March 17, 2014
Little Foot Is The Oldest Complete Australopithecus
April Flowers for redOrbit.com - Your Universe Online
Thirteen years of meticulous excavation by South African and French scientists has shown that the nearly complete fossil skeleton of Australopithecus, nicknamed Little Foot, is most likely around 3 million years old.
Professor Ron Clark from the University of Witwatersrand led the study, which refutes previous dating claims that suggest Little Foot is younger. The findings, published in a recent issue of the Journal of Human Evolution, are the result of a detailed study of the stratigraphy, micro-stratigraphy, and geochemistry around the skeleton.
Since 1936, the Sterkfontein caves of Gauteng, South Africa have been famous for the large numbers of fossil specimens of the ape-man Australopithecus found there. For the first sixty years, however, those fossils consisted of only partial skulls and jaws, isolated teeth and fragments of limb bones. These partial remains were obtained by either blasting or drilling and breaking of the ancient cave infill, or by pick and shovel excavation of the softer decalcified infills.
Scientists were unable to answer the questions of how old these fossils were, how they came to be in the caves, or how a complete skeleton would appear. In 1997, a Witwatersrand team consisting of Ron Clarke, Stephen Motsumi and Nkwane Molefe discovered an almost complete Australopithecus skeleton with the skull embedded in the hard, calcified sediment of an underground chamber of the caves. Careful excavation of the skeleton begin to expose the skeleton in place so that it could be studied, and the ancient processes that contributed to its burial and preservation could be understood.
This is the first time that an excavation of Australopithecus has taken place in an ancient calcified deposit. The researchers found, during the course of the excavation, that the skeleton had been subjected to ancient disturbance and breakage through partial collapse into a lower cavity. Calcareous flowstone subsequently filled voids that were formed by the displaced bones.
Other research teams dated the flowstones, claiming that such dates represented the age of the skeleton, despite the publication of the excavators findings, creating the impression that the skeleton is much younger than the new study asserts.
Clarke worked with Dominic Stratford, also of Wits University, and a French team of specialists in the study of limestone caves, Laurent Bruxelles, Richard Maire and Richard Ortega. The results of their work show that the dated flowstones filled voids formed by ancient erosion and collapse and that the skeleton is therefore older, probably considerably older, than the dated flowstones.
The new study puts Little Foot's age at approximately 3 million years old, not the 2.2 million years that has been proposed by other researchers. Currently, the skeleton has been completely excavated from the cave and the skull, arms, legs, pelvis and other bones have been largely cleaned of encasing rock.
By studying the skull, Professor Clarke has concluded that Little Foot belongs to Australopithecus prometheus, a species named by Professor Raymond Dart in 1948 on fragmentary ape-man fossils from Makapansgat in what is now Limpopo Province.
Two species of ape-man exist at the site in Sterkfontein; Australopithecus africanus (for example, Mrs Ples) and Australopithecus prometheus, many specimens of which have been identified by Clarke from two deposits at Sterkfontein.