Grateful Dead logo

I used to listen to the Grateful Dead a lot in high school (and still enjoy their greatest hits now and then). Being the morbid person that I am, I liked their logos and album artwork - lots of skulls and skeletons! I always thought the image at the top to be a highly stylized and distorted drawing of the human skull, but when I was searching through a library book as an undergraduate, I found a drawing that was anatomically accurate and very similar. Of course, I can't find a similar drawing on the web despite an hour's search, but did find the above photograph. You can see that from above, with the cranium removed, the Dead logo is not far off the mark!