An international team has described and named a new species of hominid, Australopithecus sediba, almost two million years old. Two papers related to this find will be published Friday in the journal Science.

"Sediba, which means natural spring, fountain or wellspring in Sotho, one of the 11 official languages of South Africa, was deemed an appropriate name for a species that might be the point from which the genus Homo arises," said Lee R. Berger, lead author and palaeoanthropologist from the University of the Witwatersrand, Johannesburg.

"I believe that this is a good candidate for being the transitional species between the southern African ape-man Australopithecus africanus and either Homo habilis or even a direct ancestor of Homo erectus."

The fossils, a juvenile male and an adult female, were deposited within a single debris flow and occur together in a near articulated state in the remains of a deeply eroded cave system. The sedimentary and geological context indicates that the timing of their death was closely related and occurred shortly before the debris flow carried them to their place of burial.

The species has long arms, like an ape, short powerful hands, a very advanced pelvis (hip bone) and long legs capable of striding and possibly running like a human. It is likely that they could have climbed.

"It is estimated that they were both about 1.27 meters, although the child would certainly have grown taller. The female probably weighed about 33 kilograms and the child about 27 kilograms at the time of his death," adds Berger.

"The brain size of the juvenile was between 420 and 450 cubic centimeters, which is small (when compared to the human brain of about 1200 to 1600 cubic centimeters) but the shape of the brain seems to be more advanced than that of australopithecines."

The skeletons were found among the articulated skeletons of a saber-toothed cat, antelope, mice and rabbits. They are preserved in a hard, concrete like substance known as calcified clastic sediment that formed at the bottom of what appears to be a shallow underground lake or pool.