A new late Pliocene toad of the genus Rhinella (Bufonidae) from northwestern Argentina

Abstract

The best known Neotropical fossil bufonid discovered to date is described herein. This material includes well-preserved cranial and postcranial disarticulated remains that were part of a microvertebrate fossil assemblage generated by the accumulation of predatory bird pellets. The remains were recovered from the Middle Unit of the Uquía Formation (late Pliocene) that crops out next to the locality of Humahuaca, Jujuy Province, northwestern Argentina. In this contribution, we present a detailed osteological description of this taxon and compare the morphological characters with respect to other related members of the large genus Rhinella. Several distinctive character states present in these fossil remains allows us to refer to them as part of a new species of the Andean R. spinulosa Group. The new species described here together with the fossil marsupials and sigmodontines rodents suggest that by the late Pliocene, the Uquía area, the Andean region of Bolivia, and southern Peru were part of the same biogeographic unit.