Paper No. 162-75
Presentation Time: 9:00 AM-6:30 PM
COPROLITES OR PSEUDO-COPROLITES? PRELIMINARY ANALYSIS OF PURPORTED HERBIVORE COPROLITES FROM THE MORRISON FORMATION IN UTAH
Many confirmed dinosaur coprolites have been described in the scientific literature to date. Confirmation of a mineral mass as a coprolite relies on the identification of undigested organic remains (usually bone fragments or comminuted plant remains). Silicified masses resembling “cow pies” are commonly collected from the Morrison Formation and sold as herbivorous dinosaur coprolites, but there is no published evidence of organic content, suggesting that they may in fact be pseudo-coprolites. We obtained 19 specimens of putative Morrison Fm. silicified coprolites from a collector in Fruitlands, Utah on eBay, including several specimens with possible gastroliths embedded within the mineral mass. The length, width, height and mass were measured for each specimen. The shapes of the 19 specimens range from oblong to flattened spheres, with some oblong specimens marked by syneresis cracks. Specimens range in size from 70 mm to 432 mm in longest dimension and from 132 grams to 22 kilograms in mass. Each specimen was sectioned with a rock saw to expose the interior and digital microphotos were obtained to search for organic textures indicative of bone or plant material, but no such textures have been detected so far. Ongoing analyses of the mineral content and elemental chemistry of the mineral masses is utilizing petrography, SEM imaging, and XRF elemental mapping to determine if there is any substantial carbon content. SEM analysis of the surface texture of the potential gastroliths and comparison to gastroliths from chickens or crocodilians is also planned. To date we have found no evidence of organic remains within the interior of any of the specimens, although we have identified small amounts of possible carbonaceous material.