I posted some tortoises earlier that had only vestigial spines and few if any ribs, using their shell as a stressed structure. These, from the Museum of Comparative Anatomy in Paris, have a complete spine and ribs. It works quite well in stereo, so have a go.
To resolve in stereo, go cross eyed so that one image registers over the other (register features rather than the frame). When you see three images concentrate on the middle one and relax until the three dimensional image pops out. If you have problems, make the image smaller.