There is fossil evidence for the early hominin genus, Australopithecus, from 4.2 to 2.1 million years ago. The most well known of these species are A. afarensis, from East Africa, and A. africanus, found solely in South Africa. Paleoanthropologists know that these species were bipedal, but many aspects of their ecological behavior remain elusive and hypothetical only. Australopithecus afarensis lived in a variety of habitats from Tanzania to Ethiopia, for example, but did the eventual cooling and drying of Africa cause its extinction? In South Africa, A. africanus appears much later in time and exists to a much younger time period than A. afarensis; are there fundamental ecological differences between these species that may account for this? The behavioral ecology and biogeography of the other mammals that were recovered with these hominin species provide interesting patterns that can be compared with ecological patterns and processes in the living world to provide contextual evidence to begin to answer these questions.