The biggest dinosaur ever discovered—belonging to a group known as titanosaurs— is thought to have weighed as much as 12 elephants. | National Geographic

Liopleurodon was a powerful marine reptile that lived during the Late Jurassic period, around 160 million years ago. It was a plesiosaur, known for its long, tooth-filled jaws and large size, with estimates suggesting it could grow up to 25 meters (82 feet) long. Liopleurodon had a streamlined body, built for speed and agility in the water, and was an apex predator in its ocean environment. It likely preyed on fish, squid, and smaller marine reptiles, using its sharp teeth to capture and hold it