New Fossil Discoveries Clinch Ancient Age Of Huma...( UNIVERSITY PARK Pa. -- Newly discover...)

UNIVERSITY PARK, Pa. -- Newly discovered African fossils could resolve questions over the age and evolution of a species thought to be the most ancient known upright-walking ancestor of humans, according to research to be published in today's (May 7) issue of the journal Nature.

The research team includes Meave G. Leakey, curator of paleontology at the National Museums of Kenya; Craig S. Feibel, assistant professor of anthropology at Rutgers University; Ian McDougall, professor of earth sciences at the Australian National University; Carol Ward, assistant professor of anthropology at the University of Missouri; and Alan C. Walker, distinguished professor of anthropology and biology at Penn State.

The researchers, who first named the new species Australopithecus anamensis, in a paper published in Nature in 1995 based on 22 fossils discovered in northern Kenya, now have unearthed 38 additional fossils that paint a more complete picture of the species. Some scientists questioned the antiquity of the fossil bones described in the 1995 paper, which were found sandwiched at different depths between layers of rock and ancient soils, because a definite time of origin could not then be measured for the youngest layer.

"The fossils found in younger deposits were the most human-looking, so some people said we could have two species instead of just one--an older one and a much younger one," Walker says.

"In 1995 we could not firmly establish the age of the youngest geologic layer associated with these fossils because the best dating technique, the 40 Argon/39 Argon method, needs crystals and this particular layer is mostly powdery ash," Walker explains.

"Since then--after much sifting through the ashes--we have managed to get enough good crystals to determine quite firmly that these fossils are between 4.1 and 4.2 million years old," he says. "We also have discovered 38 more fossils at t
'"/>

Contact: Barbara Kennedy
bkk1@psu.edu
814-863-4682
Penn State
7-May-1998