The first remains of pterosaurs were found in Germany in the 1780s, and it was not clear what sort of animals they were. Regarded as aberrant birds by some and aberrant bats by others, they were established as reptiles by the French comparative anatomist Georges Cuvier in the early 1800s. He noted they were not at all like typical reptiles: they stood erect like birds, they had hollow bones and probably an insulatory covering, and they flew.