Ecomorphological study of large canids from the lower Pleistocene of southeastern Spain

An ecomorphological analysis of the skeletal remains of large canids, Canis (Xenocyon) falconeri and Canis etruscus (Mammalia, Carnivora, Canidae), preserved in an assemblage of large mammals from the lower Pleistocene site at Venta Micena (Guadix–Baza Basin, Orce, Granada, southeastern Spain) is reported. Mean body mass of adult individuals was estimated to be around 10 kg for C. etruscus and approximately 28 kg for C. falconeri using multiple regression. A comparative study of tooth measurements in modem canids, using principal components and discriminant function analysis, infers quite different ecomorphological adaptations and feeding behavior for both fossil species. The craniodental morphology of C. falconeri is similar to that shown by extant hypercarnivorous canids whose diet include more than 70% of vertebrate meat, whereas C. etruscus shows a cranial morphology similar to those of modem omnivorous species, thus indicating a dietary niche in which vertebrate meat represented less than 70% of its diet, with other feeding resources making up the balance. These results suggest that there was a marked ecological segregation between both sympatric species of large canids. The find of a complete skull of C. falconeri showing bilateral asymmetry and marked dental anomalies could suggest high levels of genetic homozygosis in the population which inhabited this region during early Pleistocene times, possibly as a consequence of isolation and the low number of individuals. This may have subsequently led to the extinction of C. falconeri in the Western fringe of Europe. The survival of this pathological individual to adulthood indicates that this species may have developed cooperative behavior similar to that of modem African wild dogs.