August 31 , 2016

by Vasika Udurawane

Quetzalcoatlus dominated the skies of North America at the end of the Dinosaur Age and flew high over such famous creatures as Tyrannosaurus and Triceratops. As tall as a giraffe, the biggest Quetzalcoatlus species were also the largest of all flying creatures. They were the ultimate in pterosaur evolution.

The pterosaurs or flying reptiles produced some of the largest flying creatures ever known. The largest and most famous of these aerial titans was Quetzalcoatlus. Named after a Mesoamerican deity, Quetzalcoatlus is the most famous member of the azhdarchids, a family of pterosaurs limited to the Cretaceous period, the time between 144 and 66 million years ago.

In other words, the family spanned the entirety of the Cretaceous, a period of roughly 80 million years. These pterosaurs were all very large animals with long, pointed skulls and some had short crests at the backs of their heads. They had very long necks, small torsos, long legs and a short pair of wings in proportion to their bodies. All these animals were known to be predatory, although for a long time it was not known how they searched for prey.

For a while, Quetzalcoatlus and kin were cast in the light of giant vultures that scavenged the carcasses of dinosaurs. This conclusion was reached by the fact that unlike other large pterosaurs such as the crested Pteranodon, Quetzalcoatlus fossils were found inland. They were also thought to have been skimmers, hunting for fish over freshwater systems.

Yet it was concluded that neither azhdarchids nor any other flying reptiles were suited for skimming so the hypothesis was dropped. They lacked the jaws and neck structure for such a lifestyle, so any fishing pterosaurs would either have to dive for their prey or simply pluck fish off the water’s surface.

More recently, the azhdarchids were cast as stork-like terrestrial stalkers that picked up small animals while walking overland on dry ground. This model worked, with the animals swallowing up almost anything that could fit into their mouths. Thus the azhdarchids spent more time on land rather than close to the water. An animal the size of Quetzalcoatlus could consume victims as large as small dinosaurs, picking them up in its huge toothless jaws.

Despite this terrestrial hunting, Quetzalcoatlus and kin were incredible aeronauts. Like all flying reptiles, they launched off the ground in a four-footed leap. This launch style was supported by an immense amount of power. Quetzalcoatlus’ torso, though small in comparison to its body, was very dense and packed with huge muscles. A single leap could get one of these giants into the air, and it needed just a few flaps to keep it aloft. They could likely travel nonstop for 16,000 kilometers after launching, only rarely flapping to keep themselves in the air and to steer their path. Its short wings were not just thin membranes of skin, but densely packed muscle fibers called actinofibrils. Like all other pterosaurs, Quetzalcoatlus was warm-blooded and had an incredible metabolism to power its lifestyle.

Quetzalcoatlus occupied the role of medium-level hunter. It was midway between the contemporary tyrannosaurs and the smaller dromaeosaurs or raptor dinosaurs by way of size and choice of prey. Two species of this genus existed in the southern parts of North America, specifically in the Javelina Formation of Texas.

The bigger one, the huge Quetzalcoatlus northropi stood as tall as a giraffe on the ground, more than five meters tall and weighed 250 kilograms. This is the maximum weight limit for a flying animal, and only a few other azhdarchids come close to Q.northropi’s size. The smaller species is Quetzalcoatlus sp, an animal just half as big as the giant species. It is also known from much better fossil remains.

Despite being featured prominently in popular culture, it is very poorly known. Fossils of Q. northropi have always been scarce. So it has to be reconstructed on the basis of its close relatives. The skull of this species for example, is unknown and instead the head of the contemporary Q. sp. is used in reconstructions. This results in a creature which is a combination of two species.

Often the animal we see in illustrations is just a scaled-up version of the smaller species. But the larger size of Q. northropi instantly results in it being the more popular animal and the most represented azhdarchid in popular culture.

http://www.eartharchives.org/articles/quetzalcoatlus-the-largest-flying-animal-of-all-time/