I focus on the evolutionary morphology of the hindquarters of theropod dinosaurs, analyzing characteristics of the musculoskeletal apparatus within a phylogenetic context, using other saurians as outgroups. I analyze musculoskeletal data from extant and extinct saurian reptiles to develop a broad picture of the evolution of the theropod hindquarters. My data support the hypothesis that the evolution of the terrestrial locomotory module seen in extant birds was a pattern of sequential assembly and modification, with numerous independent specializations and instances of convergence.
Fossils are important for reconstructing polarity of musculoskeletal changes.
Many instances of musculoskeletal specialization, plesiomorphy, and homoplasy in extant clades cannot be identfied without a broad phylogenetic framework including fossils. I also compare musculoskeletal reconstructions generated by my analysis with attempts by previous researchers. Such reconstructions must adopt a more rigorous methodology that uses an integrative approach to homology. A major concern is the absence or equivocality of a large amount of musculoskeletal data, especially in taxa without very similar extant relatives. Muscle scars and other osteological correlates must be carefully interpreted with reference to myological data from extant relatives.