Prehistoric Wonders

I'm sure this has been touched on before or there's a mod I don't know of, but I would love if Civ had "prehistoric wonders" that would be somewhat of a hybrid between natural and world wonders, in that they can't be built but you get a larger bonus + tourism for stumbling upon them. An example would be something like Gobleki Tepe or other prehistoric sites that precede the established timeline on Civ games. Doesn't even have to be a bunch in the game

Thoughts?