures associated with the onset of Northern Hemisphere glacial cycles. African climate before 2.8 Ma was regulated by low-latitude insolation forcing of monsoonal climate due to Earth orbital precession. Major steps

  15. Centering on Fossils and Dinosaurs.

    ERIC Educational Resources Information Center

    Coble, Charles R.; McCall, Gregory K.

    1986-01-01

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

  16. Fossil energy materials needs assessment

    Microsoft Academic Search

    R. T. King; R. R. Judkins

    1980-01-01

    An assessment of needs for materials of construction for fossil energy systems was prepared by Oak Ridge National Laboratories staff members who conducted a literature search and interviewed various individuals and organizations that are active in the area of fossil energy technology. Critical materials problems associated with fossil energy systems are identified. Background information relative to the various technologies is

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

    PubMed

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

    2015-07-01

    The origin and evolution of clitellate annelids-earthworms, leeches and their relatives-is poorly understood, partly because body fossils of these delicate organisms are exceedingly rare. The distinctive egg cases (cocoons) of Clitellata, however, are relatively common in the fossil record, although their potential for phylogenetic studies has remained largely unexplored. Here, we report the remarkable discovery of fossilized spermatozoa preserved within the secreted wall layers of a 50-Myr-old clitellate cocoon from Antarctica, representing the oldest fossil animal sperm yet known. Sperm characters are highly informative for the classification of extant Annelida. The Antarctic fossil spermatozoa have several features that point to affinities with the peculiar, leech-like 'crayfish worms' (Branchiobdellida). We anticipate that systematic surveys of cocoon fossils coupled with advances in non-destructive analytical methods may open a new window into the evolution of minute, soft-bodied life forms that are otherwise only rarely observed in the fossil record. PMID:26179804

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

    E-print Network

    Bourke, Mary C.

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

  19. Bibliography of Fossil Vertebrates

    NSDL National Science Digital Library

    1997-01-01

    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.

  20. 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.

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

    E-print Network

    Kammen, Daniel M.

    Schewel and Schipper 1 FOSSIL FREIGHT: HOW MUCH FOSSIL FUEL DOES IT TAKE TO MOVE FOSSIL1 FUEL?2 #12;Schewel and Schipper 2 Abstract1 This paper asks as the question: how much fossil fuel does it take to move fossil fuel inside the U.S.? An2 understanding of this "fossil freight", which takes up

  2. Fossilization Processes in Thermal Springs

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

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

    PubMed

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

    2014-01-01

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

  4. 21,000 years of Ethiopian African monsoon variability recorded in sediments of the western Nile deep-sea fan: impact of the Nile freshwater inflow for the Mediterranean thermo-haline circulation

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  5. 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

  6. African Arts

    NSDL National Science Digital Library

    University of Nebraska State Museum

    2001-01-01

    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.

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

    PubMed Central

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

    2012-01-01

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

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

    PubMed

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

    2012-01-01

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

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

    Microsoft Academic Search

    Thomas M. Kaiser; Gesa Brinkmann

    2006-01-01

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

  10. iSSlON HIGHLIGHTS^^AM ANNUAL MEETING/EB 2013 BOSTON, MA New Fossils, New

    E-print Network

    Taylor, Jerry

    iSSlON HIGHLIGHTS^^AM ANNUAL MEETING/EB 2013 BOSTON, MA New Fossils, New Questions, New Clues said, that picture isprobablywrong. Todayweseean "incredible diversity of hominids in the fossil record fossils discovered in the last20 years don't look much like modern chimpanzees or gorillas or orangutans

  11. Triassic leech cocoon from Antarctica contains fossil bell animal

    PubMed Central

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

    2012-01-01

    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

  12. Fossilized Dinosaur Teeth Adaptations

    NSDL National Science Digital Library

    Rick Crosslin

    2004-01-01

    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.

  13. The Cenozoic Record of Continental Mineral Deposition on Broken and Ninetyeast Ridges, Indian Ocean: Southern African Aridity and Sediment Delivery from the Himalayas

    NASA Astrophysics Data System (ADS)

    Hovan, Steven A.; Rea, David K.

    1992-12-01

    The mineral component of pelagic sediments recovered from the Indian Ocean provides both a history of eolian deposition related to climatic changes in southern Africa and a record of terrigenous input related to sediment delivery from the Himalayas. A composite Cenozoic dust flux record from four sites in the central Indian Ocean is used to define the evolution of the Kalahari and Namib desert source regions. The overall record of dust input is one of very low flux for much of the Cenozoic indicating a long history of climate stability and regional hyperaridity. The most significant reduction in dust flux occurred near the Paleocene/Eocene boundary and is interpreted as a shift from semiarid climates during the Paleocene to more arid conditions in the early Eocene. Further aridification is recorded as stepwise reductions in the input of dust material which occur from about 35 to 40 Ma, 27 to 32 Ma, and 13 to 15 Ma and correlate to significant enrichments in benthic foraminifer ?18O values. The mineral flux in sediments from the northern Indian Ocean, site 758, records changes in the terrigenous input apparently related to the erosion of the Himalayas and indicates a rapid late Cenozoic uplift history. Three major pulses of increased terrigeneous sediment flux are inferred from the depositional record. The initial increase began at about 9.5 Ma and continued for roughly 1.0 million years. A second pulse with approximately the same magnitude occurred from about 7.0 to 5.6 Ma. The largest pulse of enhanced terrigenous influx occurred during the Pliocene from about 3.9 to 2.0 Ma when average flux values were severalfold greater than at any other time in the Cenozoic.

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

    PubMed

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

    2013-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  16. Austrian phase on the northern African margin inferred from sequence stratigraphy and sedimentary records in southern Tunisia (Chotts and Djeffara areas)

    Microsoft Academic Search

    Marzouk Lazzez; Taher Zouaghi; Mohamed Ben Youssef

    2008-01-01

    A multidisciplinary study concerning Aptian and Albian deposits is reported from petroleum wells and the exposed section. The biostratigraphic and sedimentological analysis defined four sedimentary units. Well-logging signals’ analysis allows us to refine the record resolution on Aptian series and reveals, in the Djeffara field, a transgressive system tract (TST) and a highstand system tract (HST). Exceptionally, the first sequence

  17. 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

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

    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

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

    ERIC Educational Resources Information Center

    Riddick, William P.

    2013-01-01

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

  19. Fossil plant self assessment

    SciTech Connect

    Bozgo, R.H. [Consolidated Edison Company of New York, Inc., New York, NY (United States); Maguire, B.A. [VPA Corp., Reston, VA (United States)

    1996-07-01

    The increasingly competitive environment of the electric utility business is focusing utilities attention on reducing the cost of electricity generation. By using benchmark indicators, gains are being sought in plant material condition with corresponding improvements in operating efficiency and capacity factor as well as reductions in Operating and Maintenance (O&M) costs. In designing a process for improvement, Consolidated Edison Company of New York, Inc. (Con Edison) plant managers were asked to review and approve objectives and criteria for Fossil Plant Operations. The program methods included optimizing work processes (including material condition, maintenance programs, work control systems, and personnel performance); team building techniques to foster personnel buy-in of the process; and long term cultural change to insure an ongoing continuous improvement process with measurable results. The program begins with a self assessment of each plant based upon the approved Objectives and Criteria. The Criteria and Review Approaches (CRAs) are established by senior management and the review team. The criteria cover Management, Operations, Maintenance, and Support Functions including Technical Support, Training and Qualification, Environmental Compliance, Chemistry, and Safety and Emergency Preparedness. The Assessment is followed by a review of corrective action plans and an interim corrective action review. Annual Assessments are planned to ensure continuous improvement. Emphasis is placed on progress made in maintenance at the fossil stations.

  20. Fossils 2: Uncovering the Facts

    NSDL National Science Digital Library

    Science Netlinks

    2001-10-20

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

  1. Genetic Variants That Confer Resistance to Malaria Are Associated with Red Blood Cell Traits in African-Americans: An Electronic Medical Record-based Genome-Wide Association Study

    PubMed Central

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

    2013-01-01

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

  2. African & African-American Studies University of Kansas

    E-print Network

    ................................................................. 4 Language/Research Skills Requirement........................................................................................................... 9 African & African-American Studies Core Faculty ......................................................... 11 African & African-American Studies Adjunct Faculty

  3. Fossil turbulence and fossil turbulence waves can be dangerous

    E-print Network

    Carl H Gibson

    2012-11-25

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

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

    E-print Network

    Thornton, Charles Anthony

    1994-01-01

    sediments, and there is a great need to test the taphofacies concept on the rock record. The taphofacies concept has been tested in the Stone City/Cook Mountain formations, middle Eocene, in Southeast Texas. The strata consist of brown shales, pelleted green...

  5. "African Connection."

    ERIC Educational Resources Information Center

    Adelman, Cathy; And Others

    This interdisciplinary unit provides students in grades kindergarten through seventh grade an opportunity to understand diversity through a study of Africa as a diverse continent. The project is designed to provide all elementary students with cultural enrichment by exposing them to African music, art, storytelling, and movement. This project can…

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

    Microsoft Academic Search

    Robert Bleiweiss

    1998-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2006-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

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

  9. 22 CFR 1502.5 - Records available at the Foundation.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 true Records available at the Foundation. 1502.5 Section 1502.5 Foreign Relations AFRICAN DEVELOPMENT FOUNDATION AVAILABILITY OF RECORDS § 1502.5 Records available at the Foundation. The Administration and...

  10. 22 CFR 1502.3 - Access to Foundation records.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 2010-04-01 true Access to Foundation records. 1502.3 Section 1502...Foreign Relations AFRICAN DEVELOPMENT FOUNDATION AVAILABILITY OF RECORDS § 1502.3 Access to Foundation records. Any person desiring to...

  11. 22 CFR 1502.5 - Records available at the Foundation.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

  12. 22 CFR 1502.5 - Records available at the Foundation.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  13. 22 CFR 1502.3 - Access to Foundation records.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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

  14. 22 CFR 1502.5 - Records available at the Foundation.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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

  15. 22 CFR 1502.3 - Access to Foundation records.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

  16. 22 CFR 1502.3 - Access to Foundation records.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  17. 22 CFR 1502.3 - Access to Foundation records.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 2014-04-01 false Access to Foundation records. 1502.3 Section 1502...Foreign Relations AFRICAN DEVELOPMENT FOUNDATION AVAILABILITY OF RECORDS § 1502.3 Access to Foundation records. Any person desiring to...

  18. 22 CFR 1502.5 - Records available at the Foundation.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... false Records available at the Foundation. 1502.5 Section 1502.5 Foreign Relations AFRICAN DEVELOPMENT FOUNDATION AVAILABILITY OF RECORDS § 1502.5 Records available at the Foundation. The Administration and...

  19. Plio-pleistocene African climate

    SciTech Connect

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

    1995-10-06

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

  20. Dating Fossil Pollen: A Simulation.

    ERIC Educational Resources Information Center

    Sheridan, Philip

    1992-01-01

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

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

    PubMed Central

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    PubMed Central

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

    2012-01-01

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

  4. Technology Treaties and Fossil-Fuels Extraction

    Microsoft Academic Search

    Jon Strand

    2007-01-01

    We consider some unintended effects of a technology treaty to increase the (stochastic) possibility of developing an energy alternative to fossil fuels which, when available, makes fossil fuels redundant. One implication of such a treaty is to increase the incentives for fossil-fuels producers to extract fossil fuels existing in given quantity more rapidly, under competition when the equilibrium price path

  5. Ignoring Authentic African Literature Means Ignoring Africans

    ERIC Educational Resources Information Center

    Romano, Carlin

    2005-01-01

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

  6. Details of North African tectonics

    NSDL National Science Digital Library

    Meghraoui et al.

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  8. African Outreach Workshop 1974.

    ERIC Educational Resources Information Center

    Schmidt, Nancy J.

    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…

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

    PubMed Central

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

    2012-01-01

    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

  10. Mandibular fossa morphology in the Ngandong and Sambungmacan fossil hominids.

    PubMed

    Durband, Arthur C

    2008-10-01

    There has been debate in recent years concerning the significance of the mandibular fossa morphology in the Ngandong and Sambungmacan hominids. These fossils lack a postglenoid process and their squamotympanic fissure runs along the apex of the fossa for its entire length. This configuration differs from that seen in other fossil and modern humans, which have a prominent postglenoid process and a squamotympanic fissure that takes a more posterior course that does not lie in the apex of the fossa. Some recent studies have suggested that the Ngandong and Sambungmacan hominids are not unique in their expression of these characteristics, and that they can also be found in other fossil crania from Africa and Indonesia. The present study reexamines these morphologies in an effort to better understand their distribution in the hominid fossil record. The results confirm that the lack of a prominent postglenoid process in combination with a squamotympanic fissure that lies wholly in the apex of the mandibular fossa along its entire length is indeed autapomorphic for the Ngandong and Sambungmacan fossils. This finding, in conjunction with work on other nonmetric features in these hominids, suggests that at least two hominid morphs, possibly representing separate species, were present on Java during the Pleistocene. In addition, if this apparent autapomorphy is confirmed, then it is also unlikely that the Ngandong hominids contributed to the gene pool of modern humans. PMID:18521904

  11. Fossils, rocks, and time

    USGS Publications Warehouse

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

    1993-01-01

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

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

    PubMed

    Luo, Cui; Reitner, Joachim

    2014-06-01

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

  13. Innovative tephra studies in the East African Rift System

    Microsoft Academic Search

    Giday WoldeGabriel; William K. Hart; Grant Heiken

    2005-01-01

    Geosciences investigations form the foundation for paleoanthropological research in the East African Rift System. However, innovative applications of tephra studies for constraining spatial and temporal relations of diverse geological processes, biostratigraphic records, and paleoenvironmental conditions within the East African Rift System were fueled by paleoanthropological investigations into the origin and evolution of hominids and material culture. Tephra is a collective,

  14. 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.

  15. Biological fossil CO 2 mitigation

    Microsoft Academic Search

    Evan Hughes; John R Benemann

    1997-01-01

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

  16. Fossil Reptiles of Great Britain

    E-print Network

    Benton, Michael

    Fossil Reptiles of Great Britain M.J. Benton and P.S. Spencer Department of Geology, University CONSERVATION REVIEW SERIES The comparatively small land area of Great Britain contains an unrivalled sequence by generations of leading geologists, thus giving Britain a unique status in the development of the science. Many

  17. Fossil Identification and Classification Lab

    NSDL National Science Digital Library

    Ralph Willoughby

    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.

  18. Progress of Fossil Fuel Science

    Microsoft Academic Search

    M. F. Demirbas

    2007-01-01

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

  19. 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.

  20. Synthetic soup ground trace fossils

    NSDL National Science Digital Library

    Clint Cowan

    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. 1041â1049

  1. Mitochondrial genomes as living 'fossils'.

    PubMed

    Small, Ian

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  3. DNA and Morphology Unite Two Species and 10 Million Year Old Fossils

    PubMed Central

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

    2012-01-01

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

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

    PubMed

    Strotz, Luke C; Allen, Andrew P

    2013-02-19

    Assessing the extent to which population subdivision during cladogenesis is necessary for long-term phenotypic evolution is of fundamental importance in a broad range of biological disciplines. Differentiating cladogenesis from anagenesis, defined as evolution within a species, has generally been hampered by dating precision, insufficient fossil data, and difficulties in establishing a direct link between morphological changes detectable in the fossil record and biological species. Here we quantify the relative frequencies of cladogenesis and anagenesis for macroperforate planktic Foraminifera, which arguably have the most complete fossil record currently available, to address this question. Analyzing this record in light of molecular evidence, while taking into account the precision of fossil dating techniques, we estimate that the fraction of speciation events attributable to anagenesis is <19% during the Cenozoic era (last 65 Myr) and <10% during the Neogene period (last 23 Myr). Our central conclusion--that cladogenesis is the predominant mode by which new planktic Foraminifera taxa become established at macroevolutionary time scales--differs markedly from the conclusion reached in a recent study based solely on fossil data. These disparate findings demonstrate that interpretations of macroevolutionary dynamics in the fossil record can be fundamentally altered in light of genetic evidence. PMID:23378632

  5. Proboscidean die-offs and die-outs: Age profiles in fossil collections

    Microsoft Academic Search

    Gary Haynes

    1987-01-01

    Distinctive age profiles result from certain types of mortality processes that affect modern African elephants. Large collections of fossil proboscidean bones sometimes have similar age profiles-for example, those of the Lehner and Dent assemblages are identical to age profiles seen in modern drought-caused die-offs. Two other samples of mammoths (one from the Fairbanks muck deposits and one from a site

  6. Protein molecular data from ancient (>1 million years old) fossil material: pitfalls, possibilities and grand challenges.

