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Cartilaginous Epiphyses in Extant Archosaurs and Their Implications for Reconstructing Limb Function in Dinosaurs
Extinct archosaurs, including many non-avian dinosaurs, exhibit relatively simply shaped condylar regions in their appendicular bones, suggesting potentially large amounts of unpreserved epiphyseal (articular) cartilage. This “lost anatomy” is often underappreciated such that the ends of bones are t...
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Formato: | Texto |
Lenguaje: | English |
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Public Library of Science
2010
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2948032/ https://www.ncbi.nlm.nih.gov/pubmed/20927347 http://dx.doi.org/10.1371/journal.pone.0013120 |
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author | Holliday, Casey M. Ridgely, Ryan C. Sedlmayr, Jayc C. Witmer, Lawrence M. |
author_facet | Holliday, Casey M. Ridgely, Ryan C. Sedlmayr, Jayc C. Witmer, Lawrence M. |
author_sort | Holliday, Casey M. |
collection | PubMed |
description | Extinct archosaurs, including many non-avian dinosaurs, exhibit relatively simply shaped condylar regions in their appendicular bones, suggesting potentially large amounts of unpreserved epiphyseal (articular) cartilage. This “lost anatomy” is often underappreciated such that the ends of bones are typically considered to be the joint surfaces, potentially having a major impact on functional interpretation. Extant alligators and birds were used to establish an objective basis for inferences about cartilaginous articular structures in such extinct archosaur clades as non-avian dinosaurs. Limb elements of alligators, ostriches, and other birds were dissected, disarticulated, and defleshed. Lengths and condylar shapes of elements with intact epiphyses were measured. Limbs were subsequently completely skeletonized and the measurements repeated. Removal of cartilaginous condylar regions resulted in statistically significant changes in element length and condylar breadth. Moreover, there was marked loss of those cartilaginous structures responsible for joint architecture and congruence. Compared to alligators, birds showed less dramatic, but still significant changes. Condylar morphologies of dinosaur limb bones suggest that most non-coelurosaurian clades possessed large cartilaginous epiphyses that relied on the maintenance of vascular channels that are otherwise eliminated early in ontogeny in smaller-bodied tetrapods. A sensitivity analysis using cartilage correction factors (CCFs) obtained from extant taxa indicates that whereas the presence of cartilaginous epiphyses only moderately increases estimates of dinosaur height and speed, it has important implications for our ability to infer joint morphology, posture, and the complicated functional movements in the limbs of many extinct archosaurs. Evidence suggests that the sizes of sauropod epiphyseal cartilages surpassed those of alligators, which account for at least 10% of hindlimb length. These data suggest that large cartilaginous epiphyses were widely distributed among non-avian archosaurs and must be considered when making inferences about locomotor functional morphology in fossil taxa. |
format | Text |
id | pubmed-2948032 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2010 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-29480322010-10-06 Cartilaginous Epiphyses in Extant Archosaurs and Their Implications for Reconstructing Limb Function in Dinosaurs Holliday, Casey M. Ridgely, Ryan C. Sedlmayr, Jayc C. Witmer, Lawrence M. PLoS One Research Article Extinct archosaurs, including many non-avian dinosaurs, exhibit relatively simply shaped condylar regions in their appendicular bones, suggesting potentially large amounts of unpreserved epiphyseal (articular) cartilage. This “lost anatomy” is often underappreciated such that the ends of bones are typically considered to be the joint surfaces, potentially having a major impact on functional interpretation. Extant alligators and birds were used to establish an objective basis for inferences about cartilaginous articular structures in such extinct archosaur clades as non-avian dinosaurs. Limb elements of alligators, ostriches, and other birds were dissected, disarticulated, and defleshed. Lengths and condylar shapes of elements with intact epiphyses were measured. Limbs were subsequently completely skeletonized and the measurements repeated. Removal of cartilaginous condylar regions resulted in statistically significant changes in element length and condylar breadth. Moreover, there was marked loss of those cartilaginous structures responsible for joint architecture and congruence. Compared to alligators, birds showed less dramatic, but still significant changes. Condylar morphologies of dinosaur limb bones suggest that most non-coelurosaurian clades possessed large cartilaginous epiphyses that relied on the maintenance of vascular channels that are otherwise eliminated early in ontogeny in smaller-bodied tetrapods. A sensitivity analysis using cartilage correction factors (CCFs) obtained from extant taxa indicates that whereas the presence of cartilaginous epiphyses only moderately increases estimates of dinosaur height and speed, it has important implications for our ability to infer joint morphology, posture, and the complicated functional movements in the limbs of many extinct archosaurs. Evidence suggests that the sizes of sauropod epiphyseal cartilages surpassed those of alligators, which account for at least 10% of hindlimb length. These data suggest that large cartilaginous epiphyses were widely distributed among non-avian archosaurs and must be considered when making inferences about locomotor functional morphology in fossil taxa. Public Library of Science 2010-09-30 /pmc/articles/PMC2948032/ /pubmed/20927347 http://dx.doi.org/10.1371/journal.pone.0013120 Text en Holliday et al. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited. |
spellingShingle | Research Article Holliday, Casey M. Ridgely, Ryan C. Sedlmayr, Jayc C. Witmer, Lawrence M. Cartilaginous Epiphyses in Extant Archosaurs and Their Implications for Reconstructing Limb Function in Dinosaurs |
title | Cartilaginous Epiphyses in Extant Archosaurs and Their Implications for Reconstructing Limb Function in Dinosaurs |
title_full | Cartilaginous Epiphyses in Extant Archosaurs and Their Implications for Reconstructing Limb Function in Dinosaurs |
title_fullStr | Cartilaginous Epiphyses in Extant Archosaurs and Their Implications for Reconstructing Limb Function in Dinosaurs |
title_full_unstemmed | Cartilaginous Epiphyses in Extant Archosaurs and Their Implications for Reconstructing Limb Function in Dinosaurs |
title_short | Cartilaginous Epiphyses in Extant Archosaurs and Their Implications for Reconstructing Limb Function in Dinosaurs |
title_sort | cartilaginous epiphyses in extant archosaurs and their implications for reconstructing limb function in dinosaurs |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2948032/ https://www.ncbi.nlm.nih.gov/pubmed/20927347 http://dx.doi.org/10.1371/journal.pone.0013120 |
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