four families of river dolphins (iniidae, pontoporiidae, lipotidae and platanistidae) are currently recognized, comprising three superfamilies (inioidea, lipotoidea and platanistoidea). platanistidae, containing the two subspecies of south asian river dolphin, is the only living family in the superfamily platanistoidea. previously, many taxonomists had assigned all river dolphins to a single family, platanistidae, and treated the ganges and indus river dolphins as separate species. a december 2006 survey found no members of "lipotes vexillifer" (commonly known as the baiji, or chinese river dolphin) and declared the species functionally extinct. with their disappearance, one of the recently accepted superfamilies, lipotoidea, has become extinct.