Quetzalcoatlus northropi, skeletal model
Quetzalcoatlus northropi from the Late Crebeous Javalna Formation of Big bend region of West Texas is the largest known member of the family of giant pterodactloid pterosaurs called azhdarchids. Azhdarchids were probably distributed worldwide during the Cretaceaus Period and are characterized by greatly elongated neck vertebrae. Other evidence of azhdarchids include the fragmentatry remains of Titanopteryx from the Cretaceous of Jordan and Azhdarcho from the Creaceous of Uzbekistan. With an estimated wingspan of 36-39 feet, Quetzalcoatlus northropi may have been the largest creature ever to fly.