gary-ramey
Contributor
You cannot determine if a species is bipedial from its skull, and the fact you seem to think that is the case pretty clearly demonstrates you know little of the field.
The baby chimps skull would never be mistaken for a human, or for a member of the homo genus. And it would be blatantly obvious, from the shape and orientation of the hands, that it was not a bipedial species.
Oh that's right was have size of limbs, metacarpals etc which if you examine humans from across the globe can range significantly in size, especially in pre teen children. You might not be certain of the baby chimps orgin if found in early strata, but I'm certain some scientist would have pinned legs on it and we'd have another data point to hang our hats on. The problem you have is the science community has a handful of datapoints and have used that to extrapolate from apes to humans. As a matter of fact, the data is so sketchy they're not even quite sure where to classify some of the earlier hominids. Ultimately, outside of an artists rendition of what it might look like, you have apes, and you have humans.
"And a seven-million-year-old hominid from Chad, known as Sahelanthropus tchadensis and nicknamed Toumai, may also have been bipedal. The assessment is based on an analysis of where the animal's spine would have entered the skull and the position of muscle attachments on its head. "