The oldest fossil record of a marine reptile that dominated the oceans in the age of the dinosaurs was found in the Arctic: the ichthyosaur, an animal with a shape similar to that of modern whales that went extinct shortly before it became extinct. Dinosaurs that lived in the seas around the planet for 160 million years. This discovery is described in the scientific journal Current Biology.
In 2014, Norwegian and Swedish scientists discovered 11 articulated tail vertebrae of an ichthyosaur preserved in rocks on the island of Spitsbergen, which is rich in rock formed from sediments that lay on the sea floor some 250 million years ago. This challenged the main theory about the evolution of ichthyosaurs, because those rocks were so old.
Until now, it was believed that these marine reptiles were a product of the evolution of terrestrial reptiles and that they evolved in the sea after the Permian-Triassic extinction era, which wiped out the vast majority of animal species by extinction, about 252 million years ago. With no large predators on the coast, land reptiles became amphibians.
The most widely accepted thesis is that ichthyosaurs are an evolution of amphibious reptiles, which at some point stopped laying eggs—becoming viviparous, with the young developing directly into the mother’s organism—gaining flippers and ending up with a body more like that. Of today’s whales swim better.
These changes are too complex to occur in just two million years—the time period between the Permian-Triassic extinction event and the estimated age of the rocks found in the Arctic. Therefore, the paleontologists who discovered the new fossils believe that ichthyosaurs appeared much earlier than previously thought.
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