Also, I could be a science dork and point out even if a megalodon-like shark were discovered, it wouldn't BE megalodon any longer. It would have evolved for deeper water and different conditions and so on. So scientists could discover a closest-living-relative, but while pinpointing the moment a species should be classified as a new species is hard, it's an important distinction (Otherwise there wouldn't even be a hybrid topic with corn snakes, because if they can produce fertile offspring with cali kings, they must be the same species, right?) A "modern day megalodon" would be calling a jungle corn a "pure corn" or a "pure king."