The archaeopteryx was part reptile, and part bird. It is a wonderful example of an in-between creature. Several fossils of this reptile-bird have been found in fine grained stone. The skeleton looks like that of a dinosaur, but it shows the presence of feathers. Feathers evolved from the scales of reptiles, and are the most important feature of birds. The archaeopteryx had a toothed jaw, a long tail, and a weak breast bone. Unlike the bones of birds, all the bones of archaeopteryx were solid. The feathers of the archaeopteryx tell us that the crocodile is related to the cuckoo.