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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.

Contents

Systematics and evolution

References

Footnotes

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 suffiently 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''^[1],
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^[2],
but these birds were completely unrelated.

Subfamily 'Casuariinae' - cassowaries

★ Genus '''Casuarius'''

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★ Southern Cassowary, ''Casuarius casuarius''

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★ Dwarf Cassowary, ''Casuarius bennetti''

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★ Northern Cassowary, ''Casuarius unappendiculatus''
Subfamily 'Dromaiinae' - emus

★ Genus '''Dromaius'''

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★ Emu, ''Dromaius novaehollandiae''

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★ Tasmanian Emu, ''D. n. diemenensis'' (extinct)

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★ South Eastern Emu, ''D. n. novaehollandiae''

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★ South Western Emu, ''D. n. rothschildi''

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★ Northern Emu, ''D. n. woodwardi''

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★ Kangaroo Island Emu, ''Dromaius baudinianus'' (extinct)

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★ King Island Emu, ''Dromaius ater'' (extinct)

★ Genus '''Emuarius''' - "emuwaries" (fossil)

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★ ''Emuarius guljaruba'' (Late Oligocene - Late Miocene)

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★ ''Emuarius gidju'' (Wipajiri Early Miocene of Lake Ngapakaldi)

References

★ Boles, Walter E. (2001): A new emu (Dromaiinae) from the Late Oligocene Etadunna Formation. ''Emu '101': 317–321. HTML abstract

Footnotes

1.
From "Emu" + "''Casuarius''". Describer W. E. Boles commonly refers to the genus as "emuwaries" or "cassomus".
2.
The vernacular name "mihirung" is derived from ''mihirung paringmal'', which means "giant emu" in the Chaap Wuurong language