as 56 days. If no continued pressures warrant the energy expenditure to maintain the structures of flight, selection will tend towards these other traits. The only known species of flightless bird in which wings completely disappeared was the gigantic, herbivorous moa of New Zealand, hunted to extinction by humans by the 15th century. In moa, the entire pectoral girdle is reduced to a paired scapulocoracoid, which is the size of a finger. List of flightless birds Many flightless birds are extinct; this list shows species that are either still extant, or became extinct in the Holocene (no more than 11,000 years ago). Extinct species are indicated with a cross (†). A number of species suspected, but not confirmed to be flightless, are also included here. Longer-extinct groups of flightless birds include the Cretaceous patagopterygiformes, hesperornithids, the Cenozoic phorusrhacids ("terror birds") and related bathornithids, the unrelated eogruids, geranoidids, gastornithiforms, and dromornithids (mihirungs or "demon ducks"), and the plotopterids. Ratites Ostriches Common ostrich, Struthio camelus Somali ostrich, Struthio molybdophanes Asian ostrich, Struthio asiaticus † Emus Emu, Dromaius novaehollandiae King Island emu, Dromaius (novaehollandiae) minor † Kangaroo Island emu, Dromaius (novaehollandiae) baudinianus † Tasmanian emu, Dromaius novaehollandiae diemenensis † Cassowaries Dwarf cassowary, Casuarius bennetti Southern cassowary, Casuarius casuarius Northern cassowary, Casuarius unappendiculatus Moa (Dinornithiformes) †, several species Elephant birds (Aepyornithiformes) †, several species Kiwis Southern brown kiwi, Apteryx australis Great spotted kiwi, Apteryx haastii North Island brown kiwi, Apteryx mantelli Little spotted kiwi, Apteryx owenii Okarito kiwi, Apteryx rowi Rheas Greater rhea, Rhea americana Lesser rhea, Rhea pennata Galliformes (game birds) New Caledonian giant scrubfowl, Sylviornis neocaledoniae † Noble megapode, Megavitornis altirostris † Viti Levu scrubfowl, Megapodius amissus † Anseriformes (waterfowl) Auckland Island teal, Anas aucklandica Campbell teal, Anas nesiotis Steamer ducks Fuegian steamer duck, Tachyeres pteneres Falkland steamer duck, Tachyeres brachypterus Chubut steamer duck, Tachyeres leucocephalus Amsterdam wigeon, Anas marecula † Bermuda flightless duck, Anas pachyscelus † Finsch's duck, Chenonetta finschi † Moa-nalo † Turtle-jawed moa-nalo, Chelychelynechen quassus † Small-billed moa-nalo, Ptaiochen pau † O'ahu moa-nalo, Thambetochen xanion † Maui Nui large-billed moa-nalo, Thambetochen chauliodous † Nēnē-nui, Branta hylobadistes † (possibly flightless or very weak flier) Giant Hawaiʻi goose, Branta rhuax † Mihirung, Genyornis newtoni † California flightless sea-duck or Law's diving goose, Chendytes lawi † Kaua'i mole duck, Talpanas lippa † New Zealand geese, Cnemiornis gracilis and C. calcitrans † Aegotheliformes (owlet-nightjars) New Zealand owlet-nightjar, Aegotheles novaezealandiae † Mesitornithiformes (mesites) Brown