Pachypteris

Pachypteris is a Mesozoic pteridosperm ("seed fern") genus of fossil leaves. It has either been aligned with the peltasperms[1] or the corystosperms.[2]

Pachypteris
Scientific classification
Kingdom:
Plantae
Division:
†Pteridospermatophyta
Order:
†Peltaspermales
Genus:
Pachypteris

Species

See text

Synonyms
  • Thinnfeldia

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) [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.

Distribution

Fossils of Pachypteris have been registered in:[10]

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
  1. Taylor, Thomas N.; Taylor, Edith L.; Krings, Michael (2008). Paleobotany: The Biology and Evolution of Fossil Plants. Elsevier Science. pp. 695–696. ISBN 978-0-12-373972-8.
  2. Slodownik, Miriam; Hill, Robert S.; McLoughlin, Stephen (October 2023). "Komlopteris: A persistent lineage of post-Triassic corystosperms in Gondwana". Review of Palaeobotany and Palynology. 317: 104950. doi:10.1016/j.revpalbo.2023.104950.
  3. Doludenko, M.P., 1971. Thinnfeldia - mladsii sinonim Pachypteris. Paleontological Journal, 2: 99-104.
  4. Harris, T.M., 1964. The Yorkshire Jurassic Flora. Part 2: Caytoniales, Cycadales and Pteridospermales, 2. British Museum (Natural History), London, 1-192 pp.
  5. 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.
  6. 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.
  7. 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.
  8. Gordenko, N. V. (2007). "A new species of Pachypteris (Brongniart) Harris (Corystospermales) from the Bathonian continental deposits of the Kursk Region, Russia". Paleontological Journal. 41 (11): 1091–1102. doi:10.1134/S0031030107110081. S2CID 129422912.
  9. Barbacka, M., 1994. Komlopteris Barbacka, gen. nov., a segregate from Pachypteris Brongniart. Review of Palaeobotany and Palynology(83): 339-349.
  10. Pachypteris at Fossilworks.org
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