CONICET | Buscador de Institutos y Recursos Humanos

An anatomical and taxonomic analysis of the mammalian record in the locality of La Poma in Salta Province,Argentina, is here presented. This record consists in two specimens exhumed in levels of the Quebrada delos Colorados Formation referred to the middle late Eocene. The first specimen is represented by a partialskull preserving mostly the rostrum and some dental pieces and was identified as a member of Leontiniidae,although it does not bear enough information for generic or specific determination. The second specimenis represented by more complete material, preserving much of the dentition. It was identified as a newspecies of the genus Pampahippus, traditionally included in the paraphyletic family Notohippidae. Theleontiniid here studied presents several plesiomorphic features identified in other taxa of northwesternArgentina, and this material represents a new example of a pre-Deseadan basal morphotype within thefamily. Regarding the new species of Pampahippus, it shows clear signs of rising hypsodonty, representingthe first case for a notoungulate lineage in the Paleogene of northwestern Argentina.