The Cretaceous Period is one of the real-world periods of time from when dinosaurs lived on the Earth. In the Mario franchise, the Cretaceous Period is represented as a location in every version of Mario's Time Machine, including its Nintendo Entertainment System version.
In Mario Discovery series[]
Mario's Time Machine[]
In PC versions, Mario ends up in the Cretaceous Period if he enters an incorrect date in the Timulator. Mario can only escape by catching some falling eggs from a Pterodactyl while dodging Bullet Bills. After catching enough eggs, Yoshi appears, and Mario hops onto him to somehow return back to the present.
The Cretaceous Period also appears in the good endings for the PC and Super Nintendo Entertainment System versions. If everything is done correctly, Bowser attempts to use the Timulator to escape Mario, but it malfunctions and sends him back to the Cretaceous Period. Bowser is soon squished by a large dinosaur. In PC versions, this is followed by Bowser's crushed form being thrown away like a flying disc.
Mario's Time Machine (Nintendo Entertainment System)[]
Mario's Time Machine (NES) map of the Cretaceous Period
The Cretaceous Period has a larger role, now being an entire level, taking place about eighty million years ago. Bowser time-travels back to here to steal a Dinosaur Egg. After retrieving the Dinosaur Egg, Mario eventually time-travels back to here to return the Dinosaur Egg to its original location. However, Mario has to avoid Koopas and Bodyslam Koopas along the way. There is a cave at the rightmost part of the Cretaceous Period, where Mario drops off the Dinosaur Egg before returning to the present.