Paleoecology of the largest carnivorans (Carnivora: Mammalia) of the Brazilian Quaternary

BERNARDES, CAMILA; LONGSTAFFE, FRED; DANTAS, MARIO; XIMENES, CELSO; LUNA, CARLOS ALBERTO; AVILLA, LEONARDO

Gramado, RS

Congreso; XXIII Congresso Brasileiro de Paleontologia; 2013

Sociedade Brasileira de Paleontologia

The canid Protocyon troglodytes Lund, 1838, the saber-toothed cat Smilodon populator Lund, 1842, the jaguar Panthera onca Linnaeus, 1758 and the short-faced bear Arctotherium wingei Ameghino, 1902 were the largest Carnivora during the Pleistocene in Brazil. S. populator and P. troglodytes are considered as hypercarnivores, whereas A. wingei is considered an omnivore that feed mostly onplants. The majority of the paleoecological inferences made for these carnivoran species have been based on craniodental morphology. However, morphological features are closely linked to the systematic affinities of a group, such that form does not always reflect the true feeding habit of a species. This study aims to infer the paleoecology of the large Pleistocene carnivorans A. wingei, P. onca, P. troglodytes, and S. populator through stable carbon and oxygen isotope analysis. Bone and tooth samples were selected from the following South American localities: Aurora do Tocantins (Tocantins), Itapipoca (Ceará), Poço Redondo (Sergipe), Ourolândia (Bahia), Belo Horizonte (Minas Gerais), in Brazil, and from Tarija, in Bolivia and Córdoba, in Argentina. The carbon isotopecompositions suggest that the analyzed specimens lived in a region where both C3 and C4 plants were present. However, it has not been possible to identify differences in diet among species or among latitudes, probably because the diet of these large carnivorans was rarely composed of only one species. The oxygen isotope compositions of most specimens were somewhat higher than predictedbased on estimates for current average annual precipitation at each analyzed site. This might indicate that these specimens lived during a warmer time period such as the Early Holocene. By the Early Holocene, after the Last Glacial Maximum, successive shifts towards a warmer and drier climate started to modify the phytophysiognomy of South America. Of all the analyzed species, only P. oncaremains as an extant species. At the present time, it inhabits subtropical and tropical forests with permanent water sources. Hence, the climatic shift that occurred by the Early Holocene may have been a significant factor leading to the extinction of A. wingei, P. troglodytes and S. populator.