"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 Universitat Autònoma de Barcelona.At that time, the large marine predators in the European zone were mainly sharks and mosasaurs," said Oscar Castillo, a student in a master's degree program in paleontology at Universitat Autònoma de Barcelona and lead author of the study published in the journal Scientific Reports.Stupendemys prowled the lakes and rivers of northern South America about 7-13 million years ago during the Miocene Epoch.Scientists unearthed the Leviathanochelys remains near the village of Coll de Nargó in Catalonia's Alt Urgell county after fossils protruding from the ground were spotted by a hiker in the Southern Pyrenees mountains.The presence of a couple of bony bulges on the front side of the pelvis differs from any other known sea turtle, indicating that Leviathanochelys represents a newly discovered lineage."