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Back to the bones: do muscle area assessment techniques predict functional evolution across a macroevolutionary radiation?

Bates, Karl T.; Wang, Linjie; Dempsey, Matthew; Broyde, Sarah; Fagan, Michael J.; Cox, Philip G.


Karl T. Bates

Linjie Wang

Matthew Dempsey

Sarah Broyde

Michael J. Fagan

Philip G. Cox


Measures of attachment or accommodation area on the skeleton are a popular means of rapidly generating estimates of muscle proportions and functional performance for use in large-scale macroevolutionary studies. Herein, we provide the first evaluation of the accuracy of these muscle area assessment (MAA) techniques for estimating muscle proportions, force outputs and bone loading in a comparative macroevolutionary context using the rodent masticatory system as a case study. We find that MAA approaches perform poorly, yielding large absolute errors in muscle properties, bite force and particularly bone stress. Perhaps more fundamentally, these methods regularly fail to correctly capture many qualitative differences between rodent morphotypes, particularly in stress patterns in finite-element models. Our findings cast doubts on the validity of these approaches as means to provide input data for biomechanical models applied to understand functional transitions in the fossil record, and perhaps even in taxon-rich statistical models that examine broad-scale macroevolutionary patterns. We suggest that future work should go back to the bones to test if correlations between attachment area and muscle size within homologous muscles across a large number of species yield strong predictive relationships that could be used to deliver more accurate predictions for macroevolutionary and functional studies.


Bates, K. T., Wang, L., Dempsey, M., Broyde, S., Fagan, M. J., & Cox, P. G. (2021). Back to the bones: do muscle area assessment techniques predict functional evolution across a macroevolutionary radiation?. Interface, 18(180), Article 20210324.

Journal Article Type Article
Acceptance Date Jun 30, 2021
Online Publication Date Jul 21, 2021
Publication Date 2021-07
Deposit Date Mar 30, 2022
Publicly Available Date Mar 30, 2022
Journal Journal of the Royal Society, Interface
Electronic ISSN 1742-5662
Publisher The Royal Society
Peer Reviewed Peer Reviewed
Volume 18
Issue 180
Article Number 20210324
Keywords Finite-element analysis; Rodent mastication; Biomechanics; Multi-body dynamics; Macroevolution
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