Jump to content

Conulariida: Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
← Previous edit
Content deleted Content added
VisualWikitext
→Fossil record: Added image.
m fixed fossil range
 
(46 intermediate revisions by 20 users not shown)
Line 1: Line 1:
{{Short description|Extinct order of cnidarians}}
{{Automatic taxobox
{{Automatic taxobox
|taxon = Conulariida
| taxon = Conulariida
| authority = Miller and Gurley, 1896
|fossil_range = {{fossil range|Upper Cambrian|earliest=555|Triassic}}
| fossil_range = Late [[Ediacaran]]-[[late Triassic]], {{fossil range|545|205}}
| image = Conulariid03.jpg
| image = Conulariid03.jpg
| image_caption = Conulariid from the [[Mississippian (geology)|Mississippian]] (c. 360 to 325 mya) of Indiana; scale in mm.
| image_caption = Conulariid from the [[Mississippian (geology)|Mississippian]] (c. 360 to 325 mya) of Indiana; scale in mm.
| image2 = Conularia gratiosa (fossil conulariids) (Salem Limestone, Middle Mississippian; Spergen Hill, Indiana, USA) 3.jpg
| image2_caption = Two ''[[Conularia]] gratiosa'' specimens from the [[Salem Limestone]] aged to the Middle Mississippian.
| subdivision_ranks = Genera
| subdivision_ranks = Genera
| subdivision = See text.
| subdivision = See text.
}}
}}


'''Conulariida''' is a poorly understood fossil group that has possible affinity with the [[Cnidaria]]. Their exact position as a family or suborder of extinct [[scyphozoa]]n [[cnidaria]]ns is highly speculative. Members of the Conulariida are commonly referred to as '''conulariids''' and appear in the fossil record from the mid or late [[Cambrian]] Period.<ref>{{Cite book|chapter-url=http://insugeo.org.ar/publicaciones/docs/scg_17/43.htm |chapter=Study of conulariid and related phosphatic conical exoskeletons from the Prague Basin (Czech Republic)|title=Ordovician from the Andes |author1=Ben M. Waggoner |author2=David Smith |date=1994|publisher=INSTITUTO SUPERIOR DE CORRELACIÓN GEOLÓGICA|series=Serie Correlación Geológica Nº 17|editor=G. L. Albanesi |editor2=M. S. Beresi |editor3=S. H. Peralta}}</ref>
'''Conulariida''' are an extinct group of [[Medusozoa|medusozoan]] [[Cnidaria|cnidarians]] known from fossils spanning from the latest [[Ediacaran]] up until the [[Triassic|Late Triassic]].<ref>{{Cite book|chapter-url=http://insugeo.org.ar/publicaciones/docs/scg_17/43.htm |chapter=Study of conulariid and related phosphatic conical exoskeletons from the Prague Basin (Czech Republic)|title=Ordovician from the Andes |author1=Ben M. Waggoner |author2=David Smith |date=1994|publisher=INSTITUTO SUPERIOR DE CORRELACIÓN GEOLÓGICA|series=Serie Correlación Geológica Nº 17|editor=G. L. Albanesi |editor2=M. S. Beresi |editor3=S. H. Peralta}}</ref><ref name=":0">{{cite journal |last1=Leme |first1=J. M. |last2=Van Iten |first2=H. |last3=Simões |first3=M. G. |year=2022 |title=A New Conulariid (Cnidaria, Scyphozoa) From the Terminal Ediacaran of Brazil |journal=Frontiers in Earth Science |volume=10 |pages=Article 777746 |bibcode=2022FrEaS..10.7746L |doi=10.3389/feart.2022.777746 |doi-access=free}}</ref><ref name=":1">{{Cite journal |last1=Van Iten |first1=Heyo |last2=Hughes |first2=Nigel C. |last3=John |first3=Douglas L. |last4=Gaines |first4=Robert R. |last5=Colbert |first5=Matthew W. |date=2023-04-27 |title=Conulariid soft parts replicated in silica from the Scotch Grove Formation (lower Middle Silurian) of east-central Iowa |url=https://www.cambridge.org/core/product/identifier/S0022336023000069/type/journal_article |journal=Journal of Paleontology |language=en |pages=1–10 |doi=10.1017/jpa.2023.6 |s2cid=258389436 |issn=0022-3360|doi-access=free }}</ref> They are almost exclusively known from their hard external structures (alternatively referred to as a theca, periderm or test), which were pyramidal in shape and made up of numerous lamellae.


