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,
Archaeopteryx are limited to a sort of "proto-down" not dissimilar to that found in the dinosaur "Sinosauropteryx": decomposed and fluffy, and possibly even appearing more like fur than feathers in life (although not in their microscopic structure). These occur on the remainder of the body—although some feathers did not fossilize and others were obliterated during preparation, leaving bare patches on specimens—and the lower neck. There is no indication of feathering on the upper neck and head. While these conceivably may have been nude, this may still be an artefact of preservation. It appears that most "Archaeopteryx" specimens became embedded in anoxic