El registro más antiguo del género Bothrops (Serpentes, Viperidae), proveniente del Pleistoceno inferior a medio de Argentina

Resumen

The oldest record of the genus Bothrops (Serpentes-Viperidae), from the Early to Middle
Pleistocene of Argentina. The genus Bothrops has 32 living species distributed in the Neotropic. However,
the fossil record of this serpent restricts to a specimen of B. alternatus found in the archaeological site Cueva
Tixi (Upper Pleistocene-Holocene), Buenos Aires Province. Here we add a new record of Bothrops sp. excavated
from sediments attributed to the Ensenada Formation (Early to Middle Pleistocene), exposed at José Hernandez
locality, La Plata, Buenos Aires. The fossil is found 1,5 m. below the boundary betwen Matuyama and Brunhes
polarity zones, thus corresponding to the Jaramillo Subchron (i.e., 0,915-1,01 million years before present). The
specimen consists of an incomplete right compound bone, that exhibits features of Bothrops (e.g., mandibular
fossae transversally and longitudinally wide; prearticular crest with a notable development compared with the
surangular crest). The new specimen suggests that Bothrops entered South America more than 1 million years
ago, an evidence that is in agreement with DNA information.