Trimerophytopsida

{{Short description|Extinct class of vascular plants}} {{Automatic taxobox | fossil_range = Devonian | image = Psilophyton dawsonii-rev.jpg | image_caption = Fossil of ''Psilophyton dawsonii'' | taxon = Trimerophytopsida | authority = A.S.Foster & E.M.Gifford 1974 | subdivision_ranks = Order | subdivision = †'''Trimerophytales''' | synonyms = * Trimerophyta (''orth. var.'') * Psilophyta (''orth. var.'') * Trimerophytophyta Bold 1973 * Trimerophytophytina Banks 1975 * Psilophytophyta Zimmermann 1930 * Psilophytophytina Kryshtofovich 1945 | synonyms_ref = {{citation needed|date=August 2016}} }}

'''Trimerophytopsida''' (or '''Trimeropsida''') is a class of early vascular plants from the Devonian, informally called '''trimerophytes'''. It contains genera such as ''Psilophyton''. This group is probably paraphyletic, and is believed to be the ancestral group from which both the ferns and seed plants evolved. Different authors have treated the group at different taxonomic ranks using the names '''Trimerophyta''', '''Trimerophytophyta''', '''Trimerophytina''', '''Trimerophytophytina''' and '''Trimerophytales'''.

==Taxonomy== At first most of the early land plants other than the bryophytes (i.e. the polysporangiophytes) were placed in a single class Psilophyta, established in 1917 by Kidston and Lang.<ref name="Crane_2004">{{Citation |last1=Crane |first1=P.R. |last2=Herendeen |first2=P. |last3=Friis |first3=E.M. |year=2004 |title=Fossils and plant phylogeny |journal=American Journal of Botany |volume=91 |pages=1683–99 |doi=10.3732/ajb.91.10.1683 |name-list-style=amp |issue=10 |pmid=21652317|doi-access=free }}</ref> 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 the rank of subdivision; he clarified his proposal in 1975. One of the three groups was the Trimerophytina.<ref>{{Citation |last=Banks |first=H.P. |year=1968 |editor-last=Drake |editor-first=E.T. |contribution=The early history of land plants |title=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 |pages=73–107 |location=New Haven, Conn. |publisher=Yale University Press }}, cited in {{Citation |last=Banks |first=H.P. |year=1980 |title=The role of ''Psilophyton'' in the evolution of vascular plants |journal=Review of Palaeobotany and Palynology |volume=29 |pages=165–176 |doi=10.1016/0034-6667(80)90056-1 }}</ref><ref>{{Citation |last=Banks |first=H.P. |year=1975 |title=Reclassification of Psilophyta |journal=Taxon |volume=24 |issue=4 |pages=401–413 |doi=10.2307/1219491|jstor=1219491 }}</ref> The subdivision is based on the type genus ''Trimerophyton'', which might be expected to produce 'Trimerophytophytina' as the name of the subdivision, but the ''International 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'.<ref>{{Citation |year=2012 |author1=McNeill, J. |author2=Barrie, F.R. |author3=Buck, W.R. |author4=Demoulin, V. |author5=Greuter, W. |author6=Hawksworth, D.L. |author7=Herendeen, P.S. |author8=Knapp, S. |author9=Marhold, K. |author10=Prado, J. |author11=Prud'homme Van Reine, W.F. |author12=Smith, G.F. |author13=Wiersema, J.H. |author14=Turland, N.J. |volume=Regnum Vegetabile 154 |title=International Code of Nomenclature for algae, fungi, and plants (Melbourne Code) adopted by the Eighteenth International Botanical Congress Melbourne, Australia, July 2011 |edition=electronic |location=Vienna |publisher=A.R.G. Gantner Verlag KG |url=http://www.iapt-taxon.org/nomen/main.php?page=title |access-date=2014-07-02 }}, Article 16.4</ref>

The group has also since been treated as a division under the name Trimerophyta<ref name="Taylor_et_al_2009_227">{{Citation |last1=Taylor |first1=T.N. |last2=Taylor |first2=E.L. |last3=Krings |first3=M. |year=2009 |title=Paleobotany, The Biology and Evolution of Fossil Plants |edition=2nd |location=Amsterdam; Boston |publisher=Academic Press |isbn=978-0-12-373972-8 |name-list-style=amp }}, p. 227</ref> or Trimerophytophyta, as a class under the name Trimeropsida or Trimerophytopsida (as here),<ref>See, e.g., {{harvc |last=Berry |first=C.M. |last2=Fairon-Demaret |first2=M. |contribution=The Middle Devonian Flora Revisited |name-list-style=amp |in=Gensel|in2=Edwards|year=2001|pp=120–139}}</ref> and as an order under the name Trimerophytales.<ref>{{Citation |last=Banks |first=H.P. |year=1970 |title=Evolution and Plants of the Past |location=London |publisher=Macmillan Press |isbn=978-0-333-14634-7 }}, p. 57</ref> * Subphylum †'''Trimerophytina''' Banks 1975<ref>{{cite book | author=Novíkov & Barabaš-Krasni | year=2015 | title=Modern plant systematics | pages=685 | publisher=Liga-Pres| isbn=978-966-397-276-3 |doi=10.13140/RG.2.1.4745.6164}}</ref><ref>{{cite journal | website=Collection of genus-group names in a systematic arrangement | title=Part 2- Plantae (starting with Chlorophycota) | url=http://mave.tweakdsl.nl/tn/genera2.html | archive-url=https://web.archive.org/web/20180816194336/http://mave.tweakdsl.nl/tn/genera2.html |url-status=dead |archive-date=16 August 2018 |access-date=30 June 2016}}</ref> ** Class †'''Trimerophytopsida''' Foster & Gifford 1974 [Trimeropsida Banks 1975; Psilophytopsida Kidston & Lang 1917; Psilophytidae Nemejc 1963] *** Order †Trimerophytales Banks ex Kasper et al. 1974 [Psilophytales Pia 1924] **** Family †Trimerophytaceae Banks 1967 [Psilophytaceae Hirmer 1927; Hostinellaceae Pia 1924; Dawsonitaceae Nemejc 1963] ***** Genus †''Dawsonites'' Nemejc 1963 ***** Genus †''Hostinella'' Barrande ex Stur 1882 ***** Genus †''Oocampsa'' Andrews, Gensel & Kasper 1975 ***** Genus †''Euphyllophyton'' Hao & Beck ***** Genus †''Pauthecophyton'' Xue et al. 2012 ***** Genus †''Psilophyton'' Dawson 1859 emend. Hueber & Banks 1967 ***** Genus †''Trimerophyton'' Hopping 1956

==See also== * Euphyllophyta, containing seed plants and ferns

==References== {{Reflist}}

==Bibliography== * {{Citation |year=2001 |editor-last=Gensel |editor-first=P.G. |editor2-last=Edwards |editor2-first=D. |title=Plants invade the Land : Evolutionary & Environmental Perspectives |location=New York |publisher=Columbia University Press |isbn=978-0-231-11161-4 |name-list-style=amp }}

Category:Devonian plants Category:Devonian first appearances Category:Devonian extinctions