==Structure==
==Structure==
The conulariids are [[fossil]]s preserved as shell-like structures made up of rows of calcium phosphate rods, resembling an ice-cream cone with fourfold symmetry, usually four prominently-grooved corners.<ref>Waggoner, B.M. & D. Smith (1994): The Conulariida, Mystery fossils. [[University of California Museum of Paleontology]] web page [http://www.ucmp.berkeley.edu/cnidaria/conulariida.html]</ref> New rods were added as the organism grew in length; the rod-based growth falsely gives the fossils a segmented appearance. Exceptional soft-part preservation has revealed that soft tentacles protruded from the wider end of the cone, and a [[holdfast]] from the pointed end attached the organisms to hard substrate. The prevailing reconstruction of the organism has it look superficially like a [[sea anemone]] sitting inside an angular, hard cone held perpendicular to the substrate. Conulariid shell is composed of francolite with carbonate ion concentration 8.1 wt%. The lattice parameters of conulariid apatite are a = 9.315(7) Å,
The conulariids are [[fossil]]s preserved as shell-like structures made up of rows of calcium phosphate rods, resembling an ice-cream cone with fourfold symmetry, usually four prominently-grooved corners.<ref>Waggoner, B.M. & D. Smith (1994): The Conulariida, Mystery fossils. [[University of California Museum of Paleontology]] web page [http://www.ucmp.berkeley.edu/cnidaria/conulariida.html]</ref> New rods were added as the organism grew in length; the rod-based growth falsely gives the fossils a segmented appearance. Exceptional soft-part preservation has revealed that soft tentacles protruded from the wider end of the cone, and a [[holdfast (biology)|holdfast]] from the pointed end attached the organisms to hard substrate. The prevailing reconstruction of the organism has it look superficially like a [[sea anemone]] sitting inside an angular, hard cone held perpendicular to the substrate. Conulariid shell is composed of francolite with carbonate ion concentration 8.1 wt%. The lattice parameters of conulariid apatite are a = 9.315(7) Å,
c = 6.888(3) Å.<ref name='VinnKirsimae2015'>{{cite journal
c = 6.888(3) Å.<ref name='VinnKirsimae2015'>{{cite journal
| doi = 10.4202/app.00049.2013
| doi = 10.4202/app.00049.2013
Line 21: Line 25:
| volume = 60
| volume = 60
| pages = 1001–1008
| pages = 1001–1008
}}</ref> The fine structure of their shell comprises multiple lamellae of alternately organic-rich and organic-poor layers.<ref>{{cite journal|doi=10.1017/jpa.2016.63|title=Microstructure and composition of the periderm of conulariids|journal=Journal of Paleontology|volume=90|issue=3|pages=389|year=2016|last1=Ford|first1=Robert C.|last2=Van Iten|first2=Heyo|last3=Clark|first3=George R.}}</ref>
| doi-access = free}}</ref> The fine structure of their shell comprises multiple lamellae of alternately organic-rich and organic-poor layers.<ref>{{cite journal|doi=10.1017/jpa.2016.63|title=Microstructure and composition of the periderm of conulariids|journal=Journal of Paleontology|volume=90|issue=3|pages=389|year=2016|last1=Ford|first1=Robert C.|last2=Van Iten|first2=Heyo|last3=Clark|first3=George R.|s2cid=133541791}}</ref>


==Fossil record==
==Fossil record==
[[Image:Conulariid01.jpg|thumb|right|Close-up of a conulariid from the Mississippian of Indiana; scale in mm.]]
[[Image:Conulariid01.jpg|thumb|Close-up of a conulariid from the Mississippian of Indiana; scale in mm.|left]]
[[Image:Conularia milwaukeensis.jpg|thumb|right|[[Conularia milwaukeensis]] from the Middle Devonian of Wisconsin.]]
[[Image:Conularia milwaukeensis.jpg|thumb|[[Conularia milwaukeensis]] from the Middle Devonian of Wisconsin.|left]]
[[File:UWGM 2723---Conularia niagarensis.jpg|thumb|A pair of ''[[Conularia niagarensis]]'' specimens from the Lower Silurian [[Waukesha Biota]] site in Wisconsin.]]

Setting aside for the moment the [[Precambrian]] ''[[Vendoconularia]]'', which may or may not be a conulariid at all,<ref>{{Cite journal| last1 = Van Iten| last4= Guimaraes Simoes | first1 = H.| last3=Coelho Rodrigues| last2=De Moraes Leme| first2 = J. | first3 = S. | first4 = M.| title = Reinterpretation of a Conulariid-Like Fossil from the Vendian of Russia| journal = Palaeontology| volume = 48| issue = 3| pages = 619–622| year = 2005| doi = 10.1111/j.1475-4983.2005.00471.x}}</ref> the '''Conulata''' fossil record begins with undeniable specimens in the Upper [[Cambrian]] (Hughes et al., 2000) and extends without significant break through numerous major mass extinctions. The Conulariids finally disappear from the fossil record during the Lower [[Triassic]] stage of the [[Triassic Period]] (~{{Ma|245}}).
With the inclusion of the possible [[Ediacaran]] conulariid ''[[Vendoconularia]]'', which may or may not be a conulariid at all,<ref>{{Cite journal| last1 = Van Iten| last4= Guimaraes Simoes | first1 = H.| last3=Coelho Rodrigues| last2=De Moraes Leme| first2 = J. | first3 = S. | first4 = M.| title = Reinterpretation of a Conulariid-Like Fossil from the Vendian of Russia| journal = Palaeontology| volume = 48| issue = 3| pages = 619–622| year = 2005| doi = 10.1111/j.1475-4983.2005.00471.x| hdl= 11449/31655 | s2cid= 247733826 | hdl-access = free}}</ref> and the definite late Ediacaran conulariid ''[[Paraconularia|Paraconularia ediacara]]'',<ref name=":0" /> the '''Conulata''' fossil record begins with undeniable specimens in the Upper Ediacaran and extends without significant break through numerous major mass extinctions. The Conulariids finally disappear from the fossil record during the [[Late Triassic]], by which time they were very rare, with only 8 documented occurrences across the entire Triassic. Their extinction may have been due to the rise of [[durophagous]] organisms as part of the [[Mesozoic marine revolution]].<ref>{{Cite journal |last=Lucas |first=Spencer G. |date=2012-03-22 |title=The Extinction of the Conulariids |journal=Geosciences |language=en |volume=2 |issue=1 |pages=1–10 |doi=10.3390/geosciences2010001 |issn=2076-3263 |doi-access=free }}</ref>


In North America, conulariids are generally more common in rocks of [[Ordovician]] and [[Carboniferous]] age.
In North America, conulariids are generally more common in rocks of [[Ordovician]] and [[Carboniferous]] age.


==Lifestyle==
==Lifestyle==
[[File:Estonian Museum of Natural History - Conularia.png|thumb|Life restoration of a conulariid, showing the soft-bodied anatomy ]]
Conulariids apparently lived only in normal-[[Marine (ocean)|marine]] waters, such as the oceans and inland seas. Fossils are commonly found in rocks representing offshore, even [[Anoxic sea water|anoxic]], marine bottom environments. This has led some scientists to infer that these animals may have drifted [[plankton]]ically for some or all of their lives, ultimately being buried in the anoxic sediments beneath the oxic waters in which they lived. However, basic functional considerations (such as the great weight of the shell) make such interpretations difficult to maintain.
Conulariids were [[Benthic zone|benthic]] animals that were [[Sessility (motility)|sessile]] and attached to a substrate at the base of the theca, older individuals may have become recumbent (tipped over).<ref>{{Citation |last1=Iten |first1=Heyo Van |title=14. Conulariids |date=2004-12-31 |url=https://www.degruyter.com/document/doi/10.7312/webb12678-015/html |work=The Great Ordovician Biodiversification Event |pages=119–123 |editor-last=Webby |editor-first=Barry D. |access-date=2023-06-25 |publisher=Columbia University Press |doi=10.7312/webb12678-015 |isbn=978-0-231-12678-6 |last2=Vyhlasová |first2=Zdenka |editor2-last=Paris |editor2-first=Florentin |editor3-last=Droser |editor3-first=Mary L. |editor4-last=Percival |editor4-first=Ian G.}}</ref> They are generally proposed to have been predators, using tentacles to ensnare prey.<ref>{{Cite journal |last1=Leme |first1=Juliana M. |last2=Van Iten |first2=Heyo |last3=Simões |first3=Marcello G. |date=2022-06-08 |title=A New Conulariid (Cnidaria, Scyphozoa) From the Terminal Ediacaran of Brazil |journal=Frontiers in Earth Science |volume=10 |doi=10.3389/feart.2022.777746 |bibcode=2022FrEaS..10.7746L |issn=2296-6463 |doi-access=free }}</ref>


==Phylogeny==
==Phylogeny==
About 20 genera and 150 species are known,<ref>[https://web.archive.org/web/20070927222951/http://www.zoobank.org/advancedquery.htm?searchType=tree&pp=10&so=a0&q=Conulariida]</ref> but except for local occurrences, Conulariids are relatively uncommon.
About 20 genera and 150 species are known,<ref>{{cite web |url=http://www.zoobank.org/advancedquery.htm?searchType=tree&pp=10&so=a0&q=Conulariida |title=ZooBank: The World Register of Animal Names |website=www.zoobank.org |access-date=14 January 2022 |archive-url=https://web.archive.org/web/20070927222951/http://www.zoobank.org/advancedquery.htm?searchType=tree&pp=10&so=a0&q=Conulariida |archive-date=27 September 2007 |url-status=dead}}</ref> but except for local occurrences, Conulariids are relatively uncommon.


The conulariids were originally thought to be [[anthozoa]]n cnidarians. However, the lack of septa or other features diagnostic of anthozoans led researchers to abandon this hypothesis. Ivantsov and Fedonkin (2002) posit that the conulariids were ancestrally tri-radially symmetrical, as typified with ''[[Vendoconularia]]'', typical of the structure seen in [[Ediacaran biota|Vendozooan]]s.<ref>{{Cite journal| first = A. Y.| last2 = Fedonkin| first2 = M. A.| url = http://vend.paleo.ru/pub/Ivantsov_Fedonkin_2002.pdf| last = Ivantsov| title = Conulariid-like fossil from the Vendian of Russia: a metazoan clade across the Proterozoic/Palaeozoic boundary| format = Free full text| journal = Palaeontology| volume = 45| issue = 6| pages = 1119–1129| year = 2002| doi = 10.1111/1475-4983.00283| access-date = 2015-08-29| archive-url = https://web.archive.org/web/20160128075232/http://vend.paleo.ru/pub/Ivantsov_Fedonkin_2002.pdf| archive-date = 2016-01-28| url-status = dead}}</ref> Conulariids are, however, not generally thought to be a part of the [[Ediacaran biota]] as their fossil record starts at Upper Cambrian.
The conulariids were originally thought to be [[anthozoa]]n cnidarians. However, the lack of septa or other features diagnostic of anthozoans led researchers to abandon this hypothesis. Ivantsov and Fedonkin (2002) posit that the conulariids were ancestrally tri-radially symmetrical, as typified with ''[[Vendoconularia]]'', typical of the structure seen in [[Ediacaran biota|Vendozooan]]s.<ref>{{Cite journal| first1 = A. Y.| last2 = Fedonkin| first2 = M. A.| last1 = Ivantsov| title = Conulariid-like fossil from the Vendian of Russia: a metazoan clade across the Proterozoic/Palaeozoic boundary| journal = Palaeontology| volume = 45| issue = 6| pages = 1119–1129| year = 2002| doi = 10.1111/1475-4983.00283| doi-access = free}}</ref> Conulariids are, however, technically a part of the [[Ediacaran biota]] as their fossil record starts at latest parts of that period.<ref name=":0" />


It is now also thought that the conulate trilobozoans derived their fourfold symmetry from a sixfold symmetry, as seen in ''Vendoconularia''. This in turn, is thought to be originally derived from an ancestral disk-like [[trilobozoa]]n three-fold symmetry.
It is now also thought that the conulate [[Trilobozoa|trilobozoans]] derived their fourfold symmetry from a sixfold symmetry, as seen in ''Vendoconularia''. This in turn, is thought to be originally derived from an ancestral disk-like [[trilobozoa]]n three-fold symmetry.{{citation needed|date=January 2024}}


Conulariids have generally been thought to be of [[Cnidaria]]n affinity, occupying a position near the base of the Cnidarian family tree. However, since the 2010s, authors consider conulariids to be most closely related to the [[Scyphozoa]], or the "true jellyfish". A possible arrangement is as relatives of the extant [[Staurozoa|stalked jellyfish]].<ref>{{cite book |last1=Iten & al. |authorlink1=Origin and Early Diversification of the Phylum Cnidaria: Key Macrofossils from the Ediacaran System of North and South America |editor1-last=Goffredo |editor1-first=S. |editor2-last=Dubinsky |editor2-first=Z. |title=The cnidaria, past, present and future : the world of Medusa and her sisters |publisher=Springer |isbn=978-3319313030 |pages=38–39 |date=2016-09-21 }}</ref> However, the nature of Conulariids and their phylogenetic relationships to other organisms remain poorly understood, and the supposed cnidarian affinity remains speculative.
Conulariids have generally been thought to be of [[Cnidaria]]n affinity, occupying a position near the base of the Cnidarian family tree. However, since the 2010s, authors consider conulariids to be members of the subclade [[Medusozoa]], though their exact placement within the clade is uncertain.<ref name=":1" />
{{Expand section|date=June 2008}}


==Pearls==
==Pearls==
Conulariids produced [[pearl]]s within their shells, similar to the way [[molluscs]] such as oysters, other [[pelecypod]]s, and some [[gastropod]]s do today. These pearls give a clue as to the internal anatomy of the conulariid animal. But due to their [[calcium phosphate]] composition, their crystal structure, and their extreme age, these pearls tend to be rather unattractive for use in or as decorative objects.<ref>{{cite book | url=https://books.google.com/?id=wFPgBAAAQBAJ&dq=Conulariid+pearls | title=Evolutionary Paleobiology of Behavior and Coevolution | publisher=Elsevier | author=Boucot, A.J. | year=2013 | pages=750 (page 69) | isbn=9781483290812}}</ref>
Conulariids produced [[pearl]]s within their shells, similar to the way [[molluscs]] such as oysters, other [[pelecypod]]s, and some [[gastropod]]s do today. These pearls give a clue as to the internal anatomy of the conulariid animal. But due to their [[calcium phosphate]] composition, their crystal structure, and their extreme age, these pearls tend to be rather unattractive for use in or as decorative objects.<ref>{{cite book | url=https://books.google.com/books?id=wFPgBAAAQBAJ&q=Conulariid+pearls | title=Evolutionary Paleobiology of Behavior and Coevolution | publisher=Elsevier | author=Boucot, A.J. | year=2013 | pages=750 (page 69) | isbn=9781483290812}}</ref>


