Trimerophytopsida (orTrimeropsida) is aclass of earlyvascular plants from theDevonian, informally calledtrimerophytes. It contains genera such asPsilophyton. This group is probablyparaphyletic, and is believed to be the ancestral group from which both theferns andseed plants evolved. Different authors have treated the group at differenttaxonomic ranks using the namesTrimerophyta,Trimerophytophyta,Trimerophytina,Trimerophytophytina andTrimerophytales.
At first most of the early land plants other than the bryophytes (i.e. thepolysporangiophytes) were placed in a single class Psilophyta, established in 1917 by Kidston and Lang.[1] As additional fossils were discovered and described, it became apparent that the Psilophyta were not a homogeneous group of plants. In 1968 Banks first proposed splitting this taxon into three groups, which he put at therank ofsubdivision; he clarified his proposal in 1975. One of the three groups was the Trimerophytina.[2][3] The subdivision is based on thetype genusTrimerophyton, which might be expected to produce 'Trimerophytophytina' as the name of the subdivision, but theInternational Code of Nomenclature for algae, fungi, and plants allows the 'phyton' part of a genus name optionally to be omitted before '-ophyta', '-ophytina' and '-opsida'.[4]
The group has also since been treated as a division under the name Trimerophyta[5] or Trimerophytophyta, as a class under the name Trimeropsida or Trimerophytopsida (as here),[6] and as an order under the name Trimerophytales.[7]
^Crane, P.R.; Herendeen, P. & Friis, E.M. (2004), "Fossils and plant phylogeny",American Journal of Botany,91 (10):1683–99,doi:10.3732/ajb.91.10.1683,PMID21652317
^Banks, H.P. (1968), "The early history of land plants", in Drake, E.T. (ed.),Evolution and Environment: A Symposium Presented on the Occasion of the 100th Anniversary of the Foundation of Peabody Museum of Natural History at Yale University, New Haven, Conn.: Yale University Press, pp. 73–107, cited inBanks, H.P. (1980), "The role ofPsilophyton in the evolution of vascular plants",Review of Palaeobotany and Palynology,29:165–176,doi:10.1016/0034-6667(80)90056-1
^Taylor, T.N.; Taylor, E.L. & Krings, M. (2009),Paleobotany, The Biology and Evolution of Fossil Plants (2nd ed.), Amsterdam; Boston: Academic Press,ISBN978-0-12-373972-8, p. 227
^See, e.g.,Berry, C.M. & Fairon-Demaret, M. "The Middle Devonian Flora Revisited". InGensel & Edwards (2001), pp. 120–139.
^Banks, H.P. (1970),Evolution and Plants of the Past, London: Macmillan Press,ISBN978-0-333-14634-7, p. 57
Gensel, P.G. & Edwards, D., eds. (2001),Plants invade the Land : Evolutionary & Environmental Perspectives, New York: Columbia University Press,ISBN978-0-231-11161-4
