[3][4][5] A few studies have recovered Anchiornis and Xiaotingia (usually considered part of a distinct clade, Anchiornithidae) to also be members of the Archaeopterygidae,[6] 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 archaeopterygids are more closely related to modern birds or to deinonychosaurs barring new and better specimens of relevant species.

[7] Teeth attributable to archaeopterygids are known from the earliest Cretaceous (Berriasian) Cherves-de-Cognac locality and the Angeac-Charente bonebed of France.

[10] 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.

[6] The family Dromaeosauridae, traditionally considered to be non-avian dinosaurs, have been included in this group by at least one author, although the group was paraphyletic in that classification, with Dromaeosaurus and Velociraptor (including Deinonychus and Saurornitholestes) being more closely related to modern birds than Archaeopteryx was.