Quetzalcoatlus:  One of the largest creatures ever to fly was a pterosaur known as Quetzalcoatlus, which had an immense wingspan equalling that of a twin engine jet fighter.

Name: Quetzalcoatlus (Named for the feathered Aztec god, "Quetzalcoatl"; D. A. Lawson, 1971)
Wingspan: up to 36 feet (11 meters)
Weight: 200-300 pounds
Time: 75-65 million years ago (Late Cretaceous)
Place: Texas (Big Bend National Park)
Diet: meat-eater (carnivore)