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The cassowaries () are ratites (flightless birds without a keel on their sternum bone) in the genus ''Casuarius'' and are native to the tropical forests of New Guinea, nearby islands, and northeastern Australia.〔Clements, J (2007)〕 There are three extant species. The most common of these, the southern cassowary, is the third tallest and second heaviest living bird, smaller only than the ostrich and emu. Cassowaries feed mainly on fruit, although all species are truly omnivorous and will take a range of other plant food including shoots, grass seeds, and fungi in addition to invertebrates and small vertebrates. Cassowaries are very shy, but when provoked they are capable of inflicting injuries, occasionally fatal, to dogs and people. == Taxonomy, systematics and evolution == Cassowaries (from the Malay name ''kasuari'')〔Gotch, A. T. (1995)〕 are part of the ratite group, which also includes the emu, rheas, ostriches, and kiwis, and the extinct moas and elephant birds. Three extant species are recognized, and one extinct: * Southern cassowary or double-wattled cassowary, ''Casuarius casuarius'', found in southern New Guinea, northeastern Australia, and the Aru Islands, mainly in lowlands〔 * Dwarf cassowary or Bennett's cassowary, ''Casuarius bennetti'', found in New Guinea, New Britain, and Yapen, mainly in highlands.〔 * Northern cassowary or single-wattled cassowary, ''Casuarius unappendiculatus'', found in the northern and western New Guinea, and Yapen, mainly in lowlands〔〔Davies, S. J. J. F. (2002)〕 * ''Casuarius lydekki'' Extinct〔Brands, S. (2008)〕 Most authorities consider the above monotypic, but several subspecies of each have been described 〔http://www.perron.eu/Publications/All%20cassowaries.html〕(some have even been suggested as separate species, e.g., ''C. (b) papuanus''.〔 although the taxonomic name is in need of revision to Casuarius (bennetti) westermanni 〔http://www.perron.eu/Publications/Bennetti.pdf〕). Validation of these subspecies has proven difficult due to individual variations, age-related variations, the scarcity of specimens, the stability of specimens (the bright skin of the head and neck—the basis of describing several subspecies—fades in specimens), and the practice of trading live cassowaries for thousands of years, some of which are likely to have escaped or been deliberately introduced to regions away from their origin.〔 The evolutionary history of cassowaries, as of all ratites, is not well known. A fossil species was reported from Australia, but for reasons of biogeography this assignment is not certain and it might belong to the prehistoric ''Emuarius'', which were cassowary-like primitive emus. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「cassowary」の詳細全文を読む スポンサード リンク
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