An exceptionally rich hyaena coprolites concentration in the Late Miocene mammal fossil site of La Roma 2 (Teruel, Spain): Taphonomical and palaeoenvironmental inferences

Abstract

The La Roma 2 (Alfambra, Teruel, Spain) Late Miocene vertebrate fossil site is characterised by a rich and unusual concentration of mammalian coprolites distributed along a band running in a NNE–SSW direction sub-parallel to a fossil bone assemblage. These coprolites contain residues that provide direct evidence regarding the diets of the organisms that produced them. They contain a variety of inclusions, such as small bone fragments, pollen grains and fungal spores. The bone fragments show evidence of heavy digestion, including corrosion and rounded and highly polished fracture surfaces. All the coprolites at the site are circular in section, some of them showing two convex ends, and others with both concave and convex (sometimes pointed) end. Their shape and size match the faeces produced by the extant spotted hyaena, Crocuta crocuta. X-ray diffraction analysis showed these coprolites to be mostly composed of calcium phosphate with small amounts of quartz and gypsum. All these characteristics suggest that they represent the excreted remains of digested bones; their size and morphology allow their attribution to the Late Miocene hyaenid Lycyaena chaeretis. The spatial distribution of the coprolites and the lack of tooth marks on the surface of the nearby fossil bones suggest that these elements were transported to their present positions from different places of origin by different water currents. The palynological analysis of the coprolites suggests their makers lived in an open environment with relatively scarce vegetation and under relatively cool climatic conditions but where water was available. Pines were the dominant tree taxa, but oak, hazel and birch were also present.