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

Survival of the fittest.

Basically, the large animals evolved in the first place because being large, stronger, sturdier, and more robust gave environmental advantages to creatures that were smaller, weaker, and more fragile.

However, after a certain point, changes in the environment made it less helpful to be so big and strong, in favor of other genetic selections, such as better births, more dexterous limbs, or better senses.

Fittest means whatever works best for the current environment.