Everyone's favourite icon of prehistory, the Stegosaurus lived in the late Jurassic period, between 150 and 155 million years ago. Roaming semi-arid flat floodplains, Stegosaurus is expected to have mainly eaten small trees and ferns of the savannah - however its diet is poorly understood, as it would have had to have eaten a lot to sustain its size - up to 9 metres in length!