The Jurassic ocean was a pretty scary place. Toothy marine lizards like ichthyosaurs, mosasaurs and plesiosaurs patrolled the world’s seas along with early sharks. New research adds another hungry creature to the mix. Hannah Osborne at Newsweek reports paleontologists in Germany have unearthed the fossils of a 150-million-year-old piranha-like fish along with with some of its victims.
According to the study published in the journal Current Biology, researchers discovered the fossilized fish, called Piranhamesodon pinnatomus in the limestone deposits of southern Germany. They used CT scans and microscopic examination to get a good look at the interior of the fossils mouth and examine its bone structure. While the fish—around 3 inches long—is tiny, its teeth are not. Knife like, triangular serrated choppers jut out of its top and bottom jaws. Based on the morphology, the researchers estimate it had more than enough power to rip flesh from other fish.
The finding is surprising since the fish comes from a group that is not know for eating one another. Typically, other related species specialized in cracking open organisms with hard shells.
“We were stunned that this fish had piranha-like teeth,” lead author Martina Kölbl-Ebert of Jura-Museum Eichstätt says in a press release. “It comes from a group of fishes (the pycnodontids) that are famous for their crushing teeth. It is like finding a sheep with a snarl like a wolf.”
But what was even more remarkable is that it was from the Jurassic period. Fish as we know them, bony fishes, just did not bite flesh of other fishes at that time. While sharks have been able to bite out chunks of flesh throughout history, bony fishes have either fed on invertebrates or largely swallowed their prey whole. Biting chunks of flesh or fins was something that came much later.”
P. pinnatomus, however, probably wasn’t a killer. The researchers believe that the fish attacked the fins of other fish, similar to modern day piranhas. Fish fins regrow, meaning that by targeting flippers instead of killing its prey P. pinnatomus practiced sustainable carnivorism. There’s evidence for this technique. Fossils of other fish found nearby show bite marks and missing chunks of fin.
The fish also probably swam around its prey undetected. “Judging from the body shape and fin morphology, our fish was slow swimming but highly maneuverable,” Kölbl-Ebert tells George Dvorsky at Gizmodo. “It lived in the sponge and coral reefs, where it would have looked quite inconspicuous, resembling any other contemporary coral fish. Since all other fish of this group ate hard-shelled organisms such as shells or sea urchins, it would have been able to lurk among this crowd and thus attack its unwary prey quite effectively.”
Despite its taste for fish fins, P. pinnatomus is not related to modern day piranhas. Instead, it’s penchant for flesh is an example of convergent evolution, in which different species develop the same trait at different times and through different pathways. While the ancient fish was a salt-water creature, modern piranhas are freshwater fish. The ancestors of modern piranhas didn’t evolve until about 25 million years ago—long after dinosaurs went extinct—and today’s piranha species, including a few vegetarian fish, have been around only about 1.8 million years.