Fossil of earliest known bipedal hominin found

BEIJING, March 21 (Xinhuanet) -- The origins of bipedalism -- walking upright on two feet -- have been pushed back to 6 million years ago following the discovery of a fossil of an early relative of modern humans in Kenya.

"I would say at this point it's the earliest fossil hominin that we can clearly identify as bipedal," said paleoanthropologist William Jungers of Stony Brook University, who conducted a quantitative analysis with Brian Richmond of George Washington University of a fossilized femur bone from the species named Orrorin tugenensis. It is one of the earliest known pre-humans.

The researchers compared the shape of this thigh bone to those of modern humans, apes and other early hominins, including Australopithecus (the species to which the famous "Lucy" fossil belongs). The team determined that the femur bears the signatures of bipedalism.

The research, funded by the National Science Foundation and Stony Brook and George Washington universities, is detailed in the March 21 issue of the journal Science.

Carol Ward, an anatomist at the University of Missouri-Columbia who was not involved in the research, said the team's findings are significant.

"No detailed study had ever been done on this fossil, and they did a very solid comparative metric analysis," she said.

What's special about O. tugenensis, and other early humans that lived between 6 million and 2 million years ago, is that they not only travelled on the ground on two legs but also retained the ability to climb trees, Jungers said.

"These are bipedal walkers that were also using the tress for food, sleeping and escaping from predators," Jungers told LiveScience. The researchers think O. tugenensis was a climber because of a finger bone also found belonging to the species. The finger is curved, Jungers said, a sign that it was used to grasp trees.

(Agencies)