River dolphins

Common name concerning different taxa once grouped in a single superfamily but now split into several ones

Lipotidae is a possibly extinct family of river dolphins containing the critically endangered/functionally extinct Chinese river dolphin baiji and the fossil genus Parapontoporia from the Pacific coast of North America during the Late Miocene and Pliocene The genus Prolipotes, which is based on a mandible fragment from Neogene coastal deposits in Guangxi, China, has been classified as an extinct relative of the baiji, but is dubious. The oldest known member of the family is Eolipotes from the Late Miocene of Japan.

Arktocara is an extinct genus of river dolphin from the Oligocene epoch of Alaska, containing one species, A. yakataga. Having been discovered in 25-million-year-old strata near the 60th parallel north, it is perhaps the oldest-known crown toothed whale and the northmost river dolphin discovered. It was a member of the now-extinct family Allodelphinidae, along with the genera Allodelphis, Goedertius, Ninjadelphis, and Zarhinocetus. It measured approximately , comparable to its closest living relative, the South Asian river dolphin, which measures . However, the animal probably had an elongated