Archaeopteryx following Thomas Henry Huxley's lead in 1868, argued that birds evolved within theropod dinosaurs and "Archaeopteryx" was a critical piece of evidence for this argument; it had several avian features, such as a wishbone, flight feathers, wings, and a partially reversed first toe along with dinosaur and theropod features. For instance, it has a long ascending process of the ankle bone, interdental plates, an obturator process of the ischium, and long chevrons in the tail. In particular, Ostrom found that "Archaeopteryx" was remarkably similar to the theropod family Dromaeosauridae. Specimens of "Archaeopteryx" were most notable for their well-developed flight feathers.
Specimens of Archaeopteryx skeleton of a feathered animal from the same lithographic shale deposits, which would later be known as the London specimen. Coincidentally, von Meyer proposed the name "Archaeopteryx lithographica" for the feather, but not for the skeleton. Therefore, the official name of the animal was originally linked to the single feather rather than any actual skeleton, and is formally considered the original holotype. Though 1860 is often the year named for the feather's discovery, there is no proof of this date, and some authors consider it more likely to have been found in 1861, as it seems reasonable that von Meyer's