what is tbe reason modern creatures arent as big as dinos

Question

I’ve always wondered why we never get anything as big as dinosaurs were, nowadays our biggest land animal is the african elephant with a average weight of 8500kg whilst back then we got creatures that were much bigger, what caused this

In: 4

Answer 1

A few reasons.

First Dinosaurs had less size constraints compared to mammals. Their reptilian physiology favored a larger size. Hollow bones to lighten them while maintaining strength, avian respiratory system to maintain temperature, and egg-laying make it much easier to reach massive sizes.

Second, we would see more large animals if we weren’t at the tail end of a mass extinction event that hurt megafauna more than smaller animals. Humans are bio-engineers that can exploit nearly everything, large animals need plenty of resources and large, healthy environments to thrive. We are great about destroying those things.

Also, it has nothing to do with oxygen levels. Oxygen has no real effect on vertebrate size, only invertebrate size.