    PubMed

    Schweitzer, Mary Higby; Schroeter, Elena R; Goshe, Michael B

    2014-07-15

    Advances in resolution and sensitivity of analytical techniques have provided novel applications, including the analyses of fossil material. However, the recovery of original proteinaceous components from very old fossil samples (defined as >1 million years (1 Ma) from previously named limits in the literature) is far from trivial. Here, we discuss the challenges to recovery of proteinaceous components from fossils, and the need for new sample preparation techniques, analytical methods, and bioinformatics to optimize and fully utilize the great potential of information locked in the fossil record. We present evidence for survival of original components across geological time, and discuss the potential benefits of recovery, analyses, and interpretation of fossil materials older than 1 Ma, both within and outside of the fields of evolutionary biology. PMID:24983800

  7. A fossil coral perspective on western tropical Pacific climate $$$$$$$350 ka K. Halimeda Kilbourne and Terrence M. Quinn

    E-print Network

    South Florida, University of

    A fossil coral perspective on western tropical Pacific climate $$$$$$$350 ka K. Halimeda Kilbourne Frederick W. Taylor Institute for Geophysics, University of Texas at Austin, Austin, Texas, USA Received 26 of tropical climate variability $350 ka is addressed using d18 O and Sr/Ca records from a modern and a fossil

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

    Microsoft Academic Search

    Oliver Heiri; ANDREF. LOTTER

    2005-01-01

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

  9. The Fossil Record of Star Formation from Galaxy Spectra 

    E-print Network

    Panter, Ben

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  11. Studying Function and Behavior in the Fossil Record

    Microsoft Academic Search

    Michael J. Benton

    2010-01-01

    It is easy to dismiss reconstructed organisms and behaviors from the past as “mere speculation”, but empirical evidence, comparison with modern analogs, and biomechanical modeling can provide remarkable insights.

  12. Environmental determinants of extinction selectivity in the fossil record

    E-print Network

    Peters, Shanan E.

    of epicontinental seas have influ- enced the macroevolution of marine animals7,8 , but the extent to which or unusual physical events as dri- vers of macroevolution, but they do suggest that the turnover of marine

  13. Fossil: A Robust Relational Learner Johannes Furnkranz

    E-print Network

    Fürnkranz, Johannes

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

  14. Using extant morphological variation to understand fossil

    E-print Network

    Ackermann, Rebecca Rogers

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

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

    E-print Network

    Benton, Michael

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

  17. Clustering fossils in solid inflation

    NASA Astrophysics Data System (ADS)

    Akhshik, Mohammad

    2015-05-01

    In solid inflation the single field non-Gaussianity consistency condition is violated. As a result, the long tenor perturbation induces observable clustering fossils in the form of quadrupole anisotropy in large scale structure power spectrum. In this work we revisit the bispectrum analysis for the scalar-scalar-scalar and tensor-scalar-scalar bispectrum for the general parameter space of solid. We consider the parameter space of the model in which the level of non-Gaussianity generated is consistent with the Planck constraints. Specializing to this allowed range of model parameter we calculate the quadrupole anisotropy induced from the long tensor perturbations on the power spectrum of the scalar perturbations. We argue that the imprints of clustering fossil from primordial gravitational waves on large scale structures can be detected from the future galaxy surveys.

  18. Clustering Fossils in Solid Inflation

    E-print Network

    Akhshik, Mohammad

    2014-01-01

    In solid inflation the single field non-Gaussianity consistency condition is violated. As a result, the long tensor perturbation induces observable clustering fossils in the form of quardupole anisotropy in large scale structure power spectrum. In this work we revisit the bispectrum analysis for the scalar-scalar-scalar and tensor-scalar-scalar for the general parameter space of solid. We consider the parameter space of the model in which the level of non-Gaussianity generated is consistent with Planck constraints. Specializing to this allowed range of model parameter, we calculate the quadrupole anisotropy induced from the long tensor perturbations on the power spectrum of scalar perturbations. We argue that imprints of clustering fossil from primordial gravitational waves on large scale structures can be detected from the future galaxy surveys.

  19. Clustering Fossils in Solid Inflation

    E-print Network

    Mohammad Akhshik

    2014-09-10

    In solid inflation the single field non-Gaussianity consistency condition is violated. As a result, the long tensor perturbation induces observable clustering fossils in the form of quardupole anisotropy in large scale structure power spectrum. In this work we revisit the bispectrum analysis for the scalar-scalar-scalar and tensor-scalar-scalar for the general parameter space of solid. We consider the parameter space of the model in which the level of non-Gaussianity generated is consistent with Planck constraints. Specializing to this allowed range of model parameter, we calculate the quadrupole anisotropy induced from the long tensor perturbations on the power spectrum of scalar perturbations. We argue that imprints of clustering fossil from primordial gravitational waves on large scale structures can be detected from the future galaxy surveys.

  20. Mental Health: African Americans

    MedlinePLUS

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

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

    USGS Publications Warehouse

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

    1984-01-01

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

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

    USGS Publications Warehouse

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

    1984-01-01

    Fossil worm tubes of Cretaceous age preserved in the Bayda massive sulfide deposit of the Samail ophiolite, Oman, are apparently the first documented examples of fossils embedded in massive sulfide deposits from the geologic record. The geologic setting of the Bayda deposit and the distinctive mineralogic and textural features of the fossiliferous samples suggest that the Bayda sulfide deposit and fossil fauna are remnants of a Cretaceous sea-floor hydrothermal vent similar to modern hot springs on the East Pacific Rise and the Juan de Fuca Ridge.

  3. Fossils of hydrothermal vent worms from cretaceous sulfide ores of the samail ophiolite, oman.

    PubMed

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

    1984-03-30

    Fossil worm tubes of Cretaceous age preserved in the Bayda massive sulfide deposit of the Samail ophiolite, Oman, are apparently the first documented examples of fossils embedded in massive sulfide deposits from the geologic record. The geologic setting of the Bayda deposit and the distinctive mineralogic and textural features of the fossiliferous samples suggest that the Bayda sulfide deposit and fossil fauna are remnants of a Cretaceous sea-floor hydrothermal vent similar to modern hot springs on the East Pacific Rise and the Juan de Fuca Ridge. PMID:17746052

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

    Microsoft Academic Search

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

    2011-01-01

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

  5. Generalized individual dental age stages for fossil and extant placental mammals

    Microsoft Academic Search

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

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

  6. Mitochondrial relationships and divergence dates of the African colobines: evidence of Miocene origins for the living colobus monkeys.

    PubMed

    Ting, Nelson

    2008-08-01

    The African colobines represent a neglected area of cercopithecid systematics. Resolving the phylogenetic relationships and estimating divergence dates among the living forms will provide insight into the evolution of this group and may shed light upon the evolution of other African primates as well. This is the first molecular assessment of the evolutionary relationships among the modern colobus monkeys, which are comprised of the black-and-white, olive, and red colobus groups. Over 4,000 base pairs of mitochondrial DNA were amplified and sequenced in over 40 colobus monkey individuals incorporating representatives from all commonly recognized species. Gene trees were inferred using maximum likelihood and Bayesian inference, and penalized likelihood was employed to estimate mitochondrial divergence dates among the sampled taxa. The results are congruent with some aspects of previous phylogenetic hypotheses based on morphology and vocalizations, although the relationships among several West and Central African taxa differ to some degree. The divergence date analysis suggests that the black-and-white, olive, and red colobus had diverged from one another by the end of the Miocene, and that by the Plio-Pleistocene many of the species lineages were already present. This demonstrates that the initial extant colobus monkey diversification occurred much earlier than previously thought and was likely part of the same adaptive radiation that produced the diverse colobine taxa seen in the African Plio-Pleistocene fossil record. The lack of early members from the modern lineages in fossiliferous deposits suggests that they resided in part in the forests of Central and West Africa, which also currently harbor the highest levels of colobus monkey diversity. These forests should not be ignored in models of Plio-Pleistocene human and nonhuman primate evolution. PMID:18423802

  7. Scaling relations in fossil galaxy groups

    E-print Network

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

    2007-02-04

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

  8. Mitochondrial genomes as living ‘fossils

    PubMed Central

    2013-01-01

    The huge variation between mitochondrial genomes makes untangling their evolutionary histories difficult. Richardson et al. report on the remarkably unaltered ‘fossil’ genome of the tulip tree, giving us many clues as to how the mitochondrial genomes of flowering plants have evolved over the last 150 million years, and raising questions about how such extraordinary sequence conservation can be maintained. See research article http://www.biomedcentral.com/1741-7007/11/29. PMID:23587103

  9. Dinosaurs: Ancient Fossils, New Discoveries

    NSDL National Science Digital Library

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

  10. Fossil Collection and Museum Curation

    NSDL National Science Digital Library

    Diana Boyer

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

  11. Misreading the African Landscape

    NASA Astrophysics Data System (ADS)

    Fairhead, James; Leach, Melissa

    1996-10-01

    West African landscapes are generally considered as degraded, especially on the forest edge. This unique study shows how wrong that view can be, by revealing how inhabitants have enriched their land when scientists believe they have degraded it. Historical and anthropological methods demonstrate how intelligent African farmers' own land management can be, while scientists and policy makers have misunderstood the African environment. The book provides a new framework for ecological anthropology, and a challenge to old assumptions about the African landscape.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

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

    PubMed

    Bardet, Michel; Pournou, Anastasia

    2015-01-01

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

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

    PubMed

    Morley, Robert J; Dick, Christopher W

    2003-11-01

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

  15. Further data about venous channels in South African Plio-Pleistocene hominids

    Microsoft Academic Search

    José Braga; Christophe Boesch

    1997-01-01

    Original data about venous channels in South African Plio-Pleistocene hominids are discussed. To assess possible changes in blood volume flow of fossil hominids, we test whether dimensions of three extracranial venous foramina were different betweenAustralopithecus africanusandAustralopithecus (Paranthropus) robustusMoreover, providing further data about the small sample of South African Plio-Pleistocene hominids, we also attempt to re-analyse the incidence of divided hypoglossal

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  17. The Vendian (Ediacaran) in the geological record: Enigmas in geology's prelude to the Cambrian explosion

    Microsoft Academic Search

    G. J. H. McCall

    2006-01-01

    Up to the 1950s, the Precambrian was regarded as unrewardingly unfossiliferous, records of fossils being isolated, few in number and dubious. The change came with the discovery by Reg Sprigg of body fossils in latest Proterozoic sediments in South Australia. Although there had been descriptions of isolated fossils (now recognised as Ediacaran) from rocks of this age in the nineteenth

  18. Dinosaur Fossils Predict Body Temperatures

    PubMed Central

    Allen, Andrew P; Charnov, Eric L

    2006-01-01

    Perhaps the greatest mystery surrounding dinosaurs concerns whether they were endotherms, ectotherms, or some unique intermediate form. Here we present a model that yields estimates of dinosaur body temperature based on ontogenetic growth trajectories obtained from fossil bones. The model predicts that dinosaur body temperatures increased with body mass from approximately 25 °C at 12 kg to approximately 41 °C at 13,000 kg. The model also successfully predicts observed increases in body temperature with body mass for extant crocodiles. These results provide direct evidence that dinosaurs were reptiles that exhibited inertial homeothermy. PMID:16817695

  19. Major Radiations in the Evolution of Caviid Rodents: Reconciling Fossils, Ghost Lineages, and Relaxed Molecular Clocks

    PubMed Central

    Pérez, María Encarnación; Pol, Diego

    2012-01-01

    Background Caviidae is a diverse group of caviomorph rodents that is broadly distributed in South America and is divided into three highly divergent extant lineages: Caviinae (cavies), Dolichotinae (maras), and Hydrochoerinae (capybaras). The fossil record of Caviidae is only abundant and diverse since the late Miocene. Caviids belongs to Cavioidea sensu stricto (Cavioidea s.s.) that also includes a diverse assemblage of extinct taxa recorded from the late Oligocene to the middle Miocene of South America (“eocardiids”). Results A phylogenetic analysis combining morphological and molecular data is presented here, evaluating the time of diversification of selected nodes based on the calibration of phylogenetic trees with fossil taxa and the use of relaxed molecular clocks. This analysis reveals three major phases of diversification in the evolutionary history of Cavioidea s.s. The first two phases involve two successive radiations of extinct lineages that occurred during the late Oligocene and the early Miocene. The third phase consists of the diversification of Caviidae. The initial split of caviids is dated as middle Miocene by the fossil record. This date falls within the 95% higher probability distribution estimated by the relaxed Bayesian molecular clock, although the mean age estimate ages are 3.5 to 7 Myr older. The initial split of caviids is followed by an obscure period of poor fossil record (refered here as the Mayoan gap) and then by the appearance of highly differentiated modern lineages of caviids, which evidentially occurred at the late Miocene as indicated by both the fossil record and molecular clock estimates. Conclusions The integrated approach used here allowed us identifying the agreements and discrepancies of the fossil record and molecular clock estimates on the timing of the major events in cavioid evolution, revealing evolutionary patterns that would not have been possible to gather using only molecular or paleontological data alone. PMID:23144757

  20. Fossil energy program. Summary document

    SciTech Connect

    None

    1980-05-01

    This program summary document presents a comprehensive overview of the research, development, and demonstration (RD and D) activities that will be performed in FY 1981 by the Assistant Secretary for Fossil Energy (ASFE), US Department of Energy (DOE). The ASFE technology programs for the fossil resources of coal, petroleum (including oil shale) and gas have been established with the goal of making substantive contributions to the nation's future supply and efficienty use of energy. On April 29, 1977, the Administration submitted to Congress the National Energy Plan (NEP) and accompanying legislative proposals designed to establish a coherent energy policy structure for the United States. Congress passed the National Energy Act (NEA) on October 15, 1978, which allows implementation of the vital parts of the NEP. The NEP was supplemented by additional energy policy statements culminating in the President's address on July 15, 1979, presenting a program to further reduce dependence on imported petroleum. The passage of the NEA-related energy programs represent specific steps by the Administration and Congress to reorganize, redirect, and clarify the role of the Federal Government in the formulation and execution of national energy policy and programs. The energy technology RD and D prog4rams carried out by ASFE are an important part of the Federal Government's effort to provide the combination and amounts of energy resources needed to ensure national security and continued economic growth.

  1. Teaching Through Trade Books: Fascinating Fossil Finds

    NSDL National Science Digital Library

    Chrstine Anne Royce

    2004-10-01

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

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

    PubMed Central

    Sansom, Robert S.; Wills, Matthew A.

    2013-01-01

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

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

    PubMed

    Ross, L J

    1992-01-01

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

  4. Biofilm Growth and Fossil Form

    E-print Network

    Petroff, Alexander P.

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

  5. The Microbial Origin of Fossil Fuels

    Microsoft Academic Search

    Guy Ourisson; Pierre Albrecht; Michel Rohmer

    1984-01-01

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

  6. Fossil fuel usage and the environment

    Microsoft Academic Search

    Klass

    1990-01-01

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

  7. Capturing and Storing Fossil-Fuel Carbon

    Microsoft Academic Search

    David Keith

    2002-01-01

    Can the global energy system continue to be dominated by fossil fuels throughout the 21st century without leading to an unacceptable rise in the concentration of atmospheric CO2? Yes, if a substantial fraction of the carbon in the fossil fuels can be captured and stored elsewhere than in the atmosphere. Of critical importance are: 1) the commercialization of a non-carbon

  8. The original colours of fossil beetles.

    PubMed

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

    2012-03-22

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

  9. 56 SCIENCE SCOPE Fossil sharks: Learning

    E-print Network

    Bermingham, Eldredge

    , that particular area was cov- ered with water. Plate tectonics Scientific evidence indicates that the positions of continents have changed over geologic time as a result of plate tectonics. These Earth move- ments have Fossils tell important stories about plate tectonics. Re- lated fossils are often discovered at varied

  10. HEMATITE AND CALCITE COATINGS ON FOSSIL VERTEBRATES

    Microsoft Academic Search

    HUIMING BAO; PAUL L. KOCH; ROBERT P. HEPPLE

    Hematite coatings are common on vertebrate fossils from Paleocene\\/Eocene paleosol deposits in the Bighorn Basin, Wyoming. In general, hematite coatings are found only on fossils and are limited to soils exhibiting hydromorphic features and moderate maturity. Pet- rographic and isotopic evidence suggests that hematite and micritic calcite formed at nearly the same time in a pedogenic environment, whereas sparry calcite

  11. CD Recorders.

    ERIC Educational Resources Information Center

    Falk, Howard

    1998-01-01

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

  12. Precambrian evolution and the rock record

    NASA Astrophysics Data System (ADS)

    Awramik, S.

