Do you need them as comparative material or as a reference for your manuscript? I have plenty of (unpublished) pictures of articulated fossil skeletons - also batoids that I can share
Apologies for the late reply; I've only just now come across your question. If you are still looking for published illustrations of fossil batoid centra, rajiform centra have been recovered from Albertan localities. They aren't figured in the literature very often, but this would make a good starting point:
Article Age and growth in Myledaphus bipartitus, a Late Cretaceous f...