I really like the model and the texturing, plus the cracks. It almost looks like it is made of some sort of bone which was fossilized.

Although I think you should either add a smoother metallic look to the feet under the rust, or give them a black underlay like the rest of the machine.

Hey, here's an idea: if you use the rust texturing in the end, why don't you make the animation 'rusty'?