The evolutionary history of the South American anteaters, Vermilingua, is incompletely known as consequence of the fragmentary and geographically biased nature of the fossil record of this group. The only record of a nominal extinct species for northern South America is Neotamandua borealis, from the Middle Miocene of La Venta area, southwestern Colombia (Hirschfeld 1976). A new genus and species of myrmecophagid for La Venta is described here from a new partial skull. Additionally, the taxonomic status of the genus to which was referred the co-occurrent species of Gen. et sp. nov., i.e. Neotamandua, is revised. The morphological and taxonomic analyses of these taxa indicate that Gen. et sp. nov. may be related to Tamandua and that the justification of the generic assignments of the referred species to Neotamandua is weak, with high probability of reassigning some of them to a new genus. Two species previously referred to Neotamandua (N. magna and N.? australis) were designated as species inquirendae and new diagnostic information for the redefined genus and its type species, N. conspicua, is provided. Together, these results suggest that the diversification of Myrmecophagidae was taxonomically and biogeographically more complex than that what has been proposed so far. Considering the new evidence, it is proposed a synthetic model on the diversification of these xenartrans during the late Cenozoic based on the probable relationship between their intrinsic ecological constraints and some major abiotic changes in the Americas.Facultad de Ciencias Naturales y Museo