New and more detailed analysis of a fossil thigh bone found eight years ago in Kenya presented evidence that the Orrorin tugensis stood and walked on its hind limbs, The New York Times reported. The finding is the earliest known example of walking, said scientists from George Washington University in Washington and the State University of New York at Stony Brook.

The French discoverers of the fossils had suspected the species' movement could be transformed to an upright position but weren't sure, researchers in the latest study said.

George Washington University's Brian Richmond told the Times the size of the creature's hip joint, the shape and strength of the thigh bone and other characteristics provided "convincing evidence to confirm Orrorin's bipedal adaptations."

Richmond said the new research indicated Orrorin not only was a "basal member" of the human family but also had walking mechanics that virtually went unchanged until the rise of Homo, especially in Homo erectus less than 2 million years ago.

The findings were reported in the journal Science.