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Quantitative biomechanical assessment of locomotor capabilities of the stem archosaur Euparkeria capensis

Demuth, OE, Wiseman, ALA and Hutchinson, JR (2023) Quantitative biomechanical assessment of locomotor capabilities of the stem archosaur Euparkeria capensis. Royal Society Open Science, 10 (1). ISSN 2054-5703

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Birds and crocodylians are the only remaining members of Archosauria (ruling reptiles) and they exhibit major differences in posture and gait, which are polar opposites in terms of locomotor strategies. Their broader lineages (Avemetatarsalia and Pseudosuchia) evolved a multitude of locomotor modes in the Triassic and Jurassic periods, including several occurrences of bipedalism. The exact timings and frequencies of bipedal origins within archosaurs, and thus their ancestral capabilities, are contentious. It is often suggested that archosaurs ancestrally exhibited some form of bipedalism. Euparkeria capensis is a central taxon for the investigation of locomotion in archosaurs due to its phylogenetic position and intermediate skeletal morphology, and is argued to be representative of facultative bipedalism in this group. However, no studies to date have biomechanically tested if bipedality was feasible in Eupakeria. Here, we use musculoskeletal models and static simulations in its hindlimb to test the influences of body posture and muscle parameter estimation methods on locomotor potential. Our analyses show that the resulting negative pitching moments around the centre of mass were prohibitive to sustainable bipedality. We conclude that it is unlikely that Euparkeria was facultatively bipedal, and was probably quadrupedal, rendering the inference of ancestral bipedal abilities in Archosauria unlikely.

Item Type: Article
Uncontrolled Keywords: Archosauria; bipedalism; locomotion; musculoskeletal modelling
Subjects: C Auxiliary Sciences of History > CC Archaeology
Q Science > QH Natural history > QH301 Biology
Divisions: Biological & Environmental Sciences (from Sep 19)
Publisher: The Royal Society
SWORD Depositor: A Symplectic
Date Deposited: 19 Mar 2024 14:44
Last Modified: 19 Mar 2024 14:45
DOI or ID number: 10.1098/rsos.221195
URI: https://researchonline.ljmu.ac.uk/id/eprint/22854
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