Why were prehistoric era animals so gigantic in comparison to animals from the “modern era”

Question

Why were prehistoric era animals so gigantic in comparison to animals from the “modern era”

In: 1281

Answer 1

Part is that it’s easier to find big bones than small bones. In a million years it will be easier to find elephant bones that survive than little mouse bones, so it will make it seem like there was more elephant sized animals than mice even though we have both