Fossilized traces of hunting provide excellent evidence of the relationships between predators and prey. Scratches, bite marks, and other damage can, firstly, reflect the dynamics of predation: how often the prey perished not by itself, and secondly, help reconstruct food chains: who hunted whom. Recently, Naked Science reported on such a somewhat unfortunate hunting incident. Experts first encountered mollusk shells that had been drilled from the inside by predatory snails when their prey was already dead, and the shell was empty.
Characteristic markings on the bones of animals that became someone’s meal are frequently found. However, it is not always possible to determine who left the bite marks. Sometimes, a predator's tooth breaks off, leaving a piece embedded in the bone. This was encountered 30 years ago in Canada, where an incomplete pterosaur skeleton was discovered, in which a theropod dinosaur left a fragment of its tooth. The fragment belonged to Saurornitholestes langstoni, which may not have hunted the pterosaur but instead fed on its already deceased body.
A new discovery from Canada—specifically from the Dinosaur Park Formation—revealed another ancient episode of predation. In 2023, during excavations, paleontologists found a cervical vertebra of a pterosaur with a hole that apparently resulted from an attack by a carnivore. The article describing the found bone, along with hypotheses about its owner and the predator that tried it on for size, was published in the journal Journal of Paleontology.
The struggle (if it occurred) took place nearly 76 million years ago—the fossil layer in that region dates to the Campanian stage of the Cretaceous period (83.6 ±0.2 to 72.2 ±0.2 million years ago). The vertebra specimen, nearly six centimeters long, belonged to an azhdarchid pterosaur (Azhdarchidae), a family that includes the largest flying reptiles on the planet: Hatzegopteryx and Quetzalcoatlus, whose wingspan exceeded 10 meters.
Based on the preserved features of the vertebra, paleontologists identified it as belonging to Cryodrakon boreas—the name translates from Latin as "ice dragon of the northern winds." This species was discovered in Canada in 2019, at which time its size was estimated at 250 kilograms in weight and 10 meters in wingspan. Both then and now, the remains of the flying reptile are relatively small, which suggests that the bitten pterosaur was young and had a wingspan of about two meters.
A round hole nearly four millimeters deep gaped near the edge of the preserved vertebra. The authors began to speculate about which predator could have left such a mark. Only extinct reptiles like Champsosaurus (Champsosaurus), crocodiles, or some mammals fit the bill—other carnivores had teeth of different shapes, thus could not create a round hole.
Champsosaurus teeth turned out to be thinner than the mark, and they preferred to eat fish. Among mammals, marsupials like Eodelphis and Didelphodon were considered, but they only had similar shapes in their canines. Although the bite force and their presumed diet made it quite possible for these animals to hunt a young pterosaur, the researchers believed that the most likely predator was a crocodile. Their teeth were suitable (and there was a great diversity of crocodile species in that region), as well as known instances of their attacks on flying prey.
Unfortunately, paleontologists lack sufficient data to reconstruct the struggle of these ancient animals, but there were no signs of healing on the vertebra, suggesting that the hunt (if it occurred) did take place. The "ice dragon" might have been flying over water in search of prey, but he was caught and seized by the neck. Alternatively, it could have been that the crocodile was simply feasting on an already dead young pterosaur.