In 2006, a fossil was dug out of a frozen island high in the Arctic. At 15 metres long and weighing about 45 tonnes, it was a colossal marine reptile, twice as big as most ocean predators. This was Predator X (Pliosaurus funkei), the most powerful marine reptile ever discovered. Its skull alone was nearly twice the size of a Tyrannosaurus rex's, and its bite force unmatched by anything in the Jurassic seas.

Presented by John Hurt from BBC's Earth's Planet Dinosaur programme.