Climbing adaptations, locomotory disparity and ecological convergence in ancient stem ‘kangaroos’

Title
Climbing adaptations, locomotory disparity and ecological convergence in ancient stem ‘kangaroos’
Publication Date
2019-02-06
Author(s)
Boer, Wendy Den
Campione, Nicolas E
( author )
OrcID: https://orcid.org/0000-0002-4205-9794
Email: ncampion@une.edu.au
UNE Id une-id:ncampion
Kear, Benjamin P
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
The Royal Society Publishing
Place of publication
United Kingdom
DOI
10.1098/rsos.181617
UNE publication id
une:1959.11/27542
Abstract
Living kangaroos,wallabies and rat-kangaroos (Macropodoidea) constitute the most ecologically diverse radiation of Australasian marsupials. Indeed, even their hallmark bipedal hopping gait has been variously modified for bounding, walking and climbing. However, the origins of this locomotory adaptability are uncertain because skeletons of the most ancient macropodoids are exceptionally rare. Some of the stratigraphically oldest fossils have been attributed to Balbaridae-a clade of potentially quadrupedal stem macropodoids that became extinct during the late Miocene. Here we undertake the first assessment of balbarid locomotion using two-dimensional geometric morphometrics and a correlative multivariate analysis of linear measurements. We selected the astragalus and pedal digit IV ungual as proxies for primary gait because these elements are preserved in the only articulated balbarid skeleton, as well as some unusual early Miocene balbaridlike remains that resemble the bones of modern tree-kangaroos. Our results show that these fossils manifest character states indicative of contrasting locomotory capabilities. Furthermore, predictive modelling reveals similarities with extant macropodoids that employ either bipedal saltation and/ or climbing. We interpret this as evidence for archetypal gait versatility, which probably integrated higher-speed hopping with slower-speed quadrupedal progression and varying degrees of scansoriality as independent specializations for life in forest and woodland settings.
Link
Citation
Royal Society Open Science, 6(2), p. 1-13
ISSN
2054-5703
Pubmed ID
30891280
Start page
1
End page
13
Rights
Attribution 4.0 International

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