Proximal Humerus Morphology Indicates Divergent Patterns of Locomotion in Extinct Giant Kangaroos

Christine M. Janis*, James G. Napoli, Coral Billingham, Alberto Martín-Serra

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

4 Citations (Scopus)
65 Downloads (Pure)

Abstract

Sthenurine kangaroos, extinct “giant kangaroos” known predominantly from the Plio-Pleistocene, have been proposed to have used bipedal striding as a mode of locomotion, based on the morphology of their hind limbs. However, sthenurine forelimb morphology has not been considered in this context, and has important bearing as to whether these kangaroos employed quadrupedal or pentapedal locomotion as a slow gait, as in extant kangaroos. Study of the correlation of morphology of the proximal humerus in a broad range of therian mammals shows that humeral morphology is indicative of the degree of weight-bearing on the forelimbs during locomotion, with terrestrial species being distinctly different from arboreal ones. Extant kangaroos have a proximal humeral morphology similar to extant scansorial (semi-arboreal) mammals, but sthenurine humeri resemble those of suspensory arboreal taxa, which rarely bear weight on their forelimbs, supporting the hypothesis that they used bipedal striding rather than quadrupedal locomotion at slow gaits. The humeral morphology of the enigmatic extinct “giant wallaby,” Protemnodon, may be indicative of a greater extent of quadrupedal locomotion than in extant kangaroos.

Original languageEnglish
Number of pages21
JournalJournal of Mammalian Evolution
Volume2020
DOIs
Publication statusPublished - 16 Jan 2020

Bibliographical note

Acceptance date is provisional and based on date of publication.

Keywords

  • Functional anatomy
  • Humerus
  • Locomotion
  • Macropodidae
  • Macropodoidea
  • Protemnodon
  • Sthenurinae

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