Ferns and fern allies in the Rhaetian flora of Wüstenwelsberg, Bavaria, Germany

Abstract

The Rhaetian flora from Wüstenwelsberg (Franconia, southern Germany) comprises a diverse array of cryptogam plants. Twelve species of lycophytes, sphenophytes and ferns are identified and described by means of macromorphology and in situ spores, when present. The study is part of the ongoing examination of this recently excavated and excellently preserved fossil plant assemblage. In total, two lycophyte taxa (Lepacyclotes and Selaginellites) and one sphenophyte (Equisetites) have been identified. Ferns are represented by eight species in three families; Osmundaceae with one Todites and two Cladophlebis species; Matoniaceae with two Phlebopteris species, and Dipteridaceae with Clathropteris, Dictyophyllum and Thaumatopteris with one species each. Curled fern fronds have been attributed to the fossil-genus Spiropteris.Besides several key Rhaetian taxa, two key taxa for Hettangian floras, Phlebopteris angustiloba and Thaumatopteris brauniana, are present in Wüstenwelsberg, albeit not in large numbers. The comparison of the flora from Wüstenwelsberg with adjacent Rhaetian floras revealed distinct local differences in the respective floras, which are discussed in the light of paleogeography involving dispersal patterns or mechanisms and adaptations of the plants.