Yunia: Difference between revisions
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'''''Yunia''''' is a genus of extinct [[vascular plant]]s from the [[Early Devonian]] (Pragian or Siegenian stage, around {{Period |
'''''Yunia''''' is a genus of extinct [[vascular plant]]s from the [[Early Devonian]] (Pragian or Siegenian stage, around {{Period span/brief|Pragian}}). It was first described from the Posongchong Formation of [[Yunnan]], China. The leafless plant consisted of spiny stems, some 2 to 5 cm wide, which branched dichotomously at wide angles in a cruciate arrangement. Each stem contained [[vascular tissue]] with one or two strands of [[Xylem#Primary_and_secondary_xylem|protoxylem]]. The spore-forming organs ([[Sporangium|sporangia]]) were elongated and borne on short stalks. The spores had a relatively smooth sculptural pattern and were trilete (i.e. each spore has three lines on it resulting from its formation in a tetrahedral set of four spores).<ref name="HaoBeck1991"/><ref>{{Citation |last=Taylor |first=T.N. |last2=Taylor |first2=E.L. |last3=Krings |first3=M. |year=2009 |title=Paleobotany : The Biology and Evolution of Fossil Plants |edition=2nd |publication-place=Amsterdam; Boston |publisher=Academic Press |isbn=978-0-12-373972-8 |lastauthoramp=yes }}, p. 262</ref> |
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In 2004, Crane et al. published a simplified [[cladogram]] for the [[polysporangiophyte]]s in which ''Yunia'' is basal to the [[Lycopodiophyta|lycophytes]] (clubmosses and relatives).<ref>{{Citation |last=Crane |first=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 |url=http://www.amjbot.org/cgi/content/full/91/10/1683 |accessdate=2011-01-27 |doi=10.3732/ajb.91.10.1683}}</ref> It had previously been placed in the "[[trimerophyte]]s"<ref name="HaoBeck1991"/> (a group now thought to be paraphyletic), which were considered to have given rise to all the other vascular plants ''except'' the lycophytes.<ref>{{Harvnb|Taylor|Taylor|Krings|2009|p=259ff.}}</ref> |
In 2004, Crane et al. published a simplified [[cladogram]] for the [[polysporangiophyte]]s in which ''Yunia'' is basal to the [[Lycopodiophyta|lycophytes]] (clubmosses and relatives).<ref>{{Citation |last=Crane |first=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 |url=http://www.amjbot.org/cgi/content/full/91/10/1683 |accessdate=2011-01-27 |doi=10.3732/ajb.91.10.1683}}</ref> It had previously been placed in the "[[trimerophyte]]s"<ref name="HaoBeck1991"/> (a group now thought to be paraphyletic), which were considered to have given rise to all the other vascular plants ''except'' the lycophytes.<ref>{{Harvnb|Taylor|Taylor|Krings|2009|p=259ff.}}</ref> |
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Revision as of 21:51, 10 February 2011
| Yunia Temporal range: Early Devonian
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| Scientific classification | |
| Kingdom: | |
| Subkingdom: | |
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| (unranked): | |
| Genus: | † Yunia Hao & Beck (1991)[1]
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| Species | |
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† Y. dichotoma Hao & Beck (1991) | |
Yunia is a genus of extinct vascular plants from the Early Devonian (Pragian or Siegenian stage, around 411 to 408 million years ago). It was first described from the Posongchong Formation of Yunnan, China. The leafless plant consisted of spiny stems, some 2 to 5 cm wide, which branched dichotomously at wide angles in a cruciate arrangement. Each stem contained vascular tissue with one or two strands of protoxylem. The spore-forming organs (sporangia) were elongated and borne on short stalks. The spores had a relatively smooth sculptural pattern and were trilete (i.e. each spore has three lines on it resulting from its formation in a tetrahedral set of four spores).[1][2]
In 2004, Crane et al. published a simplified cladogram for the polysporangiophytes in which Yunia is basal to the lycophytes (clubmosses and relatives).[3] It had previously been placed in the "trimerophytes"[1] (a group now thought to be paraphyletic), which were considered to have given rise to all the other vascular plants except the lycophytes.[4]
| tracheophytes |
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References
- ^ a b c Hao, Shou-Gang; Beck, Charles B. (1991), "Yunia dichotoma, a Lower Devonian plant from Yunnan, China", Review of Palaeobotany and Palynology, 68 (3–4): 181–195, doi:10.1016/0034-6667(91)90022-U
{{citation}}: Unknown parameter|lastauthoramp=ignored (|name-list-style=suggested) (help) - ^ Taylor, T.N.; Taylor, E.L.; Krings, M. (2009), Paleobotany : The Biology and Evolution of Fossil Plants (2nd ed.), Amsterdam; Boston: Academic Press, ISBN 978-0-12-373972-8
{{citation}}: Unknown parameter|lastauthoramp=ignored (|name-list-style=suggested) (help), p. 262 - ^ Crane, P.R.; Herendeen, P.; Friis, E.M. (2004), "Fossils and plant phylogeny", American Journal of Botany, 91: 1683–99, doi:10.3732/ajb.91.10.1683, retrieved 2011-01-27
- ^ Taylor, Taylor & Krings 2009, p. 259ff.
