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
Bird egg 7500 pores. The shape of eggs varies considerably across bird species, ranging from near-spherical (such as those of the little bee-eater) to highly pyriform or conical (such as those of the common murre) with the familiar shape of the chicken egg lying in between. Early scientific investigators of egg shape suggested that the oval shape of eggs was caused by the egg being forced through the oviduct by peristalsis. In this often-repeated but incorrect theory of egg shape formation, the contraction and relaxation of the muscles which push the egg down the oviduct cause the spherical egg membrane to distort