ABSTRACT
Turtles are an iconic lineage in studies of animal locomotion, typifying the use of slow, alternating footfalls during walking. Alternating movements of contralateral limbs are also typical during swimming gaits for most freshwater turtles. Here, we report a novel gait in turtles, in which the pleurodire Emydura subglobosa swims using a bounding gait that coordinates bilateral protraction of both forelimbs with bilateral retraction of both hindlimbs. Use of this bounding gait is correlated with increased limb excursion and decreased stride frequency, but not increased velocity when compared with standard swimming strokes. Bounding by E. subglobosa provides a second example of a non-mammalian lineage that can use bounding gaits, and may give insight into the evolution of aquatic flapping. Parallels in limb muscle fascicle properties between bounding turtles and crocodylids suggest a possible musculoskeletal mechanism underlying the use of bounding gaits in particular lineages.
Footnotes
Author contributions
Conceptualization: C.J.M.; Methodology: C.J.M.; Software: C.J.M.; Formal analysis: C.J.M.; Investigation: C.J.M.; Data curation: C.J.M.; Writing - original draft: C.J.M.; Writing - review & editing: C.J.M., R.W.B.; Visualization: C.J.M.; Supervision: R.W.B.; Funding acquisition: C.J.M., R.W.B.
Funding
Work was supported by Clemson University (Creative Inquiry no. 479).
Data availability
Data are available from the Dryad Digital Repository (Mayerl and Blob, 2017): http://dx.doi.org/10.5061/dryad.r5v8d
