They were already living in offshore areas: > "adult megalodon were not abundant in shallow water environments, and mostly inhabited offshore areas.[1]" They'

They were already living in offshore areas: > "adult megalodon were not abundant in shallow water environments, and mostly inhabited offshore areas.[1]" They're also thought to have died out 3.6 million years ago. There's no suggestion that a descendant is still alive, but that's plenty of time for such a lineage to evolve to specialize in deepwater environments. 1. https://en.wikipedia.org/wiki/Megalodon#Paleobiology https://en.wikipedia.org/wiki/Megalodon#Paleobiology