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.