What is a swimming prehistoric dinosaurs?

Swimming prehistoric dinosaurs, often referred to as marine reptiles, include groups like ichthyosaurs, plesiOSaurs, and mosasaurs. While not true dinosaurs, these creatures lived during the Mesozoic Era and were well-adapted to life in the water, featuring streamlined bodies, powerful flippers, and in some cases, long necks. They occupied various ecological niches in ancient oceans, preying on fish and other marine life. Their adaptations allowed them to thrive in aquatic environments alongside true dinosaurs on land.