Pterosaurs were flying reptiles that lived during the time of the dinosaurs, from the late Triassic to the end of the Cretaceous period. They are not classified as dinosaurs but are closely related. Pterosaurs had a wide range of sizes, with some having wingspans of over 30 feet, while others were much smaller. Their wings were formed by a membrane of skin and muscle stretched between an elongated fourth finger and their bodies. These creatures were diverse in their diets and habitats. Some pterosaurs, like Pteranodon, were fish-eaters, while others, such as Quetzalcoatlus, may have scavenged or hunted small animals. Pterosaurs are known for their unique adaptations, including hollow bones that made them lighter for flight and specialized beaks for feeding.