Resumen de Estimación de la masa corporal de las especies de osos fósiles y actuales (Ursidae, Tremarctinae) de América del Sur
Leopoldo Soibelzon, Viviana Tarantino
Body mass estimation of extinct and extant South American bears (Ursidae, Tremarctinae).Precise estimates of body mass in fossil taxa are elementary to paleobiological reconstruction. Using demonstratedrelationships between body mass and anatomical measurements in modern mammals, several authors proposedprediction equations to estimate the body mass of fossil taxa. We calculate the body mass of extant and fossilSouth American bears (Tremarctos ornatus and Arctotherium respectively) applying 61 selected allometricequations to 19 cranial, dental and postcranial measurements. We also estimate the body mass ranges of the fiveArctotherium species by simple size comparison to size and weight of extant bears. Extrapolating on the basis ofgeometric similitude with T. ornatus we further estimated the body mass of Arctotherium in order to know if ourestimations, bias published equations, were feasible. Also we test the prediction equations results with a specimenof Tremarctos ornatus of known body mass. We found that the best prediction equations for all Arctotheriumspecies are based on femoral (8 equations) and cranial (one equation) measurements. In turn the best predictionequations for T. ornatus are based on cranial (one equation), first lower molar (one equation), femoral (twoequations) and humeral measurements (three equations).
