The fossil seed ferns (Pteridospermatophyta) were one of the earliest successful groups of land plants, and forests dominated by seed ferns were prevalent in the Permian. "Glossopteris" was the most prominent tree genus in the ancient southern supercontinent of Gondwana during the Permian period. By the Triassic period, seed ferns had declined, (perhaps were extinct) and modern gymnosperm groups were abundant and dominant to the Upper Cretaceous, when angiosperms radiated.