Biogeochemical (␦ 13 C, ␦ 15 N, and ␦ 18 O 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 ␦ 13 C 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 from canopy areas (Stephanorhinus sp. and Praemegaceros cf. verticornis). Given that ␦ 13 C values indicate that all these herbivores fed exclusively on C 3 plants, significant differences in isotopic values between perissodactyls (monogastric, hindgut fermenters) and ruminants (foregut fermenters) reflect differences in digestive efficiency. Values of ␦ 18 O 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 ␦ 15 N values than herbivores, which records the isotopic enrichment expected with an increase in trophic level. Hippopotamus antiquus and Praeovibos sp. have unexpectedly high ␦ 15 N 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. PALAIOS PALMQVIST ET AL.TABLE 2-Relative contributions (mean percentages of consumption and their standard deviations) of each of the nine ungulate prey species that are well represented in the Venta Micena assemblage to the diet of each of the four hypercarnivores, calculated in 5% increments with the software IsoSource (Phillips and Gregg, 2003; IsoSource, 2006).
Prey-predatorHomotherium latidens Megantereon whitei Panthera cf. gombaszoegensis Lycaon lycaonoides Mammuthus meridionalis 12.9 Ϯ 12.3 0.7 Ϯ 1.8 1.8 Ϯ 3.0 8.5 Ϯ 8.9 Hippopotamus antiquus 7.9 Ϯ 5.9 0.5 Ϯ 1.5 0.0 Ϯ 0.0 2.6 Ϯ 3.6
