BIOGEOCHEMICAL AND ECOMORPHOLOGICAL INFERENCES ON PREY SELECTION AND RESOURCE PARTITIONING AMONG MAMMALIAN CARNIVORES IN AN EARLY PLEISTOCENE COMMUNITY

Biogeochemical (delta C-13, delta N-15, and delta O-18 values) and ecomorphological analyses of the early Pleistocene fauna of Venta Micena (Orce, Guadix-Baza basin, SE Spain) provide interesting clues on the physiology, dietary regimes, habitat preferences, and ecological interactions of large mammals. Such inferences are useful in deciphering aspects of paleocommunity structure and predator-prey relationships. Specifically, the hypsodonty index combined with delta C-13 values allows classifying the ungulates among grazers from open habitat (Equus altidens, Bison sp., Praeovibos sp., Hemitragus albus, Hippopotamus antiquus, and Mammuthus meridionalis), mixed feeders (Soergelia minor and Pseudodama sp.), and browsers front canopy areas (Stephanorhinus sp. and Praemegaceros cf. verticornis). Given that delta C-13 values indicate that all these herbivores fed exclusively on C, plants, significant differences in isotopic values between perissodactyls (monogastric, hindgut fermenters) and ruminants (foregut fermenters) reflect differences in digestive efficiency. Values of delta O-18 indicate the dietary water source of ungulates, revealing that Pseudodama sp., Hemitragus albus, and Soergelia minor obtained a significant fraction of their metabolic water from vegetation. Carnivores show higher delta N-15 values than herbivores, which records the isotopic enrichment expected with an increase in trophic level. Hippopotamus antiquus and Praeovibos sp. have unexpectedly high delta N-15 values, suggesting that they predominantly consumed aquatic plants and lichens, respectively. Inferences on predator-prey relationships, derived from the use of linear mixing models, indicate resource partitioning among sympatric predators; saber-tooth Megantereon whitei and jaguar Panthera cf. gombaszoegensis were ambushers in closed habitat while saber-tooth Homotherium latidens and wild dog Lycaon lycaonoides were coursing predators in open plains. The giant hyena Pachycrocuta brevirostris scavenged the prey of these hypercarnivores.