Editing Archaeocyatha

{{Short description|Class of sponges}}
{{Automatic taxobox
| fossil_range = {{fossil range|earliest=545|Fortunian|Middle Cambrian|Fortunian<ref name="c507">{{cite journal | last1=Wang | first1=Qi | last2=Dai | first2=Qiaokun | last3=Vayda | first3=Prescott | last4=Luo | first4=Jinzhou | last5=Shao | first5=Tiequan | last6=Liu | first6=Yunhuan | last7=Hua | first7=Hong | last8=Xiao | first8=Shuhai | title=Fortunian archaeocyath sponges acquired biomineralization in the beginning of the Cambrian explosion | journal=Geology | date=2025-04-04 | issn=0091-7613 | doi=10.1130/G53249.1 | url=https://pubs.geoscienceworld.org/geology/article/doi/10.1130/G53249.1/653480/Fortunian-archaeocyath-sponges-acquired | access-date=2025-04-19 | page=| url-access=subscription }}</ref> - Mid Cambrian (possible [[Ediacaran]] records<ref name=arimasia>{{cite journal |last1=Runnegar |first1=Bruce |last2=Gehling |first2=James G. |last3=Jensen |first3=Sören |last4=Saltzman |first4=Matthew R. |title=Ediacaran paleobiology and biostratigraphy of the Nama Group, Namibia, with emphasis on the erniettomorphs, tubular and trace fossils, and a new sponge, Arimasia germsi n. gen. n. sp. |journal=Journal of Paleontology |date=October 2024 |volume=98 |issue=S94 |pages=1–59 |doi=10.1017/jpa.2023.81|bibcode=2024JPal...98S...1R }}</ref>)}}
| image = Archaeocyatha.jpg
| taxon = Archaeocyatha
| authority = Vologdin, 1937
| synonyms = * Cyathospongia <small>Okulitch, 1935</small>
* Pleospongia <small>Okulitch, 1935</small>
}}<!--? an adjustment needs to be made below regarding the overlapping quadrangle -->
'''Archaeocyatha''' ({{IPAc-en|ˈ|ɑr|k|i|oʊ|s|aɪ|ə|θ|ə}}), 'ancient cups') is a taxon of extinct, [[Sessility (zoology)|sessile]], [[reef]]-building<ref>Archaeocyathid reef structures ("bioherms"), although not as massive as later coral reefs, might have been as deep as ten meters (Emiliani 1992:451).</ref> [[Marine (ocean)|marine]] [[Sponge|sponges]] that lived in warm tropical and subtropical waters during the [[Cambrian]] Period. It is believed that the centre of the Archaeocyatha origin is now located in East [[Siberia]], where they are first known from the beginning of the [[Tommotian]] Age of the Cambrian, 525&nbsp;million years ago ([[mya (unit)|mya]]).<ref>{{cite journal |last1=Maloof |first1=A.C. |s2cid=128842533 |year=2010 |title=Constraints on early Cambrian carbon cycling from the duration of the Nemakit-Daldynian–Tommotian boundary $$\delta$$13C shift, Morocco |journal=Geology |volume=38 |issue=7 |pages=623–626 |doi=10.1130/G30726.1 |bibcode=2010Geo....38..623M }}</ref> In other regions of the world, they appeared much later, during the [[Atdabanian]], and quickly diversified into over a hundred [[Family (biology)|families]].

They became the planet's first [[reef]]-building animals and are an [[index fossil]]<ref>{{cite web |author=Anderson, Dr. John R. |url=http://facstaff.gpc.edu/~janderso/historic/paleolif.htm |title=Paleozoic Life |access-date=2010-07-06 |publisher=[[Georgia Perimeter College]] |url-status=dead |archive-url=https://web.archive.org/web/20110720202106/http://facstaff.gpc.edu/~janderso/historic/paleolif.htm |archive-date=2011-07-20 |df=dmy-all}}</ref> for the Lower Cambrian worldwide.

