Late Pleistocene vertebrates from northern Uruguay: tools for biostratigraphic, climatic and environmental reconstruction

An updated list of vertebrates from Quaternary sediments of northern Uruguay is provided, including new reports. A detailed study of Equus (Amerhippus) neogeus was performed, due to its biostratigraphic value in correlating the fossil assemblage with the Lujanian Stage (Late Pleistocene-Early Holocene). The faunal association is referred to the Sopas Formation, the only stratigraphic unit recognized. Three stratigraphic sections reveal the predominance of subaquous environmental deposition (Yucutuja and Malo creeks) and the development of paleosols on fluvial flood plains (Sopas creek). The mammal content and the (14)C and thermoluminescence/optically stimulated luminescence ages indicate a Late Pleistocene age. Information indicating a relationship with OIS3 is discussed. The mammals of the Sopas Formation seem to be different and older than the fauna of the Guerrero Member of the Lujan Formation. Ecological and biogeographic information provided by the fauna is used to discuss paleoenvironments and climatic processes involved. This reinforces the hypothesis of the presence of a variety of habitats composed dominantly of open areas plus some forested zones with permanent lacustrine and fluvial contexts. Brazilian and some Patagonian vertebrates occurring together in the Sopas Formation lead to discussion of the nature of the fossil assemblage. (C) 2003 Elsevier Science Ltd and INQUA. All rights reserved.