South American giant short-faced bear diet: evidence from pathology, morphology and biomechanics.

GRISPAN, G.; SOIBELZON, L.H.; ACOSTA, W.; BLANCO, R.E.; JONES, W.W.

Punta del este

Congreso; IX International Congress of Vertebrate Morphology; 2010

We are trying to asses the diet of the giant South American SFB (Arctotherium angustidens) in order to understand its role in the particular and changing South American Pleistocene ecosystems. To accomplish this objective, we are considering evidence from dental paleopathology and biomechanics. Information about diet may be brought by the relative frequency of dental lesions, fractures, attrition, etc. On turn, biomechanics provides bite force and mandibular resistance estimations from two different methods based on simple cranial measurements. Both methods were already applied to several species of living and extinct mammals including many living ursids, demonstrating to be a very powerful tool in order to realize paleobiological inferences. Our preliminary results from these two different approaches are coincident and suggests that A. angustidens was able to kill large prey and process hard food as bones. We believe that active hunting was not the unique strategy for feeding, since the large size and great power of the giant SFB may have permitted fight for preys hunted by other Pleistocene carnivore such as the Smilodon. The giant SFB become extinct at the middle Pleistocene when the other four species of SFB appeared, but it was suggested that these other species were progressively more and more omnivore being the youngest and the smallest one (A. wingei) almost herbivore. We believe that South American carnivore guild diversification during Pleistocene provoked the short-faced bears to adjust their size and modify their diet in order to survive in a more complex ecosystem.