predator are used with alien long before avp game.

Yeah, there were also comics.

If you own the special edition DVD of predator2, and listen to the director's commentary, when that scenes comes up, he talks about there being a lot of discussion over it, but they ended up throwing it in there, they really had no ideas about an avp movie till later on, after the film came out.

I thought it was Stan Winston's idea to throw that in there?

well for starters they only threw that skull in there as a gag, becos the Alien and Predator series were both owned by Fox Network and it actually became a big deal. eg. Comics, books, games, movies and legends.

they were used together in flims much later