==List of genera==
==List of genera==
Line 59: Line 63:
*''[[Climacoconus]]''
*''[[Climacoconus]]''
*''[[Conchopeltis]]''
*''[[Conchopeltis]]''
*''[[Conomedusites]]''
*''[[Conomedusites]]''?
*''[[Conulariella]]''
*''[[Conulariella]]''
*''[[Conularia]]''
*''[[Conularina]]''
*''[[Conularina]]''
*''[[Conulariopsis]]''
*''[[Conulariopsis]]''
Line 90: Line 95:


=== Bibliography ===
=== Bibliography ===
* {{cite journal|author1=Babcock, L. E. |author2=Feldmann, R. М. |year=1986|title=Devonian and Mississippian conulariids of North America. Part A. General description and Conularia|journal=Annals of Carnegie Museum|volume=55|pages=349–410}}
* {{cite journal|last1=Babcock |first1=L. E. |author2=Feldmann, R. М. |year=1986 |title=Devonian and Mississippian conulariids of North America. Part A. General description and Conularia |journal=Annals of Carnegie Museum |volume=55 |pages=349–410 |doi=10.5962/p.215203 |s2cid=251529155 |doi-access=free}}
* {{cite book|author=Babcock, L. E.|year=1991|chapter=The enigma of conulariid affinities|pages=133–143|editor1=A. M. Simonetta |editor2=S. Conway Morris |title=The Early Evolution of Metazoa and the Significance of Problematic Taxa|publisher=Cambridge University Press|location=Cambridge}}
* {{cite book |last=Babcock |first=L. E. |year=1991 |chapter=The enigma of conulariid affinities |pages=133–143 |editor1=A. M. Simonetta |editor2=S. Conway Morris |editor2-link=Simon Conway Morris |title=The Early Evolution of Metazoa and the Significance of Problematic Taxa |publisher=Cambridge University Press |location=Cambridge}}
* {{cite journal|author=Hughes, N. C.|author2=Gunderson, G. D.|author3=Weedon, M. J.|last-author-amp=yes|year=2000|title=Late Cambrian conulariids from Wisconsin and Minnesota|journal=Journal of Paleontology|volume=74|issue=5|pages=828–838|doi=10.1666/0022-3360(2000)074<0828:lccfwa>2.0.co;2}}
* {{cite journal |author=Hughes, N. C. |author2=Gunderson, G. D. |author3=Weedon, M. J. |year=2000 |title=Late Cambrian conulariids from Wisconsin and Minnesota |journal=Journal of Paleontology |volume=74 |issue=5 |pages=828–838 |doi=10.1666/0022-3360(2000)074<0828:lccfwa>2.0.co;2 |s2cid=130269674 }}
* {{cite book|author=Van Iten, H.|year=1991|chapter=Evolutionary affinities of conulariids|pages=145–155|editor1=A. M. Simonetta |editor2=S. Conway Morris |title=The Early Evolution of Metazoa and the Significance of Problematic Taxa|publisher=Cambridge University Press|location=Cambridge}}
* {{cite book |last=Van Iten |first=H. |year=1991|chapter=Evolutionary affinities of conulariids |pages=145–155 |editor1=A. M. Simonetta |editor2=S. Conway Morris |title=The Early Evolution of Metazoa and the Significance of Problematic Taxa |publisher=Cambridge University Press |location=Cambridge}}


==External links==
==External links==
Line 101: Line 106:
{{Taxonbar|from=Q2567954}}
{{Taxonbar|from=Q2567954}}


[[Category:Scyphozoa]]
[[Category:Staurozoa]]
[[Category:Prehistoric cnidarians]]
[[Category:Prehistoric cnidarians]]
[[Category:Early Triassic extinctions]]
[[Category:Early Triassic extinctions]]
[[Category:Cambrian genus extinctions]]
[[Category:Ediacaran first appearances]]

Latest revision as of 13:28, 20 November 2024

Conulariida
Temporal range: Late Ediacaran-late Triassic, 545–205 Ma
Conulariid from the Mississippian (c. 360 to 325 mya) of Indiana; scale in mm.
Two Conularia gratiosa specimens from the Salem Limestone aged to the Middle Mississippian.
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Cnidaria
Order: †Conulatae
Clade: †Conulariida
Miller and Gurley, 1896
Genera

See text.

