The vast timeline of dinosaur existence, spanning over 165 million years, means that many iconic species never actually lived at the same time. For example, a T-Rex from 66 million years ago would have roamed landscapes containing the fossilized bones of earlier dinosaurs like Stegosaurus, which lived many millions of years prior. This chronological separation placed creatures like Dreadnoughtus and T-Rex in entirely different prehistoric eras, preventing them from ever meeting.