The fossil record shows that 541 million years ago a lot of new lifeforms appeared. Not all remain. The tendency is for a lot of diversity at first, when competition is easy, and one by one species go extinct, leaving only a few of the fittest competitors.
This is happening now.
It happens with corporations too. At first there were a lot of independent bookstores. Then Barnes and Noble, Books-a-Million, etc. started to succeed and crowd out competititors. Now we have Amazon who’s even fitter.
Interesting things 