I may be misunderstanding this, but are they saying they found a common ancestor to chimps and humans? Are they saying this common ancestor walked upright? If

I may be misunderstanding this, but are they saying they found a common ancestor to chimps and humans? Are they saying this common ancestor walked upright? If so why would chimps change from walking upright, to that awkward walking on their knuckles deal? That doesn't really make sense to me.