Archaeopterygiformes
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 A model of Archaeopteryx lithographica
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Extinct (fossil)
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The Archaeopterygiformes were an order of early birds that lived during the Jurassic and possibly Cretaceous periods. They include one of the most well known and earliest birds known, Archaeopteryx. Archaeopterygiformes are distinguished from other early birds by long bony tails, and in some species, by the presence of a hyperextendible second toe.
[edit] Families
- Archaeopterygidae: Archaeopteryx and the closely related (if not synonymous) Wellnhoferia.
- ?Dromaeosauridae: The "raptors", relatively large, flightless, predatory birds.
[edit] Taxonomy
Family dromaeosauridae are traditionally considered to be non-avian dinosaurs. However, discoveries of a number of primitive forms have muddied the relationships of early birds, making it just as likely that Velociraptor and similar dinosaurs are actually true birds. Paul placed dromaeosaurids in Archaeopterygiformes for these reasons, though most cladistic analyses since have found them to be slightly more primitive, and therefore outside clade Aves (Paul, 1988).
As its name suggests, Protarchaeopteryx was also originally referred to this order, but most paleontologists now consider it an oviraptorosaur. Other referred genera, like Jurapteryx, Wellnhoferia, and Proornis, are probably synonymous with Archaeopteryx (the former two) or do not belong into this group (the last).
