Alligator osteoder, or bony armor plate. Also known as a scute. These plates function much like a solar panel, drawing in the sun's rays, which heats up the blood and converts it to energy.
Alligator vertebra. Most alligator vertebrae are convex (ball protrudes out) at one end and concave (in) at the other. But this vertebrae is convex at both ends and is located in the tail where the alligator is able to swing the tail 190 degrees.