From around 250 million years ago, gigantic fish dinosaurs, the ichthyosaurs, swam through the Triassic oceans: some species exceeded the dimensions of today’s sperm whales with a length of 20 meters and a weight of 80 tons. But there could also have been larger specimens, as indicated by finds from Switzerland, which a team led by Martin Sander from the University of Bonn and Heinz Furrer from the University of Zurich describe in the “Journal of Vertebrate Paleontology”.
Furrer had already recovered the fossils together with students between 1976 and 1990 during geological mapping in the Kössen Formation in Graubünden at an altitude of 2800 meters. After that, however, the pieces slumbered in the university’s collections until they aroused the interest of Sanders, who was then a doctoral student in Zurich. “Therefore, it seemed worthwhile to us to analyze the Swiss finds in more detail.”
The fossils are from three different animals that lived around 205 million years ago. A vertebra survives from one of the ichthyosaurs along with ten rib fragments, the measurements of which indicate that the reptile reached a length of about 20 meters. The vortex find is the largest from Europe to date; its owner rivals in size Shastasaurus sikkanniensis from British Columbia in Canada, which was 21 meters long. A second fish dinosaur was revealed by a series of vertebrae that suggest the animal was about 15 meters long compared to better preserved skeletal finds.
However, the working group was particularly impressed by the tooth that was dug up. »It is huge, even for fish dinosaurs: Its root had a diameter of 60 millimeters – the largest specimen still stuck in a complete skull was 20 millimeters. It came from an ichthyosaur that was almost 18 meters long,” says Sander. So the Swiss ichthyosaur could have grown to be well over 20 meters long, even if Sander is skeptical: »The length of its owner cannot be directly deduced from the tooth diameter. Nevertheless, the find naturally raises questions.«