I like your use of colour, and the dead-on composition works in this. Only thing I'd change is the DOF seems a little wrong... it seems to me the front teeth should have also been in focus.
Cool idea, but I find your choice of focus point not quite right. I would have focused on the teeth instead of the nasal cavity. I imagine you were trying to bring out the bone structure of the nasal cavity.
A shot closer to the skull showing teeth, nasal cavity and part of occipital bones only would have been interesting as well.
What kind of animal is this? From my limited knowledge of mammalian dentition structure, I would guess that this might be some sort of sea mammal. Seal maybe?