Evolutionary History of Apes

Last night, I watched the Discovery Channel special on "Ardi." It brought up some interesting things I hadn't known until about a week or so ago, namely: "Knuckle-walking" in chimps appears to be an evolved trait from after we split, hominids evolved in forrested areas, and in the just plain cool category, Ardi was bipedal, but still had grasping feet.One of the threads throughout the special was trying to push human ancestry back to the common ancestor with chimps, but as with Lucy, finding that Ardi was bipedal means it's even farther back.That got me thinking, what is the fossil record for Chimps and/or the other great apes? We seem to be trying to push our ancestor's back to a common one with chimps, but how far back do they have for chimps? Is it possible we've found our last common ancestor, but until we can link it in time with proto-hominid remains, we just don't know yet?I'm not sure where this would go, and I've never started a new thread since the "Proposed New Topics" strategy began, so if I need to change it, let me know.

I didn't think it was Earth-shatteringly excellent, but I thought it did very weill, considering it's target. It neatly bookended the show with a description of what we found before Ardi (namely Lucy) and then what we've begun to find since, another Ardipithecus that's a million years farther back than the species in the show, which is, I believe Ardipithecus rapidus? I'm not sure what the name is for the new one, but it seems interesting. Yeah, the thumbs are shorter than I would have thought, and as a whole, the hands seem longer than I would have thought...but then a human hand looks far different without all that skin, muscle and other tissue in the way. I can understand the draw for searching for human ancestors, but it seems to me it would be just as enlightening to follow chimps back and maybe come at it the other way and meet in the middle somewhere.

According to the show, the assumption is that bipedality is an evolved trait along the hominid line and is not a trait from before the chimp/hominid split. It seems to make sense, but a lot of things that seem to make sense turn out to be wrong, so I guess it's possible. Could Ardi's descendants split to have on line become better at bipedalism and the other become knuckle walkers with better "foot dexterity"? I'm no where near educated on the topic enough to even hazard a guess.