Australopithecus africanus

Australopithecus africanus is a fossil Hominidé which lived in Africa with the Pliocène, between approximately 3,5 and 2,5 million years BP. The majority of the fossil remainders of this Australopithèque were discovered in South Africa.

Like Australopithecus afarensis earlier appeared and known in Eastern Africa, A. africanus was relatively gracile. It is however nearer physiologically to the modern man than A. afarensis , in particular on the level of cranium sheltering a bulkier brain (approximately 450 to 530 cm ³). For this reason, he is regarded by certain authors as a potential ancestor of the kind Homo .

Famous fossils

The child of Taung

Raymond Dart was with Taung close to Kimberley, South Africa in 1924 when one of his/her colleagues deposited some fragments of bone and a cranium on the desk of a carrier. The cranium evoked a strange creature associating with the features simiens and human, such as the form of the ocular orbits, the teeth and, more important, the low position of the foramen magnum (the hole at the base of cranium allowing the communication enters the vertebral channel and the brain-pan) indicating a station Bipède.

Starting from this fossil, R. Dart defines new a kind and a new species: Australopithecus africanus , the monkey of the African south. He considered that this taxon corresponded to an intermediate species between the monkeys and the human ones. This idea was rejected by the majority of the scientific community of then. Arthur Keith suggested in particular that the cranium was to correspond to a young monkey, probably a Gorille.

Mrs. Ples

In 1938, Robert Broom allotted a moulding endocrânien of a capacity of 485 cm ³, discovered per G.W. Barlow, with new a taxon: Plesianthropus transvaalensis . April 17th, 1947, R. Broom and John T. Robinson discovered a cranium pertaining to a female of Middle Age to Sterkfontein. Recorded under the code Sts 5, this fossil was also allotted to Plesianthropus transvaalensis and was called Mrs. Ples by the press (in fact, it appeared since the cranium could correspond to a young male). The weak prognathism of the face of this fossil and the child of Taung was underlined by R. Dart; this feature moves away them from the large monkeys and brings closer them to the more advanced Hominides. These two fossils were réattribués since with A. africanus .

Morphology and interpretation

As its counterpart is African A. afarensis , the African south A. africanus one was hominidé biped even if it were equipped with arms slightly longer than the legs, milks that one finds at the Chimpanzé S. It presented other antiquated features, such as curved phalanges adapted to climbing.

These primitive features lead certain researchers to rather regard A. africanus as an ancestor of Paranthropes than of human modern. Paranthropus robustus is in particular a robust Australopithecus considered as a potential descendant of A. africanus . The craniums of P. robustus and A. africanus are very close, even if that of P. robustus presents strong muscular insertions and a powerful mandible in relation to an adaptation to the food coriaces chewing. In addition, A. africanus has a cranium close to that of the chimpanzees by its features and its cranial capacity, ranging between 400 and 500 cm ³. The pelvis of A. africanus was adapted slightly better to the bipédie than that of A. afarensis .

No lithic Industrie was put at the day in relation to the fossils of A. africanus .

Charles Darwin had suggested that the human ones evolved/moved initially in Africa, but at the beginning of the 20th century the majority of the anthropologists and the scientists supported that the origins of the man were more probably to be required in Asia. The African character of the “cradle of humanity” is from now on usually allowed, since the many discoveries of fossils carried out in East Africa, in Laetoli, Olduvai or Hadar inter alia. With its features more human than those of A. afarensis , A. africanus remains a serious candidate under direct ancestor of the first representatives of the kind Homo , namely Homo habilis and appeared Homo rudolfensis approximately 2,4 million years ago.

References

Dart, R.A. (1925) “'' Australopithecus africanus '': the Man-Ape off South Africa”, Natural , n° 2884, vol. 115, pp. 195-199.
Broom, R. (1936) “has new fossil anthropoid skull from South Africa”, Nature , vol. 138, pp. 486-488.
Broom, R. and Robinson J.T. (1947) “Further remains off the Sterkfontein ape-man, Plesianthropus ”, Natural , vol. 160, pp. 430-431.
Hilton-To bore, B. and Shepherd, L.R. (2004) Field guides to the cradle off humankind, Sterkfontein, Swartkrans, Kromdraai & surroundings world heritage site , 2nd revised edition, Struik, ISBN 1-77007-065-6.
McHenry H.M. and Berger L.R. (1998) “Body proportions in Australopithecus afarensis and A. africanus and the origin off the genus Homo ”, Newspaper off Human Evolution , 35, pp. 1-22.
McHenry H.M. (1986) “The first bipeds: has comparison off the A. afarensis and A. africanus postcranium and implications for the evolution off bipedalism”, Journal off Human Evolution , 15, pp. 177-91.
Robin Mckie (2000) Dawn off Man , BBC, ISBN 0-7894-6262-1

External bonds

'' Australopithecus africanus ''
Early human phylogeny, Smithsonian Institution
Human ancestry
Phylogenetic tree of the first Hominides

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Roa-tared: Australopithecus africanus Simple: Australopithecus africanus

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