Meeting Abstract
P3.198 Sunday, Jan. 6 Tenotomy of the caudofemoralis longus has no effect on alligator locomotion JONESON, J.R.*; OWERKOWICZ, T.; ELSEY, R.M.; California State University, San Bernardino; California State University, San Bernardino; Rockefeller Wildlife Refuge, Louisiana Dept. of Wildlife and Fisheries, Grand Chenier corbettj@coyote.csusb.edu
The caudofemoralis longus muscle (CFL) – a major retractor and medial rotator of the thigh – is particularly well-developed in reptiles with a long tail and a sprawling gait. The CFL originates on the transverse processes and chevrons of the caudal vertebrae and inserts on the fourth trochanter of the femur. As determined by electromyography in the American alligator (Alligator mississippiensis), the CFL is consistently active during the stance phase of walking, while other synergists are not. Evolutionary changes to hindlimb orientation and tail morphology among the theropod dinosaurs have been ascribed to a reduction in prominence of the CFL to locomotion, but no experimental alteration to CFL function has been attempted. In order to discern the role of the CFL in locomotion, we filmed juvenile American alligators walking on a level grid trackway before and after bilateral CFL tenotomy. We found no significant differences between surgically-tenotomised alligators (n=6) and sham-operated controls (n=6) in average speed, stride length or hip height during steady locomotion on the trackway. These preliminary results suggest that either (i) the CFL is not an important contributor to hindlimb stance and movement, or (ii) other hip muscles are able to compensate for lack of CFL function during slow and steady locomotion. Monitoring of bone growth following CFL tenotomy will allow us to investigate the effects of CFL function on femoral and vertebral morphology. Understanding the CFL-driven phenotypic plasticity of the alligator skeleton may elucidate the role of musculoskeletal strain in shaping the evolutionary transformation of the hindlimb/tail module in archosaurs.
