I feel like this is a given but do NOT use an argy to try to lead it into a trap it will just get freaked out and youll lose control of your bird.

Rather build the trap large enough to hold both a rex and the yuty (make sure the rex has impeccable health just in case) and then lead the yuty in the trap and stand on the ramp just close enough to cryo your rex. Also make sure your rex is on passive or your yuty will probably die.