Archaeopteryx of Avialae (defined by the authors as the most inclusive clade containing "Passer domesticus", but not "Dromaeosaurus albertensis" or "Troodon formosus"). "Archaeopteryx" was found to form a grade at the base of Avialae with "Xiaotingia", "Anchiornis", and "Aurornis". Compared to "Archaeopteryx", "Xiaotingia" was found to be more closely related to extant birds, while both "Anchiornis" and "Aurornis" were found to be more distantly so. Archaeopteryx Archaeopteryx (), meaning "old wing" (sometimes referred to by its German name ("original bird" or "first bird")), is a genus of bird-like dinosaurs that is transitional between non-avian feathered dinosaurs and modern birds. The name
Specimens of Archaeopteryx its aerodynamic function as a flight feather. As the feather bears little resemblance to the retrices of the other full "Archaeopteryx" skeletons, it is generally thought to be a wing feather: Griffiths and others have concluded it was a remex, while Carney in 2012 interpreted it to be a covert feather. The feather has a relatively low degree of asymmetry, which Speakman and Thompson in 1994 concluded to indicate it as a secondary remex. If this is the case, then it would have originated from an animal smaller than even the Eichstätt specimen, which is the smallest "Archaeopteryx" specimen known