Resumo

SOIBELZON, Leopoldo Héctor  e  TARANTINI, Viviana Beatriz. Body mass estimation of extinct and extant South American bears (Ursidae, Tremarctinae). Rev. Mus. Argent. Cienc. Nat. [online]. 2009, vol.11, n.2, pp.243-254. ISSN 1853-0400.

Precise estimates of body mass in fossil taxa are elementary to paleobiological reconstruction. Using demonstrated relationships between body mass and anatomical measurements in modern mammals, several authors proposed prediction equations to estimate the body mass of fossil taxa. We calculate the body mass of extant and fossil South American bears (Tremarctos ornatus and Arctotherium respectively) applying 61 selected allometric equations to 19 cranial, dental and postcranial measurements. We also estimate the body mass ranges of the five Arctotherium species by simple size comparison to size and weight of extant bears. Extrapolating on the basis of geometric similitude with T. ornatus we further estimated the body mass of Arctotherium in order to know if our estimations, bias published equations, were feasible. Also we test the prediction equations results with a specimen of Tremarctos ornatus of known body mass. We found that the best prediction equations for all Arctotherium species are based on femoral (8 equations) and cranial (one equation) measurements. In turn the best prediction equations for T. ornatus are based on cranial (one equation), first lower molar (one equation), femoral (two equations) and humeral measurements (three equations).

Palavras-chave : Body mass; Arctotherium; Tremarctos ornatus; South America; Pleistocene.

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