Quetzalcoatlus kindly adjusts a baby dino's neck. Illustration: Mark Witton A model of Quetzalcoatlus that paleontologist Mark Witton (the top half of the two stacked humans at right) designed and sculpted for the Royal Society's 350th anniversary celebration. (A word of warning regarding the models and illustrations in this gallery: Scientists have nowhere near a complete skeleton of a large azhdarchid, and base the creatures' appearances in part on complete specimens of smaller types of pterosaurs. On top of that, large azhdarchids are getting a good amount of attention from paleontologists these days, and researchers are frequently updating their reconstructions.) Image courtesy Mark Witton Quetzalcoatlus in flight over sauropods, who don't even bother to pose or anything because they just know that Quetz is totally stealing the show, as per the usual. Illustration: Mark Witton Quetzalcoatlus indulges a juvenile T. rex in a bit of playtime. Illustration: Mark Witton Hatzegopteryx thambema, another type of giant azhdarchid, shown during takeoff. Note its highly elongated vertebrae. Illustration: Mark Witton Quetzalcoatlus strikes a majestic pose just minutes before going extinct. Illustration: Mark Witton

The Mesoamerican god Quetzalcoatl is one of those great all-purpose deities – in contrast to, say, Verminus, the strangely specialized Roman god of cattle worms. A feathered serpent of sorts, Quetzalcoatl not only created the cosmos and the first people, but was also in charge of the wind, using it to, you guessed it, sweep roads and destroy existence.

This blustery god lends its name to one of the largest and most impressive creatures to ever take flight: Quetzalcoatlus northropi of the Cretaceous period, a pterosaur with a wingspan of some 33 feet that stood as tall as a giraffe. Like Quetzalcoatl, it was a feathered (well, sort of – more on that later) reptile, though Quetzalcoatlus had the body of a bat and the head and neck of a stork, except instead of delivering babies it delivered death. Which in a way makes it the exact opposite of a stork.

Quetz's similarly-sized cousin Arambourgiania philadelphiae with a giraffe at left and some sort of hominid at right. Illustration: Mark Witton

But with nowhere near a complete skeleton to work with, scientists are still trying to piece together exactly how Quetz looked and behaved. How exactly could a 16-foot-tall creature even get airborne? Why wouldn’t it just fall out of the sky?

Quetz was part of a family known as the giant azhdarchid pterosaurs, which include the similarly sized Arambourgiania philadelphiae, shown at right. When in flight, their enormity would have prohibited them from vigorous flapping, so instead these were likely highly proficient gliders, according to Mark Witton, a paleontologist, paleoartist, and author of the book Pterosaurs.

He thinks Quetz would have been capable of covering some 10,000 miles nonstop – which is like flying from London to Albuquerque and back, or, if you prefer even bigger numbers, making 58,823.53 round trips from my apartment to nearest corner store – riding rising columns of hot air called thermals and hitting speeds of 80 mph. Quetz may have been able to stay aloft for more than a week, only intermittently flapping its enormous membranous wings, which were supported, believe it or not, by an extremely elongated finger (alas, not that finger).

Yet even given its aerial prowess, Quetz was likely not only highly comfortable on terra firma, but was also a formidable land predator. “Their legs are long, their extremities compact and padded, and their trackways reveal proficient walking abilities,” Witton said in an email interview with WIRED. “We figure that these attributes point to a lifestyle of ‘terrestrial stalking,’ where relatively small animals and nutritious plant matter were procured on the ground, a bit like the way that many storks and ground hornbills live today.”

These prey items, Witton stressed, would have been relatively small to Quetz. With jaws that were over 6 feet long, it could take on fairly large game – the young of big dino species and such.

Others have suggested that Quetz was a high-speed fisher, gliding over the sea and plucking out prey. But the chief problem here, Witton said, “is the long, stiff neck, which is common to azhdarchid species,” limiting *Quetz’*s head to an up and down motion and thus making such skim-feeding difficult. (Conversely, take as a modern example the black skimmer, which is very dexterous and frenetic in this manner of hunting.)

“Quite why azhdarchids have such long necks is still debated,” he added. “It may increase their reach in feeding. It may also be a 'stealth' adaptation, permitting their mouths to reach prey before their feet disturb them.”

Those highly elongated vertebrae hide yet another remarkable feature of Quetz: Like modern birds, it had hollow bones linked to what was likely a very efficient respiratory system. “This means the skeleton is inflated by air sacs like a set of bony balloons, growing in proportion without gaining a lot of additional weight,” said Witton. “This has obvious advantages for a flying animal, permitting the development of a very large and strong skeleton which is also very lightweight for its size.”

A restored Quetz skeleton. Image: Wikimedia

Still, even though Quetz was technically on a quite strict paleo diet, Witton thinks it may have weighed in at as much as 550 pounds, about a dozen times heavier than the heftiest modern flying bird. That’s a whole lot of bulk to get airborne, so how did it do it?

Until fairly recently, scientists had operated under the assumption that Quetz took off like a bird, spreading its wings and bounding into the air with its hind limbs. But that all changed when two biomechanists, Mike Habib and Jim Cunningham, proposed that Quetz shoved off with all four limbs in what’s known as a quad launch.

“Mike and Jim were aware that there’s more than one way for a vertebrate animal to take off,” Witton said. “Some launch using their legs alone (birds), while others take off using all four limbs, with the arms generating most of the vertical thrust during takeoff (several bat species). The latter is actually a lot stronger than a hind-limb launch, as the biggest set of muscles in the body – the flight muscles – are directly employed in generating the necessary thrust to remain airborne.”

For an idea of how this worked, take a look at the video of a bat’s quad launch below. Witton stresses that Quetz would have been more graceful and powerful with its takeoff, on account of it being better adapted to the terrestrial lifestyle than a bat, but the mechanics would largely be the same. And in this way Quetz could have gone airborne in mere seconds to escape predation.

Now, about those feathers. Quetzalcoatlus had more of a fuzzy plumage resembling down, known as pycnofibers – which may or may not have shared an origin with feathers. Either way its purpose was probably to keep Quetz warm, according to Witton. With such a high ratio of surface area to volume, large pterosaurs like Quetz would have lost heat easily without some sort of protection from the elements, a necessity when you’re 1,000 feet in the air using muscles that work best while warm.

But why grow so big? Was it just a grand excuse to accessorize with lovely plumage?

"There are lots of good reasons to be a big animal: reduced transportation costs and predation risks, larger feeding ranges, increased fecundity and so forth," said Witton. "It’s likely that large size developed in Quetzalcoatlus and other giant azhdarchids because of these advantages, and that their lifestyle, anatomy and launch style 'allowed' them to grow especially large. In short, the best answer to 'why did Quetzalcoatlus get so big' is simple: Because it could."

It's unlikely anything would have been brave enough to tell it otherwise.