Down on the ground - and what next?

So, we can already imagine how it happened that our simian ancestors 'jumped' off the trees and started to develop totally new competences such as bipedalism (walking on two legs). In fact, we left behind not only the family of monkeys eating fruits and having tails but also our 'human-shaped' cousins: gorilla, orangutan, chimp. But, what next? What on earth were we supposed to do among the environment of savana being - finally - hominids?
What definately should be said is that not only one specie of hominids lived in one time or even in one place on Earth: several species could coexist in one area, the best example of which is the alleged coexistance of Anatomically Modern Humans and Neanderthals who probably weren't our direct ancestors. Moreover, they are supposed to have been 'exterminated' by Anatomically Modern Humans after merely 10 thousands years. Indeed, it seems that we dominated Earth.
But in today's post we're going to meet the one that is said to be our first relative. So, today's charming creature: Ardipithecus ramidus.

This is an exeptional creature in so far as it associated both: anthropoid and animal features. It (I guess it's too early to call it he) was probably bipedal (althought it couldn't walk or run for long distances) but in the same time it was a fruit eater. It lived about 4.4 million years ago and believe it or not but the brain of this direct ancestor of ours was smaller than the one of modern chimpanzee or bonobo.
Fortunately, it's size increased about 4 times - from 300/350 cubic centimeters to the present 1200!

Who was next to lead us evolutionally to what we are today?