Now that Cubone is confirmed to have nothing to do with Kangaskahn, I figured it would be a good time to post this little tidbit about Cubone.

Cubone's skull appears to be a loose fit, and very easy to detach, almost hard to keep on. The eyehole doesn't perfectly fit the eye, and you can see skin under it.

When it evolves into Marowak, its skull alters its shape, as if to fit its head better. The eyehole perfectly fits the eye, and the eye is the only thing showing through it. This official artwork, seen from a side view, shows that the skull has completely engulfed the head tightly, with the back of his head being covered by the skull. Detatching it at this point would require the skull to break.

When Cubone evolves, the skull adapts to fit the body. It pretty much becomes a part of its body altogether.

Figured I'd share this with you.