Cross-sectional morphology of the SK 82 and 97 proximal femora

Computed tomography scans of the proximal femoral shaft of the South Africa n "robust" australopithecine, A. robustus, reveal a total morphological pat tern that is similar to the specimen attributed to A. boisei in East Africa but unlike that of Homa erectus or modern human femora. Like femora attrib uted to H. erectus, SK 82 and 97 have very thick cortices, although they do not have the extreme increase in mediolateral buttressing that is so chara cteristic of H. erectus. And unlike H, erectus or modern humans, their femo ral heads are very small relative to shaft strength. These features are con sistent with both increased overall mechanical loading of the postcranial s keleton and a possibly slightly altered pattern of bipedal gait relative to that of H. erectus and modern humans. (C) 1999 Wiley-Liss, Inc.