From the news article The guardian , Megladon sharks used to live 3 million years ago
but have disappeared from the ocean. The shark was 16 meters long, which is the size of a
school bus!And the head would have measured 4.65 meters long and a tail
that was 3.85 meters long. Because its size was so massive, a human could be the
same size as the dorsel fin, which is 1.62 meters if they stood on the sharks back.
You can download the megladon pdf here