A team led by Wits University's Professor Lee Berger have described and named a new species of hominid, Australopithecus sediba, almost 2-million years old, which was discovered in the Cradle of Humankind World Heritage Site near Johannesburg.
Two papers related to this find, authored by Prof Lee Berger and Prof Paul Dirks (former head of the Wits School of Geosciences, and now from James Cooke University) respectively, will be published in the journal Science today (9 April 2010).
“Sediba, which means natural spring, fountain or wellspring in Sotho, was deemed an appropriate name for a species that might be the point from which the genus Homo arises,” comments Prof Berger. “I believe that this is a good candidate for being the transitional species between the southern African ape-man Australopithecus africanus (like the Taung Child and Mrs Ples) and either Homo habilis or even a direct ancestor of Homo erectus (like Turkana Boy, Java man or Peking man).”
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 metres, although the child would certainly have grown taller," says Prof Berger. "The female probably weighed about 33 kilograms and the child about 27 kilograms at the time of his death.
“The brain size of the juvenile was between 420 and 450 cubic centimetres, which is small (when compared to the human brain of about 1 200 to 1 600 cubic centimetres) but the shape of the brain seems to be more advanced than that of australopithecines.”
Prof Dirks adds: “Through a combination of faunal, U-Pb and palaeomagnetic dating techniques, the age of the rocks encasing the fossils has been determined at 1.95-1.78 Ma. Cosmogenic dating was used to interpret the landscape formation and to determine the depth of the cave at the time.”
The skeletons were found among the articulated skeletons of a sabre-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 that was possibly about 30 metres to 50 metres underground about 1,9-million years ago.
Fossil preparators have worked arduously over the last year-and-a-half to extract the bones from the rock. Around 60 leading scientists from around the world and a number of students have had the opportunity to work on these fossils. The most sophisticated scanning technology has been used to unveil the secrets of the past.
The site continues to be explored and more groundbreaking discoveries are expected.
In celebration of this find, the children of South Africa have been invited to develop a common name for the juvenile skeleton.
The fossils are owned by the people of South Africa and curated by the University of the Witwatersrand, Johannesburg. They will be on public display at Maropeng in the Cradle of Humankind until 18 April, will move to Cape Town for the launch of Palaeo-Sciences Week from 19 April and will again be on public display at the Wits Origins Centre during May.