A new look at the iconic Taung Child fossil has caused one scientist to link unfused infant skulls with bipedalism. I think. The article throws a lot of quotes about increasing brain size around, but not about bipedalism. That unfused skulls are part of what makes it possible for a bipedal ape to have children with brains all out of proportion to their bodies was known and accepted when I was an undergrad in the late 80s, so (at least from what the article presents) I'm not completely sure what's new here.