The Largest Known Bear, Arctotherium angustidens, from the Early Pleistocene Pampean Region of Argentina: With a Discussion of Size and Diet Trends in Bears

摘要: The South American giant short-faced bear (Arctotherium angustidens Gervais and Ameghino, 1880) is one of five described Arctotherium species endemic to America it known for being the earliest, largest, most carnivorous member genus. Here we report an extraordinarily large A. individual exhumed from Ensenadan sediments (early middle Pleistocene) at Buenos Aires Province, Argentina. Based on overall size, degree epiphyseal fusion, pathologies, this was old-aged male that sustained serious injuries during life. Body mass estimated compared other ursid based a series allometric equations. To our knowledge, specimen now represents largest ever recorded. In light discovery, discuss evolution body size in (from large-to-small) compare bears exhibited different evolutionary trajectories. We suggest larger more nature angustidens, later members genus, may reflect relative lack carnivores abundance herbivores just after Great Biotic Interchange.