*bangs head against table*
http://i39.photobucket.com/albums/e199/sharprm/skull-2.png
? looks like there is a jaw that stays put and a second jaw that appears and dissapears. as noted by others, maybe layer should be turned off for lower jaw when upper jaw appears.
there arnt two mouths, its more mechanical than biological
The animation seemed to work fine before the transparencies issues was fixed. 
Nice style,and skull! :D
but..it's showing the previous frame and it makes it weird...try to fix it :]
ya... I don't think this should have been approved for the gallery with that problem.
Otherwise, it looks like if everything was working I'd be a nice piece, I like the sytle of the shading on the top of the skull in particular.
Only crit would be that the human skull doesn't have any bone connecting the bottom of the jaw together like that, unless you're going for a tounge in which case you mgiht want to make it a different colour to distinguish it more.
Well... I'll give it to you. It is a different style.
I have a feeling you forgot to get rid of the first layer when you did the second frame
animation is still broken.