{{Short description|Extinct genus of Devonian plants}} {{Use dmy dates|cs1-dates=ly|date=June 2020}} {{Automatic taxobox | name = ''Taeniocrada'' | fossil_range = {{Geological range/linked|Devonian}} | image = Taeniocrada decheniana.jpg | image_caption = Taeniocrada decheniana | taxon = Taeniocrada | authority = D. White<ref name="Taylor1986cite"/> | subdivision_ranks = Species | subdivision = {{Species list |T. decheniana|(Goep.) Kräusel & Weyland (1930) |T. dubia|Kräusel & Weyland (1930) |T. elschanica|Chirkova-Zalesskaja (1957) |T. gracilis|Chirkova-Zalesskaja (1957) |T. latissima|Senkevitsch (1978) |T. lesquereuxii|White (1902) |T. orientalis|Radchenko in Lepjechina et al. (1962) |T. pilosa|Senkevitsch (1978) |T.(?) spitsbergensis|Høeg (1942) |T. stilesvillensis|Taylor (1986) |T. timanica|Chirkova-Zalesskaja (1957) |T. tuviensis| }}List taken from Taylor (1986).<ref name="Taylor1986"/> }} thumb
'''''Taeniocrada''''' is a genus of extinct plants of Devonian age ({{Period span/brief|Devonian|-1}}). It is used as a form genus for fossil plants with leafless flattened stems which divided dichotomously and had prominent midribs regarded as containing vascular tissues.<ref name="Taylor1986"/> It has been suggested that some species assigned to this genus were aquatic.<ref name="TaylorTaylorKrings2009p248"/>
==Description==
Key features of the original definition of the genus ''Taeniocrada'' were that it possessed leafless flattened stems with prominent midribs which appeared to contain vascular tissues. As more species were added to the genus, its definition became less clear.<ref name="Taylor1986"/> Three of the better-known species are ''T. decheniana'', ''T. dubia'', and ''T. stilesvillensis''.
'''''Taeniocrada decheniana''''', from the Lower Devonian,<ref name="Taylor1986"/> had separate fertile stems which repeatedly branched in a dichotomous fashion ending in sporangia between 3 and 7 mm long. A few sporangia were borne on the sides of stems. The species was found in dense stands. It has been suggested that it was aquatic or semi-aquatic because it apparently did not have stomata on the flattened stems.<ref name="TaylorTaylorKrings2009p248"/>
'''''Taeniocrada dubia''''', from the Lower Devonian,<ref name="Taylor1986"/> was originally considered to be a rhyniophyte, i.e. a very early vascular plant, but this has been questioned. The central strand appears to have been composed of tubes of differing diameters with helical thickenings which were part of the original cell wall, rather than being produced as the cell matured as would be the case in the xylem of vascular plants.<ref name="TaylorTaylorKrings2009p248"/>
'''''Taeniocrada stilesvillensis''''', from the Upper Devonian of New York, had stems which divided either into two equal branches (i.e. dichotomously) or so that one branch was more of a 'main stem' than the other (i.e. pseudomonopodially). Ridges along the stem bore hair-like structures. True vascular tissue was present.<ref name="TaylorTaylorKrings2009p248"/>
A further nine species still considered to be part of the genus are listed and in some cases briefly described by Taylor (1986).<ref name="Taylor1986"/>
==Taxonomy==
The genus ''Taeniocrada'' has a somewhat complex taxonomic history. It was created by White with the species ''T. lesquereuxii'' for fossils previously regarded as algae but which proved to have vascular tissue. (The date of creation is variously given as 1902,<ref name="Taylor1986cite"/> 1903<ref name="FryBanks1955"/> and 1913.<ref name="Schultka1991"/>) It was basically a form genus, used for fossil plants with flattened membrane-like stems, which were leafless with a prominent central thickened strand and which showed dichotomous branching. In 1986 Taylor noted that as more species had been added to the genus, the characters it possessed became wider, so that some species had sporangia which were at the ends of stems (terminal), others had sporangia borne on the sides of stems (lateral). Some species had smooth stems, other had stems with 'emergences' (e.g. spines or hairs). Some were known to have vascular tissue, others not. He concluded that the genus no longer matched any existing description and that its species probably belonged to more than one genus. He also suggested that the flattening of the stems might be artefacts of preservation.<ref name="Taylor1986"/>
In 1985, Fairon-Demaret created a new genus for fossils previously assigned to ''Taeniocrada'' but which had single lateral sporangia. She transferred ''T. langii'' (named by Stockmans in 1939) to ''Stockmansella langii'', leaving ''Taeniocrada'' for fossil plants with terminal sporangia borne on branched structures.<ref name="FaironDemaret1986"/>
==Phylogeny==
Following Taylor (1986), Crane et al. (2004) regard ''Taeniocrada'' as a polyphyletic genus (i.e. a mixture of species with no close common ancestor). Some species may belong to the Rhyniopsida as defined by Kenrick and Crane.<ref name="CraneHerendeenFriis2004p1688"/>
==References== {{Reflist|refs=
<ref name="CraneHerendeenFriis2004p1688">{{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 }}, p. 1688</ref>
<ref name="FaironDemaret1986">{{Citation |last=Fairon-Demaret |first=M. |year=1986 |title=''Stockmansella'', a new name for ''Stockmansia'' |journal=Taxon |volume=35 |page=334 |doi=10.2307/1221284|jstor=1221284 }}, cited in {{Harvnb|Taylor|Taylor|Krings|2009}} (Her first transfer from ''Taeniocrada'' was in 1985 to ''Stockmansia'', but this proved to be an illegitimate name.)</ref>
<ref name="FryBanks1955">{{Citation |last1=Fry |first1=Wayne L. |last2=Banks |first2=Harlan P. |year=1955 |title=Three New Genera of Algae from the Upper Devonian of New York |journal=Journal of Paleontology |volume=29 |issue=1 |pages=37–44 |name-list-style=amp |jstor=1300127}}</ref>
<ref name="Schultka1991">{{Citation |last=Schultka |first=S. |year=1991 |title=''Huvenia elongata'' nov. spec. (ex. Formgenus ''Taeniocrada'' White 1913) im hohen Ems des Rheinischen Schiefergebirges |journal=Argumenta Palaeobotanica |volume=8 |pages=169–178 }}, cited in {{Harvnb|Taylor|Taylor|Krings|2009|p=1161}}</ref>
<ref name="Taylor1986">{{Citation |last=Taylor |first=D.W. |year=1986 |title=Anatomical and morphological study of a new species of ''Taeniocrada'', a Devonian tracheophyte from New York State |journal=Review of Palaeobotany and Palynology |volume=47 |issue=1–2 |pages=63–87 |doi=10.1016/0034-6667(86)90006-0 |bibcode=1986RPaPa..47...63T }}</ref>
<ref name="TaylorTaylorKrings2009p248">{{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 }}, pp. 248–249</ref>
<ref name="Taylor1986cite">{{Harvnb|Taylor|1986}}, citing {{Citation |last=White |first=D. |year=1902 |title=Description of a fossil alga from the Chemung of New York with remarks on the genus ''Haliserites'' Sternberg |journal=N. Y. Mus. Bull. |volume=52 |pages=593–605 }}</ref>
}}
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Category:Early Devonian plants Category:Early Devonian first appearances Category:Late Devonian genus extinctions Category:Middle Devonian plants Category:Late Devonian plants Category:Paleozoic life of Ontario Category:Paleozoic life of New Brunswick Category:Paleozoic life of Newfoundland and Labrador Category:Paleozoic life of Quebec Category:Prehistoric plant genera