    1985-07-01

    The Precambrian time which refers to geological time prior to the first appearance of animals with mineralized hard parts was investigated. Best estimates for this event are around 570 million years ago. Because the rock record begins some 3,800 million years ago the Precambrian encompasses about 84% of geologic time. The fossil record for this immense span of time is dominated by prokaryotes and the sedimentary structures produced by them. The first fossil remains that are considered eukaryotic are found in 1,000 million year old rocks. The first animals may be as old as 700 million years. The fossil records of the first 84% of the Earth's history are collected and described.

  13. An African Odyssey.

    ERIC Educational Resources Information Center

    DeLoach, Marva L.

    1985-01-01

    Reports on the First African and African-American International Federation of Library Associations Pre-Conference Seminar, which was held in Nairobi, Kenya, in August 1984. Papers and issues highlighted cover publishing and ethnic collections, combatting racism, children's services, school libraries, public library services, academic libraries,…

  14. Educating African American Males

    ERIC Educational Resources Information Center

    Bell, Edward E.

    2010-01-01

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

  15. Keeping African Masks Real

    ERIC Educational Resources Information Center

    Waddington, Susan

    2012-01-01

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

  16. African swine fever

    Microsoft Academic Search

    MARY-LOUISE PENRITH

    2009-01-01

    PENRITH, M-L. 2009. African swine fever. Onderstepoort Journal of Veterinary Research, 76:91-95 African swine fever (ASF) is a devastating haemorrhagic fever of pigs that causes up to 100 % mortal- ity, for which there is no vaccine. It is caused by a unique DNA virus that is maintained in an ancient cycle between warthogs and argasid ticks, making it the

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

    Microsoft Academic Search

    A. J. Boucot

    1999-01-01

    The Palaeozoic marine invertebrate fossil record in southern Africa is characterised by extensive data for the Early and Middle Devonian but extremely limited or absent for other Palaeozoic Periods. The Mesozoic Era is lacking in marine invertebrate fossils for the Triassic, Late Jurassic, and Cretaceous. For the Cenozoic Era there is limited marine megafossil information. Overall, in benthic, cool waters,

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

    PubMed Central

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

    2014-01-01

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

  19. The oldest gibbon fossil (Hylobatidae) from insular Southeast Asia: evidence from Trinil, (East Java, Indonesia), Lower/Middle Pleistocene.

    PubMed

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Kohn, Matthew J.; Schoeninger, Margaret J.; Barker, William W.

    1999-09-01

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

  1. Lifetime of the Fossil Field in Titan's Ionosphere

    NASA Astrophysics Data System (ADS)

    Ma, Yingjuan; Russell, Christopher T.; Wei, Hanying; Nagy, Andrew F.; Toth, Gabor; Dougherty, Michele K.; Coates, Andrew J.; Wahlund, Jan-Erik; Edberg, Niklas J. T.

    2015-04-01

    Cassini spacecraft has made more than 100 Titan flybys since October 2004. Among these flybys, there are a few special ones (T32, T42, T85, T96). During or shortly before periapsis on these encounters, Titan was found to be outside the Saturnian magnetosphere, in the magnetosheath region or directly exposed in the solar wind. During the T32 flyby, the first magnetosheath encounter, simulation results and observations clearly demonstrated the existence of fossil field, because the magnetic field direction in the magnetosheath region was opposite to the field orientation surrounding Titan when it had been inside the Saturnian magnetosphere. However, because Cassini passed by Titan shortly after the magnetopause crossing, this flyby only provides a lower limit of the lifetime of the fossil field. Quantifying the lifetime of the fossil field has important implications for understanding the magnetic field of other Titan flybys. Since the plasma is highly dynamic in Saturn's outer magnetosphere, even though the ambient plasma condition is not changing as dramatically as discussed in the presented flyby, Titan's ionosphere could still record some of those changes so that the observed field in the deep ionosphere might have very complicated signatures. The same behavior could also occur at Venus and Mars (in the weak crustal field region), which would help us to understand the complicated magnetic signatures in un-magnetized planetary ionospheres. In this paper, we present observations and simulation results for the other three Titan flybys to provide a better constraint on the lifetime of the fossil field in Titan's ionosphere.

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

    SciTech Connect

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

    1999-09-01

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

  3. Albian extrusion evidences of the Triassic salt and clues of the beginning of the Eocene atlasic phase from the example of the Chitana-Ed Djebs structure (N.Tunisia): Implication in the North African Tethyan margin recorded events, comparisons

    NASA Astrophysics Data System (ADS)

    Slama, Mohamed-Montassar Ben; Masrouhi, Amara; Ghanmi, Mohamed; Youssef, Mohamed Ben; Zargouni, Fouad

    2009-07-01

    In the northern part of Tunisia, close to Testour/Slouguia, new observations and updated biostratigraphy make it possible to highlight the relation between the Triassic saliferous mass and the surrounding Mesozoic beds (T. M.). Near the (T. M.) boundary, the formations observed consist dominantly of Triassic evaporites reworked in the Early and Late Albian deep-water sedimentary deposits. Throughout the studied area, Jurassic rocks are absent. We propose to interpret the Chitana-Ed Djebs structure originally emplaced as gravitational stretch masses in a passive margin in the same way as the salt bodies of widespread salt province in the Gulf of Mexico. A reconstructed schematic position of the Chitana-Ed Djebs salt body displays a scenario of setting of the salt mass on a submarine palaeo-slope. Moreover, the starting clues of the paroxysmal event of the Late Mesozoic tectonic inversion clearly fossilized through the discordance of the Middle Eocene-Early Lutetian limestone on the Albian series.

  4. Diabetes in African Americans

    PubMed Central

    Marshall, M

    2005-01-01

    African Americans have a high risk for type 2 diabetes. Genetic traits, the prevalence of obesity, and insulin resistance all contribute to the risk of diabetes in the African American community. African Americans have a high rate of diabetic complications, because of poor glycaemic control and racial disparities in health care in the USA. African Americans with diabetes may have an atypical presentation that simulates type 1 diabetes, but then their subsequent clinical course is typical of type 2 diabetes. Culturally sensitive strategies, structured disease management protocols, and the assistance of nurses, diabetic educators, and other health care professionals are effective in improving the outcome of diabetes in the African American community. PMID:16344294

  5. Is evolutionary history repeatedly rewritten in light of new fossil discoveries?

    E-print Network

    Benton, Michael

    these datasets are premature? We use two exemplars--catarrhine primates (Old World monkeys and apes) and non they are exploited to derive grand macroevolutionary hypotheses. Keywords: fossil record; macroevolution; primate merely fill previously known gaps rather than identifying entirely new (and previously unknown) clades

  6. Preservation of Fossilized Biogenic Organic Matter and Associated Biominerals in High Pressure Metamorphic Rocks

    Microsoft Academic Search

    S. Bernard; O. Beyssac; K. Benzerara; N. Menguy; F. Guyot; G. E. Brown; B. Goffe

    2006-01-01

    Detecting traces of life in fossilized Organic Matter (OM) from metasedimentary rocks is a challenge for the search of life in the geological record. For instance, the respective influences of pressure, temperature, time, and the chemistry of both the host sediments and OM precursor on the conversion of OM during diagenetic and metamorphic processes remain tentative. By combining Raman Microspectroscopy

  7. Disentangling temporal patterns in our perception of the fossil history of gymnosperms

    Microsoft Academic Search

    Borja Cascales-Miñana

    2011-01-01

    By taking gymnosperms as a case study, this article evaluates the perception of plant life history from the fossil record to test the biases associated with the time-dependent aspects of the taxonomy, following a stepwise modelling procedure based on two divergent sets of time units. The idea that the effects of the temporal component of paleobiological inference need to be

  8. Disentangling temporal patterns in our perception of the fossil history of gymnosperms

    Microsoft Academic Search

    Borja Cascales-Miñana

    2012-01-01

    By taking gymnosperms as a case study, this article evaluates the perception of plant life history from the fossil record to test the biases associated with the time-dependent aspects of the taxonomy, following a stepwise modelling procedure based on two divergent sets of time units. The idea that the effects of the temporal component of paleobiological inference need to be

  9. African bees to control African elephants

    NASA Astrophysics Data System (ADS)

    Vollrath, Fritz; Douglas-Hamilton, Iain

    2002-11-01

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

  10. Clean Fossil Energy Conversion Processes

    NASA Astrophysics Data System (ADS)

    Fan, L.-S.

    2007-03-01

    Absolute and per-capita energy consumption is bound to increase globally, leading to a projected increase in energy requirements of 50% by 2020. The primary source for providing a majority of the energy will continue to be fossil fuels. However, an array of enabling technologies needs to be proven for the realization of a zero emission power, fuel or chemical plants in the near future. Opportunities to develop new processes, driven by the regulatory requirements for the reduction or elimination of gaseous and particulate pollutant abound. This presentation describes the chemistry, reaction mechanisms, reactor design, system engineering, economics, and regulations that surround the utilization of clean coal energy. The presentation will cover the salient features of the fundamental and process aspects of the clean coal technologies in practice as well as in development. These technologies include those for the cleaning of SO2, H2S, NOx, and heavy metals, and separation of CO2 from the flue gas or the syngas. Further, new combustion and gasification processes based on the chemical looping concepts will be illustrated in the context of the looping particle design, process heat integration, energy conversion efficiency, and economics.

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

    PubMed Central

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

    2004-01-01

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

  12. Notes on African Pannariaceae (lichenized ascomycetes)

    Microsoft Academic Search

    Per M. Jørgensen

    2003-01-01

    Abstract:The African continent is shown to contain only 38 species in the lichen familyPannariaceae , all of which are listed in the conclusion. Four new species are described: Pannaria planiuscula (Republic of South Africa [RSA] and Kenya), Pannaria squamulosa (RSA), Parmeliella dactylifera (RSA), and Parmeliella triptophylloides (Kenya). Four species are recorded as new to the continent: Pannaria centrifuga P.M. Jørg.

  13. Colorectal Cancer in African Americans

    Microsoft Academic Search

    Sangeeta Agrawal; Anand Bhupinderjit; Manoop S. Bhutani; Lisa Boardman; Cuong Nguyen; Yvonne Romero; Radhika Srinvasan; Colmar Figueroa-Moseley

    2005-01-01

    Colorectal cancer in African Americans has an increased incidence and mortality relative to Whites. The mean age of CRC development in African Americans is younger than that of Whites. There is also evidence for a more proximal colonic distribution of cancers and adenomas in African Americans.African Americans are less likely to have undergone diagnostic testing and screening for colorectal cancer.

  14. Scleractinian Fossil Corals as Archives of Seawater ?26Mg

    NASA Astrophysics Data System (ADS)

    Gothmann, A. O.; Higgins, J. A.; Adkins, J. F.; Stolarski, J.; Bender, M. L.

    2014-12-01

    The recovery of environmental signatures from coral skeletons is often made difficult by 'vital effects', which cause skeletal chemistry to deviate from the expected composition of aragonite in equilibrium with seawater. Recent studies show that Mg isotopes in scleractinian corals are subject to vital effects, which appear as a departure of the ?26Mg coral temperature dependence from that of inorganic aragonite [1]. However, different from the case for Mg/Ca or ?44Ca in coral, the magnitude of the observed Mg-isotope vital effect is small (on the order of 0.1 ‰ or less). In addition, measurements of different species of modern coral show similar fractionations, suggesting that coral ?26Mg is not species dependent [2]. Together, these observations indicate that corals should faithfully record the seawater Mg-isotope composition, and that vital effects will not bias reconstructions. We measured Mg isotopes in a set of extremely well-preserved fossil scleractinian corals, ranging in age from Jurassic through Recent, to reconstruct past seawater ?26Mg. Well-preserved fossil corals of similar age show a range in ?26Mg of ~0.2 ‰, pointing to the presence of vital effects. However, our results show little variability in the ?26Mg of fossil corals across different geologic ages, suggesting that seawater ?26Mg has remained relatively constant throughout the Cenozoic and Mesozoic. This pattern has implications for our understanding of the mechanisms driving secular variations in seawater Mg/Ca. In particular, our data imply that dolomitization rates have not changed enough during the Mesozoic and Cenozoic to account for secular variations in seawater Mg/Ca. Our coral ?26Mg record agrees with a Cenozoic record from bulk foraminifera, further supporting the faithfulness of the coral archive. However, both of these records disagree with a third Cenozoic Mg-isotope record, derived from species-specific planktic forams [3]. [1] Saenger, C. et al. (2014) Chem. Geol. 360-361, 105-117. [2] Wombacher, F. et al. (2011) Geochim. Cosmochim. Acta 75, 5797-5818. [3] Pogge von Strandmann, P.A.E. et al. (2014) Biogeosciences Discuss. 11, 7451-7484.

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2012-01-01

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

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

    PubMed Central

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

    2012-01-01

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

  18. Relationship of Plasma Growth Hormone to Slow-Wave Sleep in African Sleeping Sickness

    Microsoft Academic Search

    Manny W. Radomski; Alain Buguet; Félix Doua; Pascal Bogui; Philippe Tapie

    1996-01-01

    Human African trypanosomiasis (sleeping sickness) is a unique disease model of disrupted circadian rhythms in the sleep-wake cycle and cortisol and prolactin secretion. This study examined the temporal relationship between growth hormone (GH) secretion and the sleep-wake cycle in 8 infected African patients and 6 healthy indigenous African subjects. Twenty-four-hour sleep patterns were recorded by polysomnography and hourly blood samples

  19. African American History

    NSDL National Science Digital Library

    1997-01-01

    The Mississippi State University African American History Archive is a great place to start for pointers to African American history sites, as well as an excellent repository of African American history primary documents. The sites include Adonis Productions' Black Pioneers page (with pages on African American pioneers in all fields), Great Day In Harlem (jazz), Mississippi State's AfriGeneas genealogy mailing list and Web site, Small Towns-Black Lives in New Jersey, African American pioneers in Kentucky law, and the International Museum of the Horse's Buffalo Soldier pages. Full text documents include Dr. Martin Luther King's "I Have a Dream" speech, Booker T. Washington's "Up From Slavery", Frederick Douglass' "Autobiography" and "My Escape from Slavery", and Henry David Thoreau's "A Plea for Captain John Brown" and "Slavery in Massachussetts", among others. The site also contains African American bibliographies in the arts, education, history, and science, as well as pointers to other African American sites. http://www.msstate.edu/Archives/History/USA/Afro-Amer/afro.html

  20. Traditional African Informal Instructional Paradigm in African and African-American Children's Literature.

    ERIC Educational Resources Information Center

    Osa, Osayimwense

    1997-01-01

    Demonstrates the use of African storytelling for informal teaching of African traditions and values in today's African-American community. The instruction is shown in content and context in three literary works: "An African Night's Entertainment,""The Passport of Mallam Ilia," and "The Secret of Gumbo Grove." (MMU)

  1. The African Water Page

    NSDL National Science Digital Library

    Abrams, Leonard John.

    1995-01-01

    Created by Len Abrams, the goal of the African Water Page is to "increase communication on the Continent of Africa between people working in water." Issues for discussion include "water policy, water resource management, water supply and environmental sanitation, water conservation and demand management." Visitors to this page can find information about recent policy initiatives in South Africa, water related documents concerning South Africa, Zimbabwe, the African continent, and some international topics. Also included are links to South and Southern African and International sites.

