Taking a shot to the Occipital bone is very dangeorus. Most don't know exactly where it is and when they see a fighter punching the back of the head they think right away "oh thats illegal." Not exactly. It is the lower potion of the back of the head. The Parietal bone is a lot stronger (the green portion of the 2nd pic). Taking a punch to the parietal bone is not as dangerous. Getting hit in the occipital portion is (the portion right under the green) That is why Renzo couldn't continue, and Cole shouldn't had continued. By far the most dangerous part of the head to hit. VERY DANGEROUS! I hope that clears it up a bit. The photos should help.