Peligrotherium tropicalis (Mammalia Dryolestida) from the early Paleocene of Patagonia, a survival from a Mesozoic Gondwanan radiation

Peligrotherium tropicalis was originally diagnosed as a placental mammal (Peligrotheriidae, Condylarthra? Bonaparte, Van Valen & Kramartz, 1993), based on lower molariforms features and the inferred dental formula. Herein we describe the first upper cheekteeth associated with lower ones, coming from the same Patagonian locality and level (early Paleocene) as the holotype. Neither the upper cheekteeth nor the lower ones shows any tribosphenic feature. On the contrary, they show features that can be perfectly derived from a pre-tribosphenic pattern, as that characterizing the Dryolestida, and particularly from that found in the Late Cretaceous Gondwanan Mesungulatum houssayi Bonaparte & Soria, 1984. This is not only the first Cenozoic dryolestid but also the second South American Paleocene survivor of a Mesozoic Gondwanan radiation.