These “fish lizards” first appeared in the ocean about 250 million years ago, resembling dolphins with elongated bodies and small heads. They appeared after the mass extinction of Permia exterminated more than 95% of marine species. But 200 million years ago, giant fish lizards were extinct and only the smallest, dolphin-like ones lived until 90 million years ago. A study detailing the discovery was published Thursday in the Journal of Vertebrate Paleontology. So how did the remains of huge sea creatures, including a bowling alley, reach an altitude of 9,186 feet (2,800 meters)? About 200 million years ago, these layers of rock were the bottom of a large lagoon. “We believe the large fish lizards followed herds of fish into the lagoon. The fossils may also have come from stray animals that died there,” said study co-author Heinz Furrer, a retired curator at the University Institute of Paleontology and Museum. But the Alpine fold, which began 95 million years ago, when the African tectonic plate began to push the European tectonic plate, formed piles of rock layers about 30 to 40 million years ago. The fossils were “tectonically deformed”, crushed by the movements of the tectonic plates that pushed them into a rock formation on top of a mountain. “You have to be a mountain goat to access the beds,” said study co-author P. Martin Sander, a professor of vertebrate paleontology at the University of Bonn in Germany, in a statement. “They have the annoying property of not appearing below about 8,000 feet (2,438.4 meters), well above the line of trees.” Although these creatures once ruled the seas, fossils are rare, which has created a great mystery for paleontologists. But the remains of these fish lizards have shed new light on these enigmatic, extinct creatures.
A huge tooth
The fossils belonged to three different fish lizards. One was about 65 feet (20 meters) long while the other 49 feet (15 meters). But the most fascinating find associated with these fossils is the largest fish lizard tooth ever found. “This is huge by the standards of the fish lizard: Its root was 60 millimeters in diameter – the largest specimen still in full skull to date was 20 millimeters and it came from a fish lizard almost 18 meters long,” Sander said. Scientists know that the smaller fish lizards had teeth, but most of the giants had no teeth, and were supposed to feed on cephalopods, such as squid, by suction. Giant toothed fish lizards were probably similar to sperm whales and killer whales today, using their teeth to capture prey such as giant squid. But the tooth presents a challenge because it was cut in the crown. While researchers know that it was a ichthyosaur tooth due to unique features, such as the dentin reflection at the root of the tooth, they can not be sure that the size of the tooth reflects the size of the animal. “It’s hard to tell if the tooth is from a big fish with giant teeth or from a giant fish with medium teeth,” Sander said. This is because, according to researchers, being a giant and being a predator (with teeth) do not align – so the blue whale, which weighs 150 tons and can reach 98 feet (30 meters) in length, does not has any teeth. Instead, it filters out tiny creatures from the water. Sperm whales, meanwhile, weighing 50 tons and reaching 65 feet (20 meters) in length, are hunters. “Therefore, marine predators can not grow much larger than a sperm whale,” Sander said.
Giants in the mountains
The fossils were first discovered during the geological mapping of the Alps between 1976 and 1990. Furrer was a member of the original team that pulled the fossils from the rocks, known as the Kössen Formation, and remembers holding the fossils in his hands as a doctoral student at the University of Zurich. In time, the fossils were largely forgotten. “Recently, however, more remains of giant fish lizards have appeared,” Furrer said. “Thus, we found it useful to re-analyze the Swiss findings in more detail.” Fish lizard fossils have been found all over the world, but the remains of giant species have been collected in North America. The finding of these specimens in modern Switzerland expands their range. Previous data have shown that some of them could reach the size of blue whales, the largest animal in the world. “In Nevada, we see the beginnings of the real giants and the end in the Alps,” Sander said. “Only the medium to large-sized dolphin – and orca-like forms survived in the Jurassic (Period)”, between 145 and 201 million years ago. Sander wonders if there are more “giant sea creatures hidden beneath glaciers.” But these fossils help fill a gap in knowledge about giant sea lizards. “It’s a great embarrassment to paleontology that we know so little about these giant fish lizards despite the sheer size of their fossils,” Sander said. “We hope to meet this challenge and find new and better fossils soon.”
