Revisión del perezoso terrestre Nothropus (Mammalia, Xenarthra, Tardigrada) del Pleistoceno de Argentina y Bolivia

Abstract

The Nothrotheriinae Ameghino (Xenarthra, Pilosa) are recorded in Argentina from the middle Miocene to the late Pleistocene. In the Quaternary of the current territories of Argentina and Bolivia it is possible to recognize the existence of the genus Nothropus Burmeister, which includes three Pleistocene species, all of them known only by their type materials: (i) Nothropus priscus Burmeister (Santa Fe Province, Argentina); (ii) Nothropus carcaranensis Bordas (Santa Fe Province, Argentina); (iii) Nothropus tarijensis (Burmeister) (Tarija Valley, Bolivia). This study shows that N. priscus is a juvenile specimen and must be considered as a species inquirenda. In turn, the mandible morphology of N. tarijensis is very different compared to that of N. priscus and N. carcaranesis. N. tarijensis shows a very robust dentary and a greater angle between the occlusal plane and the anterior margin of the ascending ramus, suggesting that this is a valid species. In summary, the evidence suggests that the diversity of Nothropus is limited to two species: N. carcaranensis in Argentina and N. tarijensis in Bolivia.