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Australian Journal of Zoology Australian Journal of Zoology Society
Evolutionary, molecular and comparative zoology
RESEARCH ARTICLE (Open Access)

Understanding Australia’s unique hopping species: a comparative review of the musculoskeletal system and locomotor biomechanics in Macropodoidea

Lauren H. Thornton https://orcid.org/0000-0002-9667-0951 A * , Taylor J. M. Dick B , Mike B. Bennett B and Christofer J. Clemente https://orcid.org/0000-0001-8174-3890 A
+ Author Affiliations
- Author Affiliations

A School of Science, Technology, and Engineering, University of the Sunshine Coast, Sippy Downs, Qld, Australia.

B School of Biomedical Sciences, University of Queensland, St Lucia, Qld, Australia.


Handling Editor: Paul Cooper

Australian Journal of Zoology 69(4) 136-157 https://doi.org/10.1071/ZO21048
Submitted: 8 November 2021  Accepted: 5 April 2022   Published: 13 May 2022

© 2021 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Kangaroos and other macropodoids stand out among mammals for their unusual hopping locomotion and body shape. This review examines the scaling of hind- and forelimb bones, and the primary ankle extensor muscles and tendons. We find that the scaling of the musculoskeletal system is sensitive to the phylogenetic context. Tibia length increases with positive allometry among most macropodoids, but negative allometry in eastern grey kangaroos and isometry in red kangaroos. Femur length decreases with stronger negative allometry in eastern grey and red kangaroos than among other macropodoids. Muscle masses scale with negative allometry in western grey kangaroos and with isometry in red kangaroos, compared to positive allometry in other macropodoids. We further summarise the work on the hopping gait, energetics in macropodoids, and stresses in the musculoskeletal system in an evolutionary context, to determine what trade-offs may limit locomotor performance in macropodoids. When large kangaroos hop, they do not increase oxygen consumption with speed, unlike most mammals, including small hopping species. We conclude that there is not enough information to isolate the biomechanical factors that make large kangaroos so energy efficient. We identify key areas for further research to fill these gaps.

Keywords: bone, efficiency, gait, locomotion, macropod, muscle, saltation, tendon.


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