Three things the study of bones tells us, is that we haven't found them all, when we make another find, it often refutes earlier evidence and finally, to make a profound statement based solely on the existing evidence is a foolish thing to do. So state that it's unlikely domestic camels existed prior to a certain date, simply based on a single find is foolish. It would be like trying to find the exact date of the domestic dog based only on the earliest find and suggesting that's the rule.
When one seeks proof, one seeks only validation. When one seeks evidence, they seek understanding. Evidence is waiting to be found. Unfortunately, a significant amount of evidence will never be found and our understanding will be incomplete and based on one of two things: #1, incomplete data, or #2, faith.
