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 b...

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Autores principales:	Casey M Holliday, Ryan C Ridgely, Jayc C Sedlmayr, Lawrence M Witmer
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2010
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/cd3d29e907ca445893f5c68897bc2012
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spelling	oai:doaj.org-article:cd3d29e907ca445893f5c68897bc20122021-11-18T07:03:47ZCartilaginous epiphyses in extant archosaurs and their implications for reconstructing limb function in dinosaurs.1932-620310.1371/journal.pone.0013120https://doaj.org/article/cd3d29e907ca445893f5c68897bc20122010-09-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/20927347/?tool=EBIhttps://doaj.org/toc/1932-6203Extinct 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.Casey M HollidayRyan C RidgelyJayc C SedlmayrLawrence M WitmerPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 5, Iss 9 (2010)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Casey M Holliday Ryan C Ridgely Jayc C Sedlmayr Lawrence M Witmer Cartilaginous epiphyses in extant archosaurs and their implications for reconstructing limb function in dinosaurs.
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	article
author	Casey M Holliday Ryan C Ridgely Jayc C Sedlmayr Lawrence M Witmer
author_facet	Casey M Holliday Ryan C Ridgely Jayc C Sedlmayr Lawrence M Witmer
author_sort	Casey M Holliday
title	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_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_sort	cartilaginous epiphyses in extant archosaurs and their implications for reconstructing limb function in dinosaurs.
publisher	Public Library of Science (PLoS)
publishDate	2010
url	https://doaj.org/article/cd3d29e907ca445893f5c68897bc2012
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Cartilaginous epiphyses in extant archosaurs and their implications for reconstructing limb function in dinosaurs.

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