Genete...it's a little late here so near time for bed. The T-Rex only has the 4 main control bones for rotation as per the human head. T-Rex has 14 bones in total including a root bone for parenting to the body but most of these bones do nothing but scale selected points in the head.
Capricorn:
This is the key, I have found that giving bones bound to selected points a different scale factor moves them at a different rate. So the points that need to stretch the most (the elongated parts of the head) have a higher scale value and move more dramatically.
Really...It's just a matter of figuring out a what a basic shape will look like in front and 3/4 view then figure out what points need to to move quicker in a rotation, ie the points at the back of the head and then assign a bone to them with a scale factor to match. It takes a little while to make a model but when it's done...man the animation is a breeze. I can really see a definate look and style starting to emerge. You can see that the model is kind of 2D based yet it has all the qualities of a 3D model.
AND SO QUICK TO RENDER!
Toonertime:
All the models should work fine in all versions of AS. There is no scripts just bones and switch layers. Try loading in the open source head model in this thread and see if it works ok.
I need to go to bed.

More tomorrow.
Cheers
D.K