Fossils of marine reptiles resembling giant dolphins discovered in the Swiss Alps
A team of paleontologists has discovered fossils of three impressive new ichthyosaurs – ancient marine reptiles – in rocks 9,000 feet above sea level.
The ichthyosaurs were found during excavations that took place between 1976 and 1990, but the remains were very fragmentary. Since then, more comparative ichthyosaur research has been produced, and now a team of paleontologists have finally been able to assess Alpine fossils at a higher level of detail.
Among the outstanding finds were ribs, the largest tooth yet attributed to an ichthyosaur (the width of its root is twice that of any other aquatic reptile), and vertebrae larger than a human head. The team’s research is published today in the Journal of Vertebrate Paleontology.
“The new findings show an interesting diversity of very large ichthyosaurs during the late Triassic, just before the mass extinction 201 million years ago,” said Heinz Furrer, paleontologist at the University of Zürich and co-author. of the article, in an email to Gizmodo. “With an almost equivalent discovery in time in British Columbia, they were the largest marine reptiles that ever lived on Earth.”
To remove these fossilized ichthyosaur bones from the mountain, Furrer said he and his team had to haul hundreds of pounds of bones on their backs and in a Jeep loaned by the Swiss military. They slid the vertebrae through a glacier to a mountain hut, and the fossils were eventually brought down the mountain in a cable car usually used for transporting food.
Just over 200 million years ago, the rocks at the top of the Swiss Alps were sediments at the bottom of a lagoon or shallow basin at the edge of a Tethys, part of the ocean surrounding the supercontinent Pangea. This is where ichthyosaurs – aquatic reptiles with bodies resembling whales and dolphins – fed on smaller cephalopods, fish and ichthyosaurs. Most ichthyosaurs were smaller than these behemoths.
The ichthyosaur of British Columbia, Shastasaurus sikkaniensis, was nearly 70 feet long and toothless; it is believed to have actually inhaled its prey, according to at National Geographic. Martin Sander, a paleontologist at the University of Bonn in Germany and lead author of the paper, said “bigger is better” and that “life will go there if it can” in a Press release. Sander noted that sauropod dinosaurs, modern whales, and Triassic ichthyosaurs are the only groups of animals whose masses exceed 20 metric tons.
The ichthyosaur teeth discovered by paleontologists are curved in the same way as sea mammals that feed on boneless cephalopods, hinting at their favorite food. But “it’s hard to tell if the tooth is from a large ichthyosaur with giant teeth or a giant ichthyosaur with medium-sized teeth,” Sander said.
In an email to Gizmodo, Sander noted that ichthyosaur teeth had deep grooves along their roots, a pattern similar to those seen in modern monitor lizards. But the two animals are unrelated, so exactly what the dental grooves were for remains a mystery.
Researchers know that the remains do not belong to any known ichthyosaurs. Based on the measurements of the different specimens – although distorted by the tectonic changes that lifted the fossils from the seafloor to the tops of the mountains – they suspect that the fossils represent three different species, but it is possible that there are fewer. .
But the team did not assign new species names to the fossils, saying they were too fragmentary to warrant such a decision; sometimes, animals identified too hastily as a new species later turn out to belong to an already known species, and their the species must be “embedded” in the existing fossil record.
The discovery of ichthyosaurs in the Alps greatly expands the geographical footprint of swimming reptiles. “The evolution of vertebrates in general is influenced by the realization that giant ichthyosaurs were distributed globally in the Late Triassic,” Sander said.
With such behemoths prowling prehistoric seas around the world, the small inhabitants of the Triassic oceans had much to fear, as even the toothless ichthyosaurs were formidable predators.
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