Prehistoric Creatures

Prehistoric Creatures are/were creatures that existed before the establishment of modern creatures and overall civilisation that sadly no long walk among us (or as commen logic dictates) cause of natrol selection, being too dominated by a much more evolved force, climent change, astromonical dishastors (the asteriod that killed the dinosaurs as a infamous exsample), the change of the world itself or from evolving into a new creature that ends up doing too well then the original. Contuaray to commen belief, it doesn't mean these relics of history are truthfully gone, as modern successers still thrive, and in the United Universes, some worlds would still hold these such creatures.