Beginning with Ramapithecus, there has been a continued search for an ape-like hominid ancestor in the Miocene Epoch. Sahelanthropus tchadensis is an enigmatic new Miocene species, whose characteristics are a mix of those of apes and Homo erectus and which has been proclaimed by Brunet et al. to be the earliest hominid¹. However, we believe that features of the dentition, face and cranial base that are said to define unique links between this Toumaï specimen and the hominid clade are either not diagnostic or are consequences of biomechanical adaptations. To represent a valid clade, hominids must share unique defining features², and Sahelanthropus does not appear to have been an obligate biped.

1. Paleoanthropology Laboratory, Department of Anthropology, University of Michigan, Ann Arbor, Michigan 48109-1382, USA
2. Laboratoire de Paléontologie du Muséum National d'Histoire Naturelle, UMR 8569 CNRS, 75005 Paris, France
3. Chaire de Paléoanthropologie et de Préhistoire du Collège de France, UMR 8569 CNRS, 75005 Paris, France
4. Department of Anthropology, University of Wisconsin, Madison, Wisconsin 53706, USA

Correspondence to: Milford H. Wolpoff¹ e-mail: Email: wolpoff@umich.edu