The Fight Over Toumai

According to a story in Yahoo News, a ruckus has broken out over the Sahelanthropus tchadensis remains that were unearthed in 2001 in the Chad desert. The dispute seems to focus on whether or not the cranium, known as Toumai, dated to between 6.8 and 7.2 million years ago, can actually be dated at all. Although Michel Brunet, its most ardent defender believes the dates, the actual discoverer, Alain Beauvilain, is not so sure:

In general, radiodating of the sediment in which a fossil is found is considered to be a good guide to when the creature died, its remains eventually becoming covered by soil or other debris. But Beauvilain, a Chadian fossil expert of long standing, says that, contrary to Brunet's assertions that the fossil had been "unearthed," the cranium was found loose on the sand.

A thick blue ferruginous, or iron-based, mineral encrusted the skull, which showed clear signs of weathering from desert conditions, Beauvilain says in a commentary in the South African Journal of Science. Beauvilain says it is clear that the soil around the find, and possibly the find itself, had been shifted by wind or erosion, a phenomenon that can happen swiftly and frequently in the desert. So carbon-dating the soil and attributing that to the skull was a perilous exercise, he says. "How many times was it exposed and reburied by shifting sands before being picked up?".

This will obviously need to be cleared up. If that does not happen, Orrorin will rise to the occasion as the best stem hominid.