Plicodendrocrinus casei

Classification
Phylum: Echinodermata
Class: Crinoidea
Order: Cladida
Family: Dendrocrinidae
Genus: Plicodendrocrinus
Species: Plicodendrocrinus casei (Meek, 1871)

Taxonomic Details

Formerly: Dendrocrinus casei

Stratigraphic Occurrences

P.casei_strat

Geographic Occurrences

Map point data provided by iDigBio.

Stratigraphic Description

Sequences (Formations)

  • C5 Sequence (Lower Whitewater, Liberty)

Identification in Hand Sample

  • Conical aboral cup with distinctive stellate (star-shaped) pattern of ridges
  • Large, multiplated anal sac; each sac plate has fine stellate ridges
  • Arms are laterally separated, branch many times, and decrease in width gradually with successive branching
  • Columnals are pentalobate
  • Large anal sack with stellate ridges lacks differentiated ridge on median row of plates

Plicodendrocrinus casei from the Whitewater Formation of Brookville, Indiana (OUIP 2189)

Published Description

Holland (UGA Strat Lab, 2013):

  • Large anal sack with stellate ridges; calyx also with stellate plates

Hess (1999):

  • In fossil stems, torsion is documented by twisted pluricolumnals of the Upper Ordovician Plicodendrocrinus casei (Donovan et al. 1995).

Fossils of Ohio (1996) :

  • Characterized by a conical aboral cup and dominant plate sculpturing. Aboral cup plates have a distinctive stellate (star-shaped) pattern of ridges.
  • Has a large, multiplated anal sac; each sac plate has fine stellate ridges. Although inflated during life, the fossilized anal sac commonly is flattened and may be detached from the cup. The arms of P. casei are laterally separated, branch many times, and decrease in width gradually with successive branching. Brachials are as high as wide. Columnals are pentalobate.
  • Known from the Middle to Late Ordovician of North America and Europe. Reported from the Waynesville and Liberty formations of SW Ohio.
  • Aboral cup has stellate (star-shaped) ridges on plates; arms separated laterally and have many branches, arm width decreases gradually with successive branching; brachials as wide as high; anal sac long, individual plates have fine stellate pattern of ridges; columnals pentalobate.

Brower (1995):

  • A species of Plicodendrocrinus with adult ornamentation of moderately sharp single to multiple stellate ridges on aboral cup plates; plates lacking small nodes or sinuous rugose ridges. Aboral cup moderately wide relative to height; radial facets relatively wide. Anal sac high, with straight sides; anal sac lacks differentiated ridge on median row of plates; one side of anal sac with four to six columns of plates that are much wider than high. Arms and brachs moderately wide compared to height.