Ecological Interactions of Miocene to Pleistocene Siwalik Bovids, Suids and Giraffids Traced Out by Enamel Hypoplasia Analysis

Abstract

Enamel hypoplasia is the thinning of enamel caused by depletion of ameloblasts (enamel forming cells) during tooth development. The depletion of ameloblasts is associated with the physiological or environmental stress that an animal faced during its life history, so this dental defect can provide us a permanent and reliable record of the ecological stress faced by an animal during its tooth development. The fossils discovered from the Siwalik deposits of Pakistan having chronological age from 18.3 to 0.6 Ma and belonging to thirteen bovid, eight suid and seven giraffid species of the Siwalik regions were analyzed for comparative occurrence of enamel hypoplasia. The moderate level of stress throughout the Siwaliks for all the three studied families was inferred by enamel hypoplasia results. This shows that even though the studied three Siwalik artiodactyle families have diversity in their ecological behavior, the changing climatic condition throughout the Siwaliks had strong impact on the species of all the three studied taxa.