Descripción de una mandíbula de ARTRASPOTHERIA (Mammalia, Placentalia) de la formación Cerro Bandera (Mioceno temprano) de la provincia del Neuquén

Abstract

The Astrapotheria were one of the groups of extinct placental mammals that inhabited South America during part of the Cenozoic era. Along with the Pyrotheria, Xenungulata, Notoungulata, and Litopterna, they represent the native South American ungulates. Here, a complete jaw of Astrapotheria is described, recovered from the Cerro Bandera Formation, west of Plaza Huincul city (Neuquén, Argentina), from levels assigned to the Colhuehuapense age (Early Miocene). The material (MCF-PVPH-375) consists of a jaw with the left incisor 2, alveoli of premolars 3, complete premolar 4-molar 3 series, the angular process, and part of the ascending process. The specimen is assigned to the genus Parastrapotherium due to the following characteristics: a similar dental formula, presence of labial flexion in the molariforms easily observed, presence of a "pillar" in the molars 3, bucco-lingual base of incisor 2 wider than in Astrapotherium. The angular process exhibits crests (possible muscle insertions) not found in Astrapotherium magnum. Some characteristics of MCF-PVPH-375 are more similar to P. martiale and P. crassum more than P. holmbergi, such as dental measurements, greater development of the labial cingulum compared to P. holmbergi, and the presence of a "pillar" absent in P. voghti. MCF-PVPH-375 presents a longitudinal groove on the lingual face of the incisor 2, absent in P. symmetrum. The absence of canines in the specimen studied, prevented its specific assignment. MCF-PVPH-375 confirms the presence of the genus Parastrapotherium for the Cerro Bandera Formation and extends the diversity of astrapotheres for this unit and for the early Miocene in North Patagonia.