Conulariida are an extinct group of medusozoan cnidarians known from fossils spanning from the latest Ediacaran up until the Late Triassic.[1][2][3] They are almost exclusively known from their hard external structures (alternatively referred to as a theca, periderm or test), which were pyramidal in shape and made up of numerous lamellae.

Structure

[edit]

The conulariids are fossils preserved as shell-like structures made up of rows of calcium phosphate rods, resembling an ice-cream cone with fourfold symmetry, usually four prominently-grooved corners.[4] New rods were added as the organism grew in length; the rod-based growth falsely gives the fossils a segmented appearance. Exceptional soft-part preservation has revealed that soft tentacles protruded from the wider end of the cone, and a holdfast from the pointed end attached the organisms to hard substrate. The prevailing reconstruction of the organism has it look superficially like a sea anemone sitting inside an angular, hard cone held perpendicular to the substrate. Conulariid shell is composed of francolite with carbonate ion concentration 8.1 wt%. The lattice parameters of conulariid apatite are a = 9.315(7) Å, c = 6.888(3) Å.[5] The fine structure of their shell comprises multiple lamellae of alternately organic-rich and organic-poor layers.[6]

Fossil record

[edit]
Close-up of a conulariid from the Mississippian of Indiana; scale in mm.
Conularia milwaukeensis from the Middle Devonian of Wisconsin.
A pair of Conularia niagarensis specimens from the Lower Silurian Waukesha Biota site in Wisconsin.

With the inclusion of the possible Ediacaran conulariid Vendoconularia, which may or may not be a conulariid at all,[7] and the definite late Ediacaran conulariid Paraconularia ediacara,[2] the Conulata fossil record begins with undeniable specimens in the Upper Ediacaran and extends without significant break through numerous major mass extinctions. The Conulariids finally disappear from the fossil record during the Late Triassic, by which time they were very rare, with only 8 documented occurrences across the entire Triassic. Their extinction may have been due to the rise of durophagous organisms as part of the Mesozoic marine revolution.[8]

In North America, conulariids are generally more common in rocks of Ordovician and Carboniferous age.

Lifestyle

[edit]
Life restoration of a conulariid, showing the soft-bodied anatomy

Conulariids were benthic animals that were sessile and attached to a substrate at the base of the theca, older individuals may have become recumbent (tipped over).[9] They are generally proposed to have been predators, using tentacles to ensnare prey.[10]

Phylogeny

[edit]

About 20 genera and 150 species are known,[11] but except for local occurrences, Conulariids are relatively uncommon.

The conulariids were originally thought to be anthozoan cnidarians. However, the lack of septa or other features diagnostic of anthozoans led researchers to abandon this hypothesis. Ivantsov and Fedonkin (2002) posit that the conulariids were ancestrally tri-radially symmetrical, as typified with Vendoconularia, typical of the structure seen in Vendozooans.[12] Conulariids are, however, technically a part of the Ediacaran biota as their fossil record starts at latest parts of that period.[2]

It is now also thought that the conulate trilobozoans derived their fourfold symmetry from a sixfold symmetry, as seen in Vendoconularia. This in turn, is thought to be originally derived from an ancestral disk-like trilobozoan three-fold symmetry.[citation needed]

Conulariids have generally been thought to be of Cnidarian affinity, occupying a position near the base of the Cnidarian family tree. However, since the 2010s, authors consider conulariids to be members of the subclade Medusozoa, though their exact placement within the clade is uncertain.[3]

Pearls

[edit]

Conulariids produced pearls within their shells, similar to the way molluscs such as oysters, other pelecypods, and some gastropods do today. These pearls give a clue as to the internal anatomy of the conulariid animal. But due to their calcium phosphate composition, their crystal structure, and their extreme age, these pearls tend to be rather unattractive for use in or as decorative objects.[13]

List of genera

[edit]

