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Dinosauromorpha |
The Ornithodira are a division of the Archosauromorpha (and perhaps Archosauria) clade. Members of this clade were considered to be typically characterized by an upright gait and an S-curved neck, hence the name "Ornithodira" (= bird neck). It contains two chief superorders, Dinosauromorpha and Pterosauromorpha.
The prior, Dinosauromorpha, contains lagosuchians, and their famous descendants the Dinosauria, which, in turn, are believed by most researchers to be the ancestors of modern birds. The latter, Pterosauromorpha, contains the Pterosauria which are famously the flying reptiles, and were perhaps the first vertebrates capable of true flight. It should be noted that today most researchers think pterosaurians had neither a S-curved neck, nor an upright gait. However this doesn't invalidate the clade Ornothodira, which is strictly defined by descent as containing the last common ancestor of dinosaurs and pterosaurs and all its descendants. Which species exactly are implicated by this definition, is still not very clear.