Ziphius cavirostris (Cuvier 1823, up to 6.9m males) is the extant Cuvier's beaked whale, goose-beaked whale. Here it nests basal to other tested extant odontocetes, but lost teeth after the odontocete radiation. Suction draws in prey. The maxilla extends over the frontals to accommodate a melon, a fatty-tissue organ to focus sounds for echolocation. This cosmopolitan whale is adapted to deep diving.

Orcinus orca (killer whale; extant; Linneaus 1758; 6-8m in length) is the largest member of the dolphin family. All of the teeth are canine-shaped. No upper incisors are present on the premaxilla. The naris and premaxilla are extended to the forehead, as in all whales. The jugal is a slender strut. The nasals are wider than long. The manus is a flipper. The hind limbs are absent. The tail ends in flukes for rapid swimming.

Tursiops truncatus (Montagu 1821; 2-4m in length) is the common bottle nose dolphin. The mandible is longer than the rostrum. The teeth are small and peg-like. The nasals remain longer than wide.

Premolar evolution in Tenrec though Tursiops. Starting with three premolars, then four, four, seven, eight and finally 17 in Tursiops. In each case 4 molars were retained. These all became canine-like in shape with a single root. This was a reversal to the early synapsid morphology. Note the absence of the upper canine, which was lost after Asioryctes. Arrow points to the narial opening, which progressively retracts to the top of the cranium.