Liopleurodon was one of the largest carnivorous reptiles ever. The largest specimen was about 15 meters long. Liopleurodon's nose allowed it to smell underwater. This allowed Liopleurodon to smell its prey from some distance away. Despite needing to breath air, Liopleurodon spent its entire life at sea and was unable to leave the water. Consequently, it would have given birth to its young alive and may have visited shallower water to breed.
With an enormous 3 metre long mouth which contained teeth twice as long as those of Tyrannosaurus, it was a formidable predator. The remains of Liopleurodon attacks are preserved in the fossil record. Half-eaten ichthyosaurs and teeth marks in plesiosaur flippers are clear evidence of their voracious appetites.