Oldest Record of the Pit-Viper Bothrops (Squamata, Viperidae), from the Lower Pliocene of Buenos Aires Province, Argentina

The fossil record of the genus Bothrops is still sparse in South America. Most records belong to extant species recovered in strata not older than the late Pleistocene. The genus was also tentatively reported from the early Pliocene and early–middle Pleistocene of Buenos Aires province, Argentina, based on fragmentary specimens. The aim of the present contribution is to report the partial vertebral column of a viperid snake discovered in the lower Pliocene layers of Farola de Monte Hermoso locality, southern Buenos Aires province. The specimen can be referred to the extant genus Bothrops, representing the oldest occurrence for this taxon. This finding supports the hypothesis sustained by previous authors that indicate a "stasis" in the evolution of the South American herpetofauna since the late Neogene, at least.