Meeting Abstract
The caudofemoralis longus (CFL) muscle is known as an integral locomotor muscle in the hindlimb of all non-erect terrestrial vertebrates and has been particularly well-studied in archosaurs (crocodilians, birds, and their relatives). CFL’s designation as the primary driver of propulsive force generation in alligators is based on relatively qualitative anatomical and electromyographical data, but lacks direct quantitative support. Here we compare hindlimb joint mechanics before and after bilateral CFL tenotomy in juvenile alligators using high-speed videography (dorsal and lateral views) and force plate ergometry. Data were collected for n=12 alligators (CONTROL) and subsequently split into two post-operative groups of n=6 each: CFL-tenotomized (SURG) and sham-operated (SHAM). Only trials where animals walked at a moderate speed (0.16 + 0.03 m/s) were analyzed. Preliminary data analyses show significant differences (RM-ANOVA p<0.05) between CONTROL and SURG groups in average peak propulsive force, time to reach peak propulsive force and stance phase duration, but no discernible differences in total propulsive impulse. Hip joint kinematics remain largely conserved, but distal hindlimb joints in SURG begin stance phase significantly more flexed, flex more during stance phase, and on average extend less during stance phase. These results suggest that specific features of hindlimb mechanics are affected by CFL tenotomy, but broader patterns remain relatively conserved with the loss of a major hindlimb muscle in walking alligators. This work directly tests the effects of complete deactivation of a major hindlimb muscle on limb mechanics, and highlights the redundancy and complex interrelationship between muscle and locomotor performance in vertebrates.
