Until recently, the earliest known hominine for which sufficient diagnostic anatomical evidence was available was Australopithecus afarensis, fossils of which have been found in Ethiopia, Tanzania, and Kenya, and most of which date between 2.9 and 3.9 million years. New finds of fossils as old or older than A. afarensis have been made in Ethiopia, Kenya, and Chad. These speciments, which are sufficiently different from A. afarensis to have been named a new species, include the following: Ardipithecus ramidus from Ethiopia, dated at 4.4 million years; Australopithecus anamensis from Kenya, with an age range of 4.2 to 3.9 million years; and Australopithecus bahrelghazali from Chad, with an age estimate of 3 to 3.5 million years.

The first afarensis fossils were found in the mid 1970s. Their initial interpretation was controversial and remains so today, albeit to a lesser degree. While many anthropologists accept that the multitude of fossil specimens that have been attributed to afarensis do indeed represent a single, sexually dimorphic species, others believe that the fossils belong to two, and perhaps more, species. For a long time afarensis was assumed to have represented the founding species of the hominine clade and the ancestor of all later species.

Height	1.0 – 1.5 metres
Weight	30 – 70 kg
Cranial Volume	400 – 500 cm³
Known Date	4.0 – 2.5 million years ago
Distribution	Eastern Africa
Physique	Light build; some ape-like features
Skull form	Low, flat forehead; projecting face; prominent brow ridges
Jaws/Teeth	Relatively large incisors and canines; gap between upper incisors and canines; moderate-sized molars
Sexual Dimorphism	Marked to moderate