A Review and Evaluation of Homology Hypotheses in Echinoderm Paleobiology PDF Download
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Author: Colin D. Sumrall
Publisher: Cambridge University Press
ISBN: 1009397168
Category : Science
Languages : en
Pages : 91
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Book Description
The extraxial-axial theory (EAT) and universal elemental homology (UEH) are often portrayed as mutually exclusive hypotheses of homology within pentaradiate Echinodermata. EAT describes homology upon the echinoderm bauplan, interpreted through early post-metamorphic growth and growth zones, dividing it into axial regions generally associated with elements of the ambulacral system and extraxial regions that are not. UEH describes the detailed construction of the axial skeleton, dividing it into homologous plates and plate series based on symmetry, early growth, and function. These hypotheses are not in conflict; the latter is rooted in refinement of the former. Some interpretive differences arise because many of the morphologies described from eleutherozoan development are difficult to reconcile with Paleozoic forms. Conversely, many elements described for Paleozoic taxa by UEH, such as the peristomial border plates, are absent in eleutherozoans. This Element recommends these two hypotheses be used together to generate a better understanding of homology across Echinodermata.
Author: Colin D. Sumrall
Publisher: Cambridge University Press
ISBN: 1009397168
Category : Science
Languages : en
Pages : 91
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Book Description
The extraxial-axial theory (EAT) and universal elemental homology (UEH) are often portrayed as mutually exclusive hypotheses of homology within pentaradiate Echinodermata. EAT describes homology upon the echinoderm bauplan, interpreted through early post-metamorphic growth and growth zones, dividing it into axial regions generally associated with elements of the ambulacral system and extraxial regions that are not. UEH describes the detailed construction of the axial skeleton, dividing it into homologous plates and plate series based on symmetry, early growth, and function. These hypotheses are not in conflict; the latter is rooted in refinement of the former. Some interpretive differences arise because many of the morphologies described from eleutherozoan development are difficult to reconcile with Paleozoic forms. Conversely, many elements described for Paleozoic taxa by UEH, such as the peristomial border plates, are absent in eleutherozoans. This Element recommends these two hypotheses be used together to generate a better understanding of homology across Echinodermata.
Author: Elizabeth Petsios
Publisher: Cambridge University Press
ISBN: 1108899846
Category : Reference
Languages : en
Pages : 88
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Book Description
This Element reviews the ecologies of skeletal trace-producing interactions on echinoids in Modern ecosystems and the recognition of those biogenic traces in the fossil record. This title is also available as Open Access on Cambridge Core.
Author: April Wright
Publisher: Cambridge University Press
ISBN: 100905872X
Category : Science
Languages : en
Pages : 80
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Book Description
Macroevolutionary inference has historically been treated as a two-step process, involving the inference of a tree, and then inference of a macroevolutionary model using that tree. Newer models blend the two steps. These methods make more complete use of fossils than the previous generation of Bayesian phylogenetic models. They also involve many more parameters than prior models, including parameters about which empiricists may have little intuition. In this Element, we set forth a framework for fitting complex, hierarchical models. The authors ultimately fit and use a joint tree and diversification model to estimate a dated phylogeny of the Cincta (Echinodermata), a morphologically distinct group of Cambrian echinoderms that lack the fivefold radial symmetry characteristic of extant members of the phylum. Although the phylogeny of cinctans remains poorly supported in places, this Element shows how models of character change and diversification contribute to understanding patterns of phylogenetic relatedness and testing macroevolutionary hypotheses.
Author: Herbert Clifton Chadwick
Publisher:
ISBN:
Category : Echinodermata
Languages : en
Pages : 64
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Book Description
Author: Bradley Deline
Publisher: Cambridge University Press
ISBN: 1108898041
Category : Science
Languages : en
Pages : 79
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Book Description
The quantification of morphology through time is a vital tool in elucidating macroevolutionary patterns. Studies of disparity require intense effort but can provide insights beyond those gained using other methodologies. Over the last several decades, studies of disparity have proliferated, often using echinoderms as a model organism. Echinoderms have been used to study the methodology of disparity analyses and potential biases as well as documenting the morphological patterns observed in clades through time. Combining morphological studies with phylogenetic analyses or other disparate data sets allows for the testing of detailed and far-reaching evolutionary hypotheses.
Author: William I. Ausich
Publisher: Indiana University Press
ISBN: 0253351286
Category : Science
Languages : en
Pages : 474
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Book Description
The dominant faunal elements in shallow Paleozoic oceans, echinoderms are important to understanding these marine ecosystems. Echinoderms (which include such animals as sea stars, crinoids or sea lilies, sea urchins, sand dollars, and sea cucumbers) have left a rich and, for science, extremely useful fossil record. For various reasons, they provide the ideal source for answers to the questions that will help us develop a more complete understanding of global environmental and biodiversity changes. This volume highlights the modern study of fossil echinoderms and is organized into five parts: echinoderm paleoecology, functional morphology, and paleoecology; evolutionary paleoecology; morphology for refined phylogenetic studies; innovative applications of data encoded in echinoderms; and information on new crinoid data sets.
Author: Bruno David
Publisher: CRC Press
ISBN: 9789054105145
Category : Science
Languages : en
Pages : 970
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Book Description
Echinoderms are now considered as a biological and geological model that underlies researches of primary importance. The extent of the contributions made by the International Echinoderm Conferences to various fields of research is attested by the scope covered by presentation at the international conferences. These proceedings contain the complete papers or abstracts of all the presentations and posters presented at the eighth International Echinoderm Conference, held in Dijon, France in September, 1994. Coverage includes: general; extinct classes; crinoids; asteroids; ophiuroids; holothuroids; and echinoids.
