ASHLEY S. HAMMOND, then a graduate student at University of Missouri, Columbia, Missouri, was awarded a grant in October 2012 to aid research on 'Fossil Evidence for Hip Joint Mobility and the Evolution of Suspensory Locomotor Abilities in Hominoids,' supervised by Dr. Carol V. Ward. Suspensory behaviors are thought to be key locomotor behaviors to understanding extant great ape morphology, and figure into most scenarios of great ape and human evolution. It is assumed that suspensory behaviors are associated with increased ranges of joint mobility, particularly range of abduction at the hip joint, although there are no empirical data on hip mobility available. This project tested the hypothesis that suspensory primates have an increased range of motion at the hip joint compared to non-suspensory anthropoids in anesthetized animals (in vivo), and investigated the utility of modeling joint mobility digitally for application to fossil hominoids. The study found support for the hypothesis that suspensory primates have significantly increased range of hip abduction. Simulations of hip abduction revealed that there is also a consistent relationship between the digital approach and range of abduction measured in vivo, providing a framework for interpreting fossil hominoids. Range of abduction was then simulated in fossil hominoids Proconsul nyanzae, hypothesized to be an above-branch quadruped, and Rudapithecus hungaricus, which is hypothesized to be suspensory. As expected, this study found that Rudapithecus would have had hip mobility similar to suspensory taxa whereas Proconsul had more limited hip mobility. This project provides the first evidence for suspensory behavior in a fossil ape based on hindlimb joint mobility.
Hammond, Ashley S. 2014. In Vivo Baseline Measurements of Hip Joint Range of Motion in Suspensory and Nonsuspensory Anthropoids. American Journal of Physical Anthropology 153(3):417-434
Hammond, Ashley S., J. Michael Plavcan, and Carol V. Ward. 2013. Precision and Accuracy of Acetabular Size Measures in Fragmentary Hominin Pelves Obtained Using Sphere-Fitting Techniques. American Journal of Physical Anthropology 150(4):565-578.