Car-sized dinosaur-era sea turtle fossils unearthed in Spain

Nov 17 (Reuters) – In the subtropical seas that washed the shores of the archipelago that formed Europe 83 million years ago, was one of the largest turtles ever recorded, a reptile the size of a small car, a Mini Cooper to be precise. . who braved dangerous waters.

Researchers on Thursday described the remains discovered in northeastern Spain of a tortoise called Leviathanochelys aenigmatica that measured about 12 feet (3.7 meters) long, weighed just under two tons and lived during the Cretaceous Period, the final chapter in the age of the dinosaurs. It is the largest known tortoise in Europe.

It eclipsed the largest turtle today: the leatherback turtle, which can reach 2 meters (7 feet) in length and is known for its marathon marine migrations. Leviathanochelys nearly matched the largest tortoise on record: Archelon, which lived about 70 million years ago and reached about 15 feet (4.6 meters) in length.

“Leviathanochelys was as long as a Mini Cooper, while Archelon was the same size as a Toyota Corolla,” said paleontologist and study co-author Albert Sellés of the Institut Català de Paleontologia (ICP), a research center affiliated with the Universitat Autònoma. from Barcelona.

It was good to be the size of a car, considering the dangerous traffic in the ancient Tethys sea that Leviathanochelys swam in. Huge marine reptiles with powerful jaws called mosasaurs were the largest predators, some over 50 feet (15 meters) long. They also stalked various sharks and rays, as well as long-necked, fish-eating marine reptiles called plesiosaurs.

“Attacking an animal the size of Leviathanochelys could possibly only have been done by large predators in a marine context. At that time, the large marine predators in the European area were mainly sharks and mosasaurs,” said Oscar Castillo, a student in a Master’s in Paleontology at the Universitat Autònoma de Barcelona and lead author of the study published in the journal scientific reports.

“During the Cretaceous, there was a tendency for sea turtles to increase their body size. Leviathanochelys and Archelon could represent the apex of this process. It has been hypothesized that the reason for this increase in body size is the predatory pressures, but there could be other factors,” Castillo added.

Other large tortoises from Earth’s past include Protostega and Stupendemys, both reaching about 13 feet (4 meters) in length. Protostega was a Cretaceous sea turtle that lived about 85 million years ago and, like its later cousin Archelon, inhabited the great inland sea that at the time divided North America in two. Stupendemys roamed the lakes and rivers of northern South America about 7-13 million years ago during the Miocene epoch.

Scientists unearthed the remains of Leviathanochelys near the village of Coll de Nargó in Catalonia’s Alt Urgell after a hiker discovered fossils sticking out of the ground in the southern Pyrenees mountains. To date, they have found parts of the back of its carapace or shell and most of the pelvic girdle, but not the skull, tail, or limbs.

Fossils indicated that it possessed a smooth shell similar to that of leatherback turtles, with a shell about 2.35 meters (7.7 ft) long and 2.2 meters (7.2 ft) wide. Leviathanochelys seems built for the open sea, rarely returning to land, for example, to lay eggs.

The presence of a pair of bony protrusions at the front of the pelvis differs from that of any other known sea turtle, indicating that Leviathanochelys represents a newly discovered lineage. It shows that gigantism in sea turtles developed independently in separate Cretaceous lineages in North America and Europe.

Leviathanochelys aenigmatica means “enigmatic leviathan turtle” due to its large size and the curious shape of its pelvis that researchers suspect was related to its respiratory system.

“Some pelagic animals (that live in the open sea) show a modification in their respiratory system to maximize their ability to breathe at great depths,” said Sellés.

Reporting by Will Dunham in Washington, Editing by Rosalba O’Brien

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