| Abstract: |
The ecology of <italic>Australopithecus africanus</italic> has been the subject of debate since it was first described in 1925. Early research suggested that <italic>Australopithecus</italic> was an omnivore that inhabited open plains, but more recent studies indicate that <italic>Australopithecus</italic> ate fleshy fruits and leaves in areas with considerable woody vegetation. Determining <italic>Australopithecus</italic>' diet has been problematic as it antedates the earliest stone tools and butchered animal remains. Thus, researchers have been forced to infer diet based primarily upon dental morphology, which is not always a good predictor of diet for even extant taxa. Therefore, other sources of paleodietary information are necessary. In this dissertation I use stable carbon isotope analysis of tooth enamel to study the ecology of 23 taxa, including <italic>A. africanus</italic>, from Makapansgat Limeworks, South Africa. A number of methodological issues are also addressed. Results indicate that: (1) Sample sizes can be reduced from 300 mg to 3 mg. (2) Very little crystallographic change occurs in enamel during fossilization, although a slight change in the ratio of B- to A-site carbonate ions occurs. (3) Oxygen isotopes in enamel carbonate of Pliocene age preserve ecological information. For instance, carnivores tend to be depleted in <super>18</super>O compared to herbivores, and mammals that drink regularly tend to be <super>18</super>O-depleted compared to water-independent taxa. (4) The percentage of bovids that consume primarily C<sub>3</sub> vegetation predicts the amount of woody vegetation present in an area. (5) Previous dietary reconstructions of the Limeworks fauna are incorrect in 7 out of 23 cases. This suggests that isotopic analysis should become a regular tool for studying the ecology of fossil taxa. (6) <italic>Australopithecus</italic> consumed significant amounts of grasses or sedges, animals that eat these plants, or both. While it is impossible to say which of these alternatives is correct at present, we can state unequivocally that <italic>A. africanus </italic> was not a fleshy fruit and leaf consumer like the modern chimpanzee. This suggests that <italic>Australopithecus</italic> was a dietary generalist capable of surviving in a wider variety of habitats than extant non-human hominoids.
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