  2. Ashfall Fossil Beds State Historical Park

    NSDL National Science Digital Library

    Approximately 12 million years ago, a massive volcano in the southwestern corner of Idaho erupted and spread a tremendous blanket of ash over a large area. Much of this ash settled over the grasslands of northeastern Nebraska. Animals consumed the ash-covered grasses, and eventually they began to perish as a result of consuming this abrasive powder. Eventually these animals and their skeletons became fossilized, and this area is now the Ashfall Fossil Beds State Historical Park. Visitors to the Park's website will be delighted to learn that they can view a range of images and videos from the fossil beds, along with an excellent interactive skeleton map that documents the fossilized remains on site. Also, the "Ashfall Geology" site is uniformly excellent, and it includes aerial views of the site and details about the geological formations in the area. Finally, the "Ashfall Animals" area contains information about the paleontological finds, which include five horse species and a saber-toothed deer.

  3. How a Dinosaur Became a Fossil

    NSDL National Science Digital Library

    WGBH Educational Foundation

    2005-12-17

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

  4. Hybrid solar-fossil fuel power generation

    E-print Network

    Sheu, Elysia J. (Elysia Ja-Zeng)

    2012-01-01

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

  5. Method of burning a fossil fuel

    Microsoft Academic Search

    Whelan

    1978-01-01

    A method is disclosed for burning a fossil fuel and air with the emmission of an exhaust gas consisting essentially of atmospheric gases, carbon dioxide and water vapor and essentially free of carbon monoxide, hydrocarbons and nitric oxide, which comprises burning the fossil fuel at a temperature between 1000°C and 1500°C with less than the stoichiometric amount of atmospheric oxygen

  6. Adventures in Paleontology: 36 Classroom Fossil Activities

    NSDL National Science Digital Library

    Irwin Slesnick

    2006-01-01

    Millions of years after vanishing from the Earth, dinosaurs still have the power to stir students' curiosity. Deepen that interest with Adventures in Paleontology, a series of lively hands-on activities especially for middle schoolers. This beautifully illustrated full color book features 36 activities that open students up to a variety of foundational sciences, including biology, geology, chemistry, physics, and astronomy. For example: ? "How Do Fossils Form?" discusses how organisms become fossils and illustrates the concept with activities that simulate fossil-making processes. ? "What Can You Learn From Fossils?" explores what fossils teach about ancient organisms. ? "Mass Extinction and Meteor Collisions With Earth" discusses recently discovered links between meteor and asteroid impacts on Earth and the demise of animals like dinosaurs. Other chapters cover how to tell the age of the Earth; how dinosaurs evolved; and diversity, classification, and taxonomy. The final chapters offer humanistic perspectives on fossils in literature and art. As an attention-grabbing complement to the text, vivid full color illustrations show not just skeletons and animal tracks but also what dinosaurs probably looked like in their natural settings. Handy line drawings guide students through each step of the activities.

  7. Geography, insolation, and vitamin D in nineteenth century US African-American and white statures

    Microsoft Academic Search

    Scott Alan Carson

    2009-01-01

    Using a new source of nineteenth century US state prison records I contrast the biological living conditions of comparable African-Americans and whites. Although blacks and whites today in the US reach similar terminal statures, nineteenth century African-American statures were consistently shorter than those of whites. Greater insolation (vitamin D production) is shown to be associated with taller black and white

  8. A fossil peronosporomycete oogonium with an unusual surface ornament from the Carboniferous of France.

    PubMed

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

    2010-01-01

    A new fossil peronosporomycete from the upper Visean (Mississippian) of France occurs as a globose oogonium at the tip of a thin-walled hypha. The oogonium surface is prominently ornamented by densely spaced, long and subtle, straight or once to several times furcated thread-like extensions; many possess an opaque, bulb-like swelling at base. Antheridia adpressed to the oogonium are clavate and paragynous. This fossil represents only the third record of an unequivocal peronosporomycete from the Carboniferous, and thus provides important details about the evolutionary history of this group of organisms. PMID:20943155

  9. Is evolutionary history repeatedly rewritten in light of new fossil discoveries?

    PubMed

    Tarver, J E; Donoghue, P C J; Benton, M J

    2011-02-22

    Mass media and popular science journals commonly report that new fossil discoveries have 'rewritten evolutionary history'. Is this merely journalistic hyperbole or is our sampling of systematic diversity so limited that attempts to derive evolutionary history from these datasets are premature? We use two exemplars-catarrhine primates (Old World monkeys and apes) and non-avian dinosaurs-to investigate how the maturity of datasets can be assessed. Both groups have been intensively studied over the past 200 years and so should represent pinnacles in our knowledge of vertebrate systematic diversity. We test the maturity of these datasets by assessing the completeness of their fossil records, their susceptibility to changes in macroevolutionary hypotheses and the balance of their phylogenies through study time. Catarrhines have shown prolonged stability, with discoveries of new species being evenly distributed across the phylogeny, and thus have had little impact on our understanding of their fossil record, diversification and evolution. The reverse is true for dinosaurs, where the addition of new species has been non-random and, consequentially, their fossil record, tree shape and our understanding of their diversification is rapidly changing. The conclusions derived from these analyses are relevant more generally: the maturity of systematic datasets can and should be assessed before they are exploited to derive grand macroevolutionary hypotheses. PMID:20810435

  10. African American Suicide

    MedlinePLUS

    ... accounted for 83.8% of Caucasian elderly suicides. Firearms were the predominant method of • suicide among African ... on 2012 Data (2014) Source: Centers for Disease Control and Prevention. National Vital Statistics System. Mortality Data. ...

  11. Aboard a spider--a complex developmental strategy fossilized in amber.

    PubMed

    Ohl, Michael

    2011-05-01

    Mantid flies (Mantispidae) are an unusual group of lacewings (Neuroptera). Adults markedly resemble mantids in their general appearance and predatory behavior. The larvae of most mantispids exclusively prey on spider eggs, whereby the first instar larva is highly mobile and active and the other two larval stages immobile and maggot like. One of the larval strategies to pursue spider eggs is spider-boarding. Here, I report on the first record of a fossil mantispid larva. It was found in Middle Eocene Baltic amber, and it is the first record of Mantispidae from this deposit. The larva is attached to a clubionoid spider in a position typical for most mantispid larvae, and, thus, it is also the first fossil record of this complex larval behavior and development. PMID:21431410

  12. National Museum of African Art: Artful Animals

    NSDL National Science Digital Library

    The Smithsonian Institution's Museum of African Art has a delightful online kid-friendly exhibit, and it can be explored in detail here. The "Introduction" explains that African art depicts some animals more than others, and some not at all. The cheetah and the zebra do not appear to be found in any of the art, and the ostrich and gorilla appear only rarely. The main page divides the artwork up by general animal type, such as "Leopards and Lions", "Mudfish, Water Spirits and Snails", and "Look for the Animals", which is a work of art that has several different animals in it. Many of the images of the artworks also have a link called "Kids! Click Here" that lead to fun facts about the animals in the artwork. The descriptions of the art that accompany the images inform visitors about the animals depicted, but also about the role or use of the animal in African societies. Finally, visitors shouldn't miss the recording of the director of the National Museum of African Art reading an Asante tale, called the Leopard's Drum, at the end of the exhibit.

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

    PubMed

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

    2015-06-01

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

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

    NASA Astrophysics Data System (ADS)

    McCormick, T.; Howe, M. P.

    2013-12-01

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

  15. Fossil echinoid (Echinoidea, Echinodermata) diversity of the Early Cretaceous (Hauterivian) in the Paris Basin (France)

    PubMed Central

    Benetti, Sophie; Saucède, Thomas; David, Bruno

    2013-01-01

    Abstract This dataset inventories occurrence records of fossil echinoid specimens collected in the Calcaires à Spatangues Formation (CSF) that crops out in the southeast of the Paris Basin (France), and is dated from the Acanthodiscus radiatus chronozone (ca. 132 Ma, early Hauterivian, Early Cretaceous). Fossil richness and abundance of the CSF has attracted the attention of palaeontologists since the middle of the nineteenth century. This dataset compiles occurrence data (referenced by locality names and geographic coordinates with decimal numbers) of fossil echinoids both collated from the literature published over a century and a half, and completed by data from collection specimens. The dataset also gives information on taxonomy (from species to order and higher taxonomic levels), which has been checked for reliability and consistency. It compiles a total of 628 georeferenced occurrence data of 26 echinoid species represented by 22 genera, 14 families, and 9 orders. PMID:24003321

  16. A methodological framework for assessing and reducing temporal uncertainty in paleovegetation mapping from late-Quaternary pollen records

    Microsoft Academic Search

    Jessica L. Blois; Eric C. Grimm; Stephen T. Jackson; Russell W. Graham

    2011-01-01

    Mapping past vegetation dynamics from heterogeneous databases of fossil-pollen records must face the challenge of temporal uncertainty. The growing collection of densely sampled fossil-pollen records with accurate and precise chronologies allows us to develop new methods to assess and reduce this uncertainty. Here, we test our methods in the context of vegetation changes in eastern North America during the abrupt

  17. Pharmacokinetics of pindolol in Africans

    Microsoft Academic Search

    L. A. Salako; A. Ragon; Risquat A. Adio; A. O. Falase

    1979-01-01

    Summary The pharmacokinetics of pindolol were determined in 12 hypertensive African subjects after a single oral dose of the drug. The estimated pharmacokinetic parameters do not differ significantly in Africans from the values which have been obtained in other races.

  18. African Magazines for American Libraries

    ERIC Educational Resources Information Center

    Berman, Sanford

    1970-01-01

    From the varied spectrum of African periodical publishing, a selection of particular interest - an annotated bibliography of English-language titles produced wholly (or mainly) by Africans in Africa. (Editor/JB)

  19. Mental Health and African Americans

    MedlinePLUS

    ... Minority Population Profiles > Black/African American > Mental Health Mental Health and African Americans Poverty level affects mental health ... compared to 120% of Non-Hispanic Whites. 1 MENTAL HEALTH STATUS Serious psychological distress among adults 18 years ...

  20. Application of biochemical interactions in fossil fuels

    SciTech Connect

    Lin, M.S.; Premuzic, E.T.

    1994-12-31

    Certain extreme environments tolerant microorganisms interact with heavy crude oils by means of multiple biochemical reactions, asphaltenes, and bituminous materials. These reactions proceed via pathways which involve characteristic components of oils and coals such as asphaltenes, and in the chemically related constituents found in bituminous coals. These chemical components serve as markers of the interactions between microorganisms and fossil fuels. Studies in which temperature, pressure, and salinity tolerant microorganisms have been allowed to interact with different crude oils and bituminous coals, have shown that biochemically induced changes occur in the distribution of hydrocarbons and in the chemical nature of organometallic and heterocyclic compounds. Such structural chemical rearrangements have direct applications in monitoring the efficiency, the extent, and the chemical nature of the fossil fuels bioconversion. Recent developments of chemical marker applications in the monitoring of fossil fuels bioconversion will be discussed.

  1. Expressions of climate perturbations in western Ugandan crater lake sediment records during the last 1000 years

    NASA Astrophysics Data System (ADS)

    Mills, K.; Ryves, D. B.; Anderson, N. J.; Bryant, C. L.; Tyler, J. J.

    2014-08-01

    Equatorial East Africa has a complex regional patchwork of climate regimes, sensitive to climate fluctuations over a variety of temporal and spatial scales during the late Holocene. Understanding how these changes are recorded in and interpreted from biological and geochemical proxies in lake sedimentary records remains a key challenge to answering fundamental questions regarding the nature, spatial extent and synchroneity of climatic changes seen in East African palaeo-records. Using a paired lake approach, where neighbouring lakes share the same geology, climate and landscape, it might be expected that the systems will respond similarly to external climate forcing. Sediment cores from two crater lakes in western Uganda spanning the last ~1000 years were examined to assess diatom community responses to late Holocene climate and environmental changes, and to test responses to multiple drivers using redundancy analysis (RDA). These archives provide annual to sub-decadal records of environmental change. Lakes Nyamogusingiri and Kyasanduka appear to operate as independent systems in their recording of a similar hydrological response signal via distinct diatom records. However, whilst their fossil diatom records demonstrate an individualistic, indirect response to external (e.g. climatic) drivers, the inferred lake levels show similar overall trends and reflect the broader patterns observed in Uganda and across East Africa. The lakes appear to be sensitive to large-scale climatic perturbations, with evidence of a dry Medieval Climate Anomaly (MCA; ca. AD 1000-1200). The diatom record from Lake Nyamogusingiri suggests a drying climate during the main phase of the Little Ice Age (LIA) (ca. AD 1600-1800), whereas the diatom response from the shallower Lake Kyasanduka is more complex (with groundwater likely playing a key role), and may be driven more by changes in silica and other nutrients, rather than by lake level. The sensitivity of these two Ugandan lakes to regional climate drivers breaks down in ca. AD 1800, when major changes in the ecosystems appear to be a response to increasing cultural impacts within the lake catchments, although both proxy records appear to respond to the drought recorded across East Africa in the mid-20th century. The data highlight the complexity of diatom community responses to external drivers (climate or cultural), even in neighbouring, shallow freshwater lakes. This research also illustrates the importance of, and the need to move towards, a multi-lake, multi-proxy landscape approach to understanding regional hydrological change which will allow for rigorous testing of climate reconstructions, climate forcing and ecosystem response models.

  2. Fossil generation restructuring in the Ukraine

    SciTech Connect

    Galambas, J.W. [Hagler Bailly Consulting, Inc., Boulder, CO (United States)

    1996-12-31

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

  3. How Do Scientists Find Dinosaur Fossils?

    NSDL National Science Digital Library

    This lesson plan is about the process by which paleontologists locate, excavate, and study dinosaurs. Students will write journal entries pretending they are on a dinosaur dig. They will also make fact sheets about this recently discovered Jobaria dinosaur; place Jobaria into a timeline to indicate the periods in which it lived; visit a website to learn about the steps involved in finding and excavating dinosaur fossils, then list these steps and explain their importance; describe what the bones in an interactive Jobaria skeleton indicate about this dinosaur; and view pictures of a trip teenagers took to look for dinosaur fossils.

  4. First discovery of Pleistocene orangutan (Pongo sp.) fossils in Peninsular Malaysia: biogeographic and paleoenvironmental implications.

    PubMed

    Ibrahim, Yasamin Kh; Tshen, Lim Tze; Westaway, Kira E; Cranbrook, Earl Of; Humphrey, Louise; Muhammad, Ros Fatihah; Zhao, Jian-xin; Peng, Lee Chai

    2013-12-01

    Nine isolated fossil Pongo teeth from two cave sites in Peninsular Malaysia are reported. These are the first fossil Pongo specimens recorded in Peninsular Malaysia and represent significant southward extensions of the ancient Southeast Asian continental range of fossil Pongo during two key periods of the Quaternary. These new records from Peninsular Malaysia show that ancestral Pongo successfully passed the major biogeographical divide between mainland continental Southeast Asia and the Sunda subregion before 500 ka (thousand years ago). If the presence of Pongo remains in fossil assemblages indicates prevailing forest habitat, then the persistence of Pongo at Batu Caves until 60 ka implies that during the Last Glacial Phase sufficient forest cover persisted in the west coast plain of what is now Peninsular Malaysia at least ten millennia after a presumed corridor of desiccation had extended to central and east Java. Ultimately, environmental conditions of the peninsula during the Last Glacial Maximum evidently became inhospitable for Pongo, causing local extinction. Following post-glacial climatic amelioration and reforestation, a renewed sea barrier prevented re-colonization from the rainforest refugium in Sumatra, accounting for the present day absence of Pongo in apparently hospitable lowland evergreen rainforest of Peninsular Malaysia. The new teeth provide further evidence that Pongo did not undergo a consistent trend toward dental size reduction over time. PMID:24210657

  5. African American Male Immersion Schools: Segregation? Separation? Or Innovation?

    ERIC Educational Resources Information Center

    National Urban League, Inc., New York, NY.

