Quetzalcoatlus

Dinosaurs > Quetzalcoatlus

Quetzalcoatlus was a pterodactyloid pterosaur known from the Late Cretaceous of North America (Maastrichtian stage) and one of the largest known flying animals of all time. It was a member of the Azhdarchidae, a family of advanced toothless pterosaurs with unusually long, stiffened necks. Its name comes from the Mesoamerican feathered serpent god Quetzalcoatl.

When it was first discovered, scientists estimated that the largest Quetzalcoatlus fossils came from an individual with a wingspan as large as 15.9 meters (52 feet), choosing the middle of three extrapolations from the proportions of other pterosaurs that gave an estimate of 11, 15.5 and 21 meters respectively (36 feet, 50.85 feet, 68.9 feet). In 1981, further study lowered these estimates to 11–12 meters (36–39 ft). More recent estimates based on greater knowledge of azhdarchid proportions place its wingspan at 10–11 meters (33–36 ft).

Mass estimates for giant azhdarchids are extremely problematic because no existing species share a similar size or body plan, and in consequence published results vary widely. While some studies have historically found extremely low weight estimates for Quetzalcoatlus, as low as 70 kilograms (150 lb) for a 10-meter (32-foot-10-inch) individual, a majority of estimates published since the 2000s have been higher, around 200–250 kilograms (440–550 lb).

Skull material (from smaller specimens, possibly a related species) shows that Quetzalcoatlus had a very sharp and pointed beak. That is contrary to some earlier reconstructions that showed a blunter snout, based on the inadvertent inclusion of jaw material from another pterosaur species, possibly a tapejarid or a form related to Tupuxuara. A skull crest was also present but its exact form and size are still unknown.

Quetzalcoatlus

Order: Pterosauria
Family: Azhdarchidae

Size: 11 m (36 ft) wingspan

Weight: 200 kg (440 lb)

When: Cretaceous Period
68 to 66 million years ago

Where: North America

Diet: Carnivore

The nature of flight in Quetzalcoatlus and other giant azhdarchids was poorly understood until serious biomechanical studies were conducted in the 21st century. One early (1984) experiment by Paul MacCready used practical aerodynamics to test the flight of Quetzalcoatlus. MacCready constructed a model flying machine or ornithopter with a simple computer functioning as an autopilot. The model successfully flew with a combination of soaring and wing flapping; however, the model was half scale based on a then-current weight estimate of around 80 kg, far lower than more modern estimates of over 200 kg. The method of flight in these pterosaurs depends largely on weight, which has been controversial, and widely differing masses have been favored by different scientists. Some researchers have suggested that these animals employed slow, soaring flight, while others have concluded that their flight was fast and dynamic. In 2010, Donald Henderson argued that the mass of Q. northropi had been underestimated, even the highest estimates, and that it was too massive to have achieved powered flight. He estimated it in his 2010 paper as 540 kg. Henderson argued that it may have been flightless.

However, most other flight capability estimates have disagreed with Henderson’s research, suggesting instead an animal superbly adapted to long-range, extended flight. In 2010, Mike Habib, a professor of biomechanics at Chatham University, and Mark Witton, a British paleontologist, undertook a further investigation into the claims of flightlessness in large pterosaurs. After factoring wingspan, body weight, and aerodynamics, a sophisticated computer program led the two researchers to conclude that Q. northropi was capable of flight “up to 80 miles an hour for 7 to 10 days at altitudes of 15,000 feet”. Mike Habib further suggested a maximum flight range of 8,000 to 12,000 miles for Q. northropi. Henderson’s work was further criticized by Habib, who pointed out that although Henderson used excellent mass estimations, they were based on outdated pterosaur models, and that anatomical study of Q. northropi and other large pterosaur forelimbs show a higher degree of robustness than would be expected if they were purely quadrupedal. Habib believes that large pterosaurs most likely utilized a short burst of powered flight in order to then transition to thermal soaring.

There have been a number of different ideas proposed about the lifestyle of Quetzalcoatlus. Because the area of the fossil site was four hundred kilometers removed from the coastline and there were no indications of large rivers or deep lakes nearby at the end of the Cretaceous, Lawson in 1975 rejected a fish-eating lifestyle, instead suggesting that Quetzalcoatlus scavenged like the Marabou Stork, but then on the carcasses of titanosaur sauropods such as Alamosaurus. Lawson had found the remains of the giant pterosaur while searching for the bones of this dinosaur, which formed an important part of its ecosystem.


Source: Wikipedia