MULTIPLE PATHS. “If correct, this would imply that there was more locomotor diversity in the fossil record than has been suggested, and raises questions over whether there was a single origin for bipedalism or not. At the very least, if bipedalism appeared only once in the hominin radiation and is therefore monophyletic, such evidence would suggest that there were multiple evolutionary pathways responding to that selection pressure.”
http://onlinelibrary.wiley.com/doi/10.1111/j.0021-8782.2004.00296.x/full