150 million years ago, dinosaurs ruled the land, but the oceans were dominated by a mysterious sea monster. Meet the pliosaur, the Tyrannosaurus rex of the seas! Now, a giant pliosaur skull has been found in the cliffs of Dorset. David's been an avid fossil collector since he was a young boy, but he has never come across a find quite like this. To help unravel the skull's mysteries, an international team of scientists and palaeontologists search for clues about how this fearsome beast not only looked but how it behaved.