Belongs within: Eucamerata. The Rhodocrinitidae are a family of crinoids known from the Middle Ordovician to the Lower Carboniferous (Ubaghs 1978b). So many arms Published 10 September 2007 Behold the majesty of the Rhodocrinitidae! The photo below shows fossils of Rhodocrinites kirbyi and Cribanocrinus watersianus, both Rhodocrinitidae, and comes from the Smithsonian. The Rhodocrinitidae are… Continue reading Rhodocrinitidae
Category: Crinoidea
Zenometrinae
Belongs within: Antedonacea. The Zenometrinae are an assemblage of feather stars with cirrus sockets arranged in numerous columns (Wienberg Rasmussen 1978). Characters (Wienberg Rasmussen 1978): Centrodorsal conical or rounded subconical to columnar, often high or very high, dorsal side often rounded or truncated. Cirrus sockets numerous, arranged in 10, 15 or 20 distinct columns, often 10 columns… Continue reading Zenometrinae
Platycrinitidae
Belongs within: Glyptocrinina. The Platycrinitidae are a group of crinoids known from the Upper Silurian or Devonian to the Permian. Their arms are biserial and pinnulate (Ubaghs 1978b). Characters (Ubaghs 1978b): Calyx confined to patina of five radials, and three unequal basals which may be fused; posterior side commonly not differentiated; orals distinct; interambulacrals and… Continue reading Platycrinitidae
Actinocrinitidae
Belongs within: Compsocrinina. The Actinocrinitidae are a Carboniferous group of crinoids in which the fixed portions of the arms are strongly grouped, forming protuberant brachial lobes in each ray (Ubaghs 1978b). <==Actinocrinitidae [Actinocrinidae, Actinocriniens, Actinocrinoidea] | