Eli5. – How were prehistoric species able to be so much larger than current species?

Question

I feel that there must be some physiological stressors or environmental factors that inhibit modern organisms of all domains from reaching the size, of say, a megaladon or brontosaurus.

In: 18

Answer 1

The blue whale is a modern organism and is much bigger than a megaladon or brontosaurus. As far as we know, it’s the largest animal to ever exist.