New Horizons of Exceptionally Well-preserved Plant Fossils from the Upper Triassic of the Transantarctic Mountains

The Transantarctic Basin preserves up to 4 km of Palaeozoic and Mesozoic sedimentary rocks, rich in fossil plants. Permian and Triassic floras are especially well represented, with both silicified and cuticle-bearing remains enabling detailed studies of high-latitude Gondwanan ecosystems. During the 13th GANOVEX Expedition (2018/2019), new Triassic plant-fossil sites were discovered in the Prince Albert Mountains. The most diverse site, an unnamed nunatak west of Timber Peak, yielded five Dicroidium species, Pteruchus africanus pollen organs, Heidiphyllum elongatum, and Dejerseya lobata leaves. Another horizon at the same site contained abundant cuticles of a single Dicroidium species with needle-like leaflets. Southeast of Timber Peak along the edge of the Polar Plateau, plant fossils include altered Heidiphyllum remains and a dense accumulation of two foliage types—needle-like Dicroidium and narrow-leaved Linguifolium—with dispersed seeds (Feruglioa, Carpolithus) and a small Pteruchus species. A third, species-rich assemblage was found in Southern Vicotria Land at Benson Knob in the Ricker Hills, with four Dicroidium species and minor amounts of Heidiphyllum and horsetails. These new discoveries expand known Triassic floral diversity in the Transantarctic Mountains. Particularly, the species-poor deposits offer valuable insights into organ associations, contributing to whole-plant reconstructions. Together, these findings contribute to a deeper understanding of Mesozoic polar forests in Gondwana.