Descriptions of non-metric or discrete dental traits form a large part of the taxonomic and phylogenetic diagnosis of fossil hominids. New diagnoses often engender debate with regards to how the ranges and patterns of dental variation in the fossils compare with variation in living great apes and humans. Since objective comparisons with living taxa are rarely included in the initial descriptions such debates seem to be without resolution. The purpose of this project is two-fold: (1) to examine the nature of variation in non-metric dental traits in Pan, Gorilla and Pongo, and (2) to use great ape traits and trait expressions to re-assess the taxonomy of southern African hominins. We will test the hypotheses that (1) the great ape and human phylogeny can be accurately reconstructed from dental traits, and (2) dental traits have taxonomic and phylogenetic relevance. We will construct plaster plaques documenting variants in the expression of discrete dental traits and use phylogenetic methods to reconstruct the great ape and human phylogeny already established from molecular data. This study will (1) establish the importance of dental traits for fossil taxonomy and phylogeny, and (2) provide a comparative hominid database of standardized traits and trait variants with which to compare fossil taxa. Given the predominance of teeth in fossil assemblages we expect this study to have wide application in fossil hominid systematics. As a test case, we will use great ape dental traits and trait expressions to re-assess the taxonomy of Paranthropus and Australopithecus in southern Africa. These taxa exemplify the debate on the taxonomic and phylogenetic relevance of dental traits for fossil hominid systematics, thus will provide good resolution of the debate.