    This document is the transcript of a videotape recording of a roundtable discussion that was produced with four panelists and a moderator and was intended to provide educators and professionals who work with African-American males an opportunity to explore the background of educational initiatives for black males. These gender- and race-specific…

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  7. Geochemical Overview of the East African Rift System

    Microsoft Academic Search

    T. Furman

    2003-01-01

    Mafic volcanics of the East African Rift System (EARS) record a protracted history of continental extension that is linked to mantle plume activity. The modern EARS traverses two post-Miocene topographic domes separated by a region of polyphase extension in northern Kenya and southern Ethiopia. Basaltic magmatism commenced ˜45 Ma in this highly extended region, while the onset of plume-related activity

  8. The Program of African Studies

    E-print Network

    MacIver, Malcolm A.

    papers (see archive of past MGAPE papers). The Hip Hop Working Group sponsored talk "The Politics and Poetics of African Hip Hop" given by P, Khalil Saucier. 3 #12;RESEARCH The emphasis is on discussion from the group. AfricanHipHopWorkingGroup The African Hip Hop Working Group is entering its 2nd year

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

    PubMed

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

    2013-07-01

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

  10. Molecular fossils in Cretaceous condensate from western India

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Sharmila; Dutta, Suryendu; Dutta, Ratul

    2014-06-01

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

  11. Student Records.

    ERIC Educational Resources Information Center

    Hollander, Patricia A.

    1992-01-01

    Students clearly have a legal right to access to and privacy of their education records; but not so clear is public access to campus crime reports and AIDS-related records. Computerized records and the use of Social Security numbers as identifiers create other legal concerns. (Author)

  12. A Qualitative and Quantitative Comparison of Sedimentary Palynomorphs, Lipid Biomarkers and Fossil DNA: Which Tool Provides the Most Detailed Paleoecological and Paleoenvironmental Information?

    NASA Astrophysics Data System (ADS)

    Boere, A. C.; Abbas, B.; Rijpstra, W. I.; Volkman, J. K.; Sinninghe Damsté, J. S.; Coolen, M. J.

    2007-12-01

    In recent years, it was shown that Holocene planktonic taxa could be identified at the species-level based on their preserved fossil genetic signatures (fossil DNA) in either cold and/or sulfidic lacustrine and marine settings. Many of those species are not known to leave morphologically recognizable remains and thus most likely would have escaped microscopic determination and enumeration. In addition, fossil DNA analysis also revealed past planktonic taxa for which no specific lipid biomarkers are known. However, the best, and yet unexplored, approach to validate fossil DNA as paleoenvironmental tool would be based on a direct qualitative and quantitative comparison of each of the above described proxies. In an up to 2700-year-old record of undisturbed sulfidic sediments from the Small Meromictic Basin in Ellis Fjord, Antarctica, we compared the quantitative and qualitative distribution of fossil ribosomal DNA of phototrophic algae like diatoms, dinoflagellates and past chemocline bacteria (green sulfur bacteria) with the distribution of their fossil lipid biomarkers: highly branched isoprenoids, dinosterol and carotenoids. For dinoflagellates, we performed a comparative microscopic (palynological) analysis of fossil dinocysts whereas comparative diatom microfossil data was available from the literature. We will discuss important new insights about the cell-specific fate of fossil DNA and the additional paleoenvironmental information which was revealed from the fossil DNA analysis.

  13. Late Pleistocene Vertebrates and Other Fossils from Epiguruk, Northwestern Alaska

    USGS Publications Warehouse

    Hamilton, T.D.; Ashley, G.M.; Reed, K.M.; Schweger, C.E.

    1993-01-01

    Sediments exposed at Epiguruk, a large cutbank on the Kobuk River about 170 km inland from Kotzebue Sound, record multiple episodes of glacial-age alluviation followed by interstadial downcutting and formation of paleosols. Vertebrate remains from Epiguruk include mammoth, bison, caribou, an equid, a canid, arctic ground squirrel, lemmings, and voles. Radiocarbon ages of bone validated by concordant ages of peat and wood span the interval between about 37,000 and 14,000 yr B.P. The late Pleistocene pollen record is dominated by Cyperaceae, with Artemisia, Salix, Betula, and Gramineae also generally abundant. The fossil record from Epiguruk indicates that the Kobuk River valley supported tundra vegetation with abundant riparian willows during middle and late Wisconsin time. Large herbivores were present during the height of late Wisconsin glaciation as well as during its waning stage and the preceding interstadial interval. The Kobuk River valley would have been a favorable refugium for plants, animals, and possibly humans throughout the last glaciation.

  14. Microbial Cretaceous park: biodiversity of microbial fossils entrapped in amber.

    PubMed

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

    2009-05-01

    Microorganisms are the most ancient cells on this planet and they include key phyla for understanding cell evolution and Earth history, but, unfortunately, their microbial records are scarce. Here, we present a critical review of fossilized prokaryotic and eukaryotic microorganisms entrapped in Cretaceous ambers (but not exclusively from this geological period) obtained from deposits worldwide. Microbiota in ambers are rather diverse and include bacteria, fungi, and protists. We comment on the most important microbial records from the last 25 years, although it is not an exhaustive bibliographic compilation. The most frequently reported eukaryotic microfossils are shells of amoebae and protists with a cell wall or a complex cortex. Likewise, diverse dormant stages (palmeloid forms, resting cysts, spores, etc.) are abundant in ambers. Besides, viral and protist pathogens have been identified inside insects entrapped in amber. The situation regarding filamentous bacteria and fungi is quite confusing because in some cases, the same record was identified consecutively as a member of these phylogenetically distant groups. To avoid these identification errors in the future, we propose to apply a more resolute microscopic and analytical method in amber studies. Also, we discuss the most recent findings about ancient DNA repair and bacterial survival in remote substrates, which support the real possibility of ancient DNA amplification and bacterial resuscitation from Cretaceous resins. PMID:19214468

  15. The African Conservation Foundation

    NSDL National Science Digital Library

    Terry Harnwell

    2001-08-15

    This portal provides in-depth information about conservation issues and initiatives in Africa. The online searchable databases and forums showcase, promote and provide background information on almost 300 conservation organisations and protected area institutions across the continent. The African Conservation Foundation (ACF) is primarily concerned with education and capacity building in Africa in the areas of environment and conservation. Its mission is to support and link African conservation initiatives, groups and NGOs, with the aim of strengthening their capacity, building partnerships and promoting effective communication and co-ordination of conservation efforts.

  16. ?44/40Ca variations of seawater from Cenozoic and Mesozoic fossil corals

    NASA Astrophysics Data System (ADS)

    Gothmann, A. O.; Higgins, J. A.; Blättler, C. L.; Stolarski, J.; Adkins, J. F.; Bender, M. L.

    2013-12-01

    Numerous archives including fossil carbonates, marine barite, and authigenic phosphates have shown that the Ca-isotope composition of seawater has varied throughout the Phanerozoic. Such changes are thought to be driven by oscillations between calcite seas and aragonite seas, with relatively heavy seawater ?44/40Ca occurring when aragonite deposition is favored and relatively light seawater ?44/40Ca when calcite deposition is favored[1,2]. While the Ca-isotope composition of Neogene and Late Paleogene seawater has been fairly well characterized, current records lack redundancy for ages >35Ma, and are sparsely sampled during the Late Mesozoic and Early Cenozoic. Fossil scleractinian corals may be good candidates for supplementing existing records of seawater Ca isotopes. Although the coral Ca-isotope effect has been shown to be somewhat variable between different taxa, it has also been shown that the Ca-isotope composition of scleractinians exhibits a weak temperature dependence, and is essentially independent of salinity and calcification rate[3]. We measured a suite of ~35 well-preserved fossil corals for Ca isotopes, ranging in age from Jurassic through Recent. We find that the ?44/40Ca seawater composition reconstructed from Neogene-age fossil corals is broadly consistent with existing records. However, Cretaceous and Late Jurassic fossil corals are ~1.1‰ lighter in ?44/40Ca than modern corals. The Cretaceous and Jurassic data support a record from Cretaceous-age authigenic phosphates, but indicate a ?44/40Ca of seawater that is ~0.8‰ lower than that inferred from fossil brachiopods and belemnites of similar ages. We are uncertain which record may best reflect the isotopic composition of seawater, but the differences between these reconstructions have implications for our current understanding of calcite and aragonite seas, and for the global calcium cycle. It is also possible that part of the depletion observed in Jurassic and Cretaceous age corals reflects a varying coral Ca-isotope effect as a result of changes in the seawater Ca concentration. [1] Blätter, C.L., et al. (2012) Geology, 40, 843-846. [2] F?rkas, J., et al. (2007) Geochimica et Cosmochimica Acta, 71, 5117-5134. [3] Pretet, C. et al. (2013) Chemical Geology, 340, 49-58.

  17. The East African Mantle: Warm but not Hot

    NASA Astrophysics Data System (ADS)

    Rooney, T. O.; Herzberg, C. T.; Bastow, I. D.

    2011-12-01

    East Africa is underlain by one of the most conspicuous features of global tomographic models: the African Super-plume. Magmatism during the African-Arabian flood basalt event and ongoing development of the East African rift have long been linked to the super-plume, with high temperatures usually cited as evidence for its existence. However, our work shows that seismic wave-speeds in the East African mantle are too low to be accounted for by only thermal effects. Other factors such as composition must also play a role. To address these issues we present mantle potential temperature estimates (TP) and preliminary high-precision compositional data from olivine crystals for East African lavas with the goal of constraining the thermo-chemical conditions of the East African upper mantle. Our estimates of mantle TP show that the East African mantle has remained warmer than ambient mantle conditions over the past 40 Myr, peaking during the Oligocene African-Arabian flood basalt episode (1520°C). These TP values, while clearly elevated, fall toward the lower end of the global temperature range of large igneous provinces, and are inconsistent with a solely thermal origin for the profound mantle seismic velocity anomalies beneath East Africa. Evidence of compositional heterogeneity in the East African upper mantle is preserved in the Fe, Mn, Ca, and Ni content of olivine crystals in lavas. We have found that Fe/Mn (42-95) within this preliminary dataset extend to the most extreme values yet recorded in the global LIP and oceanic island database, plotting well-outside fields accepted for olivine derived from peridotite-sourced melt. These data are strong evidence of a significant role for non-peridotite lithologies such as pyroxenite in the East African upper mantle. Such pyroxenites may reside in the metasomatized lithospheric mantle, or be derived from the reaction of recycled oceanic slabs upwelling in the African Superplume. Such recycled materials likely contain carbonate, which may generate the CO2-rich melts and associated low-velocity anomalies at depths significantly greater than that of volatile-free mantle lithologies. In the absence of sufficient thermal anomaly, we suggest that CO2-driven partial melting is required to explain both the depth extent and magnitude of seismic anomalies in the East African upper mantle.

  18. Solid modeling of fossil small mammal teeth

    NASA Astrophysics Data System (ADS)

    Marschallinger, Robert; Hofmann, Peter; Daxner-Höck, Gudrun; Ketcham, Richard A.

    2011-09-01

    This paper presents an approach to create solid models of fossil small mammal teeth using a combination of microcomputed tomography, object based image analysis and voxel modeling. Small mammal teeth, because of their durability, are widely found in Cenozioc sediments the world over and play a key role in stratigraphy as well as in researching the rapid evolution and the paleogeographic spreading of small mammals. Recent advances in microcomputed tomography make this non-destructive analysis method an ideal data source for high-resolution 3D models of fossil small animal teeth. To derive internally consistent solid models of such fossils from micro-CT imagery, we propose a combination of 3D object based image analysis and solid modeling. Incorporating paleontological expert knowledge in the image processing cycle, object based image analysis yields topologically consistent image stacks classified by the main tooth components—enamel, dentine and pulp. Forwarding these data to a voxel modeling system, they can be quantitatively analyzed in an unprecedented manner: going beyond the possibilities of the state-of-art surface models, solid models are capable of unambiguously portraying the entire object volume—teeth can be peeled by material properties, subvolumes can be extracted and automatically analyzed by Boolean operations. The proposed method, which can be flexibly extended to handle a range of paleontological and geological micro-objects, is demonstrated with two typical fossil small mammal teeth.

  19. The Fascinating Story of Fossil Fuels

    ERIC Educational Resources Information Center

    Asimov, Isaac

    1973-01-01

    How this energy source was created, its meaning to mankind, our drastically reduced supply, and why we cannot wait for nature to make more are considered. Today fossil fuels supply 96 percent of the energy used but we must find alternate energy options if we are to combat the energy crisis. (BL)

  20. Synthetic Trace Fossils using mechanical bugs

    NSDL National Science Digital Library

    Clint Cowan

    This activity is suitable for either an hour-long in class activity or a longer laboratory. It explores trace fossils by creating tracks in various substrates using mechanical bugs (Hexbugs). Students analyze the traces without seeing how they were made, then get to explore the traces by playing with the mechanical bugs that made them and varying the substrate.

  1. Fossil energy program. Progress report, July 1980

    Microsoft Academic Search

    McNeese

    1980-01-01

    This report - the seventy-second of a series - is a compendium of monthly progress reports for the ORNL research and development programs that are in support of the increased utilization of coal and other fossil fuel alternatives to oil and gas as sources of clean energy. The projects reported this month include those for coal conversion development, chemical research

  2. Thermal dissolution of solid fossil fuels

    SciTech Connect

    E.G. Gorlov [Institute for Fossil Fuels, Moscow (Russian Federation)

    2007-10-15

    The use of oil shales and coals in the processes of thermal dissolution is considered. It is shown that thermal dissolution is a mode of liquefaction of solid fossil fuels and can be used both independently and in combination with liquefaction of coals and processing of heavy petroleum residues.

  3. Fossil Cores In The Kepler Data

    NASA Astrophysics Data System (ADS)

    Jackson, Brian

    Most gas giant exoplanets with orbital periods < few days are unstable against tidal decay and may be tidally disrupted before their host stars leave the main sequence. These gas giants probably contain rocky/icy cores, and so their cores will be stranded near their progenitor's Roche limit (few hours orbital period). These fossil cores will evade the Kepler mission's transit search because it is focused on periods > 0.5 days, but finding these fossil cores would provide unprecedented insights into planetary interiors and formation ? e.g., they would be a smoking gun favoring formation of gas giants via core accretion. We propose to search for and characterize fossil cores in the Kepler dataset. We will vet candidates using the Kepler photometry and auxiliary data, collect ground-based spectra of the host stars and radial-velocity (RV) and adaptive optics (AO) data to corroborate candidates. We will also constrain stellar tidal dissipation efficiencies (parameterized by Q) by determining our survey's completeness, elucidating dynamical origins and evolution of exoplanets even if we find no fossil cores. Our preliminary search has already found several dozen candidates, so the proposed survey has a high likelihood of success.

  4. 1985 fossil plant water chemistry symposium: Proceedings

    Microsoft Academic Search

    1986-01-01

    A three day EPRI Symposium devoted to water chemistry, corrosion, and scale control in fossil utility steam cycles was held June 11-13, 1985 in Atlanta, Georgia. The purpose of the Symposium was to review and discuss US and foreign practices, corrosion control requirements for boilers, turbines, and other cycle components, sampling and instrumentation, and problems with cycling units. After the

  5. Fossils of Reionization in the Local Group

    E-print Network

    Nickolay Y. Gnedin; Andrey V. Kravtsov

    2006-01-22

    We use a combination of high-resolution gasdynamics simulations of high-redshift dwarf galaxies and dissipationless simulations of a Milky Way sized halo to estimate the expected abundance and spatial distribution of the dwarf satellite galaxies that formed most of their stars around z~8 and evolved only little since then. Such galaxies can be considered as fossils of the reionization era, and studying their properties could provide a direct window into the early, pre-reionization stages of galaxy formation. We show that 5-15% of the objects existing at z~8 do indeed survive until the present in the MW like environment without significant evolution. This implies that it is plausible that the fossil dwarf galaxies do exist in the Local Group. Because such galaxies form their stellar systems early during the period of active merging and accretion, they should have spheroidal morphology regardless of their current distance from the host galaxy. We show that both the expected luminosity function and spatial distribution of dark matter halos which are likely to host fossil galaxies agree reasonably well with the observed distributions of the luminous (L_V>10^6 Lsun) Local Group fossil candidates near the host galaxy (d300 kpc). We discuss several possible explanations for this discrepancy.

  6. Fossilized gravitational wave relic and primordial clocks

    NASA Astrophysics Data System (ADS)

    Brahma, Suddhasattwa; Nelson, Elliot; Shandera, Sarah

    2014-01-01

    If long-wavelength primordial tensor modes are coupled to short-wavelength scalar modes, the scalar curvature two-point function will have an off-diagonal component. This "fossil" remnant is a signature of a mode coupling that cannot be achieved in single-clock inflation. Any constraint on its presence allows a cross-check of the relationship between the dynamical generation of the fluctuations and the evolution of the inflationary background. We use the example of non—Bunch-Davies initial states for the tensor and scalar modes to demonstrate that physically reasonable fossils, consistent with current data, can be observable in the near future. We illustrate how the fossil off-diagonal power spectrum is a complementary probe to the squeezed limit bispectra of the scalar and tensor sectors individually. We also quantify the relation between the observable signal and the squeezed limit bispectrum for a general scalar-scalar-fossil coupling and note the effect of superhorizon tensor modes on the anisotropy in scalar modes.

