Data from: A novel, bounding gait in swimming turtles: implications for aquatic locomotor diversity

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 to 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.

龟类是动物运动学研究中的标志性演化支，其行走模式以缓慢交替的步行动作为典型特征。多数淡水龟的游泳运动同样以对侧肢体（contralateral limbs）的交替动作为典型特征。本研究报道了龟类中一种全新的运动步态：侧颈龟亚目（Pleurodira）物种红腹短颈龟（Emydura subglobosa）在游泳时采用一种跳跃步态（bounding gait），该步态通过协调双侧前肢同步前伸与双侧后肢同步后缩来完成运动。相较于标准游泳划水动作，该跳跃步态的采用与肢体摆动幅度增大、步频降低相关，但并未提升运动速度。红腹短颈龟的跳跃步态行为为非哺乳类演化支能够使用跳跃步态提供了第二个实证案例，或可为水生拍水运动的演化研究提供新的洞察视角。跳跃步态龟类与鳄科（Crocodylidae）动物在肢体肌束特性上的相似性，提示了特定演化支采用跳跃步态的潜在肌肉骨骼机制。