Pachypteris
Pachypteris is an extinct Mesozoic pteridosperm genus of fossil leaves. It has either been aligned with the peltasperms or the corystosperms.
Description
Pachypteris is represented by hypostomatic, bipinnate or unipinnate leaves, with alethopteridian venation, 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 and Ptilozamites. It includes the former denomination Thinnfeldia Ettingshausen 1852, a junior synonym of Pachypteris, as Doludenko showed. The genus was detailed by Harris, Doludenko, Schweitzer and Kirchner, Popa, and Gordenko. The genus Komlopteris, a segregate from Pachypteris, was defined by Barbacka.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 FederationJurassic
Antarctica, Argentina, Australia, Colombia, France, Georgia, India, Iran, Italy, Japan, Lithuania, Norway, Poland, Romania, the Russian Federation, Serbia and Montenegro, Tajikistan, the United Kingdom, and Uzbekistan.Cretaceous
ArgentinaSpecies
There are 9 species of Pachypteris:- P. auriculata
- P. brevipinnata
- P. crassa
- P. elegans
- P. gangapurensis
- P. haburensis
- P. holdenii
- P. indica
- ''P. lanceolata''