A reference only for those well too up on the various hypotheses for the origin of bird flight, but one which directly references this critter, the chukar partridge:
Although it might look like it, it’s not actually running but was standing statically in this odd pose when I took the photo. See at the Beijing Zoo, but for a wild example try here. Sorry, I’m very busy again and off at the weekend to check out a mystery museum and dig site, more proper posts to come soon. Honest.