Plot: Andy travels back 150 million years and all the way to North America, the home of stegosaurus - a five-tonne plant eater that was as long as a double-decker bus! Stegosaurus were covered in armoured plates that they flushed blood into when they were angry to scare away meat-eating dinosaurs like allosaurus. Andy's mission is to get a photograph of the plates of an angry stegosaurus so he can finish Hatty's painting back at the museum - but will he make it back in time, especially since a hungry allosaurus is never far away?