According to the latest discovery, how old would be the first biped human ancestor? Which bone do scientists are looking for, specifically, relevant to this matter?

"The first biped was probably Australopithecus, sometimes known as ‘ape man’. Several species of Australopithecus emerge along the evolutionary timeline, of which the earliest is Australopithecus anamensis. Based on fossil finds in Kenya between 1988 and 1994, he lived between 4.2 and 3.9 million years ago. Brawnily built, his partial tibia (the larger of the two lower leg bones) and lower humerus (the upper arm bone) were extremely humanlike and strongly suggest an upright gait."

-The Discovery Channel

First Biped

Hard to argue with the discovery channel.My source deals with new foundings (2005) of a full skeleton. Both source tends to agree on the time frame :about 4 million years old.

However the "ankle joint' is the bone I was looking for. Good job Sailracer.

News scientist