Pterosaur, any of more than 100 species of extinct flying reptiles. Each wing of a pterosaur consisted of a membrane of skin that extended from the side of the body to the tip of the elongated fourth digit of the forelimb.

Pterosaurs lived from about 225,000,000 to 65,000,000 years ago. Pterosaurs known as pterodactyls appeared about 180,000,000 years ago. Pterodactyls were generally larger than other pterosaurs. Pterodactyls had no or few teeth; most other pterosaurs had many teeth. A typical pterodactyl also had a much shorter tail than other pterosaurs and had a crest on its head.

PterosaursPterosaurs were flying reptiles that could be as large as small airplanes.

Most pterosaurs were predators, feeding on fish, aquatic invertebrates, or various land animals. Other pterosaurs may have been scavengers. Still others may have eaten fruit. On the ground, pterosaurs probably walked upright.

Some pterosaurs were about the size of a songbird; others were as large as a small airplane. The largest known pterosaur was Quetzalcoatlus northropi, with a wingspan of 39 feet (12 m).

Pterosaurs make up the order Pterosauria of the class Reptilia.