New cingulate xenarthrans from the late Oligocene of Quebrada Fiera (Mendoza, Argentina)

Abstract

The Deseadan South American Land Mammal Age fauna (late Oligocene) of Quebrada Fiera (Mendoza Province, Argentina) is of particular importance for understanding of the evolution of late Oligocene faunas in South America. It occupies an intermediate geographical position between the high-latitude faunas (southern South America/SSA localities in Patagonia) and the low-latitude faunas (northern South America/NSA localities in Bolivia, Peru and Brazil), partially filling a gap of about 20° latitude. This mammal fauna has a complex composition that includes endemic taxa, others clearly of Patagonian origin, and some shared with areas of lower latitudes. This paper describes three new species of late Oligocene (Deseadan) cingulates from Quebrada Fiera, based on the detailed description of new remains and the revision of previously described specimens with preliminary taxonomic assignments. The newly recognized species belong to three distinct lineages of Cingulata: Mendozaphractus cumpuchu gen. et sp. nov. (Dasypodidae, Euphractinae), Peltephilus quebradensis sp. nov. (Peltephilidae), and Clypeotherium mobilis sp. nov. (Glyptodontidae, Glyptatelinae). These new taxa are exclusive to this locality and join other species only known from this locality such as Fieratherium sorex (Metatheria incertae sedis), Asteromys puelche (Cavioidea), Asmodeous petrasnerus (Homalodotheriidae), Gualta cuyana (Leontiniidae), Mendozahippus fierensis (Notohippidae), and Similhapalops nivis (Megatherioidea). The diversity of Cingulata shows a unique assemblage compared to other South American Deseadan faunas, although it shows greater affinities with Patagonian faunas. From a biogeographical point of view, Quebrada Fiera is located in an area that is considered a transition zone between the Andean region (within the Austral Kingdom) and the Neotropical region (within the Holotropical Kingdom). The characteristics of the mammalian assemblage of Quebrada Fiera show features typical of transition zones (e.g., overlapping biotic elements from different regions, numerous cases of endemism). Although it is difficult to assess many biotic components from the fossil record alone, the characteristics of the Quebrada Fiera faunal assemblage could provide additional evidence to support the separation of these regions since the Oligocene.