Common ostrich other members of Palaeognathae and thus the flighted tinamous are the sister group to the extinct moa. It is distinctive in its appearance, with a long neck and legs, and can run for a long time at a speed of or even up to about , the fastest land speed of any bird. The common ostrich is the largest living species of bird and lays the largest eggs of any living bird (extinct elephant birds of Madagascar and the giant moa of New Zealand laid larger eggs). The common ostrich's diet consists mainly of plant matter, though it also eats
Rhea (bird) a rudder. During breeding season the flocks break up. For the most part, rheas are vegetarian and prefer broad-leafed plants but they also eat fruits, seeds and roots, as well as insects such as grasshoppers and small reptiles and rodents. Young rheas generally eat only insects for the first few days. Outside of the breeding season they gather in flocks and feed with deer and cattle. Rheas are polygamous, with males courting between two and twelve females. After mating, the male builds a nest, in which each female lays her eggs in turn. The nest consists of a simple scrape