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Echinodermata: Crinoids

An Illustration by Mary Williams of a Silurian Eucalyptocrinites crinoid with holdfast and stem based on specimens of Eucalyptocrinites and other closely related species from the Chicago area and Waldron, Indiana.
An Illustration by Mary Williams of a Silurian Eucalyptocrinites crinoid with holdfast and stem based on specimens of Eucalyptocrinites and other closely related species from the Chicago area and Waldron, Indiana.

CRINOIDS are a type of echinoderm, which is a group of animals that includes starfish and sea urchins. Crinoids live only in seawater, and although uncommon today, they were very abundant in the geologic past. Crinoids have a stem that is attached to the seafloor with a holdfast and topped with a crown-shaped body, or calyx, which bears feathery arms. Although they are commonly known as "sea lillies," crinoids are NOT plants. The arms gather small food particles from the water and transfer them to a mouth at the top of the calyx. The crinoid skeleton is composed of hundreds of tiny plates that usually fall apart when the animal dies. | At least 22 species of crinoids lived as dwellers in the Silurian reefs of Wisconsin. Eight of these species, shown above, have been placed in the reef diorama. Some paleontologists have also interpreted ancient reef crinoids as bafflers.

 

Kingdom Animalia
Phylum: Echinodermata

Class: Order: Family: Genus and species

Crinoidea: Levicyathocrinites? vanhorni (Miller)
Crinoidea: Monobathrida: Calliocrinus cornutus (Hall)
Crinoidea: Monobathrida: Marsupiocrinus chicagoensis Weller
Crinoidea: Monobathrida: Periechocrinus infelix (Winchell & Marcy)
Crinoidea: Monobathrida: Periechocrinus necis (Winchell & Marcy)
Crinoidea: Monobathrida: Periechocrinus urniformis (Miller)
Crinoidea: Monobathrida: Promelocrinus obpyramidalis (Winchell & Marcy)
Crinoidea: Monobathrida: Eucalyptocrinitidae: Eucalyptocrinites crassus (Hall)
Crinoidea: Monobathrida: Eucalyptocrinitidae: Eucalyptocrinites nodulosus (Weller)
Crinoidea: Monobathrida: Eucalyptocrinitidae: Eucalyptocrinites ornatus (Hall)
Crinoidea: Monobathrida: Patelliocrinidae: Macrostylocrinus obconicus Weller
Crinoidea: Diplobathrida: Dimerocrinites occidentalis (Hall)
Crinoidea: Diplobathrida: Dimerocrinites pentangularis (Hall)
Crinoidea: Diplobathrida: Lampterocrinus infiatus Hall
Crinoidea: Diplobathrida: ?Lyriocrinus melissa Hall 
Crinoidea: Diplobathrida: Siphonocrinus armosus (McChesney)
Crinoidea: Diplobathrida: Siphonocrinus nobilis
Crinoidea: Diplobathrida: Siphonocrinus sp. indet.
Crinoidea: Cladida: Crotalocrinites cora (Hall)
Crinoidea: Sagenocrinida: Icthyocrinus subangularis (Hall)
Crinoidea: Sagenocrinida: Lecanocrinus waukoma (Hall)
Crinoidea: Disparida: Pisocrinidae: pisocrinid

Photo Gallery

Silurian crinoids.
© The Field Museum - CC BY-NC
An Illustration by Tyler Ray Fewell of a Silurian Siphonocrinus nobilis crinoid based on specimens of Siphonocrinus nobiliusand other closely related species from the Chicago area.
© The Field Museum - CC BY-NC
An Illustration by Mary Williams of a Silurian Eucalyptocrinites crinoid with a platyceras gastropod based on specimens of Eucalyptocrinites and other closely related species from the Chicago area and Waldron Indiana.
© The Field Museum - CC BY-NC
An Illustration by Mary Williams of a Silurian Eucalyptocrinites crinoid based on specimens of Eucalyptocrinites and other closely related species from the Chicago area.
© The Field Museum - CC BY-NC
An Illustration by Mary Williams of a Silurian Eucalyptocrinites crinoid with holdfast and stem based on specimens of Eucalyptocrinites and other closely related species from the Chicago area and Waldron, Indiana.
© The Field Museum - CC BY-NC

Taxonomy