On the persistence of Tropical Paleofloras in central Chile during the Early Eocene

Abstract

Mixed paleofloras first appeared during the Early Eocene of southern South America. These floras were a blend of cold and warm taxa with Austral-Antarctic and Neotropical affinities. Despite the onset of mixed floras, Neotropical floras persisted in central Chile during the Early Eocene. In this study, we analyze the reasons for this persistence and also show that a relationship exists between this persistence and regional paleoclimate. We established the taxonomical composition, associated paleoclimate and phytogeographic affinities of an Early Eocene flora at Caleta Cocholgue, coastal central Chile. Our results indicate that tropical and subtropical taxa prevailed at Caleta Cocholgue. These were chiefly Lauraceae, today associated with a humid-warm climate. Physiognomic analyses indicate Mean Annual Temperature and Mean Annual Precipitation above 19 degrees C and 260 cm, respectively. Moreover, a phytogeographic analysis demonstrates that the Caleta Cocholg-be is closely related to other tropical floras, and poorly linked to contemporary mixed floras. These results strongly suggest that tropical floras persisted in central Chile during the Early Eocene and formed a belt across current subtropical latitudes from southern South America, between 25 degrees S and 37 degrees S. This persistence might be related to the Early Eocene Climatic Optimum and to a shrinking tropical belt, compared to its former Paleocene/Eocene extension.