A fictional story or theory, of prehistoric dragons described as the story of “the natural history of the most extraordinary creature that never existed but could have existed. It posits the theoretical evolution of dragons from the Cretaceous period up to the 15th century, and theories about what dragon life and behaviour might have been like if they had existed and evolved. It uses the premise that the ubiquity of dragons in world mythology suggests that dragons could have existed. They are a species that are scientifically feasible and could have evolved, although they did not.