Specimens of Archaeopteryx resembling a flying squirrel. After conducting an embryological comparison with modern birds, he noticed a similarity between "Archaeopteryx" and the embryonic stage of birds, concluding that the former was likely an "archetype", or created kind, of the bird lineage. Owen's monograph presented a description of the osteology and the plumage, though he missed a number of elements. Owing to its overall similarity to the structure of modern birds, Owen postulated a toothless, horny beak-like instrument "fitted for preening", and misinterpreted the fragment of an upper jaw with teeth, located next to the pelvis on the specimen, as the remains of
Archaeopteryx be given preference over "lithographica" in instances where scientists considered them to represent the same species. It has been noted that the feather, the first specimen of "Archaeopteryx" described, does not correspond well with the flight-related feathers of "Archaeopteryx". It certainly is a flight feather of a contemporary species, but its size and proportions indicate that it may belong to another, smaller species of feathered theropod, of which only this feather is known so far. As the feather had been designated the type specimen, the name "Archaeopteryx" should then no longer be applied to the skeletons, thus creating significant nomenclatorial