Quaternary mammalian faunas of the Pampean Region

摘要

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-mammals was used. Two principal factors affected mammalian 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 being warm and wet to being colder, drier, and more seasonal. During the Pleistocene, as a consequence of glacial cycles, cold and dry conditions were 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.