Locomotion in extinct giant kangaroos: were sthenurines hop-less monsters?

Sthenurine kangaroos (Marsupialia, Diprotodontia, Macropodoidea) were an extinct subfamily within the family Macropodidae (kangaroos and rat-kangaroos). These "short-faced browsers" first appeared in the middle Miocene, and radiated in the Plio-Pleistocene into a diversity of mostly large-...

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Autores principales:	Christine M Janis, Karalyn Buttrill, Borja Figueirido
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2014
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/e5b4b57253b14a739ae6adfbb26af2f5
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spelling	oai:doaj.org-article:e5b4b57253b14a739ae6adfbb26af2f52021-11-25T05:56:28ZLocomotion in extinct giant kangaroos: were sthenurines hop-less monsters?1932-620310.1371/journal.pone.0109888https://doaj.org/article/e5b4b57253b14a739ae6adfbb26af2f52014-01-01T00:00:00Zhttps://doi.org/10.1371/journal.pone.0109888https://doaj.org/toc/1932-6203Sthenurine kangaroos (Marsupialia, Diprotodontia, Macropodoidea) were an extinct subfamily within the family Macropodidae (kangaroos and rat-kangaroos). These "short-faced browsers" first appeared in the middle Miocene, and radiated in the Plio-Pleistocene into a diversity of mostly large-bodied forms, more robust than extant forms in their build. The largest (Procoptodon goliah) had an estimated body mass of 240 kg, almost three times the size of the largest living kangaroos, and there is speculation whether a kangaroo of this size would be biomechanically capable of hopping locomotion. Previously described aspects of sthenurine anatomy (specialized forelimbs, rigid lumbar spine) would limit their ability to perform the characteristic kangaroo pentapedal walking (using the tail as a fifth limb), an essential gait at slower speeds as slow hopping is energetically unfeasible. Analysis of limb bone measurements of sthenurines in comparison with extant macropodoids shows a number of anatomical differences, especially in the large species. The scaling of long bone robusticity indicates that sthenurines are following the "normal" allometric trend for macropodoids, while the large extant kangaroos are relatively gracile. Other morphological differences are indicative of adaptations for a novel type of locomotor behavior in sthenurines: they lacked many specialized features for rapid hopping, and they also had anatomy indicative of supporting their body with an upright trunk (e.g., dorsally tipped ischiae), and of supporting their weight on one leg at a time (e.g., larger hips and knees, stabilized ankle joint). We propose that sthenurines adopted a bipedal striding gait (a gait occasionally observed in extant tree-kangaroos): in the smaller and earlier forms, this gait may have been employed as an alternative to pentapedal locomotion at slower speeds, while in the larger Pleistocene forms this gait may have enabled them to evolve to body sizes where hopping was no longer a feasible form of more rapid locomotion.Christine M JanisKaralyn ButtrillBorja FigueiridoPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 9, Iss 10, p e109888 (2014)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Christine M Janis Karalyn Buttrill Borja Figueirido Locomotion in extinct giant kangaroos: were sthenurines hop-less monsters?
description	Sthenurine kangaroos (Marsupialia, Diprotodontia, Macropodoidea) were an extinct subfamily within the family Macropodidae (kangaroos and rat-kangaroos). These "short-faced browsers" first appeared in the middle Miocene, and radiated in the Plio-Pleistocene into a diversity of mostly large-bodied forms, more robust than extant forms in their build. The largest (Procoptodon goliah) had an estimated body mass of 240 kg, almost three times the size of the largest living kangaroos, and there is speculation whether a kangaroo of this size would be biomechanically capable of hopping locomotion. Previously described aspects of sthenurine anatomy (specialized forelimbs, rigid lumbar spine) would limit their ability to perform the characteristic kangaroo pentapedal walking (using the tail as a fifth limb), an essential gait at slower speeds as slow hopping is energetically unfeasible. Analysis of limb bone measurements of sthenurines in comparison with extant macropodoids shows a number of anatomical differences, especially in the large species. The scaling of long bone robusticity indicates that sthenurines are following the "normal" allometric trend for macropodoids, while the large extant kangaroos are relatively gracile. Other morphological differences are indicative of adaptations for a novel type of locomotor behavior in sthenurines: they lacked many specialized features for rapid hopping, and they also had anatomy indicative of supporting their body with an upright trunk (e.g., dorsally tipped ischiae), and of supporting their weight on one leg at a time (e.g., larger hips and knees, stabilized ankle joint). We propose that sthenurines adopted a bipedal striding gait (a gait occasionally observed in extant tree-kangaroos): in the smaller and earlier forms, this gait may have been employed as an alternative to pentapedal locomotion at slower speeds, while in the larger Pleistocene forms this gait may have enabled them to evolve to body sizes where hopping was no longer a feasible form of more rapid locomotion.
format	article
author	Christine M Janis Karalyn Buttrill Borja Figueirido
author_facet	Christine M Janis Karalyn Buttrill Borja Figueirido
author_sort	Christine M Janis
title	Locomotion in extinct giant kangaroos: were sthenurines hop-less monsters?
title_short	Locomotion in extinct giant kangaroos: were sthenurines hop-less monsters?
title_full	Locomotion in extinct giant kangaroos: were sthenurines hop-less monsters?
title_fullStr	Locomotion in extinct giant kangaroos: were sthenurines hop-less monsters?
title_full_unstemmed	Locomotion in extinct giant kangaroos: were sthenurines hop-less monsters?
title_sort	locomotion in extinct giant kangaroos: were sthenurines hop-less monsters?
publisher	Public Library of Science (PLoS)
publishDate	2014
url	https://doaj.org/article/e5b4b57253b14a739ae6adfbb26af2f5
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Locomotion in extinct giant kangaroos: were sthenurines hop-less monsters?

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