Iguanodon (left) fighting Megalosaurus (right), 19th-century artwork. This reconstruction shows the dinosaurs co-existing when they actually date from two different time periods, the Early Cretaceous (146-100 million years ago) and Middle Jurassic (176-161 million years ago) respectively. It was thought that Megalosaurus was a quadruped, but it was later found to be bipedal. Similarly, Iguanodon's thumb spike is incorrectly shown as a nose spike. Artwork from the 1865 English edition of 'The World before the Deluge', first published in 1863 by Louis Figuier, with illustrations by Edouard Riou.