Neogene plant macrofossils from West Antarctica reveal persistence of Nothofagaceae forests into the early Miocene.

The extinction of woody vegetation in Antarctica remains difficult to constrain due to its fragmented macrofossil record. Despite its long-standing polar position, Antarctica hosted extensive vegetation throughout the Paleogene. This changed near the Eocene-Oligocene Transition (ca. 34 Ma) as glaciation led to vegetation decline. Sparse evidence suggests tundra-like forests persisted until the Pliocene in East Antarctica, but the Neogene record from West Antarctica is largely restricted to palynoflora data. Here, we report early Miocene plant macrofossils from West Antarctica, consisting of Nothofagus leaves. U-Pb zircon geochronology confirms tundra-like vegetation existed in this region during the early Miocene (ca. 22-20 Ma), representing the youngest macrofossil record of West Antarctica. These findings suggest that Nothofagus either persisted through Antarctica's harsh Late Cenozoic Ice Age conditions or recolonised during intermittent warm periods. This substantially advances our understanding of West Antarctica's vegetation history and extends the known record of Nothofagus in Antarctic ecosystems.