may represent an ancestral hominid from the period immediately after the
separation from the chimp lineage.
DATE: 5-7 million years old
SITE: Chad, Central Africa
SPECIMENS: one cranium, probably male; jaw fragments
Sahelanthropus was discovered in Central Africa from strata dated 5.2-7.4
million years old. Hominid evolution has commonly been presented as an
East Side Storya process which occurred in East Africa,
in more open habitats of the Rift Valley. While most of the fossil excavations
have occurred in East Africa, this find indicates that hominids/hominid
ancestors were more widespread and that fossils should be sought in other
areas of Africa (Coppens, 1994).
Its primitive features include a small, ape-sized braincase (320-380 cc),
small incisors, a small sagittal crest, a massive brow ridge, shape of
basioccipital bone, and the orientation of its petrous bone. Its advanced
features include an enamel thickness intermediate between chimps and Australopithecus,
a face which protrudes less than chimps or Australopithecus, small apically
worn canines, its basicranium length and orientation, the position of
the formamen magnum, and its large supraorbital torus . The basicranium
is similar to that of Ardipithecus (Brunet, 2002, Wong, 2003). Although
the occipital region of Sahelanthropus was damaged, the structure of the
foramen magnum suggests that it was bipedal (Cela-Conde, 2003).