Bipedal Sahelanthropus tchadensis

According to research on three limb bones, the oldest known progenitor of modern humans climbed through trees and walked on two feet roughly seven million years ago.

The age of the first known representative species of humans was advanced by a million years when the skull of Sahelanthropus tchadensis or "Toumai," was found in Chad in 2001. However, at the time, the issue sparked intense controversy among scientists, in part because of the rarity and poor quality of the accessible bones. Some even asserted that it wa…