Quaternary mammalian faunas of the Pampean Region

Knowledge of the fossil mammals from the Pampean Region of Argentina has greatly increased in recent years. To analyze the patterns of change in regional climates and environments through the Quaternary, the fossil record of land-mammalswas used. Two principal factors affectedmammalian diversity in the Pampean Region during the Pleistocene: glaciations and the climatic, environmental, and sea-level changes associated with them; and the large numbers of North American taxa that immigrated to South America. From the Pliocene, the regional climatic conditions changed from beingwarmandwet to being colder, drier, andmore seasonal. During the Pleistocene, as a consequence of glacial cycles, cold and dry conditionswere interrupted by relatively short warmer and wetter periods. Several pulses of expansion and contraction of steppes and subtropical forests are recorded. This change in habitat produced the provincialism that has characterized the mammal faunas from the Pampean Region. Finally, the most notable characteristic of the Quaternary mammal fauna of South America is the almost complete extinction of large mammals during the latest Pleistocene–earliest Holocene. The evidence presented here is most consistent with a model that explains megafaunal extinction through climatic fluctuations, as it appears that only a few species of large mammals survived until the Holocene. Nevertheless, a human presence could have accelerated the process of extinction.The present work was made possible through a Research Project CGL2007-60790/BTE from DGCYT, Spain.Grants from the Universidad Nacional del Centro, Project PIP-02773, CONICET and PICTO 04-11503 ANPCYT, Argentina.Peer reviewe