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'''Ctenocystoidea''' is an [[extinct]] [[clade]] of [[echinoderm]]s, which lived during the [[Cambrian]] and [[Ordovician]] periods. Unlike other echinoderms, ctenocystoids had [[bilateral symmetry]], or were only very slightly asymmetrical. They are believed to be one of the earliest-diverging branches of echinoderms, with their bilateral symmetry a trait shared with other [[deuterostome]]s. Ctenocystoids were once classified in the taxon [[Homalozoa]], also known as Carpoidea, alongside [[Cincta|cinctans]], [[Soluta (echinoderm)|solutes]], and [[Stylophora|stylophorans]].<ref name=Rahman2009/> Homalozoa is now recognized as a polyphyletic group of echinoderms without radial symmetry. Ctenocystoids were geographically widespread during the [[Middle Cambrian]], with one species surviving into the [[Late Ordovician]]. |
'''Ctenocystoidea''' is an [[extinct]] [[clade]] of [[echinoderm]]s, which lived during the [[Cambrian]] and [[Ordovician]] periods. Unlike other echinoderms, ctenocystoids had [[bilateral symmetry]], or were only very slightly asymmetrical. They are believed to be one of the earliest-diverging branches of echinoderms, with their bilateral symmetry a trait shared with other [[deuterostome]]s. Ctenocystoids were once classified in the taxon [[Homalozoa]], also known as Carpoidea, alongside [[Cincta|cinctans]], [[Soluta (echinoderm)|solutes]], and [[Stylophora|stylophorans]].<ref name=Rahman2009/> Homalozoa is now recognized as a polyphyletic group of echinoderms without radial symmetry. Ctenocystoids were geographically widespread during the [[Middle Cambrian]], with one species surviving into the [[Late Ordovician]]. |
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==Description== |
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Like other echinoderms, ctenocystoids had a skeleton made of [[stereom]] plates. Ctenocystoids had near bilateral symmetry, with some species exhibiting slightly asymmetric plate shapes. Like cinctans and ''Ctenoimbricata'', most ctenocystoids had large marginal plates surounding the sides of their body, but unlike cinctans and ''Ctenoimbricata'', which had only one row of marginal plates, most ctenocystoids had two rows of marginal plates. ''Courtessolea'' had only one row of marginal plates, like cinctans and ''Ctenoimbricata'',<ref name=Zamora2012/> whereas ''Conollia'' lost the marginal plates entirely.<ref name=Rahman2015/> The anus of ctenocystoids was surrounded by a pyramidal [[periproct]] as in other echinoderms. It was located at the posterior end, defining a clear anterior-posterior body axis unlike other echinoderms.<ref name=Zamora2015/> |
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==Classification== |
==Classification== |
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===Relationships=== |
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Ctenocystoids are likely among the most basal stem-group echinoderms.<ref name=Rahman2009/> ''Courtessolea'' was probably the most basal ctenocystoid, given its anatomical similarities to ''Ctenoimbricata'' and cinctans.<ref name=Zamora2012/> ''Conollia'' and ''Jugoszovia'' may be closely related to each other, as both have a reduced marginal frame compared to other ctenocystoids.<ref name=Rahman2015/> |
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===Genera=== |
===Genera=== |
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==Distribution== |
==Distribution== |
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<ref name=Lefebvre2018>{{Cite journal| doi = 10.1017/S0016756817000152| volume = 155| issue = 5| pages = 1190–1204| last1 = Lefebvre| first1 = Bertrand| last2 = Lerosey-Aubril| first2 = Rudy| title = Laurentian origin of solutan echinoderms: new evidence from the Guzhangian (Cambrian Series 3) Weeks Formation of Utah, USA| journal = Geological Magazine| date = 2018| url = https://www.cambridge.org/core/product/identifier/S0016756817000152/type/journal_article}}</ref> |
<ref name=Lefebvre2018>{{Cite journal| doi = 10.1017/S0016756817000152| volume = 155| issue = 5| pages = 1190–1204| last1 = Lefebvre| first1 = Bertrand| last2 = Lerosey-Aubril| first2 = Rudy| title = Laurentian origin of solutan echinoderms: new evidence from the Guzhangian (Cambrian Series 3) Weeks Formation of Utah, USA| journal = Geological Magazine| date = 2018| url = https://www.cambridge.org/core/product/identifier/S0016756817000152/type/journal_article}}</ref> |
