Sphenophytes, pteridosperms and possible cycads from the Wuchiapingian (Lopingian, Permian) of Bletterbach (Dolomites, Northern Italy)

Abstract

The Bletterbach flora is the most important late Permian (Lopingian) flora of the Southern Alps. The study of a new fossiliferous bed stratigraphically below the cephalopod bed yielded almost 500 plant fossils, 28 of which belong to rare Lopingian plant groups: horsetails, seed ferns and possible cycads. Forty-five other fossils from the collection of Utrecht University were examined. The study of these more than fossils reveals a higher diversity of seed ferns and putative cycadophytes in the Lopingian of Europe than previously documented. Horsetails are represented by dispersed sporophylls, stem fragments and leaf sheaths too badly preserved for attribution to a species. Seed ferns are represented by Sphenopteris and the new genus Germaropteris, which includes G. martinsii (Germar in Kurtze 1839) Kustatscher, Kerp et Van Konijnenburg-van Cittert comb. nov., a species from the German Zechstein formerly assigned to various genera (e.g., Callipteris, Lepidopteris, Peltaspermum). Two species of Sphenopteris (S. suessii, S. sp.) are recorded for the first time from Lopingian strata of the Southern Alps. Remarkable are pinnae with alethopteroid pinnules, because similar forms have not been described from Lopingian deposits of Europe. Putative cycadophytes are represented by two taeniopterid leaves (Taeniopteris sp. A and T. sp. B) and a fragment of a pinnate cycad-like leaf. The Bletterbach flora is one of the most diverse European Lopingian floras, at least with regard to the non-conifer taxa. The floras of the Germanic Zechstein Basin and of the Southern Alps are more similar than previously considered, notwithstanding the vicinity of the latter region to the northern margin of the Palaeotethys; there are no obvious similarities to the floras that occurred along the southern margin of the Palaeotethys. In Europe, plant fossils are generally very rare in Lopingian strata and the presence of plant fossils in the Zechstein Basin and the Southern Alps is apparently related to sea-level changes. They appear to be most common immediately before and after the maximum transgression or sea-level high-stand.