Prehistoric Romania's top predator had wings – but it stalked dinosaurs on the ground

Let's take an imaginary trip to prehistoric Romania, just over 66 million years ago. Back then, it was an island in an ancient European sea. Tyrannosaurus was stomping around over in North America, but there were no big meat-eating dinosaurs here. Instead, the Romanian ecosystem was dominated from the sky by a flying carnivore the size of a small airplane, with a powerful beak and wings ten metres (35 feet) across.

Hatzegopteryx was the ruler of its ecosystem, taking to the ground to hunt for prey like this small dinosaur named Zalmoxes. Image: Mark Witton

This is the pterosaur Hatzegopteryx. Pterosaurs were flying relatives of the dinosaurs, and while the smallest were no bigger than a cat, the biggest – including Hatzegopteryx and its equally massive cousins in North America and Asia – were the largest flying animals in Earth's history.

Palaeontologists have pondered for a long time over how these winged giants lived. Studies have shown they were capable fliers even at their huge size, but despite what you've seen in Jurassic World, pterosaurs weren't well-equipped to grab large prey on the wing. Instead, many of the big ones probably hunted on foot like modern herons or hornbills, stalking around on the ground, using their long necks and beaks to snatch up tasty critters.

The image of a giraffe-sized flying reptile folding up its wings and walking on all fours snapping up prey is pretty epic. But pterosaurs in general were rather lanky, with long necks, thin bones and overall light builds. So even a giant would still be going for relatively small prey (including possibly some baby dinosaurs).

Hatzegopteryx (right) may not have been as tall as some of the largest pterosaurs that ever lived (centre right), but its bulky skull and thicker neck made it a more powerful predator. Modern-day giraffe (and tiny human) for scale. Image based on illustration via markwitton-com.

Hatzegopteryx wasn't quite like other pterosaurs, however: the Romanian titan had thick bones (for a pterosaur) and an unusually big head. In fact, its bones were so bulky that they were mistaken for the bones of a big dinosaur when first unearthed. So, what was life like for this mighty pterosaur?

To find out, palaeontologists Darren Naish and Mark Witton examined one of its most important hunting tools: the neck. Only one upper vertebra of Hatzegopteryx has been discovered, but it's enough to show that this pterosaur had a short, stout neck compared to its relatives. What it lacked in length, however, it made up for in strength. Calculations revealed that its neck bones were exceptionally tough, capable of resisting great force and stress.

"There is no exact modern analogue for this sort of creature, but if you imagine a giant mix of a shoebill stork, a ground hornbill, and the Terminator you might be pretty close," writes Witton in a blog post.

If you're a giant, ground-stalking stork-reptile, a powerful neck and large head mean you can go after bigger prey. Witton explains that Hatzegopteryx was likely capable of "violent and forceful foraging tactics", killing significantly larger animals than the more delicate long-necked species.

"We might even imagine Hatzegopteryx using powerful bites, bludgeoning blows of its head and stabbing motions to tackle prey too large to swallow whole," he adds.

The island Hatzegopteryx called home – Haţeg Island – was home to plenty of other animals, including some unusually small dinosaurs. Evolution can do weird things on islands, and in this case, the largest local dinosaurs were only about the size of a cow. For Hatzegopteryx, this may have been a land of plenty – plenty of prey, that is.

Even more intriguing, all the theropods (meat-eating dinosaurs) on this island were small. "These are the only sediments in the world where you stand a better chance of finding a giant pterosaur than a large theropod," Witton explains.

This means Hatzegopteryx was not only a large and powerful carnivore, but it also appears to have been the apex predator of its ecosystem. T. rex may have been king of its territory in North America, but the bizarre Haţeg Island was ruled by a giraffe-sized, reptilian stork-beast from the sky. I'm not sure which is scarier.

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This research was published in the journal PeerJ.

Top header image: Peter Montgomery, Flickr