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<ref name=Zhao2019>{{Cite journal| doi = 10.18814/epiiugs/2019/019013 | volume = 42| issue = 2| pages = 165–184| last1 = Zhao| first1 = Yuanlong| last2 = Yuan| first2 = Jinliang| last3 = Babcock| first3 = Loren E.| last4 = Guo| first4 = Qingjun| last5 = Peng| first5 = Jin| last6 = Yin| first6 = Leiming| last7 = Yang| first7 = Xinglian| last8 = Peng| first8 = Shanchi| last9 = Wang| first9 = Chunjiang| last10 = Gaines| first10 = Robert R.| last11 = Esteve| first11 = Jorge| last12 = Tai| first12 = Tongsu| last13 = Yang| first13 = Ruidong| last14 = Wang| first14 = Yue| last15 = Sun| first15 = Haijing| last16 = Yang| first16 = Yuning| title = Global Standard Stratotype-Section and Point (GSSP) for the conterminous base of the Miaolingian Series and Wuliuan Stage (Cambrian) at Balang, Jianhe, Guizhou, China| journal = Episodes| year=2019| url = http://www.episodes.org/journal/view.html?doi=10.18814/epiiugs/2019/019013}}</ref> |
<ref name=Zhao2019>{{Cite journal| doi = 10.18814/epiiugs/2019/019013 | volume = 42| issue = 2| pages = 165–184| last1 = Zhao| first1 = Yuanlong| last2 = Yuan| first2 = Jinliang| last3 = Babcock| first3 = Loren E.| last4 = Guo| first4 = Qingjun| last5 = Peng| first5 = Jin| last6 = Yin| first6 = Leiming| last7 = Yang| first7 = Xinglian| last8 = Peng| first8 = Shanchi| last9 = Wang| first9 = Chunjiang| last10 = Gaines| first10 = Robert R.| last11 = Esteve| first11 = Jorge| last12 = Tai| first12 = Tongsu| last13 = Yang| first13 = Ruidong| last14 = Wang| first14 = Yue| last15 = Sun| first15 = Haijing| last16 = Yang| first16 = Yuning| title = Global Standard Stratotype-Section and Point (GSSP) for the conterminous base of the Miaolingian Series and Wuliuan Stage (Cambrian) at Balang, Jianhe, Guizhou, China| journal = Episodes| year=2019| url = http://www.episodes.org/journal/view.html?doi=10.18814/epiiugs/2019/019013}}</ref> |
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<ref name=Zamora2012>{{Cite journal| doi = 10.1371/journal.pone.0038296| issn = 1932-6203| volume = 7| issue = 6| pages = –38296| last1 = Zamora| first1 = Samuel| last2 = Rahman| first2 = Imran A.| last3 = Smith| first3 = Andrew B.| others = Keith A. Crandall (ed.)| title = Plated Cambrian bilaterians reveal the earliest stages of echinoderm evolution| journal = PLoS ONE| accessdate = 2020-03-26| date = 2012-06-06| url = https://dx.plos.org/10.1371/journal.pone.0038296}}</ref> |
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<ref name=Zamora2015>{{Cite journal| doi = 10.1111/pala.12138| issn = 00310239| volume = 57| issue = 6| pages = 1105–1119| last1 = Zamora| first1 = Samuel| last2 = Rahman| first2 = Imran A.| others = Andrew Smith (ed.)| title = Deciphering the early evolution of echinoderms with Cambrian fossils| journal = Palaeontology| date = 2015}}</ref> |
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[[Category:Paleozoic echinoderms]] |
[[Category:Paleozoic echinoderms]] |
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[[Category:Prehistoric deuterostome classes]] |
[[Category:Prehistoric deuterostome classes]] |
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{{paleo-echinoderm-stub}} |
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Revision as of 02:50, 3 April 2020
| Ctenocystoidea Temporal range:
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | †Ctenocystoidea Robison & Sprinkle, 1969 |
Ctenocystoidea is an extinct clade of echinoderms, which lived during the Cambrian and Ordovician periods. Unlike other echinoderms, ctenocystoids had bilateral symmetry, or were only very slightly asymmetrical. They are believed to be one of the earliest-diverging branches of echinoderms, with their bilateral symmetry a trait shared with other deuterostomes. Ctenocystoids were once classified in the taxon Homalozoa, also known as Carpoidea, alongside cinctans, solutes, and stylophorans.[1] Homalozoa is now recognized as a polyphyletic group of echinoderms without radial symmetry. Ctenocystoids were geographically widespread during the Middle Cambrian, with one species surviving into the Late Ordovician.
