Wow! And amazing! 3 & 1/2 million years!
It seems to me that the great drying out from the Miocene to the Pliocene really diversified the proto-homininds! I wonder how many better adapted to the treetop apes species died out while this was going on? At one time, the great equatorial tropical forests girdled the whole globe, from West Africa, across the Middle East, India and into to all of East Asia, and most of Southern North and Northern South America.
Good thing they had Global Warming back then!...................