Ardipithecus ramidus

A.ramidus is a relatively recent discovery, announced in September 1994. It is the oldest known hominid species, with an estimated date of 4.4 million years. The remains recovered so far are mainly skull fragments. There is some evidence to suggest that it was possibly bipedal, and that some individuals were around 122 cm (4') tall.

The teeth appear to represent a midway development between those found in earlier apes and A. afarensis. Palaeoenvironmental evidence discovered with A. ramidus suggests that the species may have been forest dwelling. If this is the case then it may lead to a re-appraisal of current theories about hominid bipedalism, which generally link bipedalism with a move to a savannah environment.

Australopithecus anamensis

A.anamensis is known from a small collection of fossils found in 1988 and 1994 in Kenya. The material consists mainly of teeth and fragments of a tibia (the larger of the two lower leg bones), and a humerus (the upper arm bone) and a few skull fragments. The teeth and jaws are similar to those of older fossil apes. The tibia suggests evidence of bipedalism. A.anamensis lived between 4.2 and 3.9 million years ago.