Shrouded in mystery ichthyosaurs become even more mysterious after their wonderful discovery in a wonderful place

Shrouded in mystery ichthyosaurs become even more mysterious after their wonderful discovery in a wonderful place

In the Alps, at an altitude of 2,800 meters, researchers found remarkably large remains of three different species of ichthyosaurs. And this raises an interesting question: Have these floating reptiles become much larger than we thought?

The discoveries are presented in the journal Journal of Vertebrate Paleontology† The study considers the tooth of an ichthyosaur – a now-extinct floating reptile – that was found high in the Swiss Alps somewhere between 1976 and 1990 (see box). Analysis of the teeth now shows that they are truly gigantic – compared to the teeth of other large ichthyosaurs. For example, the thickness of the tooth root is three times that of the largest root previously recovered from the ichthyosaur.

The central tooth of this study was found in the Swiss Alps, at an altitude of about 2,800 metres. This may seem like an inconsequential place to look for the remains of swimming reptiles. But it’s good to keep in mind that ichthyosaurs arose about 250 million years ago. The specimen from which the tooth was recovered is believed to have lived about 205 million years ago. The Alps did not exist yet. Instead, the rocks we now find in the Alps, where the tooth was found, formed a shallow sea floor. This sea floor ended up on top of a mountain range when tectonic plates collided and pushed the sea floor up. “There may have been more remnants of giant marine organisms lurking under the glaciers,” researcher Martin Sander said.

For now, though, we’ll have to make do with the teeth — and some other interesting ichthyosaur remains discovered in the last century that were forgotten until researchers recently pulled them out of the dust and studied them more closely. Sander says the restored tooth particularly appeals to the imagination. The diameter of the carrot is 60 mm. The largest root found in a complete skull until recently was 20 mm wide and came from an ichthyosaur approximately 18 meters long.” If the tooth that is now central to the new study can offer any indication of how large an ichthyosaur belonged, it must That that specimen was much larger.Probably larger than the largest ichthyosaur known to us until recently, discovered Canada 21 meters long Shastasaurus sikkanniensisResearchers say.

At the same time, they have to be careful; It’s actually impossible to estimate the size of an ichthyosaur based on age alone. “It is difficult to determine whether the tooth came from a large, massive-toothed ichthyosaur or from a giant, medium-toothed ichthyosaur,” Sander admits.

Not much bigger than that
It is not immediately clear that the ichthyosaur to which this tooth belonged was much larger than the ichthyosaur S. sikkanniensis† This has to do with the fact that it contains teeth. Scientists assume that reaching maximum size and a predatory lifestyle (which requires teething) do not mix. That is why the largest animal of our time – the blue whale – is toothless. Thirty meters in size, the blue whale makes the sperm whale (the largest modern animal with teeth) distinctly pale. This can be traced back to their diet; While the blue whale swallows water completely passively and preys on delicious small animals, the sperm whale is a true hunter. However, the latter also means that it burns a lot of calories searching and searching for food. “So marine predators probably can’t grow much larger than a sperm whale,” Sander says. Thus, researchers also believe that it is certainly possible that the huge tooth now discovered in the Swiss Alps did not belong to a large, record-breaking ichthyosaur, but to a medium, giant-toothed ichthyosaur.

Ichthyosaur tooth, the root of which has been preserved, but the crown is only partially preserved. Photo: © Rosi Roth / University of Zurich.

More leftovers
However, the research warns that this record breaks the record S. sikkanniensis It had European relatives that were close to the Canadian giant in size. This also supports the second finding that the researchers presented in their study. It is a vertebra with ten fragments of ribs, which in turn belong to a different ichthyosaur than the one that left a significantly large tooth. Comparison of these vertebrae and rib parts with similar remains of other, better preserved ichthyosaurs, suggests that they likely reached about 20 meters in length when alive.

If the estimates – which are certainly somewhat complicated by the fact that layers of rock were broken down by tectonic activity – are correct, then the large-sized ichthyosaurs found in the Alps may be the last of their kind. “Only ichthyosaurs the size of medium to large dolphins and orca-like shapes survived into the Jurassic period,” Sander said.

Those dolphin-like ichthyosaurs managed to survive for millions of years, but eventually became extinct about 90 million years ago. Today, both those last dolphin-like forms and their giant ancestors are still shrouded in mystery. Fossil remains of large ichthyosaurs – which can grow to be at least 20 meters long and weigh an estimated 80 tons – are rarely found. “Why that remains a mystery to this day,” Sander says. It makes discoveries in the Swiss Alps of great value; After the remains of previously large ichthyosaurs were found mainly in North America, and later appeared in the Himalayas and New Caledonia, there is now also evidence that the giants were allowed to call the European continent today their homeland. At the same time, many questions remain unanswered even after these discoveries. For example, it is still a mystery how large ichthyosaurs could have become.

It’s almost frustrating. Because although bones have been found in Great Britain and New Zealand, for example, that suggest that some ichthyosaurs could grow to be the size of blue whales, it’s hard to prove. It seemed for a moment that they were holding the key in their hands in 1878, when a 45-centimeter-wide vertebra was described to an ichthyosaur. But the bone appears to have been lost at sea on the way to London. The discovery of the tooth—which in itself also gently suggests that ichthyosaurs grew much larger than we thought possible—is consistent with this trend; Conclusive evidence for the existence of ichthyosaurs much larger than S. sikkanniensis It doesn’t even happen after climbing in the Swiss Alps. “All of this adds to the enormous embarrassment within paleontology that despite the extraordinary size of their fossils, we know very little about these giant ichthyosaurs. We hope to change that and soon find new and better fossils.”

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