The complete skull of an extinct species of pre-human has been found in the Sterkfontein valley, an area particularly rich in fossils
Mail & Guardian reporter
South African palaeontologists have notched up another world first with the discovery of the most complete skull of an extinct species of pre-human.
The find could contribute significantly to debates about the origins of the hominid family: what species thrived, which varieties died – and why.
The discovery, in a good state of preservation, of the most complete australopithecine skull yet excavated was made by Dr Andr Keyser of the University of the Witwatersrand. He will be presenting details of his find next week at the university. The scientific details will appear in two articles in this month’s South African Journal of Science.
At the time this kind of australopithecine lived, about 1,8- million years ago, it may have shared its habitat with a variety of other hominid species – including early Homo.
Signs of the species have been found, but never before has as complete a skull been unearthed. It is believed to have belonged to one of the primitive bipedal hominid species that did not evolve into modern man, but became extinct.
The skull was found in a new hominid site in the Sterkfontein valley, a few kilometres from the caves where Dr Ron Clarke found the skeleton of ”Little Foot” – a creature which lived about 3,3- million years ago. Little Foot is to date the oldest known hominid skeleton.
Keyser is a retired geologist who spent most of his working life with the Geological Survey of South Africa (now the Council for Geological Science).
His find is the culmination so far of a lifelong passion for fossils.
Keyser’s work builds on the pioneering excavations of Dr Bob Brain at Swartkrans, whose 25 years of labour have brought to light fossil examples of the same primitive hominid. Signs of the same species have also been found by Dr Francis Thackeray at a site at Kromdraai.
The site where the fossil was found is included in the Sterkfontein valley area that was declared a world heritage site by Unesco last December.
The ongoing excavations promise further rich discoveries: the locale in which the new skull was found has already yielded 79 early hominid specimens of all kinds, as well as an abundance of other fossil material. The skull provides further dramatic confirmation of the palaeontological riches of the area, and amply rewards the faith of the World Heritage Site committee in pronouncing it worthy of the world’s special attention.
The Sterkfontein valley is particularly rich in fossils because of its geological conditions. The dolomite caves are slightly alkaline, which preserves bones by encouraging calcification. This makes the bones rock-hard, and prevents disintegration, even after millions of years. In the site where the skull has been found large areas have been decalcified, thanks to the work of ants and plant roots. This makes excavation much easier than in the caves where Little Foot was found.
The find will add to the debate about the differentiation of hominid species.
There are two basic camps in the debate. ”Lumpers” lump different kinds of hominids together to form fewer species with greater variation, while ”splitters” believe there are many species, each showing little variation.
The paucity of evidence in this debate adds to the importance of the latest find.
An in-depth feature on the latest find will appear in the Mail & Guardian next week