Dimorphodon was a genus of medium-sized pterosaur from the early Jurassic Period. It was named by palaeontologist Richard Owen in 1859. Dimorphodon means "two-form tooth", derived from Greek ‘di’ meaning 'two', morphe meaning 'shape' and ‘odon’ meaning 'tooth', referring to the fact that it had two distinct types of teeth in its jaws - which is comparatively rare among reptiles. The body structure of Dimorphodon displays many primitive characteristics, such as a very small brain-pan and proportionally short wings. The first phalanx in its flight finger is only slightly longer than its lower arm. Its neck was short but strong and flexible and may have had a membranous pouch on the underside. The vertebrae had pneumatic foramina, openings through which the air sacks could reach the hollow interior. The Dimorphodon had an adult body length of 1 metre long, with a 1.45 metre wingspan. Its tail was long and consisted of thirty vertebrae. The first five or six were short and flexible, but the remainder gradually increased in length and were stiffened by elongated vertebral processes.