Liopleurodon was a large carnivorous pliosaur - a short-necked plesiosaur - that hunted the seas of the Jurassic period in what is now Europe. Two species are known, L. ferox and L. pachydeirus. Its length is not well known, although the larger of the two is known to be L. ferox. Its length has been estimated at 5-7 metres, with one specimen approaching 10 metres. The animal was probably an ambush predator.