Was doodling today and started to develop this sketch, not looking any critique in particular but thought I'd share some progress shots of it as it evolves
EDIT: By all means critique away if you have a suggestion though! I didn't mean to seem like i was warding them off 
I based this sketch off of a
3D human skull reference I found online to get the general shapes down. Looking at the initial sketch version, the skull's left cheekbone looks like it needs to move down a touch to match the right side but overall I'm okay with the skull structure and I'm not too worried about making it look
too humanoid as it's a mythical creature of sorts.
Initial Sketch:

Initial Shading:

I'm looking forward to shaping the skull more and making the teeth look sharper and more fiendish. Im not sure at the moment but I'm kinda digging the thick outlines on the lineart and the loose, blobby shading that give it a cool graphical element. For the background, I started sketching some city ruins and rocky outcrops so who knows where that's going...
For the moment I'm focussing on just the skull and background but i might try drawing the top of the spine, shoulders and rib-cage etc. if I'm feeling brave.