Feathered dinosaur is possible that feathers first developed in an even earlier group, in light of the discovery of pycnofibers of pterosaurs. Crocodilians also possess beta keratin similar to those of birds, which suggests that they evolved from common ancestral genes. Shortly after the 1859 publication of Charles Darwin's "On the Origin of Species", British biologist Thomas Henry Huxley proposed that birds were descendants of dinosaurs. He compared the skeletal structure of "Compsognathus", a small theropod dinosaur, and the 'first bird' "Archaeopteryx lithographica" (both of which were found in the Upper Jurassic Bavarian limestone of Solnhofen). He showed that, apart from its
Specimens of Archaeopteryx that "Archaeopteryx" could have raised its short second toe in a similar manner to its dromaeosaur cousin "Deinonychus", whose second toe bore an enlarged "sickle claw" for probable use in predation. It remains unclear whether "Archaeopteryx" also used its hyperextended toe-claw in a similar fashion or for some other purpose. Taken together, many of the unique features of the skull, feet and coracoid strengthen a close relationship of archaeopterygids to deinonychosaurian theropods. Well-preserved imprints of wing and tail plumage show details of the barbs, but not barbules, and the shafts of 11 primaries can be counted on the right wing.