Pterosaurs  meaning "winged lizard") were flying reptiles of the extinct  order Pterosauria. They existed during most of the Mesozoic: from the late Triassic to the end of the Cretaceous (228 to 66 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 ankles to a dramatically lengthened fourth finger.

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