Rheiformes

Rheiformes is the order of large flightless birds containing the family Rheidae, the rheas, part of the ratite group within the infraclass Paleognathae. Two living species are recognized, the greater rhea and the lesser rhea, both native to the grasslands of South America. Some classification systems instead group rheas together with ostriches, tinamous, cassowaries, emus and kiwis inside a single broader order, Struthioniformes, so the boundaries of Rheiformes are drawn differently depending on the authority followed.