Pachypteris (Brongn.) T.M.Harris. is a Mesozoic pteridosperm leaf fossil probably belonging to the seed fern Order Peltaspermales. Description 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. Taxonomy 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) showed. The genus was detailed by Harris (1964), Doludenko (1974), Schweitzer and Kirchner (1998), Popa (2000), and Gordenko (2007). The genus Komlopteris, a segregate from Pachypteris, was defined by Barbacka (1994). 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. Distribution Fossils of Pachypteris have been registered in: Triassic Brazil, China, Germany, Japan, and the Russian Federation Jurassic Antarctica, Argentina, Australia, Colombia (Valle Alto Formation, Caldas), France, Georgia, India, Iran, Italy, Japan, Lithuania, Norway, Poland, Romania, the Russian Federation, Serbia and Montenegro, Tajikistan, the United Kingdom, and Uzbekistan. Cretaceous Argentina References Pteridospermatophyta Early Triassic genus first appearances Olenekian genera Anisian genera Ladinian genera Carnian genera Norian genera Rhaetian genera Hettangian genera Sinemurian genera Pliensbachian genera Toarcian genera Aalenian genera Bajocian genera Bathonian genera Callovian genera Oxfordian genera Kimmeridgian genera Tithonian genera Berriasian genera Valanginian genera Hauterivian genera Barremian genera Aptian genera Albian genera Cenomanian genera Triassic plants Jurassic plants Early Cretaceous plants Late Cretaceous plants Late Cretaceous genus extinctions Mesozoic Antarctica Mesozoic life of Asia Mesozoic life of Europe Mesozoic life of South America Prehistoric plants of South America Triassic Brazil Fossils of Brazil Jurassic Argentina Cretaceous Argentina Fossils of Argentina Jurassic Colombia Fossils of Colombia Fossil taxa described in 1828 Fossils of Serbia