== Preservation ==
The remains of Archaeocyatha are mostly preserved as [[carbonate]] structures in a [[limestone]] [[Matrix (geology)|matrix]]. This means that the fossils cannot be chemically or mechanically isolated, save for some specimens that have already eroded out of their matrices, and their morphology has to be determined from thin cuts of the stone in which they were preserved.

== Geological history ==
[[File:Archeocyathids.JPG|thumb|Archeocyathids from the [[Poleta formation]], eastern California|left]]
[[File:Branching archaeocyath.jpg|thumb|Branching form archaeocyath from Rowland's Reef in Nevada]]
Today, the archaeocyathan families are recognizable by small but consistent differences in their [[fossil]]ized structures: Some archaeocyathans were built like nested bowls, while others were as long as 300mm. Some archaeocyaths were solitary organisms, while others formed [[Colony (biology)|colonies]].  In the beginning of the [[Toyonian]] Age around 516 [[mya (unit)|mya]], the archaeocyaths went into a sharp decline. Almost all species became [[extinct]] by the Middle Cambrian, with the final-known species, ''[[Antarcticocyathus]] webberi'', disappearing just prior to the end of the Cambrian period.<ref>The last-recorded archaeocyathan is a single species from the late (upper) Cambrian of Antarctica.</ref> Their rapid decline and disappearance coincided with a rapid [[Adaptive radiation|diversification]] of the [[Demosponges]]. As for the earliest archaeocyathan, the Ediacaran sponge ''[[Arimasia]]'' from the [[Nama Group]] may be within the clade and specifically allied with Monocyathea, however this is unclear.<ref name=arimasia/>

The archaeocyathids were important reef-builders in the early to middle Cambrian, with reefs (and indeed any accumulation of carbonates) becoming very rare after the group's extinction until the diversification of new taxa of coral reef-builders in the [[Ordovician]].<ref name=Munnecke2010>{{Cite journal| last1 = Munnecke | first1 = A.| last2 = Calner | first2 = M.| last3 = Harper | first3 = D. A. T.| author-link3 = David Harper (palaeontologist)| last4 = Servais | first4 = T.| title = Ordovician and Silurian sea-water chemistry, sea level, and climate: A synopsis| journal = Palaeogeography, Palaeoclimatology, Palaeoecology| volume = 296| issue = 3–4| pages = 389–413| year = 2010| doi = 10.1016/j.palaeo.2010.08.001| bibcode = 2010PPP...296..389M| url = https://durham-repository.worktribe.com/output/1487372}}</ref>

''Antarcticocyathus '' was considered the only late Cambrian archaeocyath, but its reinterpretation as a lithisid sponge<ref>{{Cite journal | doi = 10.1080/08912963.2022.2155818| title = Limiting the known range of archaeocyath to the middle Cambrian: Antarcticocyathus webersi Debrenne et al. 1984 is a lithistid sponge| year = 2022| last1 = Lee| first1 = Jeong-Hyun| journal = Historical Biology| volume = 36| pages = 1–5| s2cid = 254628199}}</ref> means that there are now no archaeocyaths post the mid-Cambrian.

==Morphology==
[[Image:Archaeocyatha.png|thumb|300px|'''1'''&nbsp;– Gap (''intervallum'')
'''2'''&nbsp;– Central cavity
'''3'''&nbsp;– Internal wall
'''4'''&nbsp;– Pore (all the walls and septa have pores, not all are represented)
'''5'''&nbsp;– Septum
'''6'''&nbsp;– External wall
'''7'''&nbsp;– Rhizoid|left]]The typical archaeocyathid resembled a hollow [[horn coral]]. Each had a conical or vase-shaped porous [[skeleton]] of [[calcite]] similar to that of a [[sea sponge|sponge]]. The structure appeared like a pair of perforated, nested ice cream cones. Their skeletons consisted of either a single porous wall (Monocyathida), or more commonly as two concentric porous walls, an inner and outer wall separated by a space. Inside the inner wall was a cavity (like the inside of an [[Ice cream cone|ice cream cup]]). At the base, these pleosponges were held to the [[Substrate (marine biology)|substrate]] by a [[holdfast (biology)|holdfast]]. The body presumably occupied the space between the inner and outer shells (the intervallum).

