I have been looking at a number of turtle and tortoise skeletons. They seem to have most of the pieces that a mammal would have but some (as with the one above) do away with a redundant spine. Others appear to have a vestigial spine in parallel to the (structural) shell. This one is from the museum of comparative anatomy in the Jardin de Plants in Paris in the dinosaur section. The view below is of the same gallery from the balcony.
To resolve the stereoscopic images go cross eyed until a part in one image registers with the same part in the other. This should give you three images, where you concentrate on the middle one. Try to relax – if you have the images registered over each other the three dimensions will appear and then gain depth as you become more comfortable with it. If you are having trouble registering the images, click on the image to see it in a separate window and make the image smaller until you can resolve the stereoscopic image.
I am working on some new drawings – I hope to have some new things up in the next couple of weeks.