Illustration of an ichthyosaur. Image: © Daniel Eskridge/Stock.adobe.com
Palaeontologists discovered the thickest ichthyosaur tooth found to date and now hope that there could be more fossils hidden beneath the glaciers.
Fossils of some of the largest creatures to swim Earth’s ancient oceans were found around 2,800 metres above sea level, high in the Swiss Alps.
According to a newly published study, the fossils come from three different ichthyosaurs that lived about 205m years ago.
The first ichthyosaurs existed around 250m years ago during the early Triassic period. Before these marine reptiles went extinct around 200m years ago, they had evolved into gigantic forms that rival today’s sperm whales, reaching estimated lengths of 20 metres and weights of 80 tonnes.
The discovered fossils were first recovered Dr Heinz Furrer of the University of Zurich with students between 1976 and 1990 during geological mapping in the Kössen Formation.
The researchers believe that the rock layers with these fossils would have covered the seafloor 200m years ago. But the folding of the Alps caused the rocks to reach a much higher altitude over time.
Dr Martin Sander with a rib of the larger ichthyosaur skeleton. The estimated length of the animal is 20 meters. Image: Laurent Garbay/University of Bonn
“Maybe there are more rests of the giant sea creatures hidden beneath the glaciers,” lead author of the study Dr Martin Sander said.
Sander noted that these prehistoric creatures have left very few fossil remains, the reason for which remains “a great mystery to this day”.
“It amounts to a major embarrassment for palaeontology that we know so little about these giant ichthyosaurs despite the extraordinary size of their fossils,” Sander added. “We hope to rise to this challenge and find new and better fossils soon.”
The largest ichthyosaur tooth discovered
The findings include rib and vertebrae fossils from two ichthyosaurs, which suggests these two individuals were roughly 20 and 15 metres in size respectively.
The other “particularly exciting” fossil that was discovered was a tooth, which Sander said is “huge by ichthyosaur standards”.
“Its root was 60mm in diameter – the largest specimen still in a complete skull to date was 20mm and came from an ichthyosaur that was nearly 18 meters long,” he added.
The root of the ichthyosaur tooth fossil, with a diameter of 60mm. Image: Rosi Roth/University of Zurich
The size of the tooth raises the possibility that it could come from the longest ichthyosaur discovered to date.
However, the team explained that it is unlikely the reptiles could have grown much larger than 20 metres, as research suggests that extreme gigantism is not compatible with a predatory lifestyle.
“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.
The study was conducted by the Institute of Geosciences and the Institute of Anatomy at the University of Bonn, along with the Paleontological Institute and Museum of the University of Zurich.
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