The presence of maxillary fourth molar in the Sri Lankan toque monkey (Macaca sinica aurifrons).

We describe the presence of fourth molar teeth in the upper jaw of a subspecies (Macaca sinica aurifrons) of the endemic toque macaque of Sri Lanka. Compared to the first three molars, supernumerary ones were smaller by more than 50%, showed four cuspids in the crowns, and had three roots. This observation contributes to knowledge of orthodontic anomalies presence in primate populations while spotlighting the importance of osteological observation.