The green poles of a warmer past: how Antarctic polar forests shaped plant evolution

Today, Antarctica appears as a continent locked in eternal ice and snow, but its sedimentary record preserves rich fossil archives of past life. Because present-day Antarctic landmasses have already been circling in polar latitudes for more than 300 million years, many Antarctic fossil occurrences derive from past high-latitude palaeoecosystems without modern analogue. Of special importance are exceptional plant-fossil assemblages—some classic, some only recently discovered—from the early Mesozoic of the Transantarctic Mountains. These yield exquisitely preserved plant compressions and anatomically preserved biotas in silicified peat and wood, allowing detailed insights into the biology and ecology of past polar forests during times of global warmth. The Late Triassic vegetation of Gondwana is particularly well-known. It was dominated by Dicroidium seed-ferns, conifers, ginkgoes, cycads, and diverse fern communities, and documents sophisticated adaptations to extreme seasonal light regimes, including widespread deciduousness, growth dormancy, and specialized understorey life strategies. There is now increasing evidence that such high-latitude ecosystems acted as evolutionary refugia during major biotic crises. The iconic Triassic Dicroidium plants, for example, survived the end-Triassic mass extinction in Gondwanan high-latitude populations and persisted there long into the Jurassic, far beyond their time of disappearance at lower latitudes. Recent discoveries from previously unexplored regions of northern Victoria Land substantially expand this perspective, revealing unexpected growth strategies, complex ecological interactions, and evidence for extreme evolutionary stasis. Taken together, the fascinating fossil record of the Transantarctic Mountains highlights the varied roles of high-latitude palaeoecosystems in plant evolution during times of global change.