Author: Noriyuki Satoh
Publisher: Academic Press
ISBN: 0128030062
Category : Science
Languages : en
Pages : 222
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Book Description
Chordate Origins and Evolution: The Molecular Evolutionary Road to Vertebrates focuses on echinoderms (starfish, sea urchins, and others), hemichordates (acorn worms, etc.), cephalochordates (lancelets), urochordates or tunicates (ascidians, larvaceans and others), and vertebrates. In general, evolution of these groups is discussed independently, on a larger scale: ambulacrarians (echi+hemi) and chordates (cephlo+uro+vert). Until now, discussion of these topics has been somewhat fragmented, and this work provides a unified presentation of the essential information. In the more than 150 years since Charles Darwin proposed the concept of the origin of species by means of natural selection, which has profoundly affected all fields of biology and medicine, the evolution of animals (metazoans) has been studied, discussed, and debated extensively. Following many decades of classical comparative morphology and embryology, the 1980s marked a turning point in studies of animal evolution, when molecular biological approaches, including molecular phylogeny (MP), molecular evolutionary developmental biology (evo-devo), and comparative genomics (CG), began to be employed. There are at least five key events in metazoan evolution, which include the origins of 1) diploblastic animals, such as cnidarians; 2) triploblastic animals or bilaterians; 3) protostomes and deuterostomes; 4) chordates, among deuterostomes; and 5) vertebrates, among chordates. The last two have received special attention in relation to evolution of human beings. During the past two decades, great advances have been made in this field, especially in regard to molecular and developmental mechanisms involved in the evolution of chordates. For example, the interpretation of phylogenetic relationships among deuterostomes has drastically changed. In addition, we have now obtained a large quantity of MP, evo-devo, and CG information on the origin and evolution of chordates. - Covers the most significant advances in this field to give readers an understanding of the interesting biological issues involved - Provides a unified presentation of essential information regarding each phylum and an integrative understanding of molecular mechanisms involved in the origin and evolution of chordates - Discusses the evolutionary scenario of chordates based on two major characteristic features of animals—namely modes of feeding (energy sources) and reproduction—as the two main forces driving animal evolution and benefiting dialogue for future studies of animal evolution
Author: S. Blair Hedges
Publisher: OUP Oxford
ISBN: 019160898X
Category : Science
Languages : en
Pages : 1237
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Book Description
The evolutionary history of life includes two primary components: phylogeny and timescale. Phylogeny refers to the branching order (relationships) of species or other taxa within a group and is crucial for understanding the inheritance of traits and for erecting classifications. However, a timescale is equally important because it provides a way to compare phylogeny directly with the evolution of other organisms and with planetary history such as geology, climate, extraterrestrialimpacts, and other features.The Timetree of Life is the first reference book to synthesize the wealth of information relating to the temporal component of phylogenetic trees. In the past, biologists have relied exclusively upon the fossil record to infer an evolutionary timescale. However, recent revolutionary advances in molecular biology have made it possible to not only estimate the relationships of many groups of organisms, but also to estimate their times of divergence with molecular clocks. The routineestimation and utilization of these so-called 'time-trees' could add exciting new dimensions to biology including enhanced opportunities to integrate large molecular data sets with fossil and biogeographic evidence (and thereby foster greater communication between molecular and traditional systematists). Theycould help estimate not only ancestral character states but also evolutionary rates in numerous categories of organismal phenotype; establish more reliable associations between causal historical processes and biological outcomes; develop a universally standardized scheme for biological classifications; and generally promote novel avenues of thought in many arenas of comparative evolutionary biology.This authoritative reference work brings together, for the first time, experts on all major groups of organisms to assemble a timetree of life. The result is a comprehensive resource on evolutionary history which will be an indispensable reference for scientists, educators, and students in the life sciences, earth sciences, and molecular biology. For each major group of organism, a representative is illustrated and a timetree of families and higher taxonomic groups is shown. Basic aspects ofthe evolutionary history of the group, the fossil record, and competing hypotheses of relationships are discussed. Details of the divergence times are presented for each node in the timetree, and primary literature references are included. The book is complemented by an online database(www.timetree.net) which allows researchers to both deposit and retrieve data.
Author: Peter Trusler
Publisher: Cambridge University Press
ISBN: 9780521162999
Category : Science
Languages : en
Pages : 322
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Book Description
The Artist and the Scientists: Bringing Prehistory to Life presents the extraordinary lives and works of eminent paleontologists Patricia Vickers-Rich and Tom Rich, and Peter Trusler, one of the finest artists of scientific realism Australia has produced. Over more than thirty years, Patricia, Tom and Peter have travelled across Eastern Europe, Asia, the Americas, Africa, Australia and New Zealand in search of the remains of early life, including fish, dinosaurs, birds and mammals. Their successful expeditions, and the many publications and exquisite artworks that have ensued, are a testament to their scientific methodology, thirst for knowledge and eye for detail. The book follows the development of selected works of art covering the last 600 million years of the geological record. Told from the viewpoints of both scientist and artist, the reader is given a unique insight into the process of preserving and recording the evolution of prehistoric life.
