In short, I'm trying to figure out exactly what was on the menu: fish or cephalopods.
While sorting through some Oxford Clay fish coprolites, I came across this specimen. It was part of a batch purchased years ago. I must have just assumed the inclusions were fish vertebrae, but now I'm not too sure. I know some vertebrae from some fish fry can be hollow, but the texture/material of these inclusions look very different from anything I've seen (including vertebrae in Oxford Clay coprolites). Because of the color and layers, I'm thinking these may be chitinous. That said, I haven't s