Niche Evolution and Phylogenetic Community Paleoecology of Late Ordovician Crinoids

Niche Evolution and Phylogenetic Community Paleoecology of Late Ordovician Crinoids PDF

Author: Selina R. Cole

Publisher: Cambridge University Press

Published: 2022-05-26

Total Pages: 88

ISBN-13: 1108898947

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Fossil crinoids are exceptionally suited to deep-time studies of community paleoecology and niche partitioning. By merging ecomorphological trait and phylogenetic data, this Element summarizes niche occupation and community paleoecology of crinoids from the Bromide fauna of Oklahoma (Sandbian, Upper Ordovician). Patterns of community structure and niche evolution are evaluated over a ~5 million-year period through comparison with the Brechin Lagerstätte (Katian, Upper Ordovician). The authors establish filtration fan density, food size selectivity, and body size as major axes defining niche differentiation, and niche occupation is strongly controlled by phylogeny. Ecological strategies were relatively static over the study interval at high taxonomic scales, but niche differentiation and specialization increased in most subclades. Changes in disparity and species richness indicate the transition between the early-middle Paleozoic Crinoid Evolutionary Faunas was already underway by the Katian due to ecological drivers and was not triggered by the Late Ordovician mass extinction.

The Ecology of Biotic Interactions in Echinoids

The Ecology of Biotic Interactions in Echinoids PDF

Author: Elizabeth Petsios

Publisher: Cambridge University Press

Published: 2023-10-31

Total Pages: 88

ISBN-13: 1108899846

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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.

A Review of Blastozoan Echinoderm Respiratory Structures

A Review of Blastozoan Echinoderm Respiratory Structures PDF

Author: Sarah L. Sheffield

Publisher: Cambridge University Press

Published: 2022-12-31

Total Pages: 156

ISBN-13: 1108899609

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Echinoderms have evolved diverse and disparate morphologies throughout the Phanerozoic. Among them, blastozoans, an extinct group of echinoderms that were an important component of Paleozoic marine ecosystems, are primarily subdivided into groups based on the morphology of respiratory structures. However, systematic and phylogenetic research from the past few decades have shown that respiratory structures in blastozoans are not group-defining and they have re-evolved throughout echinoderm evolution. This Element provides a review of the research involving blastozoan respiratory structures, along with research concerning the morphology, paleoecology, and ontogeny of each of the major groupings of blastozoans as it relates to their corresponding respiratory structures. Areas of future research in these groups are also highlighted.

A Review and Evaluation of Homology Hypotheses in Echinoderm Paleobiology

A Review and Evaluation of Homology Hypotheses in Echinoderm Paleobiology PDF

Author: Colin D. Sumrall

Publisher: Cambridge University Press

Published: 2023-04-13

Total Pages: 91

ISBN-13: 1009397168

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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.

Molecular Paleobiology of the Echinoderm Skeleton

Molecular Paleobiology of the Echinoderm Skeleton PDF

Author: Jeffrey R. Thompson

Publisher: Cambridge University Press

Published: 2022-12-01

Total Pages: 120

ISBN-13: 1009189190

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The echinoderms are an ideal group to understand evolution from a holistic, interdisciplinary framework. The genetic regulatory networks underpinning development in echinoderms are some of the best known for any model group. Additionally, the echinoderms have an excellent fossil record, elucidating in in detail the evolutionary changes underpinning morphological evolution. In this Element, the echinoderms are discussed as a model group for molecular palaeobiological studies, integrating what is known of their development, genomes, and fossil record. Together, these insights shed light on the molecular and morphological evolution underpinning the vast biodiversity of echinoderms, and the animal kingdom more generally.

