View source for Conulariida

{{Short description|Family of cnidarians (fossil)}}
{{Automatic taxobox
|taxon = Conulariida
|fossil_range = {{fossil range|Upper Cambrian|earliest=555|Triassic}}
| image = Conulariid03.jpg
| image_caption = Conulariid from the [[Mississippian (geology)|Mississippian]] (c. 360 to 325 mya) of Indiana; scale in mm.
| subdivision_ranks = Genera
| subdivision = See text.
}}

'''Conulariida''' is a poorly understood fossil group that has possible affinity with the [[Cnidaria]]. Their exact position as a taxon of extinct [[medusozoa]]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 until the [[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>

==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 (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
 | doi = 10.4202/app.00049.2013 
 | title = Alleged cnidarian ''Sphenothallus'' in the Late Ordovician of Baltica, its mineral composition and microstructure 
 | year = 2015
 | author = Vinn, O.
 | author2 = Kirsimäe, K. 
 | journal = Acta Palaeontologica Polonica
 | volume = 60
 | pages = 1001–1008  
 | 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.}}</ref>

==Fossil record==
[[Image:Conulariid01.jpg|thumb|right|Close-up of a conulariid from the Mississippian of Indiana; scale in mm.]]
[[Image:Conularia milwaukeensis.jpg|thumb|right|[[Conularia milwaukeensis]] from the Middle Devonian of Wisconsin.]]

With the exception of the [[Ediacaran]] ''[[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 | hdl-access = free}}</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}}).

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

==Lifestyle==
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.

==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.

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.

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.

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. |author-link1=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.
{{Expand section|date=June 2008}}

==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>

==List of genera==
{{div col|colwidth=24em}}
*''[[Aciconularia]]''
*''[[Adesmoconularia]]''
*''[[Anaconularia]]''
*''[[Archaeoconularia]]''
*''[[Australoconularia]]''
*''[[Barbigodithreca]]''
*''[[Calloconularia]]''
*''[[Circonularia]]''
*''[[Climacoconus]]''
*''[[Conchopeltis]]''
*''[[Conomedusites]]''
*''[[Conulariella]]''
*''[[Conularia]]''
*''[[Conularina]]''
*''[[Conulariopsis]]''
*''[[Ctenoconularia]]''
*''[[Diconularia]]''
*''[[Eoconularia]]''
*''[[Exoconularia]]''
*''[[Flectoconularia]]''
*''[[Garraconularia]]''
*''[[Glyptoconularia]]''
*''[[Gondaconularia]]''
*''[[Hexangulaconularia]]''
*''[[Holoconularia]]''
*''[[Mabianoconullus]]''
*''[[Mesoconularia]]''
*''[[Metaconularia]]''
*''[[Neoconularia]]''
*''[[Notoconularia]]''
*''[[Palaenigma]]''
*''[[Paraconularia]]''
*''[[Pseudoconularia]]''
*''[[Quadrosiphogonuchites]]''
*''[[Reticulaconularia]]''
*''[[Tasmanoconularia]]''
{{Div col end}}

==References==
{{Reflist}}

=== 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 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 journal|author=Hughes, N. C.|author2=Gunderson, G. D.|author3=Weedon, M. J.|name-list-style=amp|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 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}}

==External links==
*{{Cite web|url=http://www.ucmp.berkeley.edu/cnidaria/conulariida.html|title=The Conulariida: Mystery fossils|author1=Zdenka Brabcova |author2=Petr Kraft |date= 2003-06-15|accessdate=2008-02-04}}
*http://www.uga.edu/strata/cincy/fauna/conulariida/Conularia.html

{{Taxonbar|from=Q2567954}}

[[Category:Scyphozoa]]
[[Category:Prehistoric cnidarians]]
[[Category:Early Triassic extinctions]]