Modelling take-off moment arms in an ornithocheiraean pterosaur

Griffin, Benjamin W.; Martin-Silverstone, Elizabeth; Pêgas, Rodrigo V.; Meilak, Erik Anthony; Costa, Fabiana R.; Palmer, Colin; Rayfield, Emily J.

Abstract

Take-off is a vital part of powered flight which likely constrains the size of birds, yet extinct pterosaurs are known to have reached far larger sizes. Three different hypothesised take-off motions (bipedal burst launching, bipedal countermotion launching, and quadrupedal launching) have been proposed as explanations for how pterosaurs became airborne and circumvented this proposed morphological limit. We have constructed a computational musculoskeletal model of a 5 m wingspan ornithocheiraean pterosaur, reconstructing thirty-four key muscles to estimate the muscle moment arms throughout the three hypothesised take-off motions. Range of motion constrained hypothetical kinematic sequences for bipedal and quadrupedal take-off motions were modelled after extant flying vertebrates. Across our simulations we did not find higher hindlimb moment arms for bipedal take-off motions or noticeably higher forelimb moment arms in the forelimb for quadrupedal take-off motions. Despite this, in all our models we found the muscles utilised in the quadrupedal take-off have the largest total launch applicable moment arms throughout the entire take-off sequences and for the take-off pose. This indicates the potential availability of higher leverage for a quadrupedal take-off than hypothesised bipedal motions in pterosaurs pending further examination of muscle forces.

Citation

Griffin, B. W., Martin-Silverstone, E., Pêgas, R. V., Meilak, E. A., Costa, F. R., Palmer, C., & Rayfield, E. J. (in press). Modelling take-off moment arms in an ornithocheiraean pterosaur. PeerJ, 12, Article e17678. https://doi.org/10.7717/peerj.17678

• Journal Article Type: Article
• Acceptance Date: Jul 12, 2024
• Online Publication Date: Aug 5, 2024
• Deposit Date: Aug 19, 2024
• Journal: PeerJ
• Publisher: PeerJ
• Peer Reviewed: Peer Reviewed
• Volume: 12
• Article Number: e17678
• DOI: https://doi.org/10.7717/peerj.17678
• Keywords: Pterosaur, Flight, Take-off, Biomechanics, Moment arms, Modelling
• Public URL: https://keele-repository.worktribe.com/output/885571