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

Outside of animals, check out Pando. Its a colony of aspen that all grow from the same root system so it is actually one tree, although from above ground it looks like many trees. It weighs about 30x a blue whale

Dunno how that compares to extinct plants but it’s still pretty huge

https://en.m.wikipedia.org/wiki/Pando_(tree)