  7. Renewable hydrogen production for fossil fuel processing

    Microsoft Academic Search

    Greenbaum

    1994-01-01

    The objective of this mission-oriented research program is the production of renewable hydrogen for fossil fuel processing. This program will build upon promising results that have been obtained in the Chemical Technology Division of Oak Ridge National Laboratory on the utilization of intact microalgae for photosynthetic water splitting. In this process, specially adapted algae are used to perform the light-activated

  8. Fossils: An Ancient Sea in Indiana

    NSDL National Science Digital Library

    2005-10-21

    In this interactive activity from the Children's Museum of Indianapolis, Indiana, examine a piece of the ancient Borden Sea in what is now central Indiana. Explore the types of fossils found there and the clues they offer to ancient life on Earth.

  9. Cuticle Analysis of Living and Fossil Metasequoia

    Microsoft Academic Search

    Qin Leng

    The recent discovery of two distinct cuticle types, Uneven Type and Even Type, within the native population of Metasequoia glyptostroboides Hu et Cheng has prompted re-evaluation of the taxonomic utility of cuticle characters in both living and fossil Metasequoia Miki. The result is a comprehensive review of the existing data and methods used in the past to analyze living and

  10. Fossil Energy Materials Program conference proceedings

    SciTech Connect

    Judkins, R.R. (comp.)

    1987-08-01

    The US Department of Energy Office of Fossil Energy has recognized the need for materials research and development to assure the adequacy of materials of construction for advanced fossil energy systems. The principal responsibility for identifying needed materials research and for establishing a program to address these needs resides within the Office of Technical Coordination. That office has established the Advanced Research and Technology Development (AR and TD) Fossil Energy Materials Program to fulfill that responsibility. In addition to the AR and TD Materials Program, which is designed to address in a generic way the materials needs of fossil energy systems, specific materials support activities are also sponsored by the various line organizations such as the Office of Coal Gasification. A conference was held at Oak Ridge, Tennessee on May 19-21, 1987, to present and discuss the results of program activities during the past year. The conference program was organized in accordance with the research thrust areas we have established. These research thrust areas include structural ceramics (particularly fiber-reinforced ceramic composites), corrosion and erosion, and alloy development and mechanical properties. Eighty-six people attended the conference. Papers have been entered individually into EDB and ERA. (LTN)

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

    PubMed Central

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

    2014-01-01

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

  12. Changing psychiatric perception of African-Americans with affective disorders.

    PubMed

    Jarvis, G Eric

    2012-12-01

    This article explored the origins and implications of the underdiagnosis of affective disorders in African-Americans. MEDLINE and old collections were searched using relevant key words. Reference lists from the articles that were gathered from this procedure were reviewed. The historical record indicated that the psychiatric perception of African-Americans with affective disorders changed significantly during the last 200 years. In the antebellum period, the mental disorders of slaves mostly went unnoticed. By the early 20th century, African-Americans were reported to have high rates of manic-depressive disorder compared with whites. By the mid-century, rates of manic-depressive disorder in African-Americans plummeted, whereas depression remained virtually nonexistent. In recent decades, diagnosed depression and bipolar disorder, whether in clinical or research settings, were inexplicably low in African-Americans compared with whites. Given these findings, American psychiatry needs to appraise the deep-seated effects of historical stereotypes on the diagnosis and treatment of African-Americans. PMID:23197118

  13. Quantifying denudation of the West African passive-transform margin: implications for Cenozoic erosion budget of cratons and source-to-sink systems

    NASA Astrophysics Data System (ADS)

    Grimaud, Jean-Louis; Chardon, Dominique; Rouby, Delphine; Beauvais, Anicet

    2014-05-01

    We develop an approach based on the differential elevation of dated successive topographies of the onshore part of the West African margin to calibrate in-situ volumetric denudation over a 3.9 million km2 cratonic surface for the past 45 Ma. We obtain a regionally averaged volumetric erosion rate of 5 x 10-3 km3/km2/m.y. corresponding to a total average denudation of 300 m and a denudation rate of 6 m/m.y., which remained nearly constant over the three time spans (45- 24, 24-11 and 11-0 Ma) despite spatial variations related to epeirogenic movements. Denudation is converted into a minimum yield of 12 +/- 2 t/km2/yr with a minimum solute component of 4 +/- 2 t/km2/yr accounting for the porosity of the eroded regoliths. Our results would imply a minimum contribution of 1.6 +/- 0.4 Gt/yr of the non-orogenic landmass to the global continental yield since the last peak greenhouse. Reconstruction of two incision stages of West Africa landscape from the reconstructed topographies combined with paleogeographic data shows that the current river catchments of the sub region have acquired their current configuration by the end of the Oligocene at the latest (24 Ma ago). The fairly steady geometry of the West African drainage since then offers the opportunity to effectively link the inland geomorphic record to offshore sedimentation. Volumetric denudation analysis applied to West African sub-drainage areas attests to the role of drainage reorganization and epeirogenic mouvements (flexural growth of the marginal upwarp and amplification of the Hoggar intraplate swell) on the spatial and temporal distribution of continental denudation and yield. Onshore denudation and clastic sediments accumulation in the post-24 Ma Niger catchment - delta system are within the same order of magnitude. These results suggest that cratonic-type erosion fluxes estimated from the West African margin may be used to estimate the size of drainage basins from the fossil sedimentary record.

  14. Instructing African American Students.

    ERIC Educational Resources Information Center

    Young, Clara Y.; Wright, James V.; Laster, Joseph

    2005-01-01

    Closing the educational achievement gap has been a schooling issue since Brown v. Board of Topeka, Kansas decision. Generally, the learning achievement of elementary and secondary African-American student has been an issue in majority school populations across the United States. And evidence of performance of these students appears to be more…

  15. African Trypanosomiasis Gambiense, Italy

    PubMed Central

    Beltrame, Anna; Monteiro, Geraldo; Arzese, Alessandra; Marocco, Stefania; Rorato, Giada; Anselmi, Mariella; Viale, Pierluigi

    2005-01-01

    African trypanosomiasis caused by Trypanosoma brucei gambiense has not been reported in Italy. We report 2 cases diagnosed in the summer of 2004. Theses cases suggest an increased risk for expatriates working in trypanosomiasis-endemic countries. Travel medicine clinics should be increasingly aware of this potentially fatal disease. PMID:16318728

  16. [Central African Republique].

    PubMed

    The capital of Central African Republic is Bangui. As of 1995, Central African Republic had a population of 3.3 million governed by a presidential regime. 1994 gross national product and per capita income were, respectively, $1.2 billion and $370. Per capita income declined by 2.8% per year over the period 1985-94. In 1994, Central African Republic owed $890.6 million, then being serviced at $79.6 million. For the same year, Central African Republic exported $185.5 million in goods and services and imported $280.4 million. As of 1995, the population was growing in size by 2.4% annually. In 1992-93, life expectancy at birth was 49.4 years, the infant mortality rate was 102 per 1000 births, 45% had access to health services, and 24% had access to drinkable water. Other data are presented on the country's topography, climate and vegetation, demographics, principal cities, population distribution, religions, political structure, economics and finances, foreign commerce, and transportation and communications. PMID:12347082

  17. Joint Honours AFRICAN STUDIES

    E-print Network

    Miall, Chris

    : The Joint Honours African Studies degree programme at Birmingham is broad, combining arts and social Office - Retail management - Aid work with Save the Children - Probation work - Welfare rights worker - Computer programmer - NGO work in Kurdistan - Work with adults who have learning disabilities - Research

  18. East African Rift System

    Microsoft Academic Search

    R. B. McConnell

    1969-01-01

    THE article entitled ``How far does the Rift System extend through Africa ?'' by Fairhead and Girdler1 is of great interest to geologists who are studying the structure of the African Pre-Cambrian platform, because the exact relocation of the epicentres of earthquakes could have great significance if related to known geological features. For example, in addition to the relationships suggested

  19. Mac Recording Status Mac Recording Status

    E-print Network

    Benos, Panayiotis "Takis"

    Mac Recording Status Mac Recording Status After ending a recording with the Mac Recorder you the Mac Recorder will upload recordings once the User stops the recording. Preview During the upload 1 of 6 #12;Mac Recording Status Recording Information Provides the details of the recording

  20. Fossil-Fuel-Derived Carbon Dioxide Emissions for China at Monthly Resolution

    Microsoft Academic Search

    R. J. Andres; G. Marland

    2005-01-01

    Using a mixture of official government statistics and industrial records, the relative monthly amounts of fossil-fuel-derived carbon dioxide emissions from China have been estimated for one year (2004). This analysis focused on establishing reliable monthly statistics that represent the fraction of annual-total solid, liquid, and gaseous fuels consumed during each month. Ongoing analyses may extend this time series to more

  1. Fossil Woodwardia virginica Foliage From the Middle Miocene Yakima Canyon

    NSDL National Science Digital Library

    Kathleen B. Pigg (Arizona State University; Department of Plant Biology ADR; POSTAL)

    2004-03-09

    Fossil Woodwardia virginica foliage from the middle Miocene Yakima Canyon flora of central Washington State, USA. Vegetative and fertile features of this fossil are remarkably similar to those of the modern ""Virginia chain fern"" of the Atlantic coastal region, USA.

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

    PubMed Central

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

    2010-01-01

    Background Mineralized and permineralized bone is the most common form of fossilization in the vertebrate record. Preservation of gross soft tissues is extremely rare, but recent studies have suggested that primary soft tissues and biomolecules are more commonly preserved within preserved bones than had been presumed. Some of these claims have been challenged, with presentation of evidence suggesting that some of the structures are microbial artifacts, not primary soft tissues. The identification of biomolecules in fossil vertebrate extracts from a specimen of Brachylophosaurus canadensis has shown the interpretation of preserved organic remains as microbial biofilm to be highly unlikely. These discussions also propose a variety of potential mechanisms that would permit the preservation of soft-tissues in vertebrate fossils over geologic time. Methodology/Principal Findings This study experimentally examines the role of microbial biofilms in soft-tissue preservation in vertebrate fossils by quantitatively establishing the growth and morphology of biofilms on extant archosaur bone. These results are microscopically and morphologically compared with soft-tissue extracts from vertebrate fossils from the Hell Creek Formation of southeastern Montana (Latest Maastrichtian) in order to investigate the potential role of microbial biofilms on the preservation of fossil bone and bound organic matter in a variety of taphonomic settings. Based on these analyses, we highlight a mechanism whereby this bound organic matter may be preserved. Conclusions/Significance Results of the study indicate that the crystallization of microbial biofilms on decomposing organic matter within vertebrate bone in early taphonomic stages may contribute to the preservation of primary soft tissues deeper in the bone structure. PMID:20967227

  3. Fossilized microorganisms from the Emperor Seamounts: implications for the search for a subsurface fossil record on Earth and Mars.

    PubMed

    Ivarsson, M; Lausmaa, J; Lindblom, S; Broman, C; Holm, N G

    2008-12-01

    We have observed filamentous carbon-rich structures in samples drilled at 3 different seamounts that belong to the Emperor Seamounts in the Pacific Ocean: Detroit (81 Ma), Nintoku (56 Ma), and Koko Seamounts (48 Ma). The samples consist of low-temperature altered basalts recovered from all 3 seamounts. The maximum depth from which the samples were retrieved was 954 meters below seafloor (mbsf). The filamentous structures occur in veins and fractures in the basalts, where they are attached to the vein walls and embedded in vein-filling minerals like calcite, aragonite, and gypsum. The filaments were studied with a combination of optical microscopy, environmental scanning electron microscopy (ESEM), Raman spectroscopy, and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Minerals were identified by a combination of optical microscopy, X-ray diffraction, Raman spectrometry, and energy dispersive spectrometry on an environmental scanning electron microscope. Carbon content of the filaments ranges between approximately 10 wt % and approximately 50 wt % and is not associated with carbonates. These results indicate an organic origin of the carbon. The presence of C(2)H(4), phosphate, and lipid-like molecules in the filaments further supports a biogenic origin. We also found microchannels in volcanic glass enriched in carbon (approximately 10-40 wt %) compatible with putative microbial activity. Our findings suggest new niches for life in subseafloor environments and have implications for further exploration of the subseafloor biosphere on Earth and beyond. PMID:19191540

  4. (Collection of high quality acoustical records for honeybees)

    SciTech Connect

    Kerr, H.T.; Buchanan, M.E.

    1987-02-19

    High quality acoustical data records were collected for both European and Africanized honeybees under various field conditions. This data base was needed for more rigorous evaluation of a honeybee identification technique previously developed by the travelers from preliminary data sets. Laboratory-grade recording equipment was used to record sounds made by honeybees in and near their nests and during foraging flights. Recordings were obtained from European and Africanized honeybees in the same general environment. Preliminary analyses of the acoustical data base clearly support the general identification algorithm: Africanized honeybee noise has significantly higher frequency content than does European honeybee noise. As this algorithm is refined, it may result in the development of a simple field-portable device for identifying subspecies of honeybees. Further, the honeybee's acoustical signals appear to be correlated with specific colony conditions. Understanding these variations may have enormous benefit for entomologists and for the beekeeping industry.

  5. Esophageal Carcinoma in African Americans: A Five-Decade Experience

    Microsoft Academic Search

    Hassan Ashktorab; Zahra Nouri; Mehdi Nouraie; Hadi Razjouyan; Edward E. Lee; Ehsan Dowlati; El-Waleed El-Seyed; Adeyinka Laiyemo; Hassan Brim; Duane T. Smoot

    Background  Esophageal cancer accounts for a considerable proportion of carcinomas of the upper gastrointestinal tract in African Americans.\\u000a Our aim was to describe the epidemiology of esophageal squamous cell cancer (ESCC) and esophageal adenocarcinoma (EA) among\\u000a African Americans in the last five decades.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  A total of 601 records of patients with documented esophageal cancer between 1959 and 2007 at Howard University

  6. A Will Without a Way: Barriers and Facilitators to Exercise During Pregnancy of Low-Income, African American Women

    Microsoft Academic Search

    Elizabeth E. Krans; Judy C. Chang

    2011-01-01

    The objective of the authors in this study was to identify pregnant, low-income African American women's barriers and facilitators to exercise during pregnancy. A series of six focus groups with pregnant African American women were audio-recorded and transcribed verbatim. Focus group transcripts were qualitatively analyzed for major themes and independently coded for barriers and facilitators to exercise during pregnancy. A

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

    ERIC Educational Resources Information Center

    Cheppel, Alena

    2012-01-01

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

  8. Hydrogen Related Analytical Studies Office of Fossil Energy and

    E-print Network

    prepared several conceptual designs to produce hydrogen from fossil fuel for EPRI and other private clientsHydrogen Related Analytical Studies Office of Fossil Energy and National Energy TechnologyRelatedAnalyticalStudies ­ 072604 Charter Office of Fossil Energy Describe your group's mission or objectives (group is the part

  9. FOSSIL ANTHROPOIDS OF THE r y ALEMCAMBRIDGE INDIA

    E-print Network

    Boyer, Edmond

    ; . ~ 1@'· t p t1tCO FOSSIL ANTHROPOIDS OF THE r y ALEMCAMBRIDGE INDIA EXPEDITION Q,F 1935 ? ~ -~~r J FOSSIL ANTHROPOIDS OF THE YALE-CAMBRIDGE INDIA EXPEDITION OF 1935 WILLIAM K. GREGORY MILO .. . .... . .. ... . . . . .. . .. . .... ...... . ..... . .. . ... .. . .. . .. ...... . ,, ·· following 27 1 #12;( FOSSIL ANTHROPOIDS OF THE YALE-CAMBRIDGE INDIA EXPEDITION OF 1935 INTRODUCTION The Yale

  10. EDIACARAN AND CAMBRIAN INDEX FOSSILS FROM SONORA, MEXICO

    E-print Network

    Hagadorn, Whitey

    EDIACARAN AND CAMBRIAN INDEX FOSSILS FROM SONORA, MEXICO by FRANCISCO SOUR-TOVAR*, JAMES W October 2006 Abstract: The Cambrian index fossil Treptichnus pedum is reported from the Puerto Blanco Formation near Pitiquito, Sonora, Mexico, and new occurrences of the Neoproterozoic index fossil Cloudina

  11. Fossil Groups in the Sloan Digital Sky Survey

    E-print Network

    Walter A. Santos; Claudia Mendes de Oliveira; Laerte Sodré Jr

    2007-08-14

    A search for fossil groups in the Sloan Digital Sky Survey was performed using virtual observatory tools. A cross-match of the positions of all SDSS Luminous Red Galaxies (with r fossil groups. Considering this sample, the estimated space density of fossil systems is $n =(1.0 \\pm 0.6) \\times 10^{-6}$ $h_{50}^3$ Mpc$^{-3}$.

