Climate and Vegetation of the Miocene of Tierra del Fuego: Filaret Formation

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. Key Points During the Miocene, southernmost Patagonian had a warmer and wetter climate than today, as evidenced by leaf physiognomic analysis The now‐day steppe region was occupied by Nothofagus forests during the Miocene, accompanied by other Gondwana and Neotropical taxa Landscape and climate reconstruction by the Miocene suggests the Andes could not rain‐shadow humid westerly winds in Tierra del Fuego