Permian amphibian
I'd spent some years working as an illustrator and fossil preparator in a paleontology lab, living the dream and working with fossils.
Our practice was to clean the specimens as much as possible before photographing them and then using the images in Illustrator to create the lines of each individual bone. Once the specimen was drawn, we printed the lines onto textured coquille paper to add shading and depth.
This particular specimen was a beautiful little skull that had little to no warping at all. It's hard to think of a more perfect specimen than this one.