Tooth of ‘sea dragon’ the size of a whale found in Swiss Alps
Fossils of three ichthyosaurs have been found in the Swiss Alps, raising hopes that more traces of the ocean-dwelling monsters will be discovered.
The reptiles’ remains, including the largest tooth for the species ever found, were uncovered at an altitude of 2,800 metres.
During their lifetimes, the animals, known as “sea dragons”, swam around the supercontinent Pangaea, but plate tectonics that caused the Alps to “fold” meant the fossils kept rising.
“Maybe there are more of the giant sea creatures hidden beneath the glaciers,” said Prof Martin Sander, a palaeontologist at the University of Bonn in Germany.
The size of a sperm whale at 20 metres and weighing 80 tonnes, ichthyosaurs patrolled primordial oceans more than 200 million years ago.
With long bodies but tiny heads, they were among the largest animals to have lived.
They appeared 250 million years ago, and a smaller, dolphin-like subtype survived until 90 million years ago. But the ichthyosaurs died out 200 million years ago.
Unlike dinosaurs, ichthyosaurs barely left a trace, and “why that is remains a great mystery to this day”, said Prof Sander, lead author of the paper in the Journal of Vertebrate Paleontology.
The specimens were unearthed between 1976 and 1990, but were only recently analysed in detail.
Ichthyosaurs were formerly thought to have inhabited only the deep ocean, but the rocks from which the new fossils derive are believed to have been at the bottom of a shallow coastal area. It could be that they had followed shoals of fish there.
There are two sets of remains. One consists of 10 rib fragments and a vertebra, suggesting an animal about 20 metres long.
This is about as big as one uncovered in Canada, the largest ichthyosaur to have been found.
The second animal measured 15 metres, according to an estimate taken from the set of seven vertebrae. “From our point of view, however, the tooth is particularly exciting because this is huge by ichthyosaur standards,” Prof Sander said.
“Its root was 60 millimetres in diameter. The largest specimen still in a complete skull to date was 20 millimetres and came from an ichthyosaur that was nearly 18 metres long.”
While this could indicate a beast of epic proportions, it is more likely to have come from an ichthyosaur with particularly large gnashers.
Current research holds that extreme gigantism is incompatible with a predatory lifestyle requiring teeth.
That is why the largest animal known to have lived, the blue whale, has none.