Pachypteris

Pachypteris is represented by hypostomatic, bipinnate or unipinnate leaves, with alethopteridian venation (midvein and secondary veins divided once or twice before reaching the pinnule margin), pinnules with entire margins and rounded apices. The stomata are haplocheilic, monocyclic or dicyclic, usually depressed, with the guard cells occurring in the lowermost part of the stoma.

The affinities of Pachypteris lay with Cycadopteris, Komlopteris, Dicroidium (a typical Corystospermalean foliage) and Ptilozamites. It includes the former denomination Thinnfeldia Ettingshausen 1852, a junior synonym of Pachypteris, as Doludenko (1971)^[3] showed. The genus was detailed by Harris (1964),^[4] Doludenko (1974),^[5] Schweitzer and Kirchner (1998),^[6] Popa (2000),^[7] and Gordenko (2007).^[8] The genus Komlopteris, a segregate from Pachypteris, was defined by Barbacka (1994).^[9]

Pachypteris includes about 20 species ranging from late Triassic to Lower Cretaceous, such as P. speciosa, P. rhomboidalis, P. gradinarui, etc. This genus is mainly a boreal taxon, being extensively reported in Europe, Iran, Afghanistan, China and North America, but it has been cited from Gondwanic occurrences as well, such as India, Argentina and Australia.

Fossils of Pachypteris have been registered in:^[10]