Dromaius

Dromaius is a genus of ratite present in Australia. There is one extant species, Dromaius novaehollandiae commonly known as the emu.

Dromaius Temporal range: Miocene–present PreꞒ Ꞓ O S D C P T J K Pg N
Dromaius novaehollandiae
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Casuariiformes
Family:	Casuariidae
Genus:	Dromaius Vieillot, 1816[1]
Type species
Dromaius novaehollandiae Latham, 1790
Species
D. novaehollandiae (Latham, 1790) Vieillot, 1816 †D. ocypus Miller, 1963
Geographic distribution of emu taxa and historic shoreline reconstructions around Tasmania
Synonyms
Dromiceius (sic) Vieillot, 1816 Dromæus (sic) Ranzani, 1821 Dromicejus (sic) Wagler, 1830 Dromiceus (sic) Wagler, 1830 Dromiceus (sic) Swainson, 1837 Dromaeus (sic) Agassiz, 1842 Dromajus (sic) Thienemann, 1845 Dromaeius (sic) Bonaparte, 1856 Dromeicus (sic) A. Newton,1893 Emou Griffith & Pidgeon, 1829 Peronista Mathews, 1912 Tachea Fleming, 1822

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.[2] Most modern publications, including those of the Australian government,[3] use Dromaius, with Dromiceius mentioned as an alternative spelling. Others misspelling synonyms are descript for genus (see synonyms in taxobox).[3] However, the Dromiceius spelling was used by Dale Russell in his 1972 naming of the dinosaur Dromiceiomimus.

Illustration by Charles-Alexandre Lesueur, based on life-drawings made during Baudin's journey and specimens kept at Jardin des Plantes. The animals were thought to be a male and female of the same species, but are now believed to be a Kangaroo Island emu and King Island emu[4]

Species and subspecies

Several emu species were common prior to European settlement in 1788:

• Dromaius novaehollandiae, emu, remains common in most of the more lightly settled parts of mainland Australia. Overall population varies from decade to decade according to rainfall; as low as 200,000 and as high as 1,000,000, but a typical figure is about half a million individuals. Although emus are no longer found in the densely settled southern and southwestern agricultural areas, the provision of permanent stock water in arid regions has allowed the mainland subspecies to extend its range. There are five recognised subspecies or races of the emu:
  • Dromaius novaehollandiae novaehollandiae – Southeastern Australia – whitish ruff when breeding.
  • Dromaius novaehollandiae woodwardi – Northern Australia – slender, paler (not recognised as a subspecies by all authorities).
  • Dromaius novaehollandiae rothschildi – Southwestern Australia – darker, no ruff during breeding (not recognised as a subspecies by all authorities).
  • †Dromaius novaehollandiae diemenensis – Tasmania – The Tasmanian emu, which became extinct around 1850.
  • †Dromaius novaehollandiae minor – King Island – The King Island emu was about half the size of the mainland species. By 1805 it had been hunted to extinction by sealers and visiting sailors. Some individuals were kept in captivity in Paris, the last one dying in 1822. Vieillot coined the name Dromaius ater, but in his 1907 book Extinct Birds, Walter Rothschild stated that Vieillot's description actually referred to the mainland emu and that the name D. ater was therefore invalid. It was thought to be a distinct species until 2011.[5]
  • †Dromaius novaehollandae baudinianus - Kangaroo Island - The Kangaroo Island emu became extinct around 1827 as a result of hunting and frequent fires. The larger mainland subspecies was introduced to Kangaroo Island in the 1920s.
• †Dromaius ocypus, a prehistoric species of emu,[6] described from Late Pliocene fossils (Mampuwordu Sands Formation, Lake Palankarinna, Australia), accepted as distinct nowadays.
• †Dromaius arleyekweke, a diminutive species of emu, known from dispersed skeletal elements from the Miocene Waite Formation (Northern Territory, Australia)[7]

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.[8] There are also some unidentifiable remains of emu-like birds from rocks as old as the middle Miocene.[9]

References

1. Brands, Sheila. "Genus Dromaius". The Taxonomicon. Retrieved 19 September 2017.
2. Alexander, W. B. (1927). "Generic Name of the Emu". Auk. 44 (4): 592–593. doi:10.2307/4074902.
3. Genus Dromaius Vieillot, 1816. Australian Faunal Directory
4. Pfennigwerth, S. (2010). "(William T. Stearn Prize 2009) "The mighty cassowary": The discovery and demise of the King Island emu". Archives of Natural History. 37: 74. doi:10.3366/E0260954109001661.
5. Tim H. Heupink, Leon Huynen & David M. Lambert (2011). "Ancient DNA suggests dwarf and 'giant' Emu are conspecific". PLoS One. 6 (#4): e18728. doi:10.1371/journal.pone.0018728. PMC 3073985. PMID 21494561.
6. Miller, A.H. (1963). "Fossil ratite birds of the late Tertiary of South Australia". Records of the South Australian Museum. 14: 413–420.
7. Adam M. Yates; Trevor H. Worthy (2019). "A diminutive species of emu (Casuariidae: Dromaiinae) from the late Miocene of the Northern Territory, Australia". Journal of Vertebrate Paleontology. Online edition: e1665057. doi:10.1080/02724634.2019.1665057.
8. Patterson, C.; Rich, Patricia Vickers (1987). "The fossil history of the emus, Dromaius (Aves: Dromaiinae)". Records of the South Australian Museum. 21: 85–117.
9. Walter E. Boles (2001). "A new emu (Dromaiinae) from the Late Oligocene Etadunna Formation". Emu. 101 (#4): 317–321. doi:10.1071/MU00052.

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