| Investigations of the surface morphology of the hip joint have traditionally relied on linear measures to represent curved anatomical shapes, with the result that many functional features of the hip have remained unstudied. Three-dimensional features such as the distribution of articular surface are critical in determining the nature of the joint articulation, and the relative stability and range of movement possible at the hip. This study estimates hip function in eleven species of extant anthropoids and prosimians through a three-dimensional, functional analysis of their hip joint articulations. The three-dimensional analysis is then applied to several fossil primates (adapids, omomyids, parapithecoids, hominoids) in order to reconstruct hip use in these species.;Three-dimensional coordinate data describing proximal femora and acetabula were obtained by Computed Tomography and Magnetic Resonance micro-Imaging. Three-dimensional models of the bones were reconstructed, and computer algorithms were used to quantify functionally salient features. Inferences about the functional significance of features in extant species were made and compared to behavioral data from the literature, and to angles of hip abduction measured on live, anaesthetized primates. The characters were then used to predict hip function in fossil species. Features analyzed include joint surface area, joint sphericity, the fraction of a complete sphere occupied by the articular surfaces, articular surface distribution, and size and location of the fovea capitis, acetabular fossa and acetabular notch. In addition, computer animation was used to oppose complementary joint components and estimate range of movement.;Functional predictions generated by the three-dimensional analysis were corroborated by behavioral information. Hence this study expands the character base with which morphologists can analyze form/function relationships at the hip, and reconstruct hip function in fossil species. Among the insights provided from the analysis of fossil specimens was that Australopithecus afarensis had limited hip mobility (similar to humans and unlike more arboreal primates such as chimpanzees) which would have negatively affected climbing ability. |
