Was the megalondan a great white before?

No, the megalodon was not a great white shark; they are distinct species. Megalodon (Carcharocles megalodon) lived approximately 23 to 3.6 million years ago and is considered one of the largest predatory sharks to have ever existed. While both megalodon and Great White Sharks (Carcharodon carcharias) belong to the same broader group of sharks, they are not directly ancestral to each other. Megalodon is believed to be more closely related to the ancestors of modern mako sharks.