Physeteroidea

Physeteroidea is a superfamily including just three living species of whale; the Sperm Whale, in the genus Physeter, and the Pygmy Sperm Whale and Dwarf Sperm Whale, in the genus Kogia. In the past these genera have sometimes been united in a single family, Physeteridae, with the two Kogia species in a subfamily (Kogiinae), however recent practice is to allocate the genus Kogia to its own family, Kogiidae, leaving Physeteridae as a monotypic (single extant species) family, although additional fossil representatives of both families are known (see "Evolution").