Feathered dinosaur hands and feathers, "Archaeopteryx" was quite similar to "Compsognathus". Thus "Archaeopteryx" represents a transitional fossil. In 1868 he published "On the Animals which are most nearly intermediate between Birds and Reptiles", making the case. The first restoration of a feathered dinosaur was Thomas Henry Huxley's depiction in 1876 of a feathered "Compsognathus" to accompany a lecture on the evolution of birds he delivered in New York in which he speculated that the aforementioned dinosaur might have been in possession of feathers. The leading dinosaur expert of the time, Richard Owen, disagreed, claiming "Archaeopteryx" as the first bird outside dinosaur lineage.
Archaeopteryx be related particularly closely to "Anchiornis" and "Xiaotingia", which were recovered as basal troodontids instead. Agnolín and Novas (2013) found "Archaeopteryx" and (possibly synonymous) "Wellnhoferia" to be the basalmost avialans (Avialae being defined by the authors as including "Archaeopteryx lithographica" and "Passer", their most recent common ancestor and all of its descendants), with Microraptoria, Unenlagiinae, and the clade containing "Anchiornis" and "Xiaotingia" being successively closer outgroups to the Avialae. Another phylogenetic study by Godefroit, "et al.", using a more inclusive matrix than the one from the analysis in the description of "Eosinopteryx brevipenna", also found "Archaeopteryx" to be a member