Archaeopteryx compared to its body length. It could reach up to in body length, with an estimated mass of . "Archaeopteryx" feathers, although less documented than its other features, were very similar in structure to modern-day bird feathers. Despite the presence of numerous avian features, "Archaeopteryx" had many non-avian theropod dinosaur characteristics. Unlike modern birds, "Archaeopteryx" had small teeth, as well as a long bony tail, features which "Archaeopteryx" shared with other dinosaurs of the time. Because it displays features common to both birds and non-avian dinosaurs, "Archaeopteryx" has often been considered a link between them. In the 1970s, John Ostrom,
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