A pterosaur is a type of flying reptile that lived during the age of dinosaurs, from about 228 to 66 million years ago. Despite their name, pterosaurs weren't actually dinosaurs. They were close relatives that ruled the skies while dinosaurs walked the Earth below.

Pterosaurs had wings made of skin and muscle that stretched from their bodies to their enormously long fourth finger, almost like a bat's wing. Some pterosaurs were tiny, no bigger than a sparrow, while others like Quetzalcoatlus had wingspans wider than a small airplane, up to about 36 feet across. They had lightweight, hollow bones that made flying easier, and many species had long beaks perfect for catching fish.

Scientists have discovered hundreds of pterosaur species, each adapted to different environments and diets. Some had fuzzy, hair-like coverings that kept them warm. Others had elaborate head crests, possibly used for display or to help with flight. When you see a flying creature in a dinosaur movie, it's probably a pterosaur. They vanished in the same mass extinction that wiped out the dinosaurs, leaving the skies open for birds to take over.