References

[edit]
  1. ^ Ben M. Waggoner; David Smith (1994). "Study of conulariid and related phosphatic conical exoskeletons from the Prague Basin (Czech Republic)". In G. L. Albanesi; M. S. Beresi; S. H. Peralta (eds.). Ordovician from the Andes. Serie Correlación Geológica Nº 17. INSTITUTO SUPERIOR DE CORRELACIÓN GEOLÓGICA.
  2. ^ a b c Leme, J. M.; Van Iten, H.; Simões, M. G. (2022). "A New Conulariid (Cnidaria, Scyphozoa) From the Terminal Ediacaran of Brazil". Frontiers in Earth Science. 10: Article 777746. Bibcode:2022FrEaS..10.7746L. doi:10.3389/feart.2022.777746.
  3. ^ a b Van Iten, Heyo; Hughes, Nigel C.; John, Douglas L.; Gaines, Robert R.; Colbert, Matthew W. (2023-04-27). "Conulariid soft parts replicated in silica from the Scotch Grove Formation (lower Middle Silurian) of east-central Iowa". Journal of Paleontology: 1–10. doi:10.1017/jpa.2023.6. ISSN 0022-3360. S2CID 258389436.
  4. ^ Waggoner, B.M. & D. Smith (1994): The Conulariida, Mystery fossils. University of California Museum of Paleontology web page [1]
  5. ^ Vinn, O.; Kirsimäe, K. (2015). "Alleged cnidarian Sphenothallus in the Late Ordovician of Baltica, its mineral composition and microstructure". Acta Palaeontologica Polonica. 60: 1001–1008. doi:10.4202/app.00049.2013.
  6. ^ Ford, Robert C.; Van Iten, Heyo; Clark, George R. (2016). "Microstructure and composition of the periderm of conulariids". Journal of Paleontology. 90 (3): 389. doi:10.1017/jpa.2016.63. S2CID 133541791.
  7. ^ Van Iten, H.; De Moraes Leme, J.; Coelho Rodrigues, S.; Guimaraes Simoes, M. (2005). "Reinterpretation of a Conulariid-Like Fossil from the Vendian of Russia". Palaeontology. 48 (3): 619–622. doi:10.1111/j.1475-4983.2005.00471.x. hdl:11449/31655. S2CID 247733826.
  8. ^ Lucas, Spencer G. (2012-03-22). "The Extinction of the Conulariids". Geosciences. 2 (1): 1–10. doi:10.3390/geosciences2010001. ISSN 2076-3263.
  9. ^ Iten, Heyo Van; Vyhlasová, Zdenka (2004-12-31), Webby, Barry D.; Paris, Florentin; Droser, Mary L.; Percival, Ian G. (eds.), "14. Conulariids", The Great Ordovician Biodiversification Event, Columbia University Press, pp. 119–123, doi:10.7312/webb12678-015, ISBN 978-0-231-12678-6, retrieved 2023-06-25
  10. ^ Leme, Juliana M.; Van Iten, Heyo; Simões, Marcello G. (2022-06-08). "A New Conulariid (Cnidaria, Scyphozoa) From the Terminal Ediacaran of Brazil". Frontiers in Earth Science. 10. Bibcode:2022FrEaS..10.7746L. doi:10.3389/feart.2022.777746. ISSN 2296-6463.
  11. ^ "ZooBank: The World Register of Animal Names". www.zoobank.org. Archived from the original on 27 September 2007. Retrieved 14 January 2022.
  12. ^ Ivantsov, A. Y.; Fedonkin, M. A. (2002). "Conulariid-like fossil from the Vendian of Russia: a metazoan clade across the Proterozoic/Palaeozoic boundary". Palaeontology. 45 (6): 1119–1129. doi:10.1111/1475-4983.00283.
  13. ^ Boucot, A.J. (2013). Evolutionary Paleobiology of Behavior and Coevolution. Elsevier. pp. 750 (page 69). ISBN 9781483290812.

Bibliography

[edit]
[edit]
Retrieved from "https://en.wikipedia.org/enwiki/w/index.php?title=Conulariida&oldid=1258576424"