Abstract
Cetaceans consist of the world’s whales, dolphins, and porpoises. Odontocetes are the toothed whales and dolphins and have a rich, intriguing evolutionary history. The Late Oligocene experienced an explosion in odontocete diversity, primarily from niche differentiation by adopting different feeding methods. Before the appearance of Platanistoidea and Delphinida in the early Miocene, stem odontoceti were the primary group of fossil dolphins present until their sudden disappearance at the Oligocene-Miocene boundary. Despite historic taxonomic proximity, Platanistoidea and stem odontoceti are increasingly divided. Three new waipatiid dolphins from the Waitaki Valley, Canterbury, bring new feeding strategies, information on endocranial cavity, and illuminate some phylogenetic relationships between recently described stem odontocetes. Two taxa form the basis of a new genus of dolphin with horizontal incisors that it likely used to net prey in a manner unlike any other ancient odontocete. Another new taxon forms another new genus of dolphin which utilised a powerful bite and muscular neck to squeeze prey between its jaws, unlike its more delicate relatives.