Australopithecus africanus skull replica. The original of this replica was discovered by Robert Broom in Sterkfontein, Transvaal, South Africa in 1947. 2.5 million years old.
Australopithecus africanus was discovered in 1924 by Raymond Dart in South Africa. Since then, many specimens have been discovered in East Africa, particularly in Olduvai Gorge by Mary and Louis Leakey. East African fossil sites have yielded hundreds of hominid bones, documenting human evolution over the past 4 million years.
Interbedded volcanic ash allows radiometric dating of the hominid fossils.
Australopithecus africanus skull replica. The original of this replica was discovered by
Robert Broom in Sterkfontein, Transvaal, South Africa in 1947. 2.5 million years old.
Oldest hominid fossils are 6-7 million years old, from Chad, Sahelanthropus tchadensis.
Prior to this fairly recent discovery, the oldest know hominids were 5.8-5.2 million years old. Ardipithecus ramidus from Ethopia.
Australopithecus anamensis lived from 4.2 to 3.9 million years ago. It appears to be an evolutionary intermediate between Ardipithecus ramidus and Australopithecus afarensis or "Lucy."
Australopithecus afarensis was discovered by Donald Johanson in 1974 and nicknamed "Lucy".
Lucy was an erect-walking hominid in East Africa about 3.5 million years ago. Posture is determined from analysis of pelvic and leg bones.
Further evidence of bipedalism (walking upright on two feet) of australopithecines is the discovery of footprints and a trackway in 3.2 million years volcanic ash layers (tuff) at Laetoli, eastern Africa. (Pliocene).
Australopithicine dentition (tooth structure) was essentially human.
Cranial (brain) capacity was less than that of modern humans.
(600 cm³ vs. 1400-1600³ in modern humans).
Two types of australopithicines have been distinguished:
Gracile - Smaller, lighter-bodied with smaller teeth.
Includes Australopithecus afarensis (Lucy).
This group is transitional to genus Homo.
Robust - Larger, heavy-bodied with larger teeth.
Includes Australopithecus boisei (sometimes called Paranthropus boisei) and
Australopithecus robustus (sometimes called Paranthropus robustus).
Both are evolutionary side branches.
Opinions differ as to whether the boisei and robustus species should
be included in genus Australopithecus.
The current consensus in the scientific community is that they should be placed in a separate genus,
Paranthropus, which appears to have developed from the australopithecines.
The robust australopithecines are now reclassified as belonging to genus Paranthropus.
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| Australopithecus afarensis (Lucy) skull replica. About 3.5 million years old. Photo courtesy of Pamela Gore. |
Paranthropus boisei skull replica. Nutcracker man, the most famous fossil from Olduvai Gorge, Tanzania (Central Africa). Discovered by Mary Leakey in 1959 and originally classified as Zinjanthropus boisei. Later re-classified as Australopithecus boisei and currently as Paranthropus boisei. P. boisei lived from 2.6 to 1.2 million years ago. Photo courtesy of Pamela Gore. |
Timeline for Pliocene and Pleistocene hominids
Document created by: Pamela J. W. Gore
Georgia Perimeter College, Clarkston, GA
March 6, 2006