Specimens of Archaeopteryx the results of his investigation was a talk at the Royal Society in London in November, and was published as an abstract in the Proceedings of the Royal Society the following year. Here he considered the single feather described by von Meyer in 1861 and assigned the new skeleton the same genus. Owen speculated possible short- and long-tailed forms of "Archaeopteryx" and on these grounds assigned the London specimen the species name "macrura", meaning "long-tailed". Owen, who published a monograph on the specimen in 1863, generally considered the animal to be a bird despite describing its structure and proportions as
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