Early Cretaceous fern foliage from President Head, Snow Island, Antarctica

Abstract

Fertile fern foliage described as Lophosoria cupulatus sp. nov. contains the distinctive spore Cyatheacidites annulatus. The fossil foliage is morphologically similar to the Early Cretaceous form-genera Gleichenites and Microphyllopteris, whose time and space distribution in Gondwana matches that of the dispersed spore Cyatheacidites. Some of the Cretaceous southern hemisphere material assigned to Gleichenites and Microphyllopteris is probably allied to families such as the Lophosoriaceae rather than the Gleicheniaceae as had been previously supposed. The nearest living relative, Lophosoria quadripinnata, grows within a mean annual temperature range of 8–22° C, and a mean annual precipitation range of 195–1977 mm. The presence of Lophosoria cupulatus at palaeolatitudes of 55–65° S implies that during the Aptian the southern high latitudes were a minimum of 12° C warmer than the present day.