I don't think this is shocking. A lot of painter do something like this because it's somehow easier to draw the form of skulls than the form of a face. So the skull is there as a framework for painting the face.

There are also a lot of painters who start with naked people and then dress them. This also helps with 'transparent' clothing.

And when you learn to draw comics most of the time you start with a 'skull' of the character.