The extraordinary osteology and functional morphology of the limbs in Palorchestidae, a family of strange extinct marsupial giants

Hazel L. Richards, Rod Wells, Alistair R. Evans, Erich M. G. Fitzgerald, Justin W. Adams

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The Palorchestidae are a family of marsupial megafauna occurring across the eastern Australian continent from the late Oligocene through to their extinction in the Late Pleistocene. The group is known for their odd ‘tapir-like’ crania and distinctive clawed forelimbs, but their appendicular anatomy has never been formally described. We provide the first descriptions of the appendicular skeleton and body mass estimates for three palorchestid species, presenting newly-identified, and in some cases associated, material of mid-Miocene Propalorchestes, Plio-Pleistocene Palorchestes parvus and Pleistocene Palorchestes azael alongside detailed comparisons with extant and fossil vombatiform marsupials. We propose postcranial diagnostic characters at the family, genus and species level. Specialisation in the palorchestid appendicular skeleton evidently occurred much later than in the cranium and instead correlates with increasing body size within the lineage. We conclude that palorchestid forelimbs were highly specialised for the manipulation of their environment in the acquisition of browse, and that they may have adopted bipedal postures to feed. Our results indicate palorchestids were bigger than previously thought, with the largest species likely weighing over 1000 kg. Additionally, we show that P. azael exhibits some of the most unusual forelimb morphology of any mammal, with a uniquely fixed humeroulnar joint unlike any of their marsupial kin, living or extinct.
Original languageEnglish
Article numbere0221824
Number of pages69
JournalPLoS ONE
Volume14
Issue number9
DOIs
Publication statusPublished - 13 Sep 2019

Keywords

  • humerus
  • diprotodon
  • femur
  • diaphyses
  • phalanges
  • epiphyses
  • elbow
  • skeletal joints

Cite this

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title = "The extraordinary osteology and functional morphology of the limbs in Palorchestidae, a family of strange extinct marsupial giants",
abstract = "The Palorchestidae are a family of marsupial megafauna occurring across the eastern Australian continent from the late Oligocene through to their extinction in the Late Pleistocene. The group is known for their odd ‘tapir-like’ crania and distinctive clawed forelimbs, but their appendicular anatomy has never been formally described. We provide the first descriptions of the appendicular skeleton and body mass estimates for three palorchestid species, presenting newly-identified, and in some cases associated, material of mid-Miocene Propalorchestes, Plio-Pleistocene Palorchestes parvus and Pleistocene Palorchestes azael alongside detailed comparisons with extant and fossil vombatiform marsupials. We propose postcranial diagnostic characters at the family, genus and species level. Specialisation in the palorchestid appendicular skeleton evidently occurred much later than in the cranium and instead correlates with increasing body size within the lineage. We conclude that palorchestid forelimbs were highly specialised for the manipulation of their environment in the acquisition of browse, and that they may have adopted bipedal postures to feed. Our results indicate palorchestids were bigger than previously thought, with the largest species likely weighing over 1000 kg. Additionally, we show that P. azael exhibits some of the most unusual forelimb morphology of any mammal, with a uniquely fixed humeroulnar joint unlike any of their marsupial kin, living or extinct.",
keywords = "humerus, diprotodon, femur, diaphyses, phalanges, epiphyses, elbow, skeletal joints",
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The extraordinary osteology and functional morphology of the limbs in Palorchestidae, a family of strange extinct marsupial giants. / Richards, Hazel L.; Wells, Rod; Evans, Alistair R.; Fitzgerald, Erich M. G.; Adams, Justin W.

In: PLoS ONE, Vol. 14, No. 9, e0221824, 13.09.2019.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - The extraordinary osteology and functional morphology of the limbs in Palorchestidae, a family of strange extinct marsupial giants

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AU - Adams, Justin W.

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AB - The Palorchestidae are a family of marsupial megafauna occurring across the eastern Australian continent from the late Oligocene through to their extinction in the Late Pleistocene. The group is known for their odd ‘tapir-like’ crania and distinctive clawed forelimbs, but their appendicular anatomy has never been formally described. We provide the first descriptions of the appendicular skeleton and body mass estimates for three palorchestid species, presenting newly-identified, and in some cases associated, material of mid-Miocene Propalorchestes, Plio-Pleistocene Palorchestes parvus and Pleistocene Palorchestes azael alongside detailed comparisons with extant and fossil vombatiform marsupials. We propose postcranial diagnostic characters at the family, genus and species level. Specialisation in the palorchestid appendicular skeleton evidently occurred much later than in the cranium and instead correlates with increasing body size within the lineage. We conclude that palorchestid forelimbs were highly specialised for the manipulation of their environment in the acquisition of browse, and that they may have adopted bipedal postures to feed. Our results indicate palorchestids were bigger than previously thought, with the largest species likely weighing over 1000 kg. Additionally, we show that P. azael exhibits some of the most unusual forelimb morphology of any mammal, with a uniquely fixed humeroulnar joint unlike any of their marsupial kin, living or extinct.

KW - humerus

KW - diprotodon

KW - femur

KW - diaphyses

KW - phalanges

KW - epiphyses

KW - elbow

KW - skeletal joints

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