Saturday, April 19, 2008

Paleognathae


The Paleognathae or paleognaths ("old jaws") are one of the two living superorders of birds. The other living superorder is Neognathae.
The paleognaths contain several living orders of birds, the Tinamiformes (tinamous), the Apterygiformes (kiwis), Casuariiformes (cassowaries and emus), Rheiformes (rheas), and the Struthioniformes (ostriches). All but the tinamous are flightless. There are also many extinct orders: the Lithornithiformes, the Ambiornithiformes, the Gansuiformes, the Paleocursornithiformes, the Dinornithiformes (moas), and the Aepyornithiformes (elephant birds)
Most paleognaths have long necks and long legs, and are specialized for running rather than flight; indeed, the ratites are all completely flightless (with the partial exception of the tinamous). The group is not separated because of this though, it is rather based on the form of the jaw. Paleognaths other than tinamous are commonly known as ratites from the Latin word for raft, ratis, because they have a breastbone shaped like a raft

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