Xenocrinidae

Classification
Phylum: Echinodermata
Class: Crinoidea
Order: Monobathrida
Family: Xenocrinidae (Miller, 1890)
Cincinnatian Genera: Xenocrinus

Geologic Range
Late Ordovician

Common Paleoecology
Xenocrinidae is an extinct family of stationary upper-level epifaunal suspension feeders

Description of the Family

  • Median ray and anal ridges are conspicuous
  • Radials usually adjoining each other in all interrays except posterior
  • Interbrachial areas depressed and flexible, composed of small and irregular plates
  • Stem quadrangular in cross section
  • Sutures between some adjacent radials covered by small plates

Published Descriptions

Treatise on Invertebrate Paleontology, Part T (1978):

  • Median ray and anal ridges conspicuous; radials usually adjoining each other in all interrays except posterior; sutures between some adjacent radials covered by small supplementary plates; fixed secundibrachs two, if there is further division, otherwise three to four to each half ray; few fixed tertibrachs may be present; interbrachial areas depressed, flexible composed of many small and irregular plates; CD interray with radial-like primanal and median anitaxis of prominent convex plates. Free arms 2, 3 or 4 per ray, unbranched, uniserial or composed of cuneiform and interlocking brachials. Stem quadrangular in cross section, with pentagonal axial canal.

Xenocrinus