Years and years and years back I stumbled upon a Japanese site that had serious cross-section anatomical details of various kaiju. I loved the images. As did Brad McGinty, apparently - he's taken the idea and applied it to some American movie monsters like the Mogwai and Gremlins from Gremlins, the Martians from Mars Attacks!, the Predator and the Xenomorph from Alien.
McGinty is selling t-shirts and prints of these designs at his site. Go there!
And by the way, here's that Gamera cross-section. If any of you guys know where I can get a good print of this, let me know.