Abstract

The changing climate during the Cenozoic affected the diversity of plants in Patagonia, as species richness tends to increase during warm periods and decrease during cold periods. Precipitation is a significant factor shaping diversity, as shown in the case of central Chile during the Miocene. This study presents a reconstruction of the climate and vegetation in Tierra del Fuego Island, located approximately 52°S, using fossil flora recovered from the Filaret Formation to understand the Miocene epoch, characterized by contrasting global climatic changes. Filaret flora comprises twenty-seven morpho-taxa, including nine Nothofagus species and other Gondwanan and Neotropical families, such as Atherospermataceae and Anacardiaceae, in agreement with a forest habitat. Leaf physiognomy climate reconstruction suggests microthermal conditions, with a mean annual temperature of 9.4–11°C and annual precipitation ranging from 985 to 1,130 mm. These conditions are warmer and wetter than the modern record of the area, with a MAT of 6°C and mean annual precipitation of 300 mm. As the Filaret fossil record suggests, the forest habitat under a microthermal climate is consistent with the global climatic reconstruction of the Early Miocene. This Miocene landscape on Tierra del Fuego was possible because the Andes could not rain-shadow humid westerly winds by this timeframe. © 2024. American Geophysical Union. All Rights Reserved.