Creature masks with jaw operated mouths

All of the work I have seen has the lip movement as a separate cable, not tied to the opening of the jaw. If you look at your picture of the boar man, there is no way to attach a cable to pull the top lip up from the bottom jaw.  They would actually conflict with eachother, pulling down to pull up. Just make another movement point separate from the jaw movement. I think you will see that this allows for better puppetry as you can then have the upper lip snarl without the jaw opening. It will also help if you are going to try to puppeteer the lips to talk.

Hi Jared, Now I understand what you are talking about. The movement is still done by a second control. The camera work is really poor to be able to follow the mechanism, but at the end of the clip you can see the person is holding a controller for some servos. I think the servos are controlling the lips. Watching the video again, especially when they are joking about barking like a dog, the lips do not move when the jaw does. Now the cool thing is that the comment on the video post says you can contact him. Why not see what the guy says. He might be willing to let you know how he did it. Lots of cool other videos along the side. You have a very interesting puzzle to figure out. Are you going to do a head rigging like this one?

Now I see and understand what you are going for. Would like a side view on that last link, but.... I want to help you out with this. I think, from watching this last video, that the jaw mechanism that works the entire thing has several connections to it. I think there are shorter cable connections to the lips so that as the wearer starts to open their jaw, the lips start to move. The character jaw would not start to open until the wearer has their jaw more than a quarter of the way open. You might think about the placement of the lip cables towards the back of the jaw so that with little jaw movement the lips start to move. Use the size of the head so that you can secure the cable. Sorry, quick thought. The lips seem to move in sync, like they are a clam shell opening and closing. If you can make the mechanism work like the opening and closing of scissors, with the attach points on the bottom lip, you could then have the top lip slaved to the bottom. Oh, on the video I did hear a lot of the movement of the mechanism. You should try to use elastic instead of springs to help the lips return to their original spot when you close your jaw. I hope these thoughts of mine help. It would be a lot easier to be physically where you are to show you my thoughts. But I think a scissor type of mechanism would work on the lips.