The mouth area of the skull reminds me of crumpled paper. I like the ideas of the things you draw; you can tell that there isn't really a reference for any of them, and the originality is hot as balls. Are you using just a regular pencil or do you have specific drawing pencils? I'm curious. I like the doodle page more than the skull, but that's mostly just because of the face on the doodle one. The anatomy is awesome on the face and I love the expression. The shading is also pretty sw33t, and I like how in your drawings you try to cover every object with pencil, whether it be really lightly stroked pencil or a full out dark darkgray outline of something.
Also, pizzapete8, posting that won't help anyone.