Here are a few holocephalian teeth from the Pennsylvanian LaSalle Limestone from Illinois that I have been unable to ID. I find these teeth hard to ID since the tooth plates of a single species are often so varied in morphology, and I can rarely tell if I'm looking at a fragment or whole plate. Hopefully someone more experienced than I can tell.   For the first tooth, I tooth a picture in situ before trying to split the boulder as I was afraid it would crack. Well it did unfortunately