Why go bipedal? Locomotion and morphology in Australian agamid lizards

Christofer J Clemente; P C Withers; G Thompson; D Lloyd

doi:10.1242/jeb.018044

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Why go bipedal? Locomotion and morphology in Australian agamid lizards

Journal article

Peer reviewed

Why go bipedal? Locomotion and morphology in Australian agamid lizards

Christofer J Clemente, P C Withers, G Thompson and D Lloyd

Journal of Experimental Biology, Vol.211(13), pp.2058-2065

2008

DOI: https://doi.org/10.1242/jeb.018044

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Abstract

bipedal

sprint speed

acceleration

endurance

locomotion

agamids

dragon lizards

Bipedal locomotion by lizards has previously been considered to provide a locomotory advantage. We examined this premise for a group of quadrupedal Australian agamid lizards, which vary in the extent to which they will become bipedal. The percentage of strides that each species ran bipedally, recorded using high speed video cameras, was positively related to body size and the proximity of the body centre of mass to the hip, and negatively related to running endurance. Speed was not higher for bipedal strides, compared with quadrupedal strides, in any of the four species, but acceleration during bipedal strides was significantly higher in three of four species. Furthermore, a distinct threshold between quadrupedal and bipedal strides, was more evident for acceleration than speed, with a threshold in acceleration above which strides became bipedal. We calculated these thresholds using probit analysis, and compared these to the predicted threshold based on the model of Aerts et al. Although there was a general agreement in order, the acceleration thresholds for lizards were often lower than that predicted by the model. We suggest that bipedalism, in Australian agamid lizards, may have evolved as a simple consequence of acceleration, and does not confer any locomotory advantage for increasing speed or endurance. However, both behavioural and threshold data suggest that some lizards actively attempt to run bipedally, implying some unknown advantage to bipedal locomotion.

Details

Title: Why go bipedal? Locomotion and morphology in Australian agamid lizards
Authors: Christofer J Clemente (Author) - University of Cambridge, United Kingdom
P C Withers (Author) - University of Western Australia
G Thompson (Author) - Edith Cowan University
D Lloyd (Author) - University of Western Australia
Publication details: Journal of Experimental Biology, Vol.211(13), pp.2058-2065
Publisher: Company of Biologists Ltd.
Date published: 2008
DOI: 10.1242/jeb.018044
ISSN: 0022-0949
Organisation Unit: School of Science and Engineering - Legacy; University of the Sunshine Coast, Queensland; School of Science, Technology and Engineering
Language: English
Record Identifier: 99450204202621
Output Type: Journal article

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Collaboration types: Domestic collaboration; International collaboration
Web Of Science research areas: Biology; Zoology

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