Stephanocrinidae

Stephanocrinus angulatus, from here. Belongs within: Crinoidea. The Stephanocrinidae are a group of crinoids known from the Middle Ordovician to the Upper Silurian, characterised by unique sausage-shaped cover plates and biserial arms (Moore et al. 1978). Characters (from Moore et al. 1978): Crinozoans with three circlets of regularly arranged thecal plates, without pores and infolds… Continue reading Stephanocrinidae

Hemistreptocrinida

Cup of Paractocrinus tuberculatus in (clockwise from left) lateral, base and summit view, from Moore et al. (1978). Belongs within: Crinoidea. The Hemistreptocrinida are an Ordovician group of small crinoids with plate circlets in the cups only slightly offset (Moore et al. 1978). Characters (from Moore et al. 1978, as Paractocrinidae): Small crinoid cups composed… Continue reading Hemistreptocrinida

Homocrinidae

Ectenocrinus simplex assemblage, copyright James St. John. Belongs within: Inadunata. The Homocrinidae are a group of crinoids with small, conical cups known from the Middle Ordovician to the Middle Silurian (Moore et al. 1978). Characters (from Moore et al. 1978): Cup small, conical; B, C, and E radials compound: anal X incorporated in cup between… Continue reading Homocrinidae

Sycocrinitidae

Reconstruction of Monobrachiocrinus granulatus, from Moore et al. (1978). Belongs within: Cyathocrinida. The Sycocrinitidae are a group of crinoids with a globular theca bearing a single arm, known from the Carboniferous and Permian periods (Moore et al. 1978). Characters (from Moore et al. 1978): Theca with one arm-bearing radial; other radials present or absent, commonly… Continue reading Sycocrinitidae

Streblocrinidae

Posterior (above) and aboral views of Tytthocrinus inconsuetus, from Peck & Connelly (1951). Belongs within: Cyathocrinida. The Streblocrinidae are a group of armless crinoids known from the Middle Devonian to the Upper Permian (Moore et al. 1978). Characters (from Moore et al. 1978): Theca typically composed of infrabasals, basals, and orals; abrachiate; radials and anal… Continue reading Streblocrinidae

Pelecocrinidae

Pelecocrinus insignis, from Moore et al. (1978). Belongs within: Dendrocrinida. The Pelecocrinidae are a group of crinoids with tall, ovoid crowns known from the Carboniferous and Permian periods (Moore et al. 1978). See also: The Pelecocrinidae. Characters (from Moore et al. 1978): Crown tall, ovoid. Cup low, bowl-shaped, with shallow basal concavity; infrabasals five, rarely… Continue reading Pelecocrinidae

Rutkowskicrinidae

Partial crown and column of Nassoviocrinus costatus, from McIntosh (2001). Belongs within: Dendrocrinida. The Rutkowskicrinidae are a group of crinoids with low conical cups and ridged thecal plates known from the late Silurian to the early Carboniferous (McIntosh 2001). Characters (from McIntosh 2001): Cup low conical, width approximately equal to or slightly exceeding height, with… Continue reading Rutkowskicrinidae

Cromyocrinacea

Ulocrinus sp., from Ammonit.ru. Belongs within: Dendrocrinida. Contains: Cromyocrinidae. The Cromyocrinacea are a group of crinoids with bowl-shaped cups and sparsely branching arms known from the Carboniferous and Permian periods (Moore et al. 1978). Characters (from Moore et al. 1978): Cup bowl-shaped, with or without basal concavity, radials with plenary articular facets, two or three… Continue reading Cromyocrinacea

Cromyocrinidae

Partial crown of Parulocrinus blairi, from the University of Nebraska-Lincoln. Belongs within: Cromyocrinacea. The Cromyocrinidae are a group of crinoids with globose cups known from the Carboniferous and Permian periods (Moore et al. 1978). Characters (from Moore et al. 1978): Cup more or less globe-shaped, including forms with upflared or subhorizontal infrabasals; mostly three anal… Continue reading Cromyocrinidae

Phanocrinidae

Phanocrinus formosus, from The Fossil Forum.Belongs within: Erisocrinacea. The Phanocrinidae are a group of crinoids with apposed arms known from the Carboniferous period (Moore et al. 1978). Characters (from Moore et al. 1978): Tall, comparatively narrow cylindrical crown with apposed arms. Cup bowl-shaped, medium high or low, base concave or sub-horizontal; radial articular facets plenary;… Continue reading Phanocrinidae