Denis Geraads

A new hominid from the Upper Miocene of Chad, Central Africa

The search for the earliest fossil evidence of the human lineage has been concentrated in East Africa. Here we report the discovery of six hominid specimens from Chad, central Africa, 2,500u2009km from the East African Rift Valley. The fossils include a nearly complete cranium and fragmentary lower jaws. The associated fauna suggest the fossils are between 6 and 7u2009million years old. The fossils display a unique mosaic of primitive and derived characters, and constitute a new genus and species of hominid. The distance from the Rift Valley, and the great antiquity of the fossils, suggest that the earliest members of the hominid clade were more widely distributed than has been thought, and that the divergence between the human and chimpanzee lineages was earlier than indicated by most molecular studies.

Geology and palaeontology of the Upper Miocene Toros-Menalla hominid locality, Chad

All six known specimens of the early hominid Sahelanthropus tchadensis come from Toros-Menalla site 266 (TM 266), a single locality in the Djurab Desert, northern Chad, central Africa. Here we present a preliminary analysis of the palaeontological and palaeoecological context of these finds. The rich fauna from TM 266 includes a significant aquatic component such as fish, crocodiles and amphibious mammals, alongside animals associated with gallery forest and savannah, such as primates, rodents, elephants, equids and bovids. The fauna suggests a biochronological age between 6 and 7 million years. Taken together with the sedimentological evidence, the fauna suggests that S. tchadensis lived close to a lake, but not far from a sandy desert, perhaps the oldest record of desert conditions in the Neogene of northern central Africa.

Obsidian exploitation and utilization during the Oldowan at Melka Kunture (Ethiopia)

The Oldowan assemblages of Melka Kunture represent the earliest known example of obsidian utilization. The proximity of primary and secondary sources of Balchit obsidian, a high quality raw material easily available in large quantities, is a unique situation among East African Oldowan sites. Obsidian represents a large component of the lithic assemblages at Melka Kunture, not only during the Oldowan but during the Acheulian times as well. Other volcanic rocks are incorporated into the technological system at Melka Kunture such as basalts, ignimbrites, trachytes and trachybasalts, which present completely different characteristics for knapping.