Game of Thrones’ dragons are fiction, but could an existing animal breathe fire?

As much as every Game of Thrones fan wants to secretly ride a dragon over mountains and castles and entire kingdoms, they only exist in our imagination. Or do they?

There are many creatures, extant and extinct, that come close to looking like one of Daenerys’ scaly children. You can easily look at a komodo dragon (actually a lizard) or a Gila monster (also a lizard) or an alligator and imagine it with wings, or gaze at a visual recreation of a pterosaur and almost see it breathing fire. In a recent interview, University of Florida grad student and reptile expert Rachel Keefe answered some burning questions about whether biology would allow these mythical creatures to roam the earth — and the skies — for real.

"Unfortunately, no, we do not have evidence of dragons on this planet,” said Keefe, whose upcoming book The Anthropology of Dragons: A Global Perspective explores dragon questions further. “We do have evidence of very cool extinct animals that were kind of similar to dragons, but no fire-breathing six-legged vertebrates, I'm afraid."

With that out of the way, what would the biology of a theoretical dragon be like? Keefe does believe they’d be able to survive a flight beyond the Wall. Amphibians that basically make their own antifreeze do exist. The Siberian newt and wood frog produce proteins to keep them from freezing to death as they hibernate, but Keefe believes hypothetical dragons would have to be warm-blooded because they generate way too much heat to fly and hunt. Whether some ice zombie king would be able to turn one into an ice dragon is an entirely different question.

Would those eggs have even hatched in the same fire in which Daenerys was reborn as the Mother of Dragons? The 2004 fictional documentary The Last Dragon showed a female dragon building a protective structure for her eggs out of rocks and then blasting it with fire. While there are no reptiles that use fire for that purpose, the creators of this docufic were onto something. Reptile eggs do need to be kept at certain temperatures to survive. As for the eggs still hatching after thousands of years, that is highly unlikely.

Speaking of fire, you have to wonder how a flesh-and-blood creature can shoot fire out of its mouth without getting third-degree burns. This is all fantasy. No actual animals are resistant to flame, though some can stand temperatures that would kill a human, but Keefe believes that a dragon’s mouth would have to produce gobs of flame-retardant mucus to keep it from immolating itself.

Now about the size of those dragons. Rhaegal, Drogon, and Viserion are each supposed to be the size of a 747. The largest animal ever, the blue whale, only stays alive because water supports its weight. An airplane-sized dragon’s bones would break if it tried to stand on is own legs. Even if the bone was infinitely stronger, the creature would be far too heavy to take to the air. The largest flyer was the Quetzalcoatlus pterosaur, which had a 35-foot wingspan but also weighed only around a fifth of a ton. The are also flying snakes and lizards out there, such as Draco volans, which literally means “dragon that flies”.

By they way, you have to think about the consequences of keeping more than one ginormous endothermic reptile with a metabolism so high it constantly needs to eat. That’s right. They don’t make litter boxes for that sort of thing.

So maybe dragon riding is out of the question, but at least you won’t risk ending up as a charred snack on the go.