Abstract

A new Mioclaenidae "condylarth" of the Casamayoran Land Mammal Age, Barrancan subage, from Paso de Indios, Chubut Province is described. The new taxon Pascualodus patagoniensis gen. et sp. nov., represented by a left upper first molar, is compared with other Mioclaenidae; the Didolodontidae and some primitive litopterns. A provisory phylogenetic hypothesis is represented by a strict consensus tree and a 50 percent majority rule consensus tree. Although the analysis confirms the inclusion of the South American taxa in a single monophyletic group, some relationships remain unresolved. Pascualodus patagoniensis is a terminal taxon in an unresolved politomy which also includes the South American Mioclaenidae and a clade comprising the Didolodontidae + Litopterna. The addition of upper dental characters of Escribania chubutensis, previously the only known Patagonian Mioclaenidae, clearly changes its relationships and allies it with the Didolodontidae Didolodus. The assignation of Pascualodus patagoniensis to the Mioclaenidae represents the geologically youngest and southernmost record for this family.