Pirasocrinacea

Anterior view of crown of Sciadiocrinus acanthophorus (without arms) showing mushroom-haped anal sac, from Moore et al. (1978).

Belongs within: Dendrocrinida.

The Pirasocrinacea are a group of crinoids known from the Carboniferous and Permian periods with a pyriform crown (Moore et al. 1978).

Characters (from Moore et al. 1978): Crown pyriform; cup very low bowl-shaped, with mostly deep basal concavity and rounded sides incurved at rim, arm facets peneplenary, interradial notches at rim, three anals in cup, anal sac tall, typically mushroomlike with girdle of horizontal spines around summit platform.

Pirasocrinacea
    |–Adinocrinus Kirk 1938 [Adinocrinidae] ML78
    |    `–*A. nodosus (Wachsmuth & Springer 1885) [=Zeacrinus nodosus] ML78
    `–Pirasocrinidae (see below for synonymy) ML78
         |–Eirmocrinus Strimple & Watkins 1969 ML78
         |    `–*E. grossus Strimple & Watkins 1969 ML78
         |–Zeusocrinus Strimple 1961 ML78
         |    `–*Z. foveatus (Strimple 1951) [=Tholocrinus foveatus] ML78
         |–Dasciocrinus Kirk 1939 ML78
         |    `–*D. florialis (Yandell & Shumard 1847) [=Cyathocrinus florialis] ML78
         |–Pirasocrinus Moore & Plummer 1940 ML78
         |    `–*P. scotti Moore & Plummer 1940 ML78
         |–Aatocrinus Moore & Plummer 1940 ML78
         |    `–*A. robustus (Beede 1900) [=Zeacrinus robustus] ML78
         |–Affinocrinus Knapp 1969 ML78
         |    `–*A. concavus Knapp 1969 ML78
         |–Exterocrinus Knapp 1969 ML78
         |    `–*E. pumilis (Moore & Plummer 1938) [=Perimestocrinus pumilis] ML78
         |–Metaffinocrinus Knapp 1969 ML78
         |    `–*M. perundatus (Moore & Plummer 1940) [=Plaxocrinus perundatus] ML78
         |–Metaperimestocrinus Strimple 1961 ML78
         |    `–*M. spiniferus Strimple 1961 ML78
         |–Metutharocrinus Moore & Strimple 1973 ML78
         |    `–*M. cockei Moore & Strimple 1973 ML78
         |–Platyfundocrinus Knapp 1969 ML78
         |    `–*P. typus Knapp 1969 ML78
         |–Polygonocrinus Strimple 1961 ML78
         |    `–*P. multiextensus Strimple 1961 ML78
         |–Psilocrinus Knapp 1969 ML78
         |    `–*P. omphaloides (Moore & Plummer 1940) [=Plaxocrinus omphaloides] ML78
         |–Retusocrinus Knapp 1969 ML78
         |    `–*R. lobatus (Moore & Plummer 1940) [=Plaxocrinus lobatus] ML78
         |–Schedexocrinus Strimple 1961 ML78
         |    `–*S. gibberellus Strimple 1961 ML78
         |–Separocrinus Knapp 1969 ML78
         |    `–*S. praevalens (Moore 1939) [=Plaxocrinus praevalens] ML78
         |–Simocrinus Knapp 1969 ML78
         |    `–*S. modestus (Moore 1939) [=Plaxocrinus modestus] ML78
         |–Triceracrinus Bramlette 1943 ML78
         |    `–*T. moorei Bramlette 1943 ML78
         |–Vertigocrinus Knapp 1969 ML78
         |    `–*V. subtilis (Moore 1939) [=Perimestocrinus subtilis] ML78
         |–Stenopecrinus Strimple 1961 ML78
         |    |–*S. planus (Strimple 1952) [=Perimestocrinus planus] ML78
         |    `–S. rugosus [=Anchicrinus rugosus] ML78
         |–Lasanocrinus Moore & Plummer 1940 ML78
         |    |–*L. daileyi (Strimple 1940) [=Hydreionocrinus daileyi] ML78
         |    `–L. cornutus ML78
         |–Plaxocrinus Moore & Plummer 1938 ML78
         |    |–*P. crassidiscus (Miller & Gurley 1894) [=Hydreionocrinus crassidiscus] ML78
         |    `–P. politus ML78
         |–Utharocrinus Moore & Plummer 1938 ML78
         |    |–*U. pentanodus (Mather 1915) [=Delocrinus pentanodus] ML78
         |    `–U. quinquacutus ML78
         |–Perimestocrinus Moore & Plummer 1938 [=Peremistocrinus (l. c.)] ML78
         |    |–*P. nodulifer (Miller & Gurley 1894) [=Hydreionocrinus nodulifer] ML78
         |    |–P. excavatus ML78
         |    |–P. formosus ML78
         |    `–P. impressus ML78
         `–Sciadiocrinus Moore & Plummer 1938 ML78
              |–*S. acanthophorus (Meek & Worthen 1870) [=Zeacrinus (Hydreionocrinus) acanthophorus] ML78
              |–S. confertus ML78
              |–S. disculus ML78
              |–S. harrisae ML78
              `–‘Hydreionocrinus’ pentagonus Miller & Gurley 1890 [=Adinocrinus pentagonus] ML78

Pirasocrinidae [Aatocrininae, Affinocrininae, Exterocrininae, Lasanocrininae, Pirasocrininae, Psilocrininae, Sciadiocrininae, Triceracrininae] ML78

*Type species of generic name indicated

REFERENCES

[ML78] Moore, R. C., N. G. Lane, H. L. Strimple, J. Sprinkle & R. O. Fay. 1978. Inadunata. In: Moore, R. C., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt T. Echinodermata 2. Crinoidea vol. 2 pp. T520–T759. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

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