==Ecology==
[[File:Archaeocyath observed in situ in the Flinders Ranges.jpg|thumb|Archaeocyath, ''[[in situ]]'' at the [[Flinders Ranges]].|273x273px]]{{also|Sponge reef}}
Flow tank experiments suggest that archaeocyathan [[morphology (biology)|morphology]] allowed them to exploit flow gradients, either by passively pumping water through the [[skeleton]], or, as in present-day, [[Extant taxon|extant]] sponges, by drawing water through the [[wiktionary:pore|pores]], removing nutrients, and expelling spent water and wastes through the pores into the central space.{{Citation needed|date=May 2019}}

The size of the pores places a limit on the size of plankton that archaeocyaths could have consumed; different species had different sized pores, the largest large enough to conceivably consume mesozooplankton, possibly giving rise to different ecological niches within a single reef.<ref>{{Cite journal | doi = 10.1017/pab.2019.32| title = Prey fractionation in the Archaeocyatha and its implication for the ecology of the first animal reef systems| journal = Paleobiology| volume = 45| issue = 4| pages = 652–675| year = 2019| last1 = Antcliffe| first1 = Jonathan B.| last2 = Jessop| first2 = William| last3 = Daley| first3 = Allison C.| bibcode = 2019Pbio...45..652A| s2cid = 208555519| url = https://serval.unil.ch/notice/serval:BIB_5F50FC6E8ACB}}</ref>

Although archaeocyaths have commonly been thought of as stenobionts narrowly adapted to carbonate-dominated marine settings, they were also present in siliciclastic-dominated environments as well.<ref>{{Cite journal |last1=Yang |first1=Aihua |last2=Luo |first2=Cui |last3=Han |first3=Jian |last4=Zhuravlev |first4=Andrey Yu. |last5=Reitner |first5=Joachim |last6=Sun |first6=Haijing |last7=Zeng |first7=Han |last8=Zhao |first8=Fangchen |last9=Hu |first9=Shixue |date=1 November 2024 |title=Niche expansion of archaeocyaths during their palaeogeographic migration: Evidence from the Chengjiang Biota |url=https://www.sciencedirect.com/science/article/pii/S0031018224004085 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |language=en |volume=653 |pages=112419 |doi=10.1016/j.palaeo.2024.112419 |bibcode=2024PPP...65312419Y |access-date=15 November 2024 |via=Elsevier Science Direct|url-access=subscription }}</ref>

==Distribution==
The archaeocyathans inhabited coastal areas of shallow seas. Their widespread distribution over almost the entire Cambrian world, as well as the [[Taxonomy (biology)|taxonomic]] diversity of the [[species]], might be explained by surmising that, like true sponges, they had a [[planktonic]] [[larva]]l stage that enabled their wide spread.
==Taxonomy==
[[File:Antarcticocyathus webberi.jpg|thumb|Restoration of ''Antarcticocyathus webberi'']]Their [[phylogenetic]] affiliation has been subject to changing interpretations, yet the consensus is growing that the archaeocyath was indeed a kind of sponge,<ref name="Rowland2001ArchaeocyathaPhylogeneticInterpretations">Scuba divers have discovered living [[calcium carbonate|calcareous]] sponges, including one species that -- like the archaeocyathans -- is without [[spicule (sponge)|spicule]]s, thus morphologically similar to the archaeocyaths. {{cite journal
 |author=Rowland, S.M. 
 |title=Archaeocyatha: A history of phylogenetic interpretation 
 |journal=Journal of Paleontology 
 |volume=75 
 |pages=1065–1078 
 |doi=10.1666/0022-3360(2001)075<1065:AAHOPI>2.0.CO;2 
 |year=2001 
 |issue=6 
}}</ref> thus sometimes called a pleosponge.  But some [[invertebrate]] [[paleontologist]]s have placed them in an extinct, separate [[phylum (biology)|phylum]], known appropriately as the Archaeocyatha.<ref>Debrenne, F. and J. Vacelet. 1984. "Archaeocyatha: Is the sponge model consistent with their structural organization?" in ''Palaeontographica Americana'', '''54''':pp358-369.</ref>  However, one [[cladistic analysis]]<ref>J. Reitner. 1990. "Polyphyletic origin of the 'Sphinctozoans{{'"}}, in Rutzler, K. (ed.), ''New Perspectives in Sponge Biology: Proceedings of the Third International Conference on the Biology of Sponges'' (Woods Hole) pp. 33–42. Smithsonian Institution Press, Washington, DC.</ref> suggests that Archaeocyatha is a [[clade]] nested within the [[phylum]] [[Porifera]] (better known as the true sponges).

