Sahelanthropus tchadensis has been the object of some controversy for quite awhile. Its discoverer, Michel Brunet, considers it to be close to the human-chimp split on the hominin side. While critics think it is on the hominoid side of things. I bring this up because of a recent article (press release?) on PhysOrg that questions the dating of Toumai that was published in PNAS (See my post on the subject). As Hawks points out this is a pretty abysmal article (mistakenly calling cosmogenic nuclide dating carbon dating for example).
The gist of the article is that a new paper is being published in the South African Journal of Science by one of Toumai’s co-discoverers, Alain Beauvilain, that severely criticizes the PNAS article. Here is the abstract:
The stratigraphic contexts of two important fossil hominid specimens from Chad have been repeatedly reported as being precisely known on the basis of their supposed in situ discovery. It is here demonstrated that neither of the fossils, the holotypes of Australopithecus bahrelghazali and Sahelanthropus tchadensis, was in situ at the time of discovery.
As Hawks points out, this really doesn’t do much for the debate. A younger S. tchadensis would bring it closer to the chimp-human divergence date that critics accept, but that doesn’t affect anyone’s interpretation of the morphology and phylogeny. Although I started out thinking that S. tchadensis was probably a hominin I am becoming more convinced that it is not. At this point I would love to see a morphological comparison between S. tchadensis:
and Pierolapithecus catalaunicus:
It has been awhile since I have read the descriptions in the respective papers describing the finds, but I remember being reminded of S. tchadensis while reading the P. catalaunicus paper…but I could be wrong.