 The next year, Ostrom redescribed a specimen of "Pterodactylus" in the Dutch Teyler Museum as another skeleton of "Archaeopteryx".The specimen consisted mainly of a single wing and its description made Ostrom aware of the similarities between the wrists of "Archaeopteryx" and "Deinonychus".In 1972, British paleontologist Alick Walker hypothesized that birds arose not from 'thecodonts' but from crocodile ancestors like "Sphenosuchus".