That's one hell of an underbite.

I was originally trying to draw Occult's Nightmare Dragon/End Of Days form but the angle on the torn membrane half-fused to his side was too hard to draw T--T. The lower jaw is composed of 5 mandibles and thing down toward the collar bone, allowing him to stretch his throat and maw large enough to swallow objects nearly as large as he is. Like a pelican pouch! Which is a little overkill for something so big that a human is the size of his toenails.