New Remains of Megathericulus patagonicus Ameghino, 1904 (Xenarthra, Tardigrada) from the Serravallian (Middle Miocene) of Bolivia; Chronological and Biogeographical Implications

摘要: In this contribution, we describe new remains (skull and humeri) of the Megatheriinae Megathericulus patagonicus Ameghino, 1904, recovered from middle Miocene fossiliferous locality Quebrada Honda, Bolivia. We also discuss taxonomic, biogeographical, chronological relevance discovery. Referral specimens described here to is based on metric morphological similarities with holotype a humerus that has been referred species. Shared features include: 1) molariforms are mesiodistally compressed rectangular in outline; 2) relatively less M1 labial lingual margins converge slightly mesially; 3) very long premolariform portion maxillae (rostrum); 4) anteriorly divergent lateral edges maxillae; 5) prominent, median V-shaped notch (apex posterior) between articular surfaces premaxillae; 6) long, gracile prominent anterolaterally positioned deltopectoral crest anterior surface clearly evident musculo-spiral channel. Precise geographic stratigraphic data exist for remains, which closely associated tuff dated at 12.2–12.5 Ma (Serravallian, Miocene), making it first accurately specimen 1904.