Further reading:

Rare pterosaur fossil reveals crocodilian bite 76m years ago

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

Let’s learn about a type of pterosaur that lived around 75 million years ago in what is now Canada, and we’ll specifically learn about an individual young pterosaur that had a very bad day, a bad day that’s preserved in the fossil record.

Pterosaurs were flying reptiles that lived alongside dinosaurs, but weren’t actually dinosaurs. Some of them got as big as small airplanes while some were barely the size of chickens. Cryodrakon was one of the biggest ones, with an estimated wingspan of 33 feet, or 10 meters, for an adult animal—maybe even bigger. We don’t know the adults’ size for sure because we only have a few fossils of adult Cryodrakons, and those are incomplete. Mostly we have fossils of young individuals. The older juveniles had a wingspan of around 16 feet, or 5 meters, which is still pretty darn big.

Cryodrakon was the first pterosaur discovered in Canada, with fossils found in Alberta in 1972. Since then more fossils have been discovered in the same province, especially in what’s called the Dinosaur Park Formation.

Like other pterosaurs in the family Azhdarchidae, Cryodrakon had long legs and a very long neck with long jaws. Most scientists think it spent a lot of time on land, hunting small animals. It could fold the longest part of its wings up out of the way in order to walk on all fours.

A flying animal’s wing, whether it’s a pterosaur or a bird or a bat, is a modified arm. Insects are different because they’re invertebrates. In bats, the fingers are elongated with strong skin stretched between them to form a wing. In birds, the fingers are fused into a sort of stump and most of the flying surface is feathers. In pterosaurs, one or two fingers were elongated like a bat’s, but the other fingers were short and blunt. These are the fingers that azhdarchids could walk on when the rest of the fingers, and therefore the wing, was folded up so it wouldn’t get in the way. We know it’s possible for a winged animal to walk this way because vampire bats do it just fine, and they’re able to run around quite fast on the ground.

An adult Cryodrakon walking on all fours would have been about as tall as a modern giraffe because of its long neck. Its neck was strong and its head large, so it could easily grab a little running dinosaur and swallow it whole, maybe giving it a good chomp with its toothless jaws first. While azhdarchids probably couldn’t run, because the hind legs weren’t very strong and the feet were small, it could probably walk pretty quickly. And, of course, it could fly extremely well. Scientists think it launched into the air by pushing off the ground with its wings, not its back legs.

In older episodes we’ve talked about some other species of pterosaur from this same family, especially Quetzalcoatlus, a genus of exceptionally large pterosaurs discovered in North America. The largest individuals may have had a wingspan potentially more than 36 feet, or 11 meters. But in 2002 a remarkably complete pterosaur fossil was discovered in Romania, and while we don’t have the complete wing bones, estimates suggest this new species might even be larger than Quetzalcoatlus. Some estimates put its wingspan at 39 feet across, or 12 meters. It had a shorter neck than other azhdarchids but a massive head. Its neck was about 5 feet long, or 1.5 meters, while its skull was at least that long and possibly as much as 8 feet long, or 2.5 meters.

The Romanian specimen was named Hatzegopteryx but the specimen has been nicknamed Dracula (also the name of my cat). Some scientists initially argued that Dracula was just an especially big Quetzalcoatlus, but while it was probably a close relative, it’s too different to be the same species.

Despite their huge size, pterosaur bones were delicate because the animals had to be light enough to fly. That means they had air pockets or spongy internal structures in their bones, and that means their bones were much less likely to preserve. The most likely reason we have so many more fossils from young pterosaurs than old ones is because many species of pterosaur appear to have nested together. It’s a sad fact of life for wild animals that many young ones don’t survive, so the fossils of young pterosaurs probably come from nesting areas.

And that brings us to our young Cryodrakon who had a terminally bad day. In 2023, researchers found a neck bone of a cryodrakon that had a puncture right through it. The hole in the bone is about 4 mm across and circular, and the scientists who examined it think it’s from a crocodilian tooth. We don’t know if the baby pterosaur was chomped to death by a crocodilian or if it was already dead and the crocodilian was scavenging it.

That’s not even the only Cryodrakon fossil that shows tooth marks. In 1995 the fossils of a young animal were found in a scattered state, with tooth marks on some of the bones. Even better from a scientific standpoint, but definitely not from a cryodrakon standpoint, a little piece of chipped-off tooth was found embedded in one of the bones. Researchers think the tooth comes from a small dromaeosaurid dinosaur found in the same area, Saurornitholestes. It only stood about two feet tall, or 60 cm, so if it was running around biting baby cryodrakons, I hope it was really fast. The mother pterosaur would eat a dinosaur that size like a potato chip.

Thanks for your support, and thanks for listening!