Seed ferns and Cycadophytes from the Triassic Flora of Thale (Germany)

摘要

This is the second paper on the Middle Triassic flora from Thale, dealing with the seed ferns and cycadophytes. Scytophyllum bergeri BORNEMANN is one of the common elements in the flora, in contrast to Sagenopteris sp. which is rare in the assemblage. However, it is the first evidence of Sagenopteris for the German Basin. The specimen described as ?Peltaspermum sp. is the only peltasperm ovuliferous organ known to date with attached ovule-bearing discs from the Middle Triassic of Europe. The cycad Apoldia tener (COMPTER 1883) ZIJLSTRA et al. 2009 (formerly Sphenozamites tener COMPTER) is by far the most common fossil plant in the assemblage. Nilssonia cf. neuberi STUR ex POTT et al. is relatively rare. The genus Bjuvia is emended to accommodate more species of large entire leaves characterised by amphistomy and cycadalean stomatal morphology. This includes Bjuvia thalensis n. sp., which is a common element in the Thale flora but is unknown from elsewhere. Narrow, long entire leaves from the Middle and Upper Triassic of Europe have been described under the name Taeniopteris angustifolia SCHENK, but have now been transferred to Taeniopteris kelberi n. sp. for nomenclatorial reasons. The macrosporophyll Dioonitocarpidium pennaeformis (SCHENK) RUHLE VON LILIENSTERN also occurs in the Thale flora. Two cycadalean leaf species (Apoldia tener and Bjuvia thalensis) from Thale flora sometimes have stomata with only two subsidiary cells instead of the usual 4-6, a feature that in gymnosperms occurs mainly in the Bennettitales.