Pterosaurs 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 spanned a wide range of adult sizes, from the very small
Nemicolopterus to the largest known flying creatures of all time, including
Quetzalcoatlus and
Hatzegopteryx.
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 terrestrial reptiles with a unique upright stance (superorder Dinosauria), and therefore excludes the pterosaurs, as well as the various groups of extinct aquatic reptiles, such as ichthyosaurs, plesiosaurs, and mosasaurs.
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