I would hazard a guess and say, the predators brought them to earth to mallest, many years ago, The prison acting as a form of unescapable play ground/breeding ground. Im pretty sure thats how. I dout the preds bring down a queen on a leash, let her go and shout "KILL BESSY KILL", and then say "SHIT!!! NO!!! NOT ME BESSY get them PESKY APES!" bloody aliens "WHO EXACTLY BROUGHT THIS ALIEN UP BECAUSE DAM!!!! SHE NEEDS SOME DICEPLINE". Just wouldnt work, although be it, very funny.