Liopleurodon:
was a type of pliosaur, or short-necked plesiosaur. It had four large paddle-shaped limbs, which made it a powerful swimmer. At almost 25 m long Liopleurodon was the biggest carnivore that ever existed. It had an enormous 3 metre long mouth which contained teeth twice as long as those of Tyrannosaurus. These were arranged in a distinctive rosette at the end of its snout. The remains of Liopleurodon attacks are also preserved in the fossil record. Half-eaten ichthyosaurs and teeth marks in plesiosaur flippers are clear evidence of their voracious appetites.

Recent studies on the skull of Liopleurodon have shown that it could sample the water in stereo through its nostrils. This allowed it to tell where certain smells came from. If it swam along with its mouth open, water would pass straight up into scoop-shaped nostril openings in the roof of it's mouth. It would then pass out through the nasal openings in front of the eyes.