Meeting Abstract
The evolutionary success of Archosauria makes it a compelling clade for the study of vertebrate evolution. Experimental study of living archosaur locomotion is critical to our understanding of the locomotor strategies of extinct archosaurs (including “rauisuchians”, pterosaurs, and non-avian dinosaurs). In modern crocodylians and extinct non-avian archosaurs, M. caudofemoralis longus (CFL) is thought to play a critical role in hip function. The muscle originates from the tail and inserts onto both the femur and the lower leg, the latter insertion occurring via a long, thin tendon known as the tendon of Sutton. A similar anatomical system is found in limbed lepidosaurs. Although CFL’s function as a femoral retractor has been well-studied in both archosaurs and lepidosaurs, the muscle’s potential impact on more distal joints has been largely ignored. In this study, we used a combination of in- and ex-vivo approaches to study the function of the tendon of Sutton in the American alligator. XROMM, combined with dissection and CT imaging of cadaveric specimens, reveals that the tendon of Sutton possesses several insertions into the bones and soft tissues of the lower limb, is taut from late swing to early-to-mid stance, and deflects the external head of M. gastrocnemius and the femoral tendon of CFL itself. These data suggest that the tendon of Sutton allows these two muscles to work synergistically to increase torque about the knee and hip joints, improving the animal’s ability to generate locomotor force, and have implications for anatomical and locomotor reconstruction in extinct taxa.
