(CNN) — The fossils of gigantic extinct marine reptiles were found in an unusual place: high up in the Swiss Alps.
The fossils belong to three ichthyosaurs, and they may have been some of the largest animals to ever live on Earth, according to a new study. The ancient creatures could reach 80 tons and 20 meters in length, rivaling modern sperm whales.
These “fish lizards” first appeared in the ocean about 250 million years ago, looking similar to dolphins, with elongated bodies and small heads. They emerged after the Permian mass extinction wiped out more than 95% of marine species. But 200 million years ago, the giant ichthyosaurs died out and only the smaller, dolphin-like ones survived until 90 million years ago.
A study detailing the discovery will be published this Thursday in the academic journal Journal of Vertebrate Paleontology.
So how did the remains of huge sea creatures, including one longer than a bowling pin, end up at a height of 2,800 meters?
About 200 million years ago, these rock layers were the floor of a wide lagoon.
“We believe that the large ichthyosaurs followed the schools of fish in the lagoon. The fossils may also have come from stray animals that died there,” Heinz Furrer, co-author of the study and retired curator at the University’s Paleontological Institute and Museum, said in a statement. from Zürich.
But the folding of the Alps, which began 95 million years ago when the African tectonic plate began to push against the European tectonic plate, created lots of rock layers about 30 to 40 million years ago. The fossils were “tectonically deformed,” crushed by tectonic plate movements that pushed them into a rock formation on top of a mountain.
“You have to be a kind of mountain goat to access the corresponding beds,” said the study’s lead author, P. Martin Sander, professor of Vertebrate Paleontology at the University of Bonn, Germany, in a statement. “They have the problematic property of not appearing below about 2,438.4 meters, well above the vegetation limit.”
Although these creatures once dominated the seas, fossils are scarce, generating a great mystery for paleontologists. But the remains of these ichthyosaurs shed new light on these enigmatic extinct creatures.
a huge tooth
The fossils belonged to three different ichthyosaurs. One of them was about 20 meters long, while the others were 15 meters long. But the most exciting find associated with these fossils is the largest ichthyosaur tooth ever found.
“It’s huge by ichthyosaur standards: its root was 60 millimeters in diameter, the largest specimen preserved in a complete skull to date was 20 millimeters, and it came from an ichthyosaur that was almost 18 meters tall,” Sander said.
Scientists know that the smallest ichthyosaurs had teeth, but most of the giants did not and it was assumed that they fed on cephalopods, such as squid, by sucking.
Giant toothed ichthyosaurs were probably similar to today’s sperm whales and killer whales, which used their teeth to capture prey such as giant squid.
But the tooth presents a challenge because it was broken at the crown. Although the researchers know that this is an ichthyosaur tooth because of its unique features, such as the folding of the dentin at the root of the tooth, they cannot be sure that the size of the tooth reflects the size of the animal.
This is the thickest ichthyosaur tooth found so far.
“It’s hard to tell if the tooth is from a large ichthyosaur with giant teeth or a giant ichthyosaur with medium-sized teeth,” Sander said.
This is because, according to the researchers, being a giant and being a predator (with teeth) don’t line up, so the blue whale, which weighs 150 tons and can reach 30 meters in length, doesn’t have any teeth. Instead, it filters small creatures from the water.
Meanwhile, the sperm whales, which weigh 50 tons and reach 20 meters in length, are hunters.
“So marine predators probably can’t be much larger than a sperm whale,” Sander said.
Giants in the mountains
The fossils were first discovered during a geological mapping of the Alps between 1976 and 1990. Furrer was part of the original team that recovered the fossils from the rocks, known as the Kössen Formation, and remembers holding the fossils in his hand when he was PhD student at the University of Zurich.
Study co-author Heinz Furrer holds up the largest ichthyosaur vertebra.
Over time, the fossils fell into oblivion.
“However, more giant ichthyosaur remains have turned up recently,” Furrer said. “So we thought it was worth revisiting the Swiss findings in more detail as well.”
Fossils of ichthyosaurs have been found all over the world, but the remains of giant species have been concentrated in North America. The finding of these specimens in present-day Switzerland broadens its scope.
Previous evidence suggests that some of them could reach the size of blue whales, the world’s largest animal.
“In Nevada, we see the beginnings of true giants, and in the Alps the end,” Sander said. “Only dolphins of medium-large size and with forms similar to killer whales survived until the [Periodo] Jurassic”, between 145 and 201 million years ago.
Sander wonders if there are more “giant sea creatures hiding under the glaciers.” But these fossils help fill a knowledge gap about giant sea lizards.
“It is a great embarrassment to paleontology that we know so little about these giant ichthyosaurs despite the extraordinary size of their fossils,” Sander said. “We hope to rise to this challenge and find new and better fossils soon.”