TAPHONOMY AND PALEOECOLOGY OF AN ASSEMBLAGE OF LARGE MAMMALS - HYAENID ACTIVITY IN THE LOWER PLEISTOCENE SITE AT VENTA-MICENA (ORCE, GUADIX-BAZA BASIN, GRANADA, SPAIN)

We report taphonomic and palaeoecologic data on the rich, diverse and well preserved assemblage of large mammals from lower Pleistocene depo sits at Venta Micena (Orce, Granada, south-east Spain). The biostratin omic and diagenetic characteristics of the assemblage are congruous wi th the sedimentary context deduced from the study of the site, and bot h confirm that: (i) the assemblage represents an accumulated taphonomi c stage, (ii) it was formed by demic, autochtonous palaeobiologic enti ties, which were preserved and recorded in situ, and (iii) it is the r esult of biological processes and agents. Interspecific analysis of si ze/abundance patterns in ungulates shows that the main taphonomic bias affecting the bones was produced by biological destruction before bur ial, and that the loss of information was greater for species of small er body size. Factor correspondence analysis was used to compare the f requencies at which some groups of postcranial elements are represente d in several recent and archaeological bone assemblages accumulated by carnivores, rodents and hominids. The results obtained strongly sugge st that the bones from Venta Micena were collected mainly by hyaenids, which deposited them near shallow dens excavated around the ponds tha t surrounded the Pleistocene lake of Orce. An analysis of the abundanc e of major long bones has shown that differential fragmentation was pr oduced by hyaenas as a function of their structural density and mean m arrow content. All these data allow to formulate a descriptive-quantit ative model for the characterization of bone assemblages generated fro m hyaenid activity, in which Venta Micena is an example of bone concen tration and modification activities by Pachycrocuta brevirostris. Stro ng selection of prey by carnivores (which killed preferably juveniles, females and individuals with diminished locomotive capabilities among ungulate prey species of larger body size) is indicated by (i) the ab undance of juvenile individuals with deciduous teeth in relation to th e average weight estimated for adults in each ungulate species, by (ii ) the U-shaped attritional mortality profiles deduced from crown heigt h measurements, by (iii) the presence of many metapodials with differe nt osteopathologies, and by (iv) a biased sexual ratio deduced from th e metacarpals of large bovids. Comparison between the frequencies in w hich modern African carnivores kill and scavenge ungulates from differ ent size classes and the abundance of these size categories in the ass emblage suggests that the Venta Micena hyaena was a bone-cracking scav enger which fed largely on carcasses of ungulates preyed upon and part ially consumed by flesh-eating carnivores such as saber-toothed felids and wild dogs.