I haven't studied archaeology at all but your question has to be a very relevant one. ALL data collection, in every field, is subject to various biases. In philosophy it's referred to as the "theory laden-ness of observations". We pursue data in places we have a good reason to look, or where data is easily found. In archaeology, the "fossil record" simply isn't a record for our entire history. It just doesn't exist. We find bits and fragments of the story, and we concentrate our searches in areas where we've learned that fossil-forming conditions existed, meaning there may be something more for us to find.I don't have the answer and I'd like to hear yours.