Convergent evolution of quadrupedality in ornithischian dinosaurs was achieved through disparate forelimb muscle mechanics



Dempsey, Matthew, Maidment, Susannah, Hedrick, Brandon and Bates, Karl ORCID: 0000-0002-0048-141X
(2023) Convergent evolution of quadrupedality in ornithischian dinosaurs was achieved through disparate forelimb muscle mechanics. Proceedings of the Royal Society B: Biological Sciences, 290 (1992). 20222435-.

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Abstract

The secondary evolution of quadrupedality from bipedal ancestry is a rare evolutionary transition in tetrapods yet occurred convergently at least three times within ornithischian dinosaurs. Despite convergently evolving quadrupedal gait, ornithischians exhibited variable anatomy, particularly in the forelimbs, which underwent a major functional change from assisting in foraging and feeding in bipeds to becoming principal weight bearing components of the locomotor system in quadrupeds. Here, we use three-dimensional multi-body dynamics models to demonstrate quantitatively that different quadrupedal ornithischian clades evolved distinct forelimb musculature, particularly around the shoulder. We find that major differences in glenohumeral abduction-adduction and long axis rotation muscle leverages were key drivers of mechanical disparity, thereby refuting previous hypotheses about functional convergence in major clades. Elbow muscle leverages were also disparate across the major ornithischian lineages, although high elbow extension muscle leverages were convergent between most quadrupeds. Unlike in ornithischian hind limbs, where differences are more closely tied to functional similarity than phylogenetic relatedness, mechanical disparity in ornithischian forelimbs appears to have been shaped primarily by phylogenetic constraints. Differences in ancestral bipedal taxa within each clade may have resulted in disparate ecomorphological constraints on the evolutionary pathways driving divergence in their quadrupedal descendants.

Item Type: Article
Uncontrolled Keywords: macroevolution, biomechanics, multi-body dynamics, dinosaurs, quadrupedality, moment arms
Divisions: Faculty of Health and Life Sciences
Faculty of Health and Life Sciences > Institute of Life Courses and Medical Sciences
Depositing User: Symplectic Admin
Date Deposited: 16 Jan 2023 10:19
Last Modified: 12 Oct 2023 15:50
DOI: 10.1098/rspb.2022.2435
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3167039