Carrie Mongle

CARRIE S. MONGLE, then a graduate student at Stony Brook University, Stony Brook, New York, was awarded funding in April 2016 to aid research on ‘Modeling Hominin Variability: The Alpha Taxonomy of ‘ Australopithecus africanus ‘,’ supervised by Dr. Frederick E. Grine. Our understanding of evolution and diversity in the fossil record rests on the ability to delimit fossil species. However, relatively little attention has been paid to the methods necessary for the empirical delimitation of species. The goal of this research was to resolve the alpha taxonomy of the hominin fossils subsumed under Australopithecus africanus . The possibility that Au. africanus subsumes multiple species has significant implications for the interpretation of the hominin phylogeny and the evolution of the genus Homo . To provide the necessary comparative framework to address this question, a series of statistical models were developed to understand the structure of dental variation in the hominin fossil record. Results indicate that early stages of divergence can be captured by variation in M3 morphology, while the presence of distinct distributions of M1 morphology could provide evidence for deeper divergence between fossil species. These models were then used to examine the alpha taxonomy of Au. africanus. Results suggest that the fossils from Sterkfontein represent >1 species. Specifically, models indicate that three maxillary fossils should be removed from the Au. africanus hypodigm. This revision of Au. africanus may provide greater clarity in the phylogenetic placement of this species in future analyses.