Australopithecus

A name for an early genus believed to be related to man. The species Australopithecus africanus, first known from southern and eastern Africa, was of small in size - probably under four feet tall - and had a brain in the same size range as the chimpanzee and gorilla, but with massive jaws and teeth. The posture and teeth settings were, however, clearly human. The main fossils from South Africa are said to be 2 1/2 to 3 million years old, but there are fossils from Laetoli near Olduvai which are around 3 3/4 to 5 million years old and are regarded as either an early form of africanus or as an ancestral species. At least one other species, Australopithecus robustus, has been included in the genus. This form was heavier and stockier with giant molar teeth but small front teeth. Fossil human remains from Olduvai and Koobi Fora in Kenya called Homo habilis are often regarded as a late form of Australopithecus africanus or an early form of Homo erectus and they date from 1 1/2 to 2 million years ago. Australopithecus went extinct about 900,000 years ago. There are at least five known species in this genus. Some fragments from Lothagam at c5.5 million years may also be Australopithecus. The word Australopithecus means "southern ape" and these hominids were so named (in 1924 at Taung) because their fossils were found first in southern Africa.

The baby skull found at Taung in 1924 was named Australopithecus africanus (southern ape of Africa) by Dart in 1925. A number of African fossil hominids have subsequently been included in this genus, and since 1962 many authorities have recognized two species: A. africanus, a gracile form best-known from Sterkfontein and Makapan in South Africa, and a larger species, A. robustus, represented by fossils from Swartkrans and Kromdraai. All these fossils have a small brain (400-600 cc) and large molar teeth; beyond this their differences tend to be more important than their similarities. East African finds since 1959 are often compared with the two South African species, and representatives of both species seem to be present in Tanzania, Kenya and Ethiopia. The robust type, often called A. boisei in East Africa, seems to date from c2.1 to 1.1 million years ago, and is thus contemporary with Homo erectus and Homo habilis. This form can probably be excluded from direct human ancestry and placed in a cousin lineage. A. africanus seems to date mainly to before 2.5 million years ago, and may be a direct human ancestor. Fossils from Hadar and Laetoli have been placed in a new species, A. afarensis, but may nevertheless be A. africanus. At c3.75 million years, the Laetoli find is the earliest good sample of the genus, but some fragments from Lothagam at c5.5 million years may also be See also human evolution.