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Birds Divisions
The fossil record indicates that birds evolved from theropod dinosaurs during the Jurassic period, around 150–200 Ma (million years ago), and the earliest known bird is the Late Jurassic Archaeopteryx, c. 155–150 MYA a member of the Archaeopterygidae family. Most paleontologists regard birds as the only clade of dinosaurs that survived the Cretaceous–Tertiary extinction event approximately 65.5 MYA. The Class Aves is divided into two major Subclasses: the Enantiornithes (primitive birds) and the Neornithes (modern birds). Confuciusornithidae is on a divergent lineage to the Ornithothoraces group that includes Enantiornithes and Neornithes. |
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