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Functional evolution of the feeding system in rodents

Cox, Philip G.; Rayfield, Emily; Rayfield, Emily J.; Fagan, Michael J.; Herrel, Anthony; Pataky, Todd; Pataky, Todd C.; Jeffery, Nathan


Philip G. Cox

Emily Rayfield

Emily J. Rayfield

Michael J. Fagan

Anthony Herrel

Todd Pataky

Todd C. Pataky

Nathan Jeffery


Anjali Goswami


The masticatory musculature of rodents has evolved to enable both gnawing at the incisors and chewing at the molars. In particular, the masseter muscle is highly specialised, having extended anteriorly to originate from the rostrum. All living rodents have achieved this masseteric expansion in one of three ways, known as the sciuromorph, hystricomorph and myomorph conditions. Here, we used finite element analysis (FEA) to investigate the biomechanical implications of these three morphologies, in a squirrel, guinea pig and rat. In particular, we wished to determine whether each of the three morphologies is better adapted for either gnawing or chewing. Results show that squirrels are more efficient at muscle-bite force transmission during incisor gnawing than guinea pigs, and that guinea pigs are more efficient at molar chewing than squirrels. This matches the known diet of nuts and seeds that squirrels gnaw, and of grasses that guinea pigs grind down with their molars. Surprisingly, results also indicate that rats are more efficient as well as more versatile feeders than both the squirrel and guinea pig. There seems to be no compromise in biting efficiency to accommodate the wider range of foodstuffs and the more general feeding behaviour adopted by rats. Our results show that the morphology of the skull and masticatory muscles have allowed squirrels to specialise as gnawers and guinea pigs as chewers, but that rats are high-performance generalists, which helps explain their overwhelming success as a group.


Cox, P. G., Rayfield, E. J., Fagan, M. J., Herrel, A., Pataky, T. C., & Jeffery, N. (2012). Functional evolution of the feeding system in rodents. PLoS ONE, 7(4), e36299.

Journal Article Type Article
Acceptance Date Apr 4, 2012
Online Publication Date Apr 27, 2012
Publication Date Apr 27, 2012
Deposit Date Nov 13, 2014
Publicly Available Date Oct 27, 2022
Journal PLoS ONE
Print ISSN 1932-6203
Electronic ISSN 1932-6203
Publisher Public Library of Science
Peer Reviewed Peer Reviewed
Volume 7
Issue 4
Article Number ARTN e36299
Pages e36299
Keywords General Biochemistry, Genetics and Molecular Biology; General Agricultural and Biological Sciences; General Medicine
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Copyright Statement
© 2012 Cox et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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