{{short description|Class of echinoderms}} {{Paraphyletic group | name = Eocrinoidea | fossil_range = {{fossil range|Cambrian Stage 3|Silurian}} | image = Ordovician_hardground_Utah.jpg | image_caption = Eocrinoid holdfasts (Middle Ordovician, Utah) | image2 = Gogia_ojenai.jpg | image2_caption = Colourful reconstruction of ''Gogia ojenai'' | auto = yes | taxon = Eocrinoidea | extinct = yes | authority = Jaekel, 1899 | type_genus = †''Eocrinus'' {{small|Jaekel 1918}}<ref>{{harvnb|Ubaghs|1967|p=S477}}</ref><br />(= †''Gogia'' {{small|Walcott 1917}}) | includes_ref = <ref>{{cite web|website=Paleobiology Database |url=https://paleobiodb.org/classic/basicTaxonInfo?taxon_no=31058 |title=†class Eocrinoidea Jaekel 1918 |accessdate=27 November 2024}}</ref> | includes = * †Ascocystitida ** †Ascocystitidae ** †Cambrocrinidae<ref>{{harvnb|Parsley|2021|page=975}} ({{small|Note that this paper mistakenly spells the family "Cambrocystidae" or "Cambrocystitidae" despite it being named after ''Cambrocrius''; the 1993 paper by Dzik and Orłowski that the 2021 paper references as defining the family defines it as "Cambrocrinidae"}})</ref><ref>{{harvnb|Dzik|Orłowski|1993|p=32}}</ref> ** †Rhopalocystidae ** †Ridersiidae<ref>{{harvnb|Sepkoski|2002|page=272}}</ref> * †Gogiida ** †Eocrinidae ** †Lichenoididae<ref>{{harvnb|Jell|Sprinkle|2021|page=6}}</ref> ** †Lyracystidae ** †Thorntonitidae<ref>{{harvnb|Jell|Sprinkle|2021|page=19}}</ref> ** †Turbanicystidae<ref>{{cite web|website=Paleobiology Database |url=https://paleobiodb.org/classic/basicTaxonInfo?taxon_no=31062 |title=†order Gogiida Broadhead 1982 |accessdate=27 November 2024}}</ref> * †Imbricata<ref>{{cite web|website=Interim Register of Marine and Nonmarine Genera |title=Imbricata |url=https://www.irmng.org/aphia.php?p=taxdetails&id=10832 |accessdate=12 October 2025}} {{small|(Note: Nardin ''et al.'' (2017) "discards" Imbricata in favor of "Lepidocystoidae" which appears to be a misspelling of "Lepidocystidae"; the more broadly accepted arrangement and spelling is shown here.)}}</ref> ** †Felbabkacystidae ** †Lepidocystidae * †Trachelocrinida ** †Heckerocrinidae ** †Trachelocrinidae * †Ampheristocystidae<ref>{{cite web|title=IRMNG — Ampheristocystidae |url=https://www.irmng.org/aphia.php?p=taxdetails&id=122005 |website=Interim Register of Marine and Nonmarine Genera |accessdate=19 November 2025}}</ref> * †Cryptocrinitidae * †Lingulocystidae * †Palaeocystitidae * †Rhipidocystidae * ''incertae sedis'' ** †''Cigara'' (?) ** †''Haimacystis''<ref>{{cite journal|last1=Sumrall |first1=Colin D. |last2=Sprinkle |first2=James |last3=Guensburg |first3=Thomas E. |year=2001 |title=Comparison Of Flattened Blastozoan Echinoderms: Insights From The New Early Ordovician Eocrinoid Haimacystis Rozhnovi |journal=Journal of Paleontology |volume=75 |number=5 |page=987 |doi=10.1666/0022-3360(2001)075<0985:COFBEI>2.0.CO;2}}</ref> ** †''Ubaghsicystis'' | excludes = * †Rhombifera<ref name=smith1984>{{harvnb|Smith|1984|page=439}}</ref> * †Diploporita<ref name=smith1984 /> * †Paracrinoidea<ref name=smith1984 /> * †Parablastoidea<ref>{{harvnb|Sheffield|Sumrall|2019|page=746}}</ref> * †Blastoidea<ref name=smith1984 /> * †Coronoidea<ref name=paul2024 /> * Crinoidea (?)<ref name=zs2011 /> }}
The '''Eocrinoidea''' were an extinct class of echinoderms that lived between the Early Cambrian and Late Silurian periods. They are the earliest known group of stalked, brachiole-bearing echinoderms, and were the most common echinoderms during the Cambrian.