True archaeocyathans coexisted with other enigmatic sponge-like animals. [[Radiocyatha]] and [[Cribricyatha]] were two diverse Cambrian classes comparable to Archaeocyatha, alongside genera such as ''[[Boyarinovicyathus]]'', ''[[Proarchaeocyathus]]'', ''[[Acanthinocyathus]]'', and ''[[Osadchiites]]''.<ref name=":1">''Treatise on Invertebrate Paleontology'' Part E, Revised. Porifera, Volumes 4 & 5: Hypercalcified Porifera, Paleozoic Stromatoporoidea & Archaeocyatha, liii + 1223 p., 665 figs., 2015, available [https://journals.ku.edu/InvertebratePaleo/issue/view/538 here]. {{ISBN|978-0-9903621-2-8}}.</ref>

The [[clade]] Archaeocyatha have traditionally been divided into Regulares and Irregulares (Rowland, 2001):

* [[Hetairacyathida]] ([[incertae sedis]])
* [[Regulares (Archaeocyatha)|Regulares]]
** [[Monocyathida]]
** [[Capsulocyathida]]
** [[Ajacicyathida]]
* [[Irregulares]]
** [[Thalassocyathida]]
** [[Archaeocyathida]]
** [[Kazakhstanicyathida]]

However, Okulitch (1955), who at the time regarded the archaeocyathans as outside of Porifera, divided the phylum in three classes:

*Phylum Archaeocyatha <small>Vologdin, 1937</small>
**Class [[Monocyathea]] <small>Okulitch, 1943</small>
**Class [[Archaeocyathea]] <small>Okulitch, 1943</small>
**Class [[Anthocyathea]] <small>Okulitch, 1943</small>

==Notes==
<references />

==References==
*[[Cesare Emiliani|Emiliani, Cesare]]. (1992). ''Planet Earth : Cosmology, Geology, & the Evolution of Life & the Environment''. Cambridge University Press. (Paperback Edition {{ISBN|0-521-40949-7}}), p 451
* Okulitch, V. J., 1955: Part E&nbsp;– Archaeocyatha and Porifera. Archaeocyatha, E1-E20 in Moore, R. C., (ed.) 1955: [[Treatise on Invertebrate Paleontology]]. Geological Society of America & University of Kansas Press, Lawrence, Kansas, 1955, xviii-E122.

==External links==
* knowledge base and interactive key for identification of archaeocyathan genera: http://www.infosyslab.fr/archaeocyatha/ {{Webarchive|url=https://web.archive.org/web/20160331203501/http://infosyslab.fr/archaeocyatha/ |date=2016-03-31 }}
*[http://www.ucmp.berkeley.edu/porifera/archaeo.html (UCMP Berkeley) Archaeocyathans]
*[https://web.archive.org/web/20070926221654/http://www.palaeos.com/Invertebrates/Porifera/Archaeocyatha.html (Palaeos Invertebrates) Archaeocyatha]

{{Taxonbar|from=Q510821}}

[[Category:Cambrian sponges]]
[[Category:Index fossils]]