A Last Glacial anuran assemblage from the inland Pampas of South America provides insights into climate and environments during Marine Isotope Stage 3

Abstract

Environmental and climatic conditions of the South American temperate grasslands (Pampas) during the Last Glacial Period have typically been regarded as mostly arid and cold, whereas humid and mild conditions such as those prevailing today may have been established only recently. This hypothesis has been built mostly upon fossil mammals that come from coastal areas and date from the end phase of this period and thus provide both temporally and geographically biased data. Other fossil vertebrates, including anurans, have been overlooked when addressing these conditions in spite of being potentially very informative due to their ecological requirements. Here, we analyze an anuran assemblage from the Last Glacial Period of the inland Pampas. In addition to the description of new records, we discuss the taphonomic settings and the correlation of the fossil-bearing beds with levels referred to the interstadial Marine Isotope Stage (MIS) 3 from other Pampean localities. Based on this evidence, together with what is known for extant anurans, we discuss the environmental and climatic conditions of the Pampas during the Last Glacial Period. The presence of Rhinella arenarum and, particularly, Ceratophrys ornata in the fossil assemblage and their persistence in the Pampas throughout the Quaternary suggest that the range of environmental changes in the region during the Last Glacial Period might have been more limited than has traditionally been acknowledged. In this regard, this study highlights the value of anuran fossil assemblages when addressing environmental and climatic conditions during the Quaternary.