I say that the Dinosaurs predicted the end of the world and launched a nuclear atomic bomb from their satellite to end their days before it happens to them. And they had this one genius Dinosaur to go in the future and tell the Mayans the same thing. So the Mayans didn't wanna be there when Doomsday kicks in so they asked a sorceress to make them disappear from the face of the Earth. And while doing so, they decided not to tell any of the future civilization about Doomsday, because they though they were cruel and heartless human beings that didn't deserve to die.
Wow, what the heck did I just typed...?
That was the best doomsday theory I've ever read...