Richard Cooper unearths the sea monster of all fossils.

At the bottom of a cliff on the Isle of Portland Richard Cooper and his father have found the fossilised skeleton of a Plesiosaur. At the time of this film, they had gathered over one hundred pieces from the limestone rocks on the beach. The fossil is a sea lizard or sea monster of the Order Enaliasaurian which includes the Jurassic ichthyosaurs. Plesiosaurs first appeared in the latest Triassic Period about two hundred and three million years ago.

Plesiosaurs became widespread during the Jurassic Period and present in the world's oceans. Known for a distinctive long neck, they may have evolved to be like a Pliosaur with a short neck. In 1841 paleontologist Sir Richard Owen established Pliosaurs as a new genus in biological or paleontological classification. Plesiosaurs may have lived in shallows along the coast and in estuaries with several fossil finds found whole on and around the Isle of Portland. Fossil discoveries have also been made in the privately-owned Portland Stone Quarries including dinosaur footprints. The Isle of Portland is a Site of Specific Scientific Interest or SSSI and part of the UNESCO World Heritage Jurassic Coast.