There was that bone-embedded-in-tendon thing that allows them to climb trees, as well as the necessary bones for bipedalism.
Only problem is the archeologist doesn't now jack squat where these things *really* go, which was the case of most dinosaur fossils before further research would prove earlier configurations impractical. So we don't know whether or not Ardi had a goddamn flagella sticking out of her head -- the configuration we have today is just the best thing we can think of given the evidence we have.
"I would be totally embarassed to write this, even as a fakepost. it's not funny except in how you seem to think it's good. look at all the redundancies, for fuck's sake. "insipid semantics, despicable mediocrity" ugh gross gross. I want to take a shower every time I read your prose." -Steel