teeth and jaws are very similar to those of older fossil apes. A partial tibia is strong evidence of bipedality, and a lower humerus is extremely humanlike. Australopithecus afarensisA. afarensis existed between 3.9 and 3.0 million years ago. The first of its fossils were found in the mid 1970s along the East African Rift valley. Afarensis had an apelike face with a low forehead, a bony ridge over the eyes, a flat nose, and no chin. They had protruding jaws with large back teeth. Cranial capacity varied from about 375 to 550 cc. The skull is similar to that of a chimpanzee, except for the more humanlike teeth. The canine teeth are much smaller than those of modern apes, but larger and more pointed than those of humans, and shape of the jaw is between the rectangular shape of apes and the parabolic shape of humans. However their pelvis and leg bones far more closely resemble those of modern man, and leave no doubt that they were bipedal. Their bones show that they were physically very strong. Females were substantially smaller than males, a sexual dimorphism. Height varied between about 107 cm (3'6") and 152 cm (5'0"). The finger and toe bones are curved and proportionally longer than in humans, but the hands are similar to humans in most other details. Most scientists consider this evidence that afarensis was still partially adapted to climbing in trees, others consider it evolutionary baggage. Australopithecus africanusA. africanus was found by Raymond Dart in 1925 in a limestone quarry (Tuang) in South Africa. Africanus existed between 3 and 2 million years ago. It is similar to afarensis, and was also bipedal , but body size was slightly greater. Brain size may also have been slightly larger, ranging between 420 and 500 cc. This is a little larger than chimp brains (despite a similar body size), but still not advanced in the areas necessary for speech. The back teeth were a little bigger than in afarensis. Although the teeth and jaw...
