Around 76 million years ago, something took a bite out of a young pterosaur.
Pterosaurs were large, flying reptiles that roamed our planet’s skies when dinosaurs ruled the Earth. Some species were giants. But even their large size didn’t keep them off the menu.
Paleontologists have discovered a tooth mark in a neck vertebra of a pterosaur that died in what is now Alberta. In a paper published last week in The Journal of Paleontology, they suggest that the tooth mark was made by a prehistoric relative of the crocodile that either snatched the young pterosaur from the shore or scavenged its dead body. The fossil is now on display at the Royal Tyrrell Museum in Drumheller, Alberta.
Pterosaurs came in all shapes and sizes and were found worldwide during their tenure on the planet, which lasted from 220 million to 65 million years ago. But they had fragile bones that were often destroyed before being preserved in the fossil record. Paleontologists mostly find neck and finger bones for this species, and that makes them “quite mysterious,” said David Hone, a paleontologist at Queen Mary University of London who was not involved in the research.
But scientists actually “have a much better idea of what was eating pterosaurs than what they were eating,” said Caleb Brown, a paleontologist and curator at the Royal Tyrrell Museum who was among the authors of the new study. Paleontologists have so far discovered only around four pterosaur fossils that suggest that predators occasionally dined on these winged reptiles — including a neck bone with crocodile-like teeth marks found in Romania and a partly digested long bone in the belly of a velociraptor uncovered in Mongolia.
This latest fossil — a two-inch neck vertebra — was found by students during a dig in 2023 in the Dinosaur Park Formation in the badlands of Alberta. The area is so rich in remains that “you literally can’t walk without stepping on dinosaur bones,” Dr. Brown said.
He and his team at the museum identified the fossil as belonging to a young Cryodrakon boreas. Full-grown members of this species had wingspans of more than 30 feet. This youngling was still growing and had reached a wingspan of only around six feet when it died.
While examining the fossil, Dr. Brown noticed what looked like a small bite mark. The team examined the puncture hole under a microscope and sent the bone for a CT scan. What they found was consistent with a puncture made by a tooth when the bone was still fresh.
Identifying the biter was the next piece of the puzzle. There were many potential candidates. Even though Cretaceous Alberta was farther north than it is today, it was a lush, tropical area that bordered an inland sea. Wetlands near the open water were home to many large dinosaurs, crocodilians and mammalians.
But dinosaurs seemed like unlikely culprits. Dinosaur species who lived in the area at the time had blade- or D-shaped teeth that didn’t match the circular shape of the hole. Crocodilians, on the other hand, do make circular-shaped punctures. The hole is also the right size for two species of crocs that coexisted with giant pterosaurs. For Dr. Brown, that made a crocodilian predator or scavenger the “most likely candidate” for the bite mark.
Even with a likely suspect, no one knows what the young pterosaur’s last moments were like. Did it die and become a “free lunch” for a hungry crocodilian that happened upon its body, as Dr. Brown speculated? Or was it the victim of an ambush?
Both explanations are possible. Like alligators and crocodiles today, their forebears in the Cretaceous period “probably grabbed whatever the hell they’re able to get their mouth around,” Dr. Hone said. “It’s what crocs do.”
