Casuariiformes

The bird family Casuariidae has four surviving members: the three species of cassowary, and the only remaining species of Emu. The emus were formerly classified in their own family, Dromaiidae, but are regarded as sufficiently closely related to the cassowaries to be part of the same family.

All four members of the family are very large flightless birds native to Australia-New Guinea. The characteristics of the family are those of its members.

Systematics and evolution
The emus form a distinct subfamily, characterized by legs adapted for running. As with all ratites, there are several contested theories concerning their evolution and relationships. As regards this family, it is especially interesting whether emus or cassowaries are the more primitive form: the latter are generally assumed to retain more plesiomorphic features, but this does not need to be true at all; the fossil record is also ambiguous, and the present state of genomics does not allow for sufficiently comprehensive analyses. A combination of all these approaches with considerations of plate tectonics at least is necessary for resolving this issue.

The number of cassowary species described based on minor differences in casque shape and color variations is quite large. In recent times, however, only 3 species are recognized, and most authorities only acknowledge few subspecies or none at all.

The fossil record of casuariforms is interesting, but not very extensive. Regarding fossil species of Dromaius and Casuarius, see their genus pages.

Some Australian fossils initially believed to be from emus were recognized to represent a distinct genus, Emuarius, which had a cassowary-like skull and femur and an emu-like lower leg and foot. In addition, the first fossils of mihirungs were initially believed to be from giant emus, but these birds were completely unrelated.

Subfamily Casuariinae - cassowaries
 * Genus Casuarius
 * Southern Cassowary, Casuarius casuarius located in the humid forests of northeastern Australia, New Guinea, and the Aru Islands.
 * Dwarf Cassowary, Casuarius bennetti located in New Guinea, New Britain, and Yapen Island.
 * Northern Cassowary, Casuarius unappendiculatus located in the lowlands of Yapen Island and New Guinea.
 * †Casuarius lydekki

Subfamily Dromaiinae - emus
 * Genus Dromaius
 * Emu, Dromaius novaehollandiae located in Australia.
 * Tasmanian Emu, D. n. diemenensis (extinct) formerly located in Tasmania.
 * South Eastern Emu, D. n. novaehollandiae located in Australia.
 * South Western Emu, D. n. rothschildi
 * Northern Emu D. n. woodwardi
 * †Kangaroo Island Emu, Dromaius baudinianus (extinct)
 * †King Island Emu, Dromaius ater (extinct) formerly located on King Island, Australia.
 * †Dromaius ocypus


 * Genus Emuarius - "emuwaries" (fossil)
 * †Emuarius guljaruba (Late Oligocene - Late Miocene)
 * †Emuarius gidju (Late Oligocene - Early Miocene of N Australia - see: Records of the Australian Museum (2005) Vol. 57: 179)