Description
Like other echinoderms, ctenocystoids had a skeleton made of stereom plates. Ctenocystoids had near bilateral symmetry, with some species exhibiting slightly asymmetric plate shapes. Like cinctans and Ctenoimbricata, most ctenocystoids had large marginal plates surounding the sides of their body, but unlike cinctans and Ctenoimbricata, which had only one row of marginal plates, most ctenocystoids had two rows of marginal plates. Courtessolea had only one row of marginal plates, like cinctans and Ctenoimbricata,[2] whereas Conollia lost the marginal plates entirely.[3] The anus of ctenocystoids was surrounded by a pyramidal periproct as in other echinoderms. It was located at the posterior end, defining a clear anterior-posterior body axis unlike other echinoderms.[4]
Classification
Relationships
Ctenocystoids are likely among the most basal stem-group echinoderms.[1] Courtessolea was probably the most basal ctenocystoid, given its anatomical similarities to Ctenoimbricata and cinctans.[2] Conollia and Jugoszovia may be closely related to each other, as both have a reduced marginal frame compared to other ctenocystoids.[3]
Genera
The following genera of ctenocystoids have been named:[5][6]
| Genus | Discoverers | Named | Age | Location | Notes |
|---|---|---|---|---|---|
| Conollia | Domínguez Alonso | 2004 | Sandbian |  United Kingdom
|
The geologically youngest genus[3] |
| Courtessolea | Domínguez Alonso | 2004 | Wuliuan |  France
|
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| Ctenocystis | Robison & Sprinkle | 1969 | Middle Cambrian |  United States  Australia France
|
The first genus discovered[7] |
| Etoctenocystis | Fatka & Kordule | 1985 | Middle Cambrian |  Czechia
|
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| Jugoszovia | Džik & Orłowski | 1995 | Middle Cambrian |  Poland
|
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| Pembrocystis | Domínguez Alonso | 2004 | Middle Cambrian | United Kingdom
|
Distribution
Ctenocystoids were widespread during the Middle Cambrian, and have been found in the United States, the United Kingdom, Australia, France, Czechia, Poland, Spain, and Morocco.[6] The earliest ctenocystoids date to the beginning of Stage 5 of the Cambrian,[8] now known as the Wuliuan age.[9] Most species date to the Wuliuan and Drumian ages of the Cambrian.[3] The geologically youngest ctenocystoid, the only one known from the Ordovician, is Conollia, from the Sandbian of the United Kingdom.[3]
History
The class Ctenocystoidea was named in 1969 by Richard A. Robison and James Sprinkle.[7] It originally contained one species, Ctenocystis utahensis. The name comes from the Greek words ktenos, meaning "comb", and kystis, meaning "sac". It was originally assigned to the echinoderm subphylum Homalozoa.
References
- ^ a b Rahman, Imran A.; Clausen, Sébastien (2009). "Re‐evaluating the palaeobiology and affinities of the Ctenocystoidea (Echinodermata)". Journal of Systematic Palaeontology. 7 (4): 413–426. doi:10.1017/S1477201909990046.
- ^ a b Zamora, Samuel; Rahman, Imran A.; Smith, Andrew B. (2012-06-06). "Plated Cambrian bilaterians reveal the earliest stages of echinoderm evolution". PLoS ONE. 7 (6). Keith A. Crandall (ed.): –38296. doi:10.1371/journal.pone.0038296. ISSN 1932-6203. Retrieved 2020-03-26.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ a b c d e Rahman, Imran A.; Stewart, Sarah E.; Zamora, Samuel (2015). "The youngest ctenocystoids from the Upper Ordovician of the United Kingdom and the evolution of the bilateral body plan in echinoderms". Acta Palaeontologica Polonica. 60 (1): 39–48. doi:10.4202/app.00048.2013. ISSN 0567-7920. Retrieved 2020-04-02.
- ^ Zamora, Samuel; Rahman, Imran A. (2015). "Deciphering the early evolution of echinoderms with Cambrian fossils". Palaeontology. 57 (6). Andrew Smith (ed.): 1105–1119. doi:10.1111/pala.12138. ISSN 0031-0239.
- ^ Domínguez Aloso, Patricio; Jefferies, Richard P S; Gil Cid, Dolores (2002). "An annotated check-list of genera and species of carpoids". Coloquios de Paleontología. 53: 33–68. ISSN 1132-1660.
- ^ a b Zamora, Samuel; Lefebvre, Bertrand; Javier Álvaro, J.; Clausen, Sébastien; Elicki, Olaf; Fatka, Oldrich; Jell, Peter; Kouchinsky, Artem; Lin, Jih-Pai; Nardin, Elise; Parsley, Ronald; Rozhnov, Sergei; Sprinkle, James; Sumrall, Colin D.; Vizcaïno, Daniel; Smith, Andrew B. (2013). "Cambrian echinoderm diversity and palaeobiogeography". Geological Society, London, Memoirs. 38 (1): 157–171. doi:10.1144/M38.13.
- ^ a b Robison, R. A.; Sprinkle, J. (1969). "Ctenocystoidea: New Class of Primitive Echinoderms". Science. 166 (3912): 1512–1514. doi:10.1126/science.166.3912.1512.
- ^ Lefebvre, Bertrand; Lerosey-Aubril, Rudy (2018). "Laurentian origin of solutan echinoderms: new evidence from the Guzhangian (Cambrian Series 3) Weeks Formation of Utah, USA". Geological Magazine. 155 (5): 1190–1204. doi:10.1017/S0016756817000152.
- ^ Zhao, Yuanlong; Yuan, Jinliang; Babcock, Loren E.; Guo, Qingjun; Peng, Jin; Yin, Leiming; Yang, Xinglian; Peng, Shanchi; Wang, Chunjiang; Gaines, Robert R.; Esteve, Jorge; Tai, Tongsu; Yang, Ruidong; Wang, Yue; Sun, Haijing; Yang, Yuning (2019). "Global Standard Stratotype-Section and Point (GSSP) for the conterminous base of the Miaolingian Series and Wuliuan Stage (Cambrian) at Balang, Jianhe, Guizhou, China". Episodes. 42 (2): 165–184. doi:10.18814/epiiugs/2019/019013.