Marine Isotope Stage 3 (MIS 3) and Continental Beds from Northern Uruguay (Sopas Formation): Paleontology, Chronology, and Climate

Abstract

The Sopas Formation is a late Pleistocene continental unit that includes trace fossils, woods, fresh-water mollusks, and vertebrates with mammals being the predominant taxa. Likely, relationships with the Last Interglacial Stage or with the Last Interstadial were proposed. The paleontological content of the Sopas Formation is updated, and the climatic and environmental signals provided by the fossil content are evaluated. Radiocarbon AMS dates ranging from 33,560 ± 700 year B.P. (cal 36,089 − 39,426 year) to 39,900 ± 1,100 (cal 42,025 − 45,389 year) and TL/OSL ages from 27,400 ± 3,300 to 71,400 ± 11,000 year (being the 45–28 ka time interval better represented), support a relationship with Marine Isotopic Stage 3 (MIS 3) in most outcrops. In the fossil assemblage are taxa that indicate open habitats, savannahs, and woodlands including gallery forests and perennial rivers; living representatives of taxa related to benign climatic conditions (mostly tropical to temperate climates), some taxa that suggest arid to semiarid environments, migrants, and seasonality indicators. A replacement versus mixed faunal models is discussed in the light of available evidence.