Deciduous lower fourth premolar of Afrotragulus and Siamotragulus (Tragulidae, Artiodactyla): Comparison and structural aspects.

The diversity of the tragulids from the Siwalik Group of the Indian subcontinent is enormous; however, their taxonomy remains unresolved and has been the subject of ongoing debate in recent years. This study aims to resolve some issues by describing the lower deciduous fourth premolars (dp4s) of the genus Afrotragulus, which are described and figured for the first time in the history of paleontology, and the dp4 of the genus Siamotragulus, which is described for the first time from the Siwaliks by ascribing it to this genus. The dp4s of both these genera differ at least in morphological characters such as presence or absence of an interlobular bridge, complete or incomplete M/Σ structure, morphology of first lobe, fossettes, lingual cusps, cristids, ectostylid, cingulids, valleys, and enamel, as well as in crown height, and confirm the presence of the genus Afrotragulus in the Siwaliks. We have also provided a brief overview of the structural aspects of ruminant dp4s and p4s.