A reconstruction of the thigh musculature of the extinct pseudosuchian Prestosuchus chiniquensis from the Dinodontosaurus Assemblage Zone (Middle Triassic Epoch), Santa Maria 1 Sequence, southern Brazil

Prestosuchus chiniquensis is an extinct species of terrestrial archosaur from the Middle Triassic Epoch restricted to southern Brazil. In this paper the thigh musculature of P. chiniquensis is reconstructed based on a well-preserved specimen and on myological descriptions of extant birds and crocodylians. Among the 16 analysed muscular groups, 13 were recognized as present and homologous to both extant groups of archosaurs, and two only to the crocodylian line of archosaurs, so that 15 muscular groups were reconstructed in the fossil specimen. Morphological particularities of the pelvic girdle and the hindlimbs of P. chiniquensis gave a distinct arrangement for the muscular origin and insertion sites, leading to different lines of action and functions when compared with extant archosaurs. The comparison between extinct and extant archosaurs showed a basal condition sustained in some aspects, such as the morphology of the femur and the flexion of the knee, although other aspects were considered as derived, such as the morphology of the pubis and ischium, and their associated muscle origin locations.