Yunia: Difference between revisions
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'''''Yunia''''' is a genus of extinct [[vascular plant]]s from the [[Early Devonian]] (the [[Pragian]] stage, around 410 million years ago). The leafless plant consisted of spiny stems which branched dichotomously 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. 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>{{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> |
'''''Yunia''''' is a genus of extinct [[vascular plant]]s from the [[Early Devonian]] (the [[Pragian]] stage, around 410 million years ago). The leafless plant consisted of spiny stems which branched dichotomously 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. 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>{{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 |
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' (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 10:20, 7 February 2011
| Yunia Temporal range: Early Devonian
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| Genus: | † Yunia
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Yunia is a genus of extinct vascular plants from the Early Devonian (the Pragian stage, around 410 million years ago). The leafless plant consisted of spiny stems which branched dichotomously in a cruciate arrangement. Each stem contained vascular tissue with one or two strands of protoxylem. The spore-forming organs (sporangia) were elongated. 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]
In 2004, Crane et al. published a simplified cladogram for the polysporangiophytes in which Yunia is basal to the lycophytes (clubmosses and relatives).[2] It had previously been placed in the 'trimerophytes' (a group now thought to be paraphyletic) which were considered to have given rise to all the other vascular plants except the lycophytes.[3]
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References
- ^ 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.
