Isocrinida

Isocrinida Temporal range:
Isocrinus nicoleti columnals; Middle Jurassic; Carmel Formation; Utah.
Scientific classification
Kingdom:	Animalia
Phylum:	Echinodermata
Class:	Crinoidea
Subclass:	Articulata
Order:	Isocrinida
Synonyms
Isocrinina Sieverts-Doreck, 1952

Isocrinida is an order of sea lilies which contains four families.

Characteristics

Main article: Crinoid § Morphology

Members of this order are characterised by having a "heteromorphic" stalk; the stalk consists of a series of nodes with cirri, interspersed by several nodes without cirri. There are additionally a whorl of cirri at the base on which the animal perches. The calyx is a shallow cup consisting of five basals and five radials.

They are more mobile than other stalked crinoids, and can be found as shallow as 100–170 m (300–600 ft), and on rare occasions below 400 m (1,300 ft), but is most common at depths of 200–300 m (700–1,000 ft).

Families

Ordo Isocrinida

• Family Balanocrinidae Roux, 1981
  • Subfamily Balanocrininae Roux, 1981
  • Subfamily Diplocrininae Roux, 1981
  • Subfamily Isselicrininae Klikushkin, 1977
  • Subfamily Proisocrininae Rasmussen, 1978
• Family Cainocrinidae Simms, 1988
• Family Isocrinidae Gislén, 1924
  • Subfamily Isocrininae Gislén, 1924
  • Subfamily Metacrininae Klikushin, 1977
• Family †Pentacrinitidae Gray, 1842
  • Subfamily Eocomatulinae Simms, 1988
  • Subfamily Pentacrinitinae Blumenbach, 1804

• 
  Endoxocrinus parrae (Balanocrinidae)
• 
  Isocrinus asteria
• 
  Isocrinus fossil, Shamshak Formation, Alborz province, Iran
• 
  Metacrinus rotundus (Isocrinidae)
• 
  Neocrinus decorus (Balanocrinidae)
• 
  Proisocrinus ruberrimus (Balanocrinidae)
• 
  Endoxocrinus sp. (Balanocrinidae)
• 
  Unidentified Isocrinid

References

• Hess H (2011) Isocrinida. In: Hess, H., Messing, C.G., Ausich, W.I. (Eds.), Treatise on Invertebrate Paleontology, Part T, Echinodermata 2 Revised, Crinoidea, vol. 3. University of Kansas Press, Lawrence, Kansas, pp. 42–69.