  12. PALEOZOIC TRACE FOSSILS FROM THE KUFRA BASIN, LIBYA

    E-print Network

    Benton, Michael

    PALEOZOIC TRACE FOSSILS FROM THE KUFRA BASIN, LIBYA BRIAN R. TURNER AND MICHAEL J. BENTON trace fossils. The oldest association of Cruzianu,Arthrophycus and Monocraterion comesfrom the Cambro, subsurface data and biostrati- graphic control, correlation between the two areas is uncertain. Body fossils

  13. Reducing Fossil Carbon Emissions and Building Environmental Awareness at

    E-print Network

    Reducing Fossil Carbon Emissions and Building Environmental Awareness at Dartmouth College Summary selected the mission: "To reduce Dartmouth College's fossil carbon emissions." We believe this mission's responsibility to educate others about how it is reducing its fossil carbon emissions and encourage them to do

  14. Early Evolution and Historical Biogeography of Fishflies (Megaloptera: Chauliodinae): Implications from a Phylogeny Combining Fossil and Extant Taxa

    PubMed Central

    Liu, Xingyue; Wang, Yongjie; Shih, Chungkun; Ren, Dong; Yang, Ding

    2012-01-01

    Fishflies (Corydalidae: Chauliodinae) are one of the main groups of the basal holometabolous insect order Megaloptera, with ca. 130 species distributed worldwide. A number of genera from the Southern Hemisphere show remarkably disjunctive distributions and are considered to be the austral remnants or “living fossils” of Gondwana. Hitherto, the evolutionary history of fishflies remains largely unexplored due to limited fossil record and incomplete knowledge of phylogenetic relationships. Here we describe two significant fossil species of fishflies, namely Eochauliodes striolatus gen. et sp. nov. and Jurochauliodes ponomarenkoi Wang & Zhang, 2010 (original designation for fossil larvae only), from the Middle Jurassic of Inner Mongolia, China. These fossils represent the earliest fishfly adults. Furthermore, we reconstruct the first phylogenetic hypothesis including all fossil and extant genera worldwide. Three main clades within Chauliodinae are recognized, i.e. the Dysmicohermes clade, the Protochauliodes clade, and the Archichauliodes clade. The phylogenetic and dispersal-vicariance (DIVA) analyses suggest Pangaean origin and global distribution of fishflies before the Middle Jurassic. The generic diversification of fishflies might have happened before the initial split of Pangaea, while some Gondwanan-originated clades were likely to be affected by the sequential breakup of Pangaea. The modern fauna of Asian fishflies were probably derived from their Gondwanan ancestor but not the direct descendents of the Mesozoic genera in Asia. PMID:22792287

  15. First fossil occurrence of a filefish (Tetraodontiformes; Monacanthidae) in Asia, from the Middle Miocene in Nagano Prefecture, central Japan.

    PubMed

    Miyajima, Yusuke; Koike, Hakuichi; Matsuoka, Hiroshige

    2014-01-01

    A new fossil filefish, Aluterus shigensis sp. nov., with a close resemblance to the extant Aluterus scriptus (Osbeck), is described from the Middle Miocene Bessho Formation in Nagano Prefecture, central Japan. It is characterized by: 21 total vertebrae; very slender and long first dorsal spine with tiny anterior barbs; thin and lancet-shaped basal pterygiophore of the spiny dorsal fin, with its ventral margin separated from the skull; proximal tip of moderately slender first pterygiophore of the soft dorsal fin not reaching far ventrally; soft dorsal-fin base longer than anal-fin base; caudal peduncle having nearly equal depth and length; and tiny, fine scales with slender, straight spinules. The occurrence of this fossil filefish from the Bessho Formation is consistent with the influence of warm water currents suggested by other fossils, but it is inconsistent with the deep-water sedimentary environment of this Formation. This is the first fossil occurrence of a filefish in Asia; previously described fossil filefishes are known from the Pliocene and Pleistocene of Italy, the Pliocene of Greece, and the Miocene and Pliocene of North America. These fossil records suggest that the genus Aluterus had already been derived and was widely distributed during the Middle Miocene with taxa closely resembling Recent species. PMID:24869542

  16. Fossil energy waste management. Technology status report

    SciTech Connect

    Bossart, S.J.; Newman, D.A.

    1995-02-01

    This report describes the current status and recent accomplishments of the Fossil Energy Waste Management (FE WM) projects sponsored by the Morgantown Energy Technology Center (METC) of the US Department of Energy (DOE). The primary goal of the Waste Management Program is to identify and develop optimal strategies to manage solid by-products from advanced coal technologies for the purpose of ensuring the competitiveness of advanced coal technologies as a future energy source. The projects in the Fossil Energy Waste Management Program are divided into three types of activities: Waste Characterization, Disposal Technologies, and Utilization Technologies. This technology status report includes a discussion on barriers to increased use of coal by-products. Also, the major technical and nontechnical challenges currently being addressed by the FE WM program are discussed. A bibliography of 96 citations and a list of project contacts is included if the reader is interested in obtaining additional information about the FE WM program.

  17. A phylogeny of Cenozoic macroperforate planktonic foraminifera from fossil data.

    PubMed

    Aze, Tracy; Ezard, Thomas H G; Purvis, Andy; Coxall, Helen K; Stewart, Duncan R M; Wade, Bridget S; Pearson, Paul N

    2011-11-01

    We present a complete phylogeny of macroperforate planktonic foraminifer species of the Cenozoic Era (?65 million years ago to present). The phylogeny is developed from a large body of palaeontological work that details the evolutionary relationships and stratigraphic (time) distributions of species-level taxa identified from morphology ('morphospecies'). Morphospecies are assigned to morphogroups and ecogroups depending on test morphology and inferred habitat, respectively. Because gradual evolution is well documented in this clade, we have identified many instances of morphospecies intergrading over time, allowing us to eliminate 'pseudospeciation' and 'pseudoextinction' from the record and thereby permit the construction of a more natural phylogeny based on inferred biological lineages. Each cladogenetic event is determined as either budding or bifurcating depending on the pattern of morphological change at the time of branching. This lineage phylogeny provides palaeontologically calibrated ages for each divergence that are entirely independent of molecular data. The tree provides a model system for macroevolutionary studies in the fossil record addressing questions of speciation, extinction, and rates and patterns of evolution. PMID:21492379

  18. An overview of the South American fossil squamates.

    PubMed

    Albino, Adriana María; Brizuela, Santiago

    2014-03-01

    The evolution of squamates in South America is the result of the complex geological and paleoclimatic history of this part of the world. The incomplete and episodic fossil record allows us to know only a small part of this evolution. Most Mesozoic squamate remains come from the Patagonian region, but remarkable specimens have also been recovered from Brazil. Both major squamate clades (Iguania and Scleroglossa) are present in the South American Mesozoic. Remains of Mesozoic snakes are common and diverse in Cretaceous deposits, including some of the most primitive terrestrial forms. Paleogene and Neogene squamate remains have been recognized from Argentina, Bolivia, Brazil, Colombia, Ecuador, Peru, and Venezuela. Paleogene lizard record appears to be scarce in comparison to that of the Mesozoic, whereas snakes show an important Paleogene diversity. At least two extant boid snakes appeared during this epoch (Boa and Corallus). The South American Miocene included some extant genera of Iguania, Teiidae, and Boidae but extinct genera were also present. "Colubrids" appeared at the early Miocene, whereas the first viperid is known from the late Miocene. Most of the Paleogene and early Neogene squamate families and genera have been recognized outside their current range of distribution following favorable climatic conditions for ectothermic vertebrates. During the latest Miocene and Pliocene few extant squamate taxa are found to occur outside their present distribution. The earliest amphisbaenian of South America is known from the Pliocene. Most Pleistocene and Holocene squamate remains are assigned to living genera, and some extant species were recognized. PMID:24482358

  19. Global energy resources. [Review, emphasizing fossil fuels

    Microsoft Academic Search

    Grenon

    1977-01-01

    We are in the somewhat paradoxical situation of having more confidence in the extent of our long- or very long-term energy resources than in our mid-term supply. This is why fossil-energy resources are emphasized in this article; we must rely on them for at least 80 to 90% of our energy supply until the end of the century (as far

  20. Atmospheric Lifetime of Fossil Fuel Carbon Dioxide

    Microsoft Academic Search

    David Archer; Michael Eby; Victor Brovkin; Andy Ridgwell; Long Cao; Uwe Mikolajewicz; Ken Caldeira; Katsumi Matsumoto; Guy Munhoven; Alvaro Montenegro; Kathy Tokos

    2009-01-01

    CO2 released from combustion of fossil fuels equilibrates among the various carbon reservoirs of the atmosphere, the ocean, and the terrestrial biosphere on timescales of a few centuries. However, a sizeable fraction of the CO2 remains in the atmosphere, awaiting a return to the solid earth by much slower weathering processes and deposition of CaCO3. Common measures of the atmospheric

  1. Oral Presentation of a Fossil Group

    NSDL National Science Digital Library

    Max Reams

    Each student chooses a different fossil group that interests him/her and prepares a 10 minute PowerPoint presentation about that group, lavishly illustrated and richly illuminated with fascinating facts! This can be as large a group as a phylum or as small as a species. Powerpoint handouts are given out during the oral presentation. Students must have a concluding slide citing references. The discussion must go beyond what is presented by the professor in lecture.

  2. The Undead: Fossil Galaxy Alive Again

    NASA Astrophysics Data System (ADS)

    Berglund, Kallan; Wilcots, Eric M.

    2015-01-01

    This project investigates the formation and evolution of fossil galaxies, specifically the history of active galactic nucleus (AGN) activity as it relates to galaxy mergers. We used low-frequency radio data from the J-VLA radio telescope's new P-band receivers [300-350MHz] to observe fossil galaxy J171811.93+563956.1 (referenced as FG30) at a red-shift of z=0.114. This galaxy was selected for its strong X-ray emission from the surrounding IGM, because it is indicative of an AGN. After cleaning and calibrating the data using CASA, images were generated to map the intensity of radio emission, revealing that FG30 is nearly a point source and lacks any prominent AGN jets. Analysis of the SDSS optical spectrum of FG30 revealed strong evidence of shocks. We believe that past AGN activity heated the intergalactic medium (IGM) to produce the strong X-ray emission, though the jets have been dormant for long enough that the IGM filled in the regions previously cleared by jets. The density of new material is now causing strong shocks when hit by newly restarted jets. This implies the start of a new epoch of AGN activity for FG30, which was most likely caused by a recent galaxy merger. This observation demonstrates that not all fossil groups have been quiescent, as the dominant theories suggested.*This work was supported by the National Science Foundation's REU program through NSF Award AST-1004881.

  3. Fossil avian eggshell preserves ancient DNA

    PubMed Central

    Oskam, Charlotte L.; Haile, James; McLay, Emma; Rigby, Paul; Allentoft, Morten E.; Olsen, Maia E.; Bengtsson, Camilla; Miller, Gifford H.; Schwenninger, Jean-Luc; Jacomb, Chris; Walter, Richard; Baynes, Alexander; Dortch, Joe; Parker-Pearson, Michael; Gilbert, M. Thomas P.; Holdaway, Richard N.; Willerslev, Eske; Bunce, Michael

    2010-01-01

    Owing to exceptional biomolecule preservation, fossil avian eggshell has been used extensively in geochronology and palaeodietary studies. Here, we show, to our knowledge, for the first time that fossil eggshell is a previously unrecognized source of ancient DNA (aDNA). We describe the successful isolation and amplification of DNA from fossil eggshell up to 19 ka old. aDNA was successfully characterized from eggshell obtained from New Zealand (extinct moa and ducks), Madagascar (extinct elephant birds) and Australia (emu and owl). Our data demonstrate excellent preservation of the nucleic acids, evidenced by retrieval of both mitochondrial and nuclear DNA from many of the samples. Using confocal microscopy and quantitative PCR, this study critically evaluates approaches to maximize DNA recovery from powdered eggshell. Our quantitative PCR experiments also demonstrate that moa eggshell has approximately 125 times lower bacterial load than bone, making it a highly suitable substrate for high-throughput sequencing approaches. Importantly, the preservation of DNA in Pleistocene eggshell from Australia and Holocene deposits from Madagascar indicates that eggshell is an excellent substrate for the long-term preservation of DNA in warmer climates. The successful recovery of DNA from this substrate has implications in a number of scientific disciplines; most notably archaeology and palaeontology, where genotypes and/or DNA-based species identifications can add significantly to our understanding of diets, environments, past biodiversity and evolutionary processes. PMID:20219731

  4. South African Voices

    NSDL National Science Digital Library

    Scheub, Harold

    2006-01-01

    The digital collections at the University of Wisconsin continue to be intriguing for both scholars and the general public, and the South African Voices website is another small triumph that is worth of consideration. This particular collection brings together the three-volume collection titled South African Voices, which was researched and brought together by Professor Harold Scheub. Drawing on his fieldwork beginning in the late 1960s, this set of works explores the histories, oral storytelling traditions, and poems that were part of various peoples in South Africa, Zimbabwe, and the former country of Swaziland. Visitors are welcome to search through the entire contents of all three volumes, and along the way they can also listen to various audio excerpts from the collection.

  5. African Elections Project

    NSDL National Science Digital Library

    Interest in the election results within various African nations continues to grow, and the African Elections Project is a great source of information on this timely topic. The Project is coordinated by the International Institute for ICT Journalism and a number of additional partners, such as the Open Society Initiative for West Africa and Global Voices. The material on the site is available in both French and English, and currently it covers Ghana, Cote d'Ivoire, Guinea, Malawi, and Niger. Within each country profile, visitors can view the results of recent elections, take a look at relevant weblogs, learn about the various political parties in each country, and also view past news updates. Additionally, visitors can sign up to receive email updates or RSS feeds.

  6. Fossil corals as an archive of secular variations in seawater chemistry since the Mesozoic

    NASA Astrophysics Data System (ADS)

    Gothmann, Anne M.; Stolarski, Jaros?aw; Adkins, Jess F.; Schoene, Blair; Dennis, Kate J.; Schrag, Daniel P.; Mazur, Maciej; Bender, Michael L.

    2015-07-01

    Numerous archives suggest that the major ion and isotopic composition of seawater have changed in parallel with large variations in geologic processes and Earth's climate. However, our understanding of the mechanisms driving secular changes in seawater chemistry on geologic timescales is limited by the resolution of data in time, large uncertainties in seawater chemistry reconstructions, and ambiguities introduced by sample diagenesis. We validated the preservation of a suite of ?60 unrecrystallized aragonitic fossil scleractinian corals, ranging in age from Triassic through Recent, for use as new archives of past seawater chemistry. Optical and secondary electron microscopy (SEM) studies reveal that fossil coral crystal fabrics are similar to those of modern coralline aragonite. X-ray diffractometry (XRD), cathodoluminescence microscopy (CL), and Raman studies confirm that these specimens contain little to no secondary calcite. In order to screen for geochemical changes indicative of alteration, we measured 87Sr/86Sr ratios, clumped isotopes, and trace element ratios sensitive to diagenesis (e.g., Mn/Ca). We retain samples when these tests either fail to identify any diagenetic modifications, or identify specific domains free of detectable alteration. Using the validated fossil coral archive we reconstruct seawater Mg/Ca and Sr/Ca ratios, measured by Secondary Ion Mass Spectrometry (SIMS), back to ?230 Ma. The effects of temperature on coral trace element incorporation cannot explain the trends observed in our fossil coral Mg/Ca and Sr/Ca data. In agreement with independent records, seawater Mg/Ca molar ratios inferred from corals are low (Mg/Ca ?1) during the Cretaceous and Jurassic, and increase between the Early Cenozoic and present (Mg/Ca = 5.2). Seawater Sr/Ca ratios from corals vary systematically between ?8 and 13 mmol/mol since 230 Ma, with maximum values in the Cretaceous and Paleogene. The coral Sr/Ca record disagrees with records from hydrothermal CaCO3 veins, but is similar to those reconstructed from other biogenic carbonates, especially benthic foraminifera. The agreement between corals and other archives, for both Sr/Ca and Mg/Ca ratios, further validates our records. In return, fossil coral records improve our understanding of past variations in seawater Mg/Ca and Sr/Ca.

