Psilophytites

Psilophytites is a form genus of extinct plants; it was created by Høeg for spiny stems (axes) which cannot be assigned to a more precise genus or species,[3] usually because spore-forming organs or sporangia are not present.

Psilophytites
Temporal range: Late Silurian to Pragian
Scientific classification
Kingdom: Plantae
Clade: Polysporangiophytes
Division: incertae sedis
Genus: †Psilophytites
Høeg (1952)[1]
Species
  • P. gileppensis Gerrienne (1992)[2]

Fossils which have been placed in this genus have been found, among other locations, in Wales in formations of Early Silurian age (Přídolí, around 427 to 419 million years ago);[4] in the Wutubulake Formation in Xinjiang, China, of the same age;[5] in the Paraná basin, Brazil, from the Early Devonian (Lochkovian, around 419 to 411 million years ago);[6] and in Belgium from an outcrop of Early Devonian age (Lochkovian–Pragian, around 419 to 408 million years ago).[2]

Gerrienne named a new species, P. gileppensis, on the basis of the Belgian fossils, which were the oldest spiny plants found in that country. Their stems were equally or unequally dichotomously branched, bearing spreading spines which were long, narrow and undivided. A very spiny stem was sometimes found at the point of division of two other stems. As no sporangia were found and the internal structure of the stems is unknown, they were placed in Psilophytites.[2]

Banks considered that specimens assigned to Psilophytites could be a mixture of zosterophylls and trimerophytes.[3]

References
  1. Høeg, O.A. (1952), "Psilophytites, a new form genus of Devonian plants", Palaeobotanist, 1: 212–214, cited in Banks 1975
  2. Gerrienne, P. (1992), "Psilophytites gileppensis nov. sp., une plante épineuse du Dévonien inférieur du bord sud du synclinorium de Verviers (Belgique)", Geobios (in French and English), 25 (4): 439–447, doi:10.1016/S0016-6995(92)80068-O
  3. Banks, H.P. (1975), "Reclassification of Psilophyta", Taxon, 24 (4): 401–413, doi:10.2307/1219491, JSTOR 1219491
  4. Edwards, D.; Morel, E.M.; Paredes, F.; Ganuza, D.G. & Zúñiga, A. (2001), "Plant assemblages from the Silurian of southern Bolivia and their palaeogeographic significance", Botanical Journal of the Linnean Society, 135 (3): 229–250, doi:10.1111/j.1095-8339.2001.tb01093.x, p. 246
  5. Cai, C.-Y.; Dou, Y.-W. & Edwards, D. (1993), "New Observations on a Pridoli Plant Assemblage from North Xinjiang, Northwest China, with Comments on Its Evolutionary and Palaeogeographical Significance" (PDF), Geological Magazine, 130 (2): 155–170, doi:10.1017/S0016756800009821
  6. Gerrienne, Philippe; Bergamaschi, S.; Pereira, E.; Rodrigues, M.-A. C. & Steemans, P. (2001), "An Early Devonian flora, including Cooksonia, from the Paraná Basin (Brazil)", Review of Palaeobotany and Palynology, 116 (1–2): 19–38, doi:10.1016/S0034-6667(01)00060-4
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