Choiaella

{{Short description|Extinct genus of sponges}} {{Automatic taxobox | fossil_range = {{fossil range|Chengjiang|Llandovery|ref=<ref name=Botting2007/>}} | image = Choiaella radiata (Mass Extinctions-BIG FIVE).jpg | image_caption = †''Choiaella radiata'' | taxon = Choiaella | authority = Rigby & Hou, 1995<ref>{{cite journal|last1=Rigby|first1=J. K.|last2=Hou|first2=X.-G.|year=1995|title=Lower Cambrian demosponges and hexactinellid sponges from Yunnan, China|journal=Journal of Paleontology|volume=69|issue=6|pages=1009–1019|doi=10.1017/S0022336000037999|jstor=1306406|bibcode=1995JPal...69.1009R |s2cid=133542014 }}</ref> | type_species = †''Choiaella radiata'' | type_species_authority = Rigby & Hou, 1995 | subdivision_ranks = Species | subdivision = * †''Choiaella radiata'' Rigby & Hou, 1995 * †''Choiaella scotica'' M. S. Beresi, J. P. Botting, E. Clarkson, 2010 }} '''''Choiaella''''' is an extinct genus of sea sponge that belongs to the family Choiidae. This genus lived from the Early Cambrian to the Early Silurian period having a near global distribution.<ref name="Botting2007">{{Cite journal| pages = 737–748| year = 2007| doi = 10.1016/j.geobios.2007.02.006| first1 = J.| volume = 40| title = 'Cambrian' demosponges in the Ordovician of Morocco: Insights into the early evolutionary history of sponges| journal = Geobios| last1 = Botting| issue = 6 | bibcode = 2007Geobi..40..737B}}</ref><ref name=":0">Botting, Joseph. (2021). Hexactins in the ‘protomonaxonid’ sponge Choiaella and proposal of Ascospongiae (class nov.) as aformal replacement for the Protomonaxonida. Bulletin of Geosciences. 96. 10.3140/bull.geosci.1823. </ref>

== Taxonomy == The genus was described by J. Keith Rigby and Hou Xian-Guang in 1995 with ''Choiaella radiata'' being the type species.

This genus currently contains four described species. They are listed below:

#''Choiaella'' ''hexactinophora'' J. P. Botting, 2021<ref name=":0" /> #''Choiaella'' ''ovata'' Yang, Zhao & Wu, 2003<ref name=":2">Yang, X., Zhao, Y., & Wu, W. (2003). ''Discovery of the early and middle cambrian choiidae from guizhou, sw china''. ''21''(1), 286–295. <nowiki>https://europepmc.org/article/CBA/544018</nowiki></ref> #''Choiaella radiata'' Rigby & Hou, 1995 (type species) #''Choiaella scotica'' M. S. Beresi, J. P. Botting, E. Clarkson, 2010<ref name=":1">Botting, Joseph & Clarkson, Euan. (2010). A new demosponge, Choiaella scotica, from the Caradoc (Ordovician) of Wallace's Cast, Southern Uplands. Scottish Journal of Geology - SCOT J GEOL. 46. 77-83. 10.1144/0036-9276/01-387.</ref> It is closely related to the genera ''Choia'' and ''Allantospongia''. The genus represents an intermediate stage with the gradual loss of triaxons from more basal sponge groups such as Leptomitidae and basal ascosponge to more derived genera such as Hanptonia, Halichondrites and Pirania.<ref name=":2" />

== Distribution == This genus first appears during the early Cambrian being found in the Sirius Passet Biota of Greenland, the Chengjiang Biota and Niutitang Biotas, both from of Southern China. During the Ordovician period, fossils of ''Choiaella'' are found in Wales (Early Ordovician), the Fezouata Biota of Morocco (Middle Ordovician) and Wallace’s Cast, Scotland (Late Ordovician). The early Silurian has the occurrence of ''Choiaella'' being found in the Fentou Biota of South China. Due to the fossils of ''Choiaella'' being difficult to describe taxonomically, it is possible that species belonging to this genus can be found much more widely.<ref name=":0" />

== Description == thumb|Artistic reconstruction of Choiaella radiata.|left Members of this genus are small sponges having a discoidal or low broad obconical shape. The skeleton of ''Choiaella'' is composed of a longitudinal thatch of small monaxons generally on one continuous size range that are probably oxeas. The spicules of ''Choiaella'' may be bundles locally but they don’t extend beyond the edge of the disc other than as minor fringes.<ref name=":0" />

=== ''Choiaella'' ''hexactinophora'' === ''Choiaella'' ''hexactinophora'' lived during the Middle Ordovician period. It was described in 2021 by Joseph P. Botting from specimens collected in the Castle Bank fossil deposits located in Wales. It was flat being slightly ovoid. It was fine-spiculed. This species was used to help support the creation of a new taxonomic class of sponges, Ascospongiae. It also showed that spicules in sponges evolved separately in each class.<ref name=":2" />

=== ''Choiaella scotica'' === ''Choiaella scotica'' lived in the Southern Uplands of Scotland during the Ordovician period.<ref name="Botting2007" /> It was described in 2010 by ''[https://www.researchgate.net/publication/249558094_A_new_demosponge_Choiaella_scotica_from_the_Caradoc_Ordovician_of_Wallace's_Cast_Southern_Uplands (Beresi et al. 2010)]'' based on two specimens that were held in the collections at the National Museums of Scotland.<ref name=":1" />

== Ecology == ''C. radiata'' coexisted sympatrically with sponge genera such as ''Choia'' and ''Allantospongia''.

==References== {{reflist}}

Category:Maotianshan shales fossils Category:Protomonaxonida Category:Silurian extinctions Category:Cambrian first appearances Category:Prehistoric sponge genera Category:Fossil taxa described in 1995 Category:Paleozoic sponges