Australopithecus anamensis
This page was last updated on April 16th
Australopithecus anamensis was discovered in 1995 by Meave Leakey, in Allia Bay, and was also subsequently found in Kanapoi, Eastern Turkana and Kenya. It lived from 4.2 to 3.9 million years ago, and there is indication that it is directly descended from Ardipithecus ramidus. The finds include two parts of tibia, a fibula, and a section of a mandible. Members of this species ranged in weight from 45 to 60 kg, with the two genders being extremely dimorphic. Its brain size was definitely ape-like, although the exact measurement is unknown. The articulation of the mandible was clearly ape-like and so was the external auditory meatus.
A. anamensis had more reduced canines than A. ramidus. It exhibited no honing facet on its canines, which is an un-apelike trait. And for the first time, all of its teeth had thick enamel, and had larger and squarer molars, unlike A. ramidus. It was more primitive than Australopithecus afarensis in that its front premolars were assymetrical, its molars were sloping more towards their crowns, the earhole was relatively small--resembling A. ramidus--, and the shape of the chin was different. Nevertheless, the general morphology of A. anamensis' mandible was still chimpanzee-like.
From its arm and leg bones, scientists were able to deduce that A. anamensis was fully bipedal, and that there was less flexibility in the ankle and toe bones. For example, the tibia was clearly that of a biped, and the humerus is remarkably humanlike. It was also a powerful climber, with long arms and curved phalanges, which gave it good grasping ability. However, its habitat was a more "ideal" place for the evolution of bipedalism, with less densely forested regions and some savanna. Its shoulders were ape-like, and so was its thorax.
Note: An in-depth study is yet to be done on this species.
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Introduction | History and Background | Ardipithecus ramidus | Australopithecus anamensis | Australopithecus afarensis | Australopithecus africanus | Paranthropus aethiopicus | Paranthropus robustus | Paranthropus boisei | Homo rudolfensis | Homo habilis | Homo ergaster | Homo erectus | Homo heidelbergensis | Homo neanderthalensis | Homo sapiens | Glossary | Bibliography
