Archaeopterygidae

Archaeopterygidae is a group of maniraptoran dinosaurs that lived during the late Jurassic period. In most current classifications, it contains only the genus Archaeopteryx. As its name suggests, Protarchaeopteryx was also once referred to this group, 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). Jinfengopteryx was originally described as an archaeopterygid, though it was later shown to be a troodontid. A few studies have recovered Anchiornis and Xiaotingia (usually considered more primitive members of the related group Deinonychosauria) to also be members of the Archaeopterygidae, though most subsequent analyses have failed to arrive at the same result. Uncertainties still exist, however, and it may not be possible to confidently state whether or not archaeopterygids are more closely related to modern birds or to deinonychosaurs barring new and better specimens of relevant species.

Classification
The family Archaeopterygidae is the only family in the order Archaeopterygiformes, which was coined by Max Fürbringer in 1888 to contain Archaeopterygidae and genus Archaeopteryx. A formal phylogenetic definition for Archaeopterygidae was given by Xu and colleagues in 2011: the clade comprising all animals closer to Archaeopteryx than to the house sparrow or Dromaeosaurus.

The family Dromaeosauridae, traditionally considered to be non-avian dinosaurs, have been included in this group by at least one author. Discoveries of a number of primitive forms have muddied the relationships of early birds, making it possible that Velociraptor and similar dinosaurs could be considered birds. Palaeoartist Gregory S. Paul placed dromaeosaurids in Archaeopterygiformes for these reasons, though the eventual cladistic definition of Archaeopterygidae explicitly excluded them.