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Australopithecus

Australopithecines walked the earth from over 4 million years ago (mya) until around 1 mya. In the chart below, you can see the two major groupings within the genus Australopithecus, the gracile (lightly built) australopithecines (colored light yellow), and the robust (heavily built) australopithecines (darker yellow/orange).

The gracile australopithecines are the earliest known true hominids. Recently, a new species, which was initially believed to be an australopithecine and called Australopithecus ramidus, was found at a 4.4 million year old site called Aramis in the Awash Valley in Ethiopia. Later, Tim White and Berhane Asfaw who led the expedition that discovered this species, recognised that it was a new genus and gave it the generic name Ardipithecus. This species may prove to be the first true hominid, but it has not yet been fully studied.

There are several species of Australopithecus, ranging in age from 4.1 to about 1.0 million years old. The earliest australopithecine, A. anamensis, was found at Kanapoi, a site south west of Lake Turkana, Kenya and also at Allia Bay, a site to the east of the lake. A. anamensis lived between 4.2 and 3.9 million years ago.

A. anamensis may be ancestral to A. afarensis which is better known at Laetoli in Tanzania, where Mary Leakey discovered the 80 foot long trail of footprints, and at Hadar in Ethiopia where Don Johanson discovered the almost complete skeleton known as "Lucy" as well as more than 200 other specimens of this species.

A. afarensis lived between 3.6 and 2.9 million years ago. In South Africa A. africanus is known from Makapansgat and Sterkfontein, sites believed to date between 3.5 and 2.0 million yeas ago. The robust australopithecines, A. boisei, A. aethiopicus and A. robustus, lived in east and south Africa between 2.5 and about 1.0 million years.

Australopithecines were first discovered at the limestone quarry of Taung in South Africa. In 1924, a student of Raymond Dart's (who was then Professor of Anatomy at the University of Witwatersrand), spotted an ape-like skull on the mantelpiece of the quarry foreman and brought it to Dart's attention. The skull was of a child aged about 3.3 years. Although Dart recognised that the skull represented an early human ancestor, his publication was met by scepticism and derision and was not taken seriously until Robert Broom found further specimens 10 years later at Sterkfontein.

The australopithecines are only known from Africa. None has ever been found in Europe or Asia. They had ape-sized brains; their average cranial capacity ranged from 413 to 530 cc. They had strong jaws with large teeth. Like modern gorillas the adult males were much larger than the females. The babies probably took approximately the same length of time to grow up as a modern chimpanzee and gorilla.

Though their legs were rather short relative to their bodies, the structure of the legs and feet show that the australopithecines walked bipedally (on two legs) as we do, although probably not as well as modern humans. The eighty foot long track way of footprints 3.5 million years old discovered by Mary Leakey at Laetoli provides the most dramatic and convincing evidence of the australopithecine bipedal gait.

Specimens
There are hundreds of specimens of gracile australopithecines, here are a few with images of the skulls from multiple angles for comparison:

Australopithecus anamensis
KNM-KP 29281

Australopithecus africanus
Sts5 ("Mrs. Ples")
Taung Child

Australopithecus afarensis
AL 288-1 ("Lucy")
AL 333 (this is a site with at least 13 individuals)
444-2 (a site with a good skull)

subgrouping within the australopithecines, the robust australopithecines are sometimes referred to the genus Paranthropus rather than Australopithecus, because they are so readily distinguished from the more lightly built species of Australopithecus. Robert Broom announced the discovery of the first robust australopithecine in 1939 from Kromdrai in South Africa. Three species of robust australopithecines are recognised, A. robustus, which is confined to southern Africa, and A. aethiopicus and A. boisei, both confined to east Africa and Ethiopia.

The majority of the Australopithecus robustus remains have been found at the South African sites Swartkrans and Kromdrai and, dating from just over 2 million to 1.5 million years.

In East Africa, the earliest robust australopithecine, A. aethiopicus is found at sites between 2.6 and 2.3 million years old west of Lake Turkana and in the Omo Valley. A. aethiopicus was most probably the ancestor of A. boisei.

Specimens
Selecting link will bring up small views of the skull to the left. The view you choose is then available in a larger format.

Australopithecus aethiopicus
KNM-WT 17000

Australopithecus robustus
Sk 48

Australopithecus boisei
OH 5
Peninj Mandible
Ants reconstruction (based on OH 5 and Peninj Mandible.)

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