Dromaius

Dromaius (from greek δρομαίυς "runner") is a genus of ratite present in Australia. There is one extant species, "Dromaius novaehollandiae" commonly known as the emu.
In his original 1816 description of the emu, Louis Jean Pierre Vieillot used two generic names; first "Dromiceius", then "Dromaius" a few pages later. It has been a point of contention ever since which is correct; the latter is more correctly formed, but the convention in taxonomy is that the first name given stands, unless it is clearly a typographical error, as argued by W.B. Alexander. For names published on the same day, or in the same publication, the International Code of Zoological Nomenclature states that both names have equal precedence, and that the Principle of First Reviser (Article 24.2 ) determines which name is to be used. Most modern publications, including those of the Australian government, use "Dromaius", with "Dromiceius" mentioned as an alternative spelling. Others misspelling synonyms are descript for genus (see synonyms in taxobox). However, the "Dromiceius" spelling was used by Dale Russell in his 1972 naming of the dinosaur "Dromiceiomimus".
Species and subspecies.
Several emu species were common prior to European settlement in 1788:
A number of other emu fossils from Australia described as separate species are now regarded as chronosubspecies at best, given the considerable variation even between living individuals. There are also some unidentifiable remains of emu-like birds from rocks as old as the middle Miocene.