Limb-bone scaling indicates diverse stance and gait in quadrupedal ornithischian dinosaurs.

<h4>Background</h4>The most primitive ornithischian dinosaurs were small bipeds, but quadrupedality evolved three times independently in the clade. The transition to quadrupedality from bipedal ancestors is rare in the history of terrestrial vertebrate evolution, and extant analogues do...

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Autores principales:	Susannah C R Maidment, Deborah H Linton, Paul Upchurch, Paul M Barrett
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2012
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/b559e814711c481ba8ebc0cb53557697
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spelling	oai:doaj.org-article:b559e814711c481ba8ebc0cb535576972021-11-18T07:17:46ZLimb-bone scaling indicates diverse stance and gait in quadrupedal ornithischian dinosaurs.1932-620310.1371/journal.pone.0036904https://doaj.org/article/b559e814711c481ba8ebc0cb535576972012-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/22666333/pdf/?tool=EBIhttps://doaj.org/toc/1932-6203<h4>Background</h4>The most primitive ornithischian dinosaurs were small bipeds, but quadrupedality evolved three times independently in the clade. The transition to quadrupedality from bipedal ancestors is rare in the history of terrestrial vertebrate evolution, and extant analogues do not exist. Constraints imposed on quadrupedal ornithischians by their ancestral bipedal bauplan remain unexplored, and consequently, debate continues about their stance and gait. For example, it has been proposed that some ornithischians could run, while others consider that none were cursorial.<h4>Methodology/principal findings</h4>Drawing on biomechanical concepts of limb bone scaling and locomotor theory developed for extant taxa, we use the largest dataset of ornithischian postcranial measurements so far compiled to examine stance and gait in quadrupedal ornithischians. Differences in femoral midshaft eccentricity in hadrosaurs and ceratopsids may indicate that hadrosaurs placed their feet on the midline during locomotion, while ceratopsids placed their feet more laterally, under the hips. More robust humeri in the largest ceratopsids relative to smaller taxa may be due to positive allometry in skull size with body mass in ceratopsids, while slender humeri in the largest stegosaurs may be the result of differences in dermal armor distribution within the clade. Hadrosaurs are found to display the most cursorial morphologies of the quadrupedal ornithischian cades, indicating higher locomotor performance than in ceratopsids and thyreophorans.<h4>Conclusions/significance</h4>Limb bone scaling indicates that a previously unrealised diversity of stances and gaits were employed by quadrupedal ornithischians despite apparent convergence in limb morphology. Grouping quadrupedal ornithischians together as a single functional group hides this disparity. Differences in limb proportions and scaling are likely due to the possession of display structures such as horns, frills and dermal armor that may have affected the center of mass of the animal, and differences in locomotor behaviour such as migration, predator escape or home range size.Susannah C R MaidmentDeborah H LintonPaul UpchurchPaul M BarrettPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 7, Iss 5, p e36904 (2012)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Susannah C R Maidment Deborah H Linton Paul Upchurch Paul M Barrett Limb-bone scaling indicates diverse stance and gait in quadrupedal ornithischian dinosaurs.
description	<h4>Background</h4>The most primitive ornithischian dinosaurs were small bipeds, but quadrupedality evolved three times independently in the clade. The transition to quadrupedality from bipedal ancestors is rare in the history of terrestrial vertebrate evolution, and extant analogues do not exist. Constraints imposed on quadrupedal ornithischians by their ancestral bipedal bauplan remain unexplored, and consequently, debate continues about their stance and gait. For example, it has been proposed that some ornithischians could run, while others consider that none were cursorial.<h4>Methodology/principal findings</h4>Drawing on biomechanical concepts of limb bone scaling and locomotor theory developed for extant taxa, we use the largest dataset of ornithischian postcranial measurements so far compiled to examine stance and gait in quadrupedal ornithischians. Differences in femoral midshaft eccentricity in hadrosaurs and ceratopsids may indicate that hadrosaurs placed their feet on the midline during locomotion, while ceratopsids placed their feet more laterally, under the hips. More robust humeri in the largest ceratopsids relative to smaller taxa may be due to positive allometry in skull size with body mass in ceratopsids, while slender humeri in the largest stegosaurs may be the result of differences in dermal armor distribution within the clade. Hadrosaurs are found to display the most cursorial morphologies of the quadrupedal ornithischian cades, indicating higher locomotor performance than in ceratopsids and thyreophorans.<h4>Conclusions/significance</h4>Limb bone scaling indicates that a previously unrealised diversity of stances and gaits were employed by quadrupedal ornithischians despite apparent convergence in limb morphology. Grouping quadrupedal ornithischians together as a single functional group hides this disparity. Differences in limb proportions and scaling are likely due to the possession of display structures such as horns, frills and dermal armor that may have affected the center of mass of the animal, and differences in locomotor behaviour such as migration, predator escape or home range size.
format	article
author	Susannah C R Maidment Deborah H Linton Paul Upchurch Paul M Barrett
author_facet	Susannah C R Maidment Deborah H Linton Paul Upchurch Paul M Barrett
author_sort	Susannah C R Maidment
title	Limb-bone scaling indicates diverse stance and gait in quadrupedal ornithischian dinosaurs.
title_short	Limb-bone scaling indicates diverse stance and gait in quadrupedal ornithischian dinosaurs.
title_full	Limb-bone scaling indicates diverse stance and gait in quadrupedal ornithischian dinosaurs.
title_fullStr	Limb-bone scaling indicates diverse stance and gait in quadrupedal ornithischian dinosaurs.
title_full_unstemmed	Limb-bone scaling indicates diverse stance and gait in quadrupedal ornithischian dinosaurs.
title_sort	limb-bone scaling indicates diverse stance and gait in quadrupedal ornithischian dinosaurs.
publisher	Public Library of Science (PLoS)
publishDate	2012
url	https://doaj.org/article/b559e814711c481ba8ebc0cb53557697
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Limb-bone scaling indicates diverse stance and gait in quadrupedal ornithischian dinosaurs.

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