New marsupials from the Eocene-Oligocene transition of the Andean Main Range, Chile

ABSTRACT

We describe transitional Eocene–Oligocene marsupials of the Tinguiririca Fauna of the central Chilean Andes. Phylogenetic definitions of names attaching to several higher level clades of South American marsupials are proposed. Three new taxa are described: (1) a new species of Polydolops, P. abanicoi, representing the youngest polydolopoid known; (2) Klohnia charrieri, the closest known relative of the poorly known Patagonia (Colhuehuapian SALMA), which together form the nearest outgroup to the bizarre Groeberia (Divisaderan SALMA); and (3) a new didelphimorphian, Pascualdelphys fierroensis. Analysis of dental features in Klohnia helps resolve interrelationships among argyrolagoids, with Argyrolagidae (Proargyrolagus, Argyrolaginae) as closest outgroup to Groeberiidae ((Groeberia (Klohnia, Patagonia)); support for clades within Argyrolagoidea remains weak, in part due to missing data. An unsuccessful attempt to provide a phylogenetic placement for Pascualdelphys highlights the unsatisfactory state of knowledge about interrelationships among early didelphimorphians. The phylogenetic relationships of these new marsupials are permissive of, but provide little independent support for, the inferred post-Mustersan, pre-Deseadan age of the Tinguiririca Fauna. Marsupials from the central Andes of Chile reflect Paleogene South American latitudinal faunal provincialism and help to close an important temporal gap in the group's history.