Something Big Was Eating Tetrapods and Fish in the Wujiapingian Permian of Russian

Upper Permian vertebrate coprolites from Vyazniki and Gorokhovets, Vyatkian Regional Stage, Russian Platform

Authors:

1. Krzysztof Owock (a)
2. Grzegorz Niedźwiedzki (b, c, *)
3. Andrey G. Sennikov (d)
4. Valeriy K. Golubev (d)
5. Katarzyna Janiszewska (a)
6. Tomasz Sulej (a)

Affiliations:

a. Institute of Paleobiology, Polish Academy of Sciences, Twarda 51/55, 00-818, Warsaw, Poland

b. Department of Organismal Biology, Uppsala University, Norbyvägen 18A, 752 36
Uppsala, Sweden

c. Department of Paleobiology and Evolution, Faculty of Biology, University of Warsaw, Stefana Banacha 2, 02-097 Warsaw, Poland

d. Borissiak Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya 123, Moscow, 117997 Russia,

*. Corresponding author. Email: grzegorz.niedzwiedzki@ebc.uu.se

Abstract:

Numerous coprolites have been found in the Vyazniki and Gorokhovets localities of European Russia. Five identified coprolite-bearing horizons occur in the upper Permian deposits of the Vyatkian Regional Stage. Coprolites were collected from mudstone with a coprolite breccia-like layer and also from intraformational conglomerates that were deposited in a floodplain and overbank environment. Two coprolite morphotypes (A and B) are recognized from size and shape analysis of 32 specimens. Morphotype A has long, nonsegmented feces. Smaller, cylindrical or tubular-shaped coprolites of morphotype B are commonly segmented. SEM images of the coprolite matrix show spheres and thinwalled vesicles with diameters 0.5–4 μm. Electron Micro Probe (EMP) analyses of polished thin sections show microcrystalline carbonate-fluoride-bearing calcium phosphate with small amounts of calcium replaced in the crystal lattice. Optical microscopy and EMP investigations show that iron and manganese oxides are responsible for elevated iron and manganese concentrations in the bulk mass of coprolites. Other metals (V, Ni) can be associated with oxides forming spheroids with diameters 3–10 μm. REEs (rare earth elements, U, and other trace element concentrations suggest significant eolian sediment input to the burial environment of the coprolites. The scats contain fish scales and bones of tetrapods (amphibians or reptiles). In one large-sized coprolite, a small fragment of therapsid bone was also found. Both morphotypes are matched to carnivorous taxa within the Archosaurus rossicus zone of the Eastern Europe. The size and shape of the best-preserved specimens suggest that they were possibly produced by a large therapsid, anthracosaur, or early archosauromorph predator.