Redescription and first report of Kibenikhoria (Notoungulata, Mammalia) in the early Eocene of Mendoza (Argentina)

VERA, B.; CERDEÑO, E

La Plata

Jornada; Reunión de Comunicaciones de la APA; 2019

Kibenikhoria Simpson is a small-sized and scarcely known native ungulate included into the paraphyletic ?Oldfieldthomasiidae?. It is characterized by its relatively low-crowned teeth, but higher than other coeval, small brachydont taxa such as Henricosborniidae; protoloph absent in P2, barely insinuated in P3, and well-developed in P4; labiomesial fossette on P3-4; mesiodistally concave protocone in P3?4; lower molars lacking paralophid, having short and wide protolophid, distallyexpanded metaconid, and a fossettid in the talonid. The only known species, K. get Simpson, 1935 was identified in the upper levels of the Las Flores Formation at Cañadón Hondo and Bajo Palangana ?unpublished data? (Province of Chubut). This taxon gave place to the ?Kibenikhoria fauna?, which was referred to the early Eocene Riochican South American Land Mammal Age. In this contribution, we present the first record of Kibenikhoria outside Patagonia, in an unnamed unit fromLiu Malal and Agua de Flores-Agua de Isaac localities, southeast of the Province of Mendoza. The studied material (including associated upper and lower teeth) reveals morphological differences with respect to K. get, as well as among the new sample, which leads to recognize two new species, Kibenikhoria nov. sp. 1 (MLP 96-VIII-15-1a, right m1?2; MLP 96-VIII-15-1b, right m2?3) and Kibenikhoria nov. sp. 2 (IANIGLA-PV 519, a right P4). The presence of Kibenikhoria in Mendoza extends its geographic range to central-west Argentina and supports an early Eocene age for the faunas from Agua de Flores-Agua de Isaac and Liu Malal, which could be regarded as old as the Riochican.