A shoot with attached leaves of Desmiophyllum harrisii from the Rhaetian of Bavaria

Ferns are the most diverse group in the Early Jurassic plant assemblage of the Mecsek Mountains in southern Hungary and, considering their abundance and diversity, are an important element of the flora. Five families were recognized so far from the locality; these are, in order of abundance, the Dipteridaceae (48% of collected fern remains), Matoniaceae (25%), Osmundaceae (21%), Marattiaceae (6%) and Dicksoniaceae (three specimens). Ferns are represented by 14 taxa belonging to nine genera: Marattiopsis hoerensis, Todites princeps, Todites goeppertianus, Phlebopteris angustiloba, Phlebopteris kirchneri Barbacka and Kustatscher sp. nov., Matonia braunii, Thaumatopteris brauniana, Clathropteris meniscoides, Dictyophyllum nilssoni, Dictyophyllum rugosum, Cladophlebis denticulata, Cladophlebis haiburnensis, Cladophlebis roessertii, and Coniopteris sp. Ferns from the Mecsek Mts. are rarely found in association with other plants. They co-occur mostly with leaves of Nilssonia, leaflets of Sagenopteris, and rarely with other plants. The most commonly co-occurring fern species is P. kirchneri Barbacka and Kustatscher sp. nov. According to our statistical approach (PCA, Ward cluster analysis), the fern taxa cluster in four groups corresponding to their environmental preferences, determined by moisture and disturbance. Most taxa grew in monospecific thickets in disturbed areas; a few probably formed bushes in mixed assemblages, whereas one taxon, P. kirchneri, probably was a component of the understorey in a stable, developed succession of humid environments.