1Anthropological Institute, University of Zürich, 2Primate Research Institute, Kyoto University
Friday 10:45-11:00, Galleria North
Musculoskeletal and functional biomechanical data from extant great apes and humans form an important comparative basis for the inference of structure-function relationships from fossil hominin remains. However, still relatively little is known about the detailed quantitative relationships between skeletal and soft tissue structures in extant hominoids. We show that virtopsy (virtual autopsy) is a convenient means to fill this information gap. Using biomedical imaging data of great apes permits non-invasive analysis of hard and soft tissue structures, and the characterization of muscular topography and bone morphology in one and the same specimen. Here we analyze the topographic relationship between femoropelvic muscular attachment sites and surface morphology of the proximal femoral shaft in great apes and humans. Virtopsy data indicate that, in all hominoids, the origin of the vastus lateralis muscle is anterior to the insertion of gluteus maximus, and anterior to a bony crest on the femoral diaphysis known as the lateral spiral pilaster (LSP). In gorillas and orangutans, the insertion of gluteus maximus is on the anterolateral side of the LSP, while in chimpanzees, it is on its posteromedial side, like in modern humans. Our results thus indicate that the surface morphology of the proximal femoral shaft reflects phyletic relationships rather than locomotor similarity between taxa. We discuss the implications of these findings for the functional interpretation of fossil hominin postcranial remains.