In 1972, in Hadar, Ethiopia, Dr Johnason and his research team were on an expedition in search of fossils and artifacts related to human origins. As Johanson and his team explored the area for fossils, Johnason noticed bones of knee joint. At first he assumed it was bones of an ancient monkey, but shortly noticed that it looked vaguely human. In need of conformation of his findings, Johanson turned to expert advice. Johanson took the knee joint to be examined by Owen Lovejoy, an anatomist. Owen confirmed Johanson suspension, and stated as soon as he seen the knee joint he instantly knew it was that of a human. “Walking upright is something that only humans can do. And it needs a special kind of knee joint, one that can be locked straight. A chimp gets around on all fours. If it tries to walk upright, it's knee joint doesn't lock. It's forced to walk with a bent leg and that's tiring” .
This important discovery showed an ancient bipedal creature in Johanson theory of finding the “missing link” in human ancestry. The next step in this discovery was getting the age of this