Cladida

Classification
Phylum: Echinodermata
Class: Crinoidea
Order: Cladida (Moore & Laudon, 1943)
Cincinnatian Families: Dendrocrinidae, Merocrinidae

Geologic Range
Early Ordovician – Late Permian; Middle Triassic

Common Paleoecology
Cladida is an extinct order of stationary intermediate-level epifaunal suspension feeders

Characteristics of the Order

  • Dicyclic inadunate crinoids
  • Anal sac prominent
  • Arms branched or unbranched
  • Stems mostly circular in section

Published Descriptions

Treatise on Invertebrate Paleontology, Part T, Vol. 2(2) (1978):

  • Dicyclic inadunate crinoids having two circlets of plates below radials, mostly three, two, or one anal plates in cup but a few lacking any. Anal sac generally prominent. Arms branched or unbranched. Stem mostly circular in section.

Moore & Laudon (1943):

  • The order Cladoidea comprises dicyclic inadunate crinoids. The plates of the cup are joined firmly together, and the arms are free above the radials. The mouth is subtegminal. Representatives of the order are distributed from Ordovician to Triassic.
  • This division of the Inadunata comprises genera grouped together by Bather under Dicyclica Inadunata. As already pointed out, the classificatory treatment that we use here differs importantly from that of Bather in that dicyclic inadaunates are considered to be a branch of the trunk that incorporates all inadunates rather than a branch of a trunk that contains all dicyclic crinoids. Bather’s binomial designation for this group cannot be transposed suitably into our classification.

Dendrocrinidae


Merocrinidae