Discovered in 2001 and dating to around 7-6 MYA, Sahelanthropus tchadensis is the oldest potential hominid to date. Located in Chad, the discovery expanded the known distribution of early hominids, previously believed to be limited to eastern and southern Africa. The chronological placement of tchadensis near the predicted time of the last common ancestor between chimps and humans assures the assignment of tchadensis is hotly contested. On the one hand, this species has a very pronounced brow ridge, parallel dental arcade, a small cranium (roughly equivalent to a modern chimp) and a sloping face. All of these features suggest tchadensis should be placed along the chimp branch. Howevewr, the small canines and, most significantly, the centrally located foramen magnum are derived traits shared with hominids. Crucially, the latter feature suggests bipedalism. A major challenge associated with assignment of this species is the dearth of post-cranial remains; to date, only cranial remains have been found, so much more is unknown than known about this potential early hominid.