The Great White Shark and the Meglodon

The meglodon is a giant preatory shark. They went extinct around three point six million years ago, and they had a world distribution. And because zinc is incorporated into this mineral phase of teeth, we base ly can look back millions of years study the diet of long extinct animals. So from fossil evidence, we know that both species at least occasionally fed on marine mammals. This method using zinc isotopes to infer one's position in the food chain has been used on such old samples.