Quetzalcoatlus had a large brain and big eyes (it probably had good eyesight). Fur-like fuzz (modified scales) may have covered its body. A light-weight, bony crests on the head may have been a sexual characteristic. It used to be thought that the crest acted as a rudder for flying, but this was probably not the case.

Quetzalcoatlus wings were covered by a leathery membrane and were over 9 inches (23 cm) thick at the elbow. 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. Quetzalcoatlus probably relied on updrafts (rising warm air) and breezes to help it fly.

WHEN QUETZALCOATLUS LIVED
Quetzalcoatlus lived during the late Cretaceous period and died out about 65 million years ago, during the K-T mass extinction.

DIET
Quetzalcoatlus was a carnivore, probably skimming the water to find prey. It lived inland from the sea, near fresh-water ponds (so its diet was not primarily sea fishes and marine mollusks like other pterosaurs). It probably ate arthropods (like early crayfish) and dying animals. It probably hunted its prey by gliding toward the water and swooping up its meals. It filtered its food through its long, pointed, toothless jaws. Quetzalcoatlus must have had good eyesight in order to spot meals from the air.

LOCOMOTION
Quetzalcoatlus flew long distances using large, light-weight wings.

DISCOVERY OF FOSSILS
The first Quetzalcoatlus fossil was found in Big Bend National Park, Texas, USA, by Douglas A. Lawson (who was then a geology graduate student at the University of Texas, Austin) in 1971. Lawson named Quetzalcoatlus 1975. Other smaller specimens have been found.

CLASSIFICATION
Quetzalcoatlus was a Pterosaur. Pterosaurs 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.

Pterosaurs are:

• Chordates (Phylum Chordata)
• Vertebrates (Subphylum Vertebrata)
• Tetrapods (Superclass Tetrapoda, four-legged animals)
• Reptiles (Class Reptilia)
• Diapsids (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 (Superorder Archosauria) - this group includes dinosaurs, crocodilians, pterosaurs, birds, etc.
• Pterosaurs (Order Pterosauria) - flying reptiles. There are two type of pterosaurs:
• Pterodactyloids (Family Pterodactyloidia, "wing finger") - they appeared late in the Jurassic and died in the K-T extinction, 65 million years ago, that had shorter tails. Examples include Dsungaripterus, Pterodactylus, Pteranodon, and Quetzalcoatlus.