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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 seen enough fossilized chitinous material to be sure. The only thing I've seen are cephalopod hooks in coprolite (tiny and thin with no layers) and Arthropleura tergites (note layered because they weren't exposed to digestion?). I know back in the early 1800's, William Buckland thought some of the rings found in Blue Lias coprolites could be rings from the suckers of cephalopods, but acknowledged fish vertebrae should not be ruled out (On the Discovery of Coprolites, or Fossil Faeces, in the Lias at Lyme Regis, and in other Formations - Page 226). I have a number of specimens with that type of ring, but they are smaller and fossilization/mineralization isn't the same. So here are my questions: 1. Does anyone out there have any examples of beefy chitinous inclusions in coprolite? 2. Is there a quick test for chitin? 3. Has anyone seen vertebrae that look like these? 4. Has anyone seen fossilized rings from cephalopod suckers? Some extant squid have these, but their rings have little teeth/serrations on them. 5. Any other ideas what these could be? As always, thanks for looking! @MarcoSr, @DE&i, @Carl
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This coprolite is from a marine creature that swam in the Jurassic seas that once covered this parts of England. The dark inclusions that can be seen on the surface are Onychites (cephalopod hooks). In April 2016, the University of Minnesota X-ray Computed Tomography Lab scanned the specimen using a X5000 high resolution microCT system with a twin head 225 kV x-ray source and a Dexela area detector (3073 x 3889 pixels). Many of the images shown here are of individual 3D elements/features within the coprolite that were separated/isolated using Blob3D. The taxonomic classification given is for the inclusions, not the coprolite. Aside from the hooks, it is hard to definitively identify the inclusions without damage to the coprolite. The following is a list of inclusions: 241 hooks of various sizes that are at least 75% intact. 200+ plate-like fragments of various sizes (likely similar to the surface nacre). 19 ellipsoidal structures, possibly forams or parasite eggs. 2 unidentified long, straight conical structures joined at wide end (A) 1 long rod-like structure with a bulbous end (B) 1 unidentified mass that looks like it was the attachment point for 5 rod-like structures (C) 1 1ong cylindrical (rod) structure that tapers in the center. The center density is much lower than the outer shell (D) 1 irregular structure that looks I originally thought might be an ink sack or buccal mass, but the size is wrong. Experta think it is more likely foraminifera (E) 1 irregular structure, possibly a statolith (F) Acknowledgements: Thank you to Neale Monks and Christian Klug for providing input.
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