JOBURG – A team of South African and French scientists have shown that a Sterkfontein Caves fossil named Little Foot is the world’s oldest, most complete of its kind.
According to a paper by University of the Witwatersrand’s Prof. Ron Carke and colleagues, published in the Journal of Human Evolution, the near-complete Australopithecus skeleton is probably about three million years old.
The paper, Stratigraphic analysis of the Sterkfontein StW 573 Australopithecus skeleton and implications for its age, is the result of a detailed study of the stratigraphy (rock layers), micro-stratigraphy and geochemistry around the skeleton.
The caves have been world famous for producing large numbers of fossils of partial skulls, jaws, teeth and limb fragments of the ape-man Australopithecus since 1936.
In 1997, Clarke, Stephen Motsumi and Nkwane Molefe of Wits University discovered Little Foot, its skull embedded in hard, calcified sediment in an underground chamber of the caves.
They began to excavate it to understand the processes that contributed to its burial and preservation. The skeleton had been subjected to ancient disturbance and breakage through partial collapse into a lower cavity.
Calcareous flowstone (sheetlike deposits of calcite) filled the voids formed around the bones.
“Despite this fact being published, some other researchers dated the flowstones…,” said Clarke.
“This created a false impression that the skeleton is much younger than it actually is.”
A French team of limestone caves specialists, Laurent Bruxelles, Richard Maire and Richard Ortega, with Clarke and Dominic Stratford of Wits University have shown that that the skeleton was older than the flowstones.
“Little Foot is probably around three million years old, and not the 2.2 million years… wrongly claimed by other researchers,” said Clarke.
“The skeleton has been entirely excavated from the cave, and the skull, arms, legs, pelvis and other bones… largely cleaned of encasing rock.”
Clarke concluded from studying the skull that it belonged to the Australopithecus prometheus, a species named by Prof. Raymond Dart in 1948.
This means two species of ape-man, Australopithecus africanus, such as Mrs Ples, and Australopithecus prometheus existed at Sterkfontein.