Earliest hominin

In December 2000, scientists in the Kenya Palaeontology Expedition announced their discovery of 6-million-year-old fossilized remains of early human ancestors. Orrorin tugenensis probably walked on two legs and was about the size of an adult female chimp. Two years later, an even older (c. 6–7 million years old) possible human ancestor was announced: Sahelanthropus tchadensis, discovered in what is now a desert region of Chad. The main find was a partial skull, but a thighbone (still not described) was also recovered at the site. It was argued from the shape of the base of the skull that Sahelanthropus was able to walk bipedally. However, both these discoveries are quite incomplete, and we need further evidence to place them more firmly on the human family tree.