Bipedalism in Orrorin tugenensis revealed by its femora

Three fragments of femora of Orrorin tugenensis, a 6 Ma hominid from the Lukeino Formation, Kenya, possesses a suite of derived characters that reveal that the species was habitually bipedal. Detailed anatomical comparisons with modem humans, Australopithecines and Miocene and extant African apes, reveal that Orrorin shares several apomorphic features with Australopithecines and Homo, but none with Pan or Gorilla. Within the Hominidae, the femur of Orrorin is closer morphologically to that of modern humans than it is to those of australopithecines. (C) 2002 Acadmie des sciences/Editions scientifiques et medicales Elsevier SAS.