(Even if it were true, it would not demonstrate (b), for reasons given in Lippard (1989 - 90)-- the knee joint is not the only evidence of bipedality in A. afarensis.) (talkorigins.org)
Clemente thinks these lizards might have co-opted accidental bipedality for some advantage. (sciencemag.org)
Later studies have honed in on traits such as bipedality, culture, language, humor, and, of course, a big brain as the unique birthright of our species. (science.sciencemag.org)