The Oldest Known Crinoids (early Ordovician, Utah) and a New Crinoid Plate Homology System

The Oldest Known Crinoids (early Ordovician, Utah) and a New Crinoid Plate Homology System PDF

Author: Thomas Edgar Guensburg

Publisher:

Published: 2003

Total Pages: 43

ISBN-13: 9780877104582

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Six new primitive genera from the Early Ordovician of western Utah significantly advance our understanding of early crinoid history. Two of the new genera are the oldest crinoids (early Ibexian, early Tremadoc) and represent a previously unknown protocrinoid evolutionary grade, differing from other crinoids in having a nonstandardized dorsal cup and arms bearing ambulacral floor plates. Titanocrinus sumralli, new genus and species, has hundreds of unorganized mid-cup and interbrachial plates separating the cup-base basal circlet and the ray plates. Glenocrinus globularis, new genus and species, has similar plating with a more compact globular cup and fewer mid-cup plates, and is near the origin of diplobathrid camerates. A third taxon, Eknomocrinus wahwahensis, new genus and species, from the same lower stratigraphic interval, is a stem-group monocyclic camerate crinoid with standardized but irregular cup plating and other emergent crinoid traits shared with protocrinoids. Three new camerates from higher in the section are more derived. Cnemecrinus fillmorensis, new genus and species, and Habrotecrinus ibexensis, new genus and species, both latest Ibexian (middle Arenig), are monocyclic camerates. The latter taxon has unique accessory plates and major cup plate shapes. The fossil record indicates rapid diversification of disparid, cladid, and camerate crinoids by the end of the middle Ibexian (late Tremadoc), each arising independently from the protocrinoid stem group. Evidence from ontogeny, cup-stem and radial orientation, and now, early morphologic transitions necessitates revision of long used skeletal terminology. Dual ray and cup-base references for plate homologies, rather than the traditional ray-only model, are consistent with this evidence. Consequently, infrabasals are redefined as the cup-base circlet of both dicyclic and monocyclic crinoids. The use of basals is restricted to plates between infrabasals and radials of dicyclic (and tricyclic) crinoids. Traditional classifications emphasizing cup plate circlet number is unreliable early in the crinoid record; instead, posterior and interray cup morphology provides the most consistent phylogenetic information.

Phylogenetic Comparative Methods: A User's Guide for Paleontologists

Phylogenetic Comparative Methods: A User's Guide for Paleontologists PDF

Author: Laura C. Soul

Publisher: Cambridge University Press

Published: 2021-05-27

Total Pages: 77

ISBN-13: 1108897355

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Recent advances in statistical approaches called phylogenetic comparative methods (PCMs) have provided paleontologists with a powerful set of analytical tools for investigating evolutionary tempo and mode in fossil lineages. However, attempts to integrate PCMs with fossil data often present workers with practical challenges or unfamiliar literature. This Element presents guides to the theory behind and the application of PCMs with fossil taxa. Based on an empirical dataset of Paleozoic crinoids, example analyses are presented to illustrate common applications of PCMs to fossil data, including investigating patterns of correlated trait evolution and macroevolutionary models of morphological change. The authors emphasize the importance of accounting for sources of uncertainty and discuss how to evaluate model fit and adequacy. Finally, the authors discuss several promising methods for modeling heterogeneous evolutionary dynamics with fossil phylogenies. Integrating phylogeny-based approaches with the fossil record provides a rigorous, quantitative perspective on understanding key patterns in the history of life.

Early Miocene Paleobiology in Patagonia

Early Miocene Paleobiology in Patagonia PDF

Author: Sergio F. Vizcaíno

Publisher: Cambridge University Press

Published: 2012-10-11

Total Pages: 381

ISBN-13: 052119461X

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Coastal exposures of the Santa Cruz Formation in southern Patagonia have been a fertile ground for recovery of Early Miocene vertebrates for more than 100 years. This volume presents a comprehensive compilation of important mammalian groups which continue to thrive today. It includes the most recent fossil finds as well as important new interpretations based on ten years of fieldwork by the authors. A key focus is placed on the paleoclimate and paleoenvironment during the time of deposition in the Middle Miocene Climatic Optimum (MMCO) between twenty and fifteen million years ago. The authors present the first reconstruction of what climatic conditions were like and present important new evidence of the geochronological age, habits and community structures of fossil bird and mammal species. Academic researchers and graduate students in paleontology, paleobiology, paleoecology, stratigraphy, climatology and geochronology will find this a valuable source of information about this fascinating geological formation.

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