ABSTRACT
Primate models can be applied to hominin evolution beyond the Last Common Ancestor. Beginning at about 4.5 million years ago, a variety of new hominin genera and species begin to appear in the fossil record. These early hominins occupied a geographic arc from Chad through East Africa to South Africa. They display derived human-like characteristics along with ape-like traits inherited from the LCA. Derived dental and locomotor features, including larger molar teeth and habitual bipedalism, distinguished them from their predecessors. Most of these hominins probably weighed between 30 and 45 kilograms, with significant sexual dimorphism in body size. This chapter focuses on the australopiths, a convenient informal term for species that are or have been assigned to the genus Australopithecus, famously illustrated by the skeleton called “Lucy”.
