Species discrimination in Carcharhinus shark teeth using elliptic Fourier analysis

Sharks of the genus Carcharhinus are commonly represented in fossil assemblages by isolated teeth. Neogene fossil teeth from this genus have been identified by many authors as belonging to extant species. Their association with specific modern or extinct species is particularly challenging due to similarities in tooth shape among species. This study tests the ability of elliptic Fourier analysis (EFA) and discriminant function analysis (DFA) to identify the upper teeth of twelve modern species in this genus which have been independently identified using standard morphological characters and dental formulae. Teeth were extracted from three jaws for each of the fourteen species. After extraction from the jaw, EFA was performed on the digitized images, transforming the outline into a series of elliptic Fourier coefficients. These coefficients were then subjected to principal components analysis, and DFA was performed on the principal component values. Test and training set results demonstrate the discriminatory ability of this method, with over 55% of teeth being correctly identified to species. Anterior and posterior tooth positions were more likely to be misidentified. Also, teeth that were misidentified were commonly assigned to other species with similar tooth morphologies. The practical paleontological applications of this morphometric method include species identification and the construction of artificial dentitions using isolated fossil teeth.