Mike D Interesting thought...Thing is, if you watch the Preds in AVP, when you first see them, Chopper doesn't have any skulls on his back, but then later he does; I always thought that they were from victims of the base camp they all just dispatched! (Chopper seemed pre-occupied with humans anyway...Explains why he was about to kill Lex and, subsequently, why he was killed so easily by sneaky Grid!)