After the dinosaurs went extinct, why did they not return over time through evolution?

Question

I never learned much about evolution, so please do explain it like I’m 5

In: Biology

Answer 1

What we commonly think of “dinosaurs” weren’t all around at the same time. They evolved and went extinct over many many millions of years with the conditions on earth changing throughout.

The ones that were not fit in the new environment went extinct, the ones that were fit enough to remain suddenly didn’t need to compete with the ones that died, so their evolutionary trajectory branched off.

Some dinosaurs do still exist though! Certain species of crocodile and shark are (apparently) largely unchanged over these geological timescales. Birds are some of the closest living relatives of the dinosaurs.

Evolution is not a process with an optimal “end point” — it’s not efficient or even optimal, it’s just the conditions of the earth effectively doing “selective” breeding over and over for millions of years.