Primer registro fehaciente de Nopachtus coagmentatus (Xenarthra, Cingulata, Glyptodontidae) en la región Pampeana, Argentina. Contexto estratigráfico

The species Nopachtus coagmentatus was recognized by Amegino in 1888, on the basis of sections of the caudal tube and the dorsal carapace. These remains comes from Valles de las Sierras de Cordoba near Villa Cura Brochero, and stratigraphically from the Brochero Formation (Montehermosan-Chapadmalalan [early Pliocene - late Pliocene]). Ameghino also mentioned N. coagmentatus for the Monte Hermoso Formation (Montehermosan), but the determination Ameghino is highly questionable. The exploitation of Precambrian rocks from the center of the Sierras Bayas in Olavarria (Buenos Aires province) allowed the identification from the bottom to the top, of La Alcancia Formation (Miocene), El Polvorin Formation (Pliocene), La Esperanza Formation and El Buho Formation (both late Pleistocene). In this contribution present osteoderms of the latero-dorsal portion of the posterior region of the dorsal carapace of N. coagmentatus . The specimen was extracted from brownish sandy-silt sediments of La Alcancia Quarry (36°58′40′′.06 S; 60°12′23′′.92 W) corresponding to El Polvorin Formation (Upper Chapadmalalan) and correspond to the first reliable record of N. coagmentatus for the Pampean region. Finally, we offer a detailed description of the specimen, and its geographic and stratigraphic provenance.