Archaeopteryx dromaeosaurids and troodontids: jaws with sharp teeth, three fingers with claws, a long bony tail, hyperextensible second toes ("killing claw"), feathers (which also suggest warm-bloodedness), and various features of the skeleton. These features make "Archaeopteryx" a clear candidate for a transitional fossil between non-avian dinosaurs and birds. Thus, "Archaeopteryx" plays an important role, not only in the study of the origin of birds, but in the study of dinosaurs. It was named from a single feather in 1861. That same year, the first complete specimen of "Archaeopteryx" was announced. Over the years, ten more fossils of "Archaeopteryx" have surfaced. Despite
Archaeopteryx common uses of that term. A more thorough analysis was published soon after to test this hypothesis, and failed to arrive at the same result; it found "Archaeopteryx" in its traditional position at the base of Avialae, while "Xiaotingia" was recovered as a basal dromaeosaurid or troodontid. The authors of the follow-up study noted that uncertainties still exist, and that it may not be possible to state confidently whether or not "Archaeopteryx" is a member of Avialae or not, barring new and better specimens of relevant species. Phylogenetic studies conducted by Senter, "et al." (2012) and Turner, Makovicky, and Norell