HUTCHINSON, J.R.; ANDERSON, F.C.; BLEMKER, S.S.; DELP, S.L.; Royal Veterinary College, Univ. London; Stanford Univ., CA; Stanford Univ., CA; Stanford Univ., CA: Analysis of hindlimb muscle moment arms in Tyrannosaurus rex using a three-dimensional musculoskeletal computer model.
We have developed a 3D graphics-based model of the musculoskeletal system of the theropod dinosaur Tyrannosaurus rex to examine how its muscles may have functioned. The model includes 10 degrees of joint freedom (hip to toe) and 33 main muscle groups crossing the hip, knee, ankle, and toe joints of the right hindlimb. We used this model to examine how the limb orientation (set of joint angles) of T. rex might have influenced the flexor and extensor moment arms (leverage) of its muscles. We used sensitivity analysis of uncertain parameters, such as muscle origin and insertion centroids, to inspect how much our conclusions depend on the muscle reconstruction we adopt, showing for which muscles the mechanics are most problematic to reconstruct. This information is important for determining how T. rex stood and walked, and how the muscles of a ~6000 kg biped might have worked in comparison with extant bipeds such as birds and humans.