  7. National Museum of African Art

    NSDL National Science Digital Library

    The National Museum of African Art is known for its fabulously diverse collections, which cover all aspects of artistic life across the African continent. Visitors to the site can look through areas including Highlights, Artists, and Cultural Groups. This last area is a wonderful place to start, as visitors can look through dozens of cultural groupings to find items that range from cutlery to sculpture. Each item has a detailed thumbnail image, along with information about the time period in which it was created. The Highlights area contains over a dozen themed areas, including African Mosaic, African Textiles, and Contemporary African Art. Finally, the Artists area is perfect for people who already have knowledge of a celebrated African artist and wish to learn more about his or her work, medium, and contributions to these artistic traditions.

  8. JSTOR: African American Review

    NSDL National Science Digital Library

    JSTOR has available this title in its collection of full-text, online journals. African American Review, the quarterly publication of the Division on Black American Literature and Culture of the Modern Language Association, is published by Indiana State University, and includes Volumes 1-33, 1967-1999. AAR continues Black American Literature Forum (1976-1991) and Negro American Literature Forum (1967-1976). Note: access to JSTOR content is currently available only on a site license basis to academic institutions.

  9. Charles Darwin's beagle voyage, fossil vertebrate succession, and "the gradual birth & death of species".

    PubMed

    Brinkman, Paul D

    2010-01-01

    The prevailing view among historians of science holds that Charles Darwin became a convinced transmutationist only in the early spring of 1837, after his Beagle collections had been examined by expert British naturalists. With respect to the fossil vertebrate evidence, some historians believe that Darwin was incapable of seeing or understanding the transmutationist implications of his specimens without the help of Richard Owen. There is ample evidence, however, that he clearly recognized the similarities between several of the fossil vertebrates he collected and some of the extant fauna of South America before he returned to Britain. These comparisons, recorded in his correspondence, his diary and his notebooks during the voyage, were instances of a phenomenon that he later called the "law of the succession of types." Moreover, on the Beagle, he was following a geological research agenda outlined in the second volume of Charles Lyell's Principles of Geology, which implies that paleontological data alone could provide an insight into the laws which govern the appearance of new species. Since Darwin claims in On the Origin of Species that fossil vertebrate succession was one of the key lines of evidence that led him to question the fixity of species, it seems certain that he was seriously contemplating transmutation during the Beagle voyage. If so, historians of science need to reconsider both the role of Britain's expert naturalists and the importance of the fossil vertebrate evidence in the development of Darwin's ideas on transmutation. PMID:20665232

  10. Processes of benthic foraminiferal fossil assemblage formation on the continental slope

    SciTech Connect

    Loubere, P. (Northern Illinois Univ., DeKalb (United States))

    1991-03-01

    Theoretical analysis of benethic foraminiferal fossil assemblage formation shows that the assemblage eventually preserved in the sediments is an integrated result of species' test production rate, microhabitat behavior, and biogeochemical processes that control the probability of species' test preservation. The biogeochemical processes that influence test preservation in slope sediments are controlled by the flux of organic carbon to the sea-bed and the botton water oxygen concentration. These variables also affect the depth of the biotic habitation zone in the sediments. Therefore, organic carbon flux and bottom water oxygen content should be reflected in benthic foraminiferal fossil assemblages for both ecologic and taphonomic reasons. An integrated study of fossil assemblage generation was conducted on the Gulf of Mexico continental slope using box cores collected along depth transects across the oxygen minimum, and using live and dead assemblage analysis combined with {sup 210}Pb measurements to quantify biotic activity in the sediments and pore water nutrient and metals analysis to quantify biogeochemical processes acting in the sediment habitation zone. The results show that the size of the habitation zone and live standing stock are influenced by organic carbon flux and oxygen supply to the sea-bed. The fossil assemblage is created progressively through the upper 10-20 cm of sediment and biologichemically driven test destruction (taphonomic process) is important in determining the assemblage that enters the geologic record.

  11. Flying rocks and flying clocks: disparity in fossil and molecular dates for birds.

    PubMed

    Ksepka, Daniel T; Ware, Jessica L; Lamm, Kristin S

    2014-08-01

    Major disparities are recognized between molecular divergence dates and fossil ages for critical nodes in the Tree of Life, but broad patterns and underlying drivers remain elusive. We harvested 458 molecular age estimates for the stem and crown divergences of 67 avian clades to explore empirical patterns between these alternate sources of temporal information. These divergence estimates were, on average, over twice the age of the oldest fossil in these clades. Mitochondrial studies yielded older ages than nuclear studies for the vast majority of clades. Unexpectedly, disparity between molecular estimates and the fossil record was higher for divergences within major clades (crown divergences) than divergences between major clades (stem divergences). Comparisons of dates from studies classed by analytical methods revealed few significant differences. Because true divergence ages can never be known with certainty, our study does not answer the question of whether fossil gaps or molecular dating error account for a greater proportion of observed disparity. However, empirical patterns observed here suggest systemic overestimates for shallow nodes in existing molecular divergence dates for birds. We discuss underlying biases that may drive these patterns. PMID:24943376

  12. Uncertainty in the age of fossils and the stratigraphic fit to phylogenies.

    PubMed

    Pol, Diego; Norell, Mark A

    2006-06-01

    The ages of first appearance of fossil taxa in the stratigraphic record are inherently associated to an interval of error or uncertainty, rather than being precise point estimates. Contrasting this temporal information with topologies of phylogenetic relationships is relevant to many aspects of evolutionary studies. Several indices have been proposed to compare the ages of first appearance of fossil taxa and phylogenies. For computing most of these indices, the ages of first appearance of fossil taxa are currently used as point estimates, ignoring their associated errors or uncertainties. The effect of age uncertainty on measures of stratigraphic fit to phylogenies is explored here for two indices based on the extension of ghost lineages (MSM* and GER). A solution based on randomization of the ages of terminal taxa is implemented, resulting in a range of possible values for measures of stratigraphic fit to phylogenies, rather than in a precise but arbitrary stratigraphic fit value. Sample cases show that ignoring the age uncertainty of fossil taxa can produce misleading results when comparing the stratigraphic fit of competing phylogenetic hypotheses. Empirical test cases of alternative phylogenies of two dinosaur groups are analyzed through the randomization procedure proposed here. PMID:16861213

  13. A possible role for stochastic radiation events in the systematic disparity between molecular and fossil dates

    E-print Network

    Melott, Adrian L

    2015-01-01

    Major discrepancies have been noted for some time between fossil ages and molecular divergence dates for a variety of taxa. Recently, systematic trends within avian clades have been uncovered. The trends show that the disparity is much larger for mitochondrial DNA than for nuclear DNA; also that it is larger for crown fossil dates than stem fossil dates. It was argued that this pattern is largely inconsistent with incompleteness of the fossil record as the principal driver of the disparity. A case is presented that given the expected mutations from a fluctuating background of astrophysical radiation from such sources as supernovae, the rate of molecular clocks is variable and should increase into the past. This is a possible explanation for the disparity. One test of this hypothesis is to look for an acceleration of molecular clocks 2 to 2.5 Ma due to a probable moderately nearby supernova at that time. Another is to look for reduced disparity in benthic organisms of the deep ocean.

  14. Experimental taphonomy of Artemia reveals the role of endogenous microbes in mediating decay and fossilization

    PubMed Central

    Butler, Aodhán D.; Cunningham, John A.; Budd, Graham E.; Donoghue, Philip C. J.

    2015-01-01

    Exceptionally preserved fossils provide major insights into the evolutionary history of life. Microbial activity is thought to play a pivotal role in both the decay of organisms and the preservation of soft tissue in the fossil record, though this has been the subject of very little experimental investigation. To remedy this, we undertook an experimental study of the decay of the brine shrimp Artemia, examining the roles of autolysis, microbial activity, oxygen diffusion and reducing conditions. Our findings indicate that endogenous gut bacteria are the main factor controlling decay. Following gut wall rupture, but prior to cuticle failure, gut-derived microbes spread into the body cavity, consuming tissues and forming biofilms capable of mediating authigenic mineralization, that pseudomorph tissues and structures such as limbs and the haemocoel. These observations explain patterns observed in exceptionally preserved fossil arthropods. For example, guts are preserved relatively frequently, while preservation of other internal anatomy is rare. They also suggest that gut-derived microbes play a key role in the preservation of internal anatomy and that differential preservation between exceptional deposits might be because of factors that control autolysis and microbial activity. The findings also suggest that the evolution of a through gut and its bacterial microflora increased the potential for exceptional fossil preservation in bilaterians, providing one explanation for the extreme rarity of internal preservation in those animals that lack a through gut. PMID:25972468

  15. THE GB/3D Fossil Types Online Database

    NASA Astrophysics Data System (ADS)

    Howe, M. P.; McCormick, T.

    2012-12-01

    The ICZN and the International Code of Nomenclature for algae, fungi and plants require that every species or subspecies of organism (living & fossil), should have a type or reference specimen to define its characteristic features. These specimens are held in collections around the world and must be available for study. Over time, type specimens can deteriorate or become lost. The British Geological Survey, the National Museum of Wales, the Sedgwick Museum Cambridge and the Oxford Museum of Natural History are working together to create an online database of the type fossils they hold. The web portal provides data about each specimen, searchable on taxonomic, stratigraphic and spatial criteria. For each specimen it is possible to view and download high resolution photographs, and for many of them, 'anaglyph' stereo pairs and 3D scans are available. The portal also provides educational resources (OERs). The rise to prominence of the Web has transformed expectations in accessing information and the Web is now usually the first port of call. However, while many geological museums are providing web-searchable text catalogues, few have undertaken a large-scale program of providing images and 3D models. This project has tackled the issues of merging four distinct data holdings, and setting up workflows to image and scan large numbers of disparate fossils, ranging from small invertebrate macrofossils to large vertebrate skeletal elements. There are three advantages in providing such resources: (1) All users can exploit the collections more efficiently. End-users can view specimens remotely and assess their nature, preservation quality and completeness - in some cases this may be sufficient. It will reduce the need for institutions to send specimens (which are often fragile and always irreplaceable) to researchers by post, or for researchers to make possibly long, expensive and environmentally damaging journeys. (2) A public outreach and education dividend - the ability to view specimens greatly enriches the experience and information content of an institution's website. (3) The ability to digitally image specimens enables museums to have an archive record in case the physical specimens are lost or destroyed by accident or warfare.; Digital model of type of Kreterostephanus kreter Buckmann (GSM49334), an ammonite from the Jurasssic of Dorset, UK - displayed as an anaglyph

  16. African Burial Ground

    NSDL National Science Digital Library

    As the city of New York has grown up, out, and over an increasingly vast area of land during the past few centuries, various sites of human activity and habitation have become one of the many layers that continue to interest urbanologists, sociologists, planners, and anthropologists. One such layer is the African burial ground that was found in lower Manhattan in 1991, and which has been celebrated by a diverse group of individuals ever since. Visitors will want to start by looking at the "Rites of Ancestral Return" section. Here they may elect to view video clips from past celebrations and view an interactive map that highlights the various ways in which the colonial African experience has been relived and commemorated along the Eastern seaboard. The other section on the site is also quite engaging, as it allows visitors to explore the African burial ground through educational features about the artifacts and graves found within the context of the bustling city which had grown up around the site through the ensuing centuries.

  17. Diversity among African Pygmies

    PubMed Central

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

    2010-01-01

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

  18. East African Rift Valley, Kenya

    NASA Technical Reports Server (NTRS)

    1990-01-01

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

  19. The contribution of fossil sources to carbonaceous aerosol derived from the LOTOS-EUROS model and radiocarbon measurements

    NASA Astrophysics Data System (ADS)

    Dusek, Ulrike; Meijer, Harro A. J.; Röckmann, Thomas; Manders, Astrid M. M.; Walter, Anne; Schaap, Martijn

    2015-04-01

    Carbonaceous material constitutes a significant fraction of the atmospheric aerosol. We used the LOTOS-EUROS model to calculate elemental carbon (EC) and primary organic carbon (OC) as well as the contribution of fossil sources for the year 2011 using different emission inventories. The model results are compared to a year-long source apportionment record of fossil versus contemporary carbon sources at a regional background station in the Netherlands. This record was derived from measurements of the radioactive carbon isotope 14C on carbonaceous aerosol and gives a unique opportunity for detailed model evaluation, since a comparison of model results to measured OC and EC concentrations alone is often inconclusive. First results using the EUCARII EC-OC emission inventory show that at a regional background site in the Netherlands the modeled fossil fraction for EC is on average 0.9, with higher values around 0.95 in the summer and lower values in the winter due to increased biomass combustion. Overall, EC is overestimated by a factor of 1.8 on average by the LOTOS-EUROS model. Radiocarbon data show that this is mainly due to an overestimate of the fossil carbon, whereas the EC from biomass combustion was only slightly overestimated. Consequently the LOTOS-EUROS model gave a somewhat higher fossil fraction for EC than the measurements. Overall the temporal trend in EC concentrations was well reproduced in the model, with exception in air masses arriving from Eastern Europe, where concentrations could be severely underestimated. The primary OC calculated by LOTOS-EUROS was on average 1/3 of the measured OC, which implies that the majority of the OC is secondary in origin. The modeled fossil fraction of primary OC was around 0.7 on average, indicating a dominance of fossil sources for primary OC. The measured fossil fraction of the total OC is significantly lower, around 0.3, which indicates that most SOA should be from contemporary sources. Even water insoluble OC, which is considered a better proxy for primary OC shows lower fossil fractions around 0.5. This might indicate that OC from biomass burning is underestimated, however we will present strong evidence that primary fossil OC is overestimated by a similar factors as EC. These results show that secondary organic aerosol formation needs to be included to adequately model the organic aerosol. We will present first model results of total OC concentrations including SOA formation, which closely resemble the measured OC concentration in the Netherlands.

  20. Emissions Scenarios and Fossil-fuel Peaking

    NASA Astrophysics Data System (ADS)

    Brecha, R.

    2008-12-01

    Intergovernmental Panel on Climate Change (IPCC) emissions scenarios are based on detailed energy system models in which demographics, technology and economics are used to generate projections of future world energy consumption, and therefore, of greenhouse gas emissions. Built into the assumptions for these scenarios are estimates for ultimately recoverable resources of various fossil fuels. There is a growing chorus of critics who believe that the true extent of recoverable fossil resources is much smaller than the amounts taken as a baseline for the IPCC scenarios. In a climate optimist camp are those who contend that "peak oil" will lead to a switch to renewable energy sources, while others point out that high prices for oil caused by supply limitations could very well lead to a transition to liquid fuels that actually increase total carbon emissions. We examine a third scenario in which high energy prices, which are correlated with increasing infrastructure, exploration and development costs, conspire to limit the potential for making a switch to coal or natural gas for liquid fuels. In addition, the same increasing costs limit the potential for expansion of tar sand and shale oil recovery. In our qualitative model of the energy system, backed by data from short- and medium-term trends, we have a useful way to gain a sense of potential carbon emission bounds. A bound for 21st century emissions is investigated based on two assumptions: first, that extractable fossil-fuel resources follow the trends assumed by "peak oil" adherents, and second, that little is done in the way of climate mitigation policies. If resources, and perhaps more importantly, extraction rates, of fossil fuels are limited compared to assumptions in the emissions scenarios, a situation can arise in which emissions are supply-driven. However, we show that even in this "peak fossil-fuel" limit, carbon emissions are high enough to surpass 550 ppm or 2°C climate protection guardrails. Some indicators are presented that the scenario presented here should not be disregarded, and comparisons are made to the outputs of emission scenarios used for the IPCC reports.