The earliest genera had a short holdfast and irregularly structured plates. Later forms had a fully developed stalk with regular rows of plates. They were benthic suspension feeders, with five ambulacra on the upper surface, surrounding the mouth and extending into a number of narrow arms.<ref>{{harvnb|Prothero|2004|page=324}}</ref><ref name=IZ>{{harvnb|Barnes|1982}}</ref>
==Phylogeny== {{see also|List of echinoderm orders}} Eocrinoids were a paraphyletic group that are seen as the basal stock from which all other blastozoan groups evolved.<ref>{{harvnb|Smith|1984|page=439}}</ref>
===Early evolution===
The following cladogram, after Nardin et al. 2017 with slight modifications,<ref name=nardin2017>{{harvnb|Nardin|Lefebvre|Fatka|Nohejlová|2017|page=680}} {{small|(Note: This source misspells "Lichenoididae" as "Lichenoidae", contrary to the Treatise on Invertebrate Paleontology, [https://journals.ku.edu/InvertebratePaleo/issue/view/519 Part S, Echinodermata 1], and incorrectly (per PBDB) and IRMNG) includes ''Lyracystis'' in Eocrinidae instead of Lyracystidae; this cladogram shows the more common spellings and placements.)}}</ref> shows the progression of early eocrinoid families, with all other eocrinoid families (including representatives ''Trachelocrinus'' and ''Ridersia'') grouped with "derived Blastozoans" as their relationships with each other and with other blastozoans are not addressed.
{{Clade|style=font-size:85%;line-height:85% |label1=Lepidocystidae |1={{Clade |1=''Kinzercystis'' |2=''Vyscystis'' |3=''Lepidocystis'' }} |2={{Clade |label1=Felbabkacystidae |1=''Felbabkacystis'' |2={{Clade |grouplabel1={{Clade labels |bar1=indigo |label1=Lyracystidae}} |barbegin1=indigo |1=''Lyracystis'' |barend1=indigo |2={{Clade |grouplabel1={{Clade labels |bar1=violet |label1=Eocrinidae}} |barbegin1=violet |1={{Clade |1=''Akadocrinus'' |2=''Gogia'' |3=''Sinoeocrinus'' |4=''Ubaghsicystis'' }} |barend1=violet |2={{Clade |grouplabel1={{Clade labels |bar1=purple |label1=Lichenoididae}} |barbegin1=purple |1=''Lichenoides'' |barend1=purple |2={{Clade |1=''Trachelocrinus'' |2=''Ridersia'' |3=(derived Blastozoa) }} }} }} }} }} }}
===Relationships to other groups===
Relationships among the eocrinidae and other blastozoan clades are an area of ongoing study. Below are two of many cladograms showing some aspect of eocrinoid paraphyly or polyphyly.
{{col-begin|width=auto}} {{col-break}}
{{thumb|width=400|content=<div style="text-align:left;"> {{barlabel|style=font-size:85%;line-height:85% |size=14 |at1=0 |bar1=brown |label1=Lepidocystids (Eocrinoids) |at2=1 |bar2=indigo |label2=Crinoids |at3=5 |bar3=brown |label3=Eocrinoids |at4=10 |bar4=green |label4=Dibrachicystids (Rhombiferans) |at5=12 |bar5=lightgreen |label5=Pleurocystitids (Rhombiferans) |at6=13 |bar6=darkgreen |label6=Glyptocystitids (Rhombiferans) |at7=14 |bar7=brown |label7=Eocrinoids |cladogram= {{clade |1={{clade |1=''Kinzercystis'' |barbegin1=brown |2={{clade |1={{clade |1={{clade |1=''Titanocrinus'' |barbegin1=indigo |2=''Aethocrinus''|barend2=indigo }} |2=''Lyracystis'' |bar2=brown }} |2={{clade |1=''Gogia'' |bar1=brown |2=''Sinoeocrinus'' |bar2=brown |3={{clade |1=''Akadocrinus'' |bar1=brown |2={{clade |1=''Tatonkacystis'' |bar1=brown |2=''Ubaghsicystis'' |bar2=brown |3={{clade |1=''Dibrachicystis'' |barbegin1=green |barend1=green |2=''Pleurocystites'' |barbegin2=lightgreen |barend2=lightgreen |3={{clade |1=''Velieuxicystis'' |barbegin1=darkgreen |2={{clade |1=''Macrocystella'' |barend1=darkgreen |2=''Ridersia'' |barend2=brown }} }} }} }} }} }} }} }} }} }} </div> |caption=Stalked Cambrian (and select Ordovician) echinoderms, after Zamora & Smith, 2011.<ref name=zs2011>{{harvnb|Zamora|Smith|2011}}</ref> All genera except those bracketed as "Crinoids" are blastozoans.}}
{{col-break}}
{{thumb|width=400|content=<div style="text-align:left;"> {{barlabel|style=font-size:85%;line-height:85% |size=17 |at1=0 |label1=Eocrinoids |bar1=brown |at2=5 |label2=Glyptocystitoids (Rhombiferans) |bar2=darkgreen |at3=12 |label3=Blastoids |bar3=darkblue |at4=14 |label4=Eublastoids (Blastoids) |bar4=purple |at5=15 |label5=Coronoids (Blastoids) |bar5=indigo |at6=17 |label6=Hemicosmitoids (Rhombiferans) |bar6=green |cladogram={{Clade |1={{Clade |1={{Clade |1=''Akadocrinus'' |2=''Cambrocrinus'' }} |barbegin1=brown |2=''Ridersia'' |barend2=brown |3=''Sanducystis'' |4={{Clade |1={{Clade |1=''Cystobsastus'' |2={{Clade |1=''Lepadocystis'' |2={{Clade |1=''Echinoencrinites'' |2={{Clade |1=''Cheirocystella'' |2=''Macrocystella'' }} }} }} }} |barbegin1=darkgreen |2={{Clade |1={{Clade |1=''Rhombifera'' |barend1=darkgreen |2=''Lysocystites'' |barbegin2=indigo |3={{Clade |1=''Macurdablastus'' |bar1=indigo |2=''Codaster'' |barbegin2=purple |barend2=purple }} |4=''Stephanocrinus'' |barbegin4=darkblue |barend4=darkblue }} |barbegin2=green |barend2=green |2={{Clade |1=''Thomacystis'' |2={{Clade |1=''Caryocrinites'' |2=''Hemicosmites'' }} }} }} }} }} }} }} </div> |caption=This cladogram, after Paul et al. 2024, shows several eocrinoids in a polytomy with a clade containing several other blastozoan groups.<ref name=paul2024>{{harvnb|Paul|Lefebvre|Nohejlová|Zamora|2024|page=12–13}} {{small|(Note: The text groups ''Sanducystis'' with eocrinoids as the outgroup, but the paper cited classifies it as a glyptocystitoid; it is shown un-bracketed on this page. Similarly, the text classifies ''Macurdablastus'' as a eublastoid, but the cited paper has it as the sister of Eublastoidea; it is shown outside of Eublastoidea on this page.)}}</ref> }} {{col-end}}
==References== {{reflist}}
===Works cited=== {{refbegin}} * {{cite book|last1=Barnes |first1=Robert D. |year=1982 |title= Invertebrate Zoology |publisher= Holt-Saunders International |location= Philadelphia, PA|pages= 1007–1008|isbn= 978-0-03-056747-6}} * {{cite journal|last1=Dzik |first1=Jerzy |last2=Orłowski |first2=Stanisław |year=1993 |title=The Late Cambrian eocrinoid Cambrocrinus |journal=Acta Palaeontologica Polonica |volume=38 |number=1/2 |pages=21–34}} * {{cite journal|last1=Jell |first1=Peter A. |last2=Sprinkle |first2=James |year=2021 |title=Revision of Whitehouse's eocrinoids Peridionites and Cymbionites, with description of the associated fauna including two new echinoderm genera, lower Middle Cambrian Thorntonia Limestone, northwestern Queensland |journal=Alcheringa: An Australasian Journal of Palaeontology |volume=45 |number=1 |pages=1–55 |doi=10.1080/03115518.2021.1913512}} * {{cite journal|last1=Nardin |first1=Elise |last2=Lefebvre |first2=Bertrand |last3=Fatka |first3=Oldřich |last4=Nohejlová |first4=Martina |last5=Kašička |first5=Libor |last6=Šinágl |first6=Miroslav |last7=Szabad |first7=Michal |title=Evolutionary implications of a new transitional blastozoan echinoderm from the middle Cambrian of the Czech Republic |journal=Journal of Paleontology |volume=91 |number=4 |year=2017 |pages=672–684|doi=10.1017/jpa.2016.157 |bibcode=2017JPal...91..672N }} * {{cite journal|last1=Parsley |first1=R. L. |title=Evolution, Functional Morphology and Paedomorphism in the Gogiid-Ascocystitid Lineage (Eocrinoidea; Cambrian-Ordovician) |journal=Paleontological Journal |volume=55 |number=9 |year=2021 |pages=966–976 |doi=10.1134/S0031030121090100|bibcode=2021PalJ...55..966P }} * {{cite journal|last1=Paul |first1=Christopher R. C. |last2=Lefebvre |first2=Bertrand |last3=Nohejlová |first3=Martina |last4=Zamora |first4=Samuel |title=''Rhombifera Barrande'', 1867, and the origin of the Blastoidea (Echinodermata, Blastozoa) |journal=Spanish Journal of Palaeontology |volume=39 |year=2024 |page=90 |doi=10.7203/sjp.28729|hdl=10550/118357 |hdl-access=free }} * {{cite book|last1=Prothero |first1=D. R. |year=2004 |title=Bringing Fossils to Life; An Introduction to Paleobiology |edition=2 |location=New York |publisher=The McGraw-Hill companies}} * {{cite journal|last1=Sepkoski |first1=John J., Jr. |date=16 September 2002 |title=A Compendium of Fossil Marine Animal Genera |journal=Bulletins of American Paleontology |volume=362 }} * {{cite journal|last1=Sheffield |first1=S. L. |last2=Sumrall |first2=C. D. |year=2019 |title=The phylogeny of the Diploporita: a polyphyletic assemblage of blastozoan echinoderms |journal=Journal of Paleontology |volume=93 |issue=4 |pages=740–752 |doi=10.1017/jpa.2019.2}} * {{cite journal|last1=Smith |first1=Andrew B. |title=Classification of the Echinodermata |journal=Palaeontology |volume=27 |number=3 |year=1984 |pages=431–459 }} * {{cite book|last1=Ubaghs |first1=Georges |date=1967 |chapter=Eocrinoidea |editor-last1=Moore |editor-first1=Raymond C. |title=Treatise on Invertebrate Paleontology, Part S: Echinodermata 1 |volume=1 |pages=S455–S495 |publisher=University of Kansas Press |url=https://journals.ku.edu/InvertebratePaleo/issue/view/519 |access-date=29 October 2024}} * {{Cite journal|last1=Zamora |first1=Samuel |last2=Smith |first2=A. B. |year=2011 |title=Cambrian stalked echinoderms show unexpected plasticity of arm construction |journal=Proceedings of the Royal Society B |volume=279|issue= 1727|pages= 293–298|doi=10.1098/rspb.2011.0777 |pmid=21653588 |pmc=3223674}} {{refend}}
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Category:Blastozoa Category:Paleozoic echinoderms Category:Cambrian echinoderms Category:Silurian echinoderms Category:Cambrian first appearances Category:Silurian extinctions Category:Paraphyletic groups Category:Long stubs with short prose
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