Fossil hunters discovered remains of a 6-million-year-old human ancestor, dubbed Orrorin tugenensis, at a Kenyan site in 2000. Their analysis of upper-leg fossils from Orrorin suggested that it walked upright in a surprisingly modern way, more like 2-million-year-old Homo erectus than the 3- to 4-million-year-old australopithecines, the group that includes the partial skeleton known as Lucy.
A new study of the most complete Orrorin leg bone, which includes the shaft and knob that connected the upper leg to the pelvis, reaches a different conclusion. Orrorin in fact shared a distinctive hip arrangement with australopithecines, as well as with a related line of fossil species (Paranthropus) that eventually died out, say Brian G. Richmond of George Washington University in Washington, D.C., and William L. Jungers of Stony Brook University in New York.
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