Fig. 13
From: From Land to Water: the Origin of Whales, Dolphins, and Porpoises
The teeth of Indohyus (left) are different from the teeth of pakicetids (right) in that Indohyus has upper molar teeth with four cusps. Pakicetid upper molars have three cusps. The wear facets (indicated by patterns of reflected light) may indicate that pakicetids were eating fish