Pachypteris
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Pachypteris
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Pachypteris (Brongn.) T.M.Harris.[1] is a Mesozoic pteridosperm leaf fossil probably belonging to the seed fern Order Peltaspermales.[2]
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).[1] The genus Komlopteris, a segregate from Pachypteris, was defined by Barbacka (1994).[8]
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.
References
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- ↑ Doludenko, M.P., 1971. Thinnfeldia - mladsii sinonim Pachypteris. Paleontological Journal, 2: 99-104.
- ↑ Harris, T.M., 1964. The Yorkshire Jurassic Flora. Part 2: Caytoniales, Cycadales and Pteridospermales, 2. British Museum (Natural History), London, 1-192 pp.
- ↑ Doludenko, M.P., 1974. On the relation of the genera Pachyperis, Thinnfeldia and Cycadopteris, Symposium on Morphological and Stratigraphical Paleobotany. Birbal Sahni Institute of Paleobotany, Lucknow, pp. 8-16.
- ↑ Schweitzer, H.-J. and Kirchner, M., 1998. Die Rhato-Jurassischen Floren des Iran und Afghanistans: 11. Pteridospermophyta und Cycadophyta. I. Cycadales. Palaeontographica Abt. B, 248: 1-85.
- ↑ Popa, M.E., 2000. Aspects of Romanian Early Jurassic palaeobotany and palynology. Part II. A new species of Pachypteris from Cristian. Review of Palaeobotany and Palynology, 111: 31-47.
- ↑ Barbacka, M., 1994. Komlopteris Barbacka, gen. nov., a segregate from Pachypteris Brongniart. Review of Palaeobotany and Palynology(83): 339-349.
