Toothed whale porpoise as a fish. Toothed whales, as well as baleen whales, are descendants of land-dwelling mammals of the artiodactyl order (even-toed ungulates). They are closely related to the hippopotamus, sharing a common ancestor that lived around 54 million years ago (mya). The primitive cetaceans, or archaeocetes, first took to the sea approximately 49 mya and became fully aquatic by 5–10 million years later. The adaptation of echolocation and enhanced fat synthesis in blubber occurred when toothed whales split apart from baleen whales, and distinguishes modern toothed whales from fully aquatic archaeocetes. This happened around 34 mya. Unlike toothed whales, baleen
Spade-toothed whale small fish. The young probably become independent of their mothers at about one year of age, as is the case in most whales. The population status of the spade-toothed whale is entirely unknown, but it is unlikely to be abundant. The spade-toothed whale is covered by the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MOU). The sex of the 20th-century specimens is not known. By recovering or failing to recover DNA sequences of the Y chromosome, it could, in theory, be resolved. Little material is shared between the Pitt