Pterosaurs, meaning "winged lizard", often referred to as pterodactyls, were flying reptiles of the clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period (220 to 65.5 million years ago). Pterosaurs are the earliest vertebrates known to have evolved powered flight. Their wings were formed by a membrane of skin, muscle, and other tissues stretching from the legs to a dramatically lengthened fourth finger. Early species had long, fully-toothed jaws and long tails, while later forms had a highly reduced tail, and some lacked teeth. Many sported furry coats made up of hair-like filaments known as pycnofibres, which covered their bodies and parts of their wings.
Pterosaurs are sometimes referred to in the popular media as dinosaurs, but this is incorrect. The term "dinosaur" is properly restricted to a certain group of reptiles with a unique upright stance (superorder Dinosauria, which includes birds), and therefore excludes the pterosaurs, as well as the various groups of extinct marine reptiles.