Long-extinct “fish lizards” first appeared in the ocean about 250 million years ago, and their fossils were found high in the Swiss Alps.
According to a study published Thursday in the Journal of Vertebrate Paleontology, the fossil discovery of the marine reptile carnivores, known as ichthyosaurs, make them some the largest creatures to ever live on Earth – even bigger than sperm whales and on par with dinosaurs – given that they weighed about 80 tons and spanned 65 feet.
“Bigger is always better,” study co-author and paleontologist P. Martin Sander said in a statement. “There are distinct selective advantages to large body size. Life will go there if it can. There were only three animal groups that had masses greater than 10-20 metric tonnes: long-necked dinosaurs (sauropods); whales; and the giant ichthyosaurs of the Triassic.”
The animal took the shape of a dolphin with an elongated body and small head. Research suggests it emerged after the Permian mass extinction wiped out more than 95% of marine species. Yet by 200 million years ago, the giant ichthyosaurs became extinct, and only smaller, dolphin-like animals lived until 90 million years ago.
Researchers explained how an ichthyosaurs fossil was discovered at an altitude of 9,186 feet, noting that 200 million years ago the rock layers were part of a lagoon.
“We think that the big ichthyosaurs followed schools of fish into the lagoon,” study co-author and paleontologist Heinz Furrer said in a statement. “The fossils may also derive from strays that died there.”
Unearthed in the Swiss Alps between 1976 and 1990, the fossils were from three different types of ichthyosaurs, the most meaningful of which was the largest tooth of an ichthyosaur ever found. That changes the narrative for what scientists had believed, because fossils of ichthyosaurs discovered earlier were mostly toothless and caught prey via suction. It’s unusual that they would be both a predator and large in size, researchers said.
“It is hard to say if the tooth is from a large ichthyosaur with giant teeth or from a giant ichthyosaur with average-sized teeth,” Sander said in a statement.
The discovery is somewhat of an anomaly. ichthyosaur fossils have been concentrated mostly in North America.