Final answer:
Australopithecus africanus lived between two and three million years ago, had a brain size of 500 cubic centimeters, and was bipedal.
Step-by-step explanation:
Australopithecus africanus lived roughly two and three million years ago. This species, known for its bipedalism and experiencing a trend towards reduced dentition and jaws size, is a critical part of our understanding of human evolution. With a brain size of about 500 cubic centimeters, slightly less than one-third the size of modern human brains, it provides insight into the cognitive abilities of early hominids. The discovery of australopith fossils, such as the famous Lucy, has been crucial in piecing together the characteristics and lifestyle of early human ancestors, including aspects like their brain size and locomotion habits. The genus Australopithecus also includes other notable species such as Australopithecus afarensis and Australopithecus bahrelghazali.