Stephanodonty in Fossil Murids

Abstract

Landmark based morphometric methods were used to study shape variation in fossil murid teeth. Nineteen landmarks were defined and recorded on the occlusal surfaces of first upper molars belonging to eight populations from Late Miocene and Pliocene localities in Spain. The study focused on an evolutionary sequence characterized by development towards a specialized crown structure known as stephanodonty. Population differences were investigated using Bookstein shape coordinates and analyzed using analysis of variance and Mahalanobis distances. Relative warp analysis was used to study the nature of the shape variation among the landmarks. The results are consistent with the accepted taxonomic classification, although the taxonomic position of one of the populations is problematic. The analyses show that the development towards stephanodonty (a feature defined by the presence of ridges) is correlated with changes in shape, which are themselves correlated with size in the evolutionary sequence studied. It is apparent that landmark-based approaches show promise for functional morphological and paleoenvironmental interpretations of fossil murid teeth.