Skip to main content

Research Repository

Advanced Search

Relating neuromuscular control to functional anatomy of limb muscles in extant archosaurs

Cuff, A R; Daley, M A; Michel, K B; Allen, V R; Lamas, L P; Adami, C; Monticelli, P; Pelligand, L; Hutchinson, J R


A R Cuff

M A Daley

K B Michel

V R Allen

L P Lamas

C Adami

P Monticelli

L Pelligand

J R Hutchinson


Electromyography (EMG) is used to understand muscle activity patterns in animals. Understanding how much variation exists in muscle activity patterns in homologous muscles across animal clades during similar behaviours is important for evaluating the evolution of muscle functions and neuromuscular control. We compared muscle activity across a range of archosaurian species and appendicular muscles, including how these EMG patterns varied across ontogeny and phylogeny, to reconstruct the evolutionary history of archosaurian muscle activation during locomotion. EMG electrodes were implanted into the muscles of turkeys, pheasants, quail, guineafowl, emus (three age classes), tinamous and juvenile Nile crocodiles across 13 different appendicular muscles. Subjects walked and ran at a range of speeds both overground and on treadmills during EMG recordings. Anatomically similar muscles such as the lateral gastrocnemius exhibited similar EMG patterns at similar relative speeds across all birds. In the crocodiles, the EMG signals closely matched previously published data for alligators. The timing of lateral gastrocnemius activation was relatively later within a stride cycle for crocodiles compared to birds. This difference may relate to the coordinated knee extension and ankle plantarflexion timing across the swing‐stance transition in Crocodylia, unlike in birds where there is knee flexion and ankle dorsiflexion across swing‐stance. No significant effects were found across the species for ontogeny, or between treadmill and overground locomotion. Our findings strengthen the inference that some muscle EMG patterns remained conservative throughout Archosauria: for example, digital flexors retained similar stance phase activity and M. pectoralis remained an ‘anti‐gravity’ muscle. However, some avian hindlimb muscles evolved divergent activations in tandem with functional changes such as bipedalism and more crouched postures, especially M. iliotrochantericus caudalis switching from swing to stance phase activity and M. iliofibularis adding a novel stance phase burst of activity.


Cuff, A. R., Daley, M. A., Michel, K. B., Allen, V. R., Lamas, L. P., Adami, C., …Hutchinson, J. R. (2019). Relating neuromuscular control to functional anatomy of limb muscles in extant archosaurs. Journal of Morphology, 280(5), 666-680.

Journal Article Type Article
Acceptance Date Feb 11, 2019
Publication Date Mar 8, 2019
Deposit Date Mar 12, 2019
Publicly Available Date Mar 13, 2019
Print ISSN 0362-2525
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 280
Issue 5
Pages 666-680
Public URL


You might also like

Downloadable Citations