Species radiation
And hominids.
We know the fossil record underestimates diversity at least a little, and we know that forested environments in Africa tend to be underrepresented. Given this, the diversity of Miocene apes may have been rather impressive, because there is a fairly high diversity in what we can assume is a biased record.
But I'd like to make the argument from another angle, that of modern ecological analogues. Let us assume that the greater apparent diversity of apes in the middle and late Miocene compared today can be accurately translated as a modern reduction in ape diversity. Not…