Hyena and ‘false’ sabre-toothed cat coprolites from the late Middle Miocene of south-eastern Austria

An association of eighteen coprolites (specimens 01–18) and one isolated coprolite (specimen 209,210) were found in a vertebrate fossil-rich paleosol at the Gratkorn site (south-eastern Austria; late Middle Miocene). The specimens consist mostly of calcium phosphate (apatite) and a matrix formed by microglobules. Coprolites 01–18 show cylindrical and spherical morphologies and are considerably smaller than the tube-shaped specimen 209,210, in which no inclusions were observed. In contrast, coprolites 01–18 contain numerous, highly altered bone fragments (sub-mm-sized long bones and several mm-sized trabecular bone remains) as well as hair imprints, plant detritus and palynomorphs. Based on composition, morphology, size, microstructure, and inclusions, and considering the body fossil record of this site, we assume the hyaenid Protictitherium and the barbourofelid Albanosmilus, as producers of coprolites 01–18 and 209,210, respectively. The preserved bone remains in specimens 01–18 suggest that Protictitherium fed on small vertebrates, but possibly also cracked bones of medium-sized animals. The hair imprints found were either from the hyaenid itself or its prey, while the plant material was probably ingested accidentally. The lack of inclusions in specimen 209,210 is related to the presumably hypercarnivorous diet of Albanosmilus, which was certainly the apex predator in this biome.