In 1965, archaeologists working in the Smoky Hill Chalk region of Kansas discovered the fossil of a large Pteranodon, a pterosaur (or flying reptile) that soared through the air during the Late Cretaceous Period. Pteranodon remains are quite common in the fossil record; some 1,100 specimens have been found, more than any other prehistoric winged reptile. But there was something unusual about this particular specimen: it had a shark tooth lodged against its neck vertebrae.
Now, as Stephanie Pappas reports for Live Science, researchers have taken a closer look at the fossil to try and determine how the tooth came to be embedded in the Pteranodon remains. And the results of their inquiry, published in Peer J, suggest that this great predator of the sky may have fallen victim to a great predator of the sea.
The area where the Pteranodon fossil was discovered is a marine deposit created by the Western Interior Seaway, a huge waterway that once stretched from the Gulf of Mexico to Canada. After it was excavated, the Pteranodon was stored at the Los Angeles County Natural History Museum and eventually put on permanent display, shark tooth and all. It was a big creature, with a wingspan stretching more than 16 feet, and it weighed around 100 pounds. Like other members of its species, it had a crested skull and fed by catching fish in its pelican-like jaws.
The shark tooth, according to the study authors, belonged to the species Cretoxyrhina mantelli, a large and fearsome predator that stalked the Late Cretaceous seas. These sharks could grow as long as 23 feet, but the owner of the lost tooth was only around eight feet in length, based on the size of the tooth in question.
When trying to figure out why the remains of two distinct animals were intertwined in the fossil record, the researchers had to consider the possibility that they were pulled together by the sea's currents. But Michael Habib, study co-author and a paleontologist at the University of Southern California, tells Pappas that sediment in the area suggests the waters were relatively calm millions of years ago. Additionally, the study authors write, “the spatial relationship between the tooth and the vertebra is complex and intimate, and unlike that expected to have occurred by chance association.” Other ancient shark species have also been known to feast on flying pteroaurs; earlier this year, a series of bite marks from the prehistoric Squalicorax shark were found on the wing bone of a Pteranodon.
The researchers thus suspected that the Cretoxyrhina mantelli shark had taken a hefty bite out of the pteranodon, losing its tooth in the process. It is possible, they study authors say, that the shark was simply scavenging on a pteranodon carcass. But it is also possible that the pteranodon was actively hunted.
Today’s sharks are known to dramatically breach the water while pursuing prey, but Habib tells Atlas Obscura’s Matthew Taub that the ancient Cretoxyrhina mantelli probably didn’t have to leap out of the sea to catch the pteranodon mid-flight. Pteranodons are thought to have hunted by diving after fish or scooping them up from an alighted position on the water. The winged reptile’s feeding habits, in other words, brought it within range of hungry sharks lurking below the surface.
According to the study authors, an unsuspecting pteranodon would have been no match for even a mid-sized Cretoxyrhina mantelli. “[W]e have little doubt that such predators could subdue these pterosaurs if they caught them,” they write.
Though it is impossible for the researchers to come up with a definitive story of how the pteranodon met its end, the implications of their hypothesis are important to the study of the species. It is rare to find signs of predation on Pteranodon skeletons; only seven of the more than 1,000 known specimens show evidence of predator-prey interaction. The new study also suggests that there may be parallels between the hunting behaviors of today’s sharks, which are known to prey on sea birds, and those that swam through ancient waters.
“Understanding the ecology of these animals is important to understanding life on Earth through time,” Habib says. “We now know sharks were hunting flying animals as long ago as 80 million years.”