Pterodactyloid wings were covered by a leathery membrane. This thin but tough membrane stretched between its body, the top of its legs and its elongated fourth fingers, forming the structure of the wing. Claws protruded from the other fingers.

Pterodactyloids could flap their wings and fly with power, but the largest ones (like Quetzalcoatlus) probably relied on updrafts (rising warm air) and breezes to help in flying.

Some pterodactyloids include:

Pterodactylus, a small pterodactyloid with a wingspan of about 20-30 inches. It lived during the late Jurassic on lake shores. Pterodactylus was originally named Ptero-Dactyle by Cuvier in 1809 and was Latinized by Rafinesque in 1815.

Dsungaripterus, a pterodactyloid about 10 feet (3 m) wide leathery wings. It had an unusual bony crest running along its snout and had long, narrow, curved jaws with a pointed tip. It lived during the early Cretaceous period.

Pteranodon, a pterodactyloid about 6 feet (1.8 m) long, had a 25 foot (7.8 m) wingspan. It lived during the late Cretaceous period.

Quetzalcoatlus, a pterodactyloid which had a wingspan of 40 feet but only weighed about 110 pounds (50 kg). It lived during the late Cretaceous period.

CLASSIFICATION
Pterodactyloids were reptiles, but not dinosaurs. By definition, all dinosaurs were diapsid reptiles with an upright stance. Pterosaurs probably had a semi-upright stance. There is a small minority of paleontologists who think that the pterosaurs' stance could have been upright and that pterosaurs should therefore be included in the clade of dinosaurs (being derived theropods). Either way, dinosaurs and pterosaurs are certainly closely related.

Pterodactyloids were:

• Kingdom Animalia (animals)
• Phylum Chordata
• Subphylum Vertebrata (vertebrates)
• Superclass Tetrapoda (four-legged animals)
• Class Reptilia (reptiles) or
• Subclass Diapsida - these include all the reptiles (except turtles) and birds. They are distinguished by having two holes in the rear upper part of their skulls and two holes behind the eyes.
• Archosaurs - this group includes dinosaurs, crocodilians, pterosaurs, birds, etc.
• Order Pterosauria - flying reptiles. There are two type of pterosaurs:
  • Suborder Rhamphorhynchoids ("prow beaks") - early pterosaurs that appeared during the Triassic period and went extinct at the end of the Jurassic, that had long tails, short necks, and long, narrow wings. These were the first flying vertebrates. Examples include Dimorphodon , Rhamphorhynchus, and Sordes.
  • Suborder Pterodactyloids ("wing finger") - their descendants that appeared late in the Jurassic and died in the K-T extinction, 65 million years ago, that had shorter tails. Examples include Pterodactylus, Dsungaripterus, Pteranodon, and Quetzalcoatlus.