Additions to the knowledge of Notiolofos (Mammalia: Sparnotheriodontidae) early Eocene of West Antarctica

GELFO J. N.; DE LOS REYES, M.; ACOSTA HOSPITALECHE, CAROLINA; REGUERO, M.

Goa

Simposio; XII International Symposium on Antarctic Earth Science; 2015

SCAR

The Sparnotheriodontidae were a geographically widespread group of medium to large sizeherbivorous mammals during the Eocene, and part of the radiation of the so called, South American native ungulates. They were low-crowned browser characterized by a lophoselenodont and bicrescentic lower dentition, a strong lophoselenodont ectoloph and usually a bunoid lingual cusp in the upper molars. Known sparnotheriodontids include Victorlemoinea prototypica (Itaboraian SALMA - Itaboraí, Brazil), Victorlemoinea labyrinthica (Riochican SALMA - Patagonia), Sparnotheriodon epsilonoides (Casamayoran SALMA, Vaca subage - Patagonia), Phoradiadus divortiensis (Casamayoran? SALMA -Mendoza, Argentina), Heteroglyphis dewoletzky, assigned to the family with some doubts (Mustersan SALMA - Patagonia), and Notiolofos arquinotiensis, the most abundant terrestrial placental mammal in the Paleogene of Antarctica. The paleobiogeographic analysis of Sparnotheriodontidae, and also Astrapotheria, yields a widespread ancestral distribution, including South America and Antarctica, since the lower Paleocene up to middle-late Paleocene, when a vicariant event took place. It was recorded through most of the La Meseta Formation allomembers, including from base to top, Acantilados II,Campamento, Cucullaea I, and, Submeseta Formation. By now Notiolofos was only known by isolated teeth. Here we present the first associated jaw remains of Notiolofos. The material MLP 15-I-10-1 comes from a filling channel at the new locality IAA2/15 in Acantilados II Allomember. The same unit but stratigraphically higher, than the bearing horizon of the oldest Antarctic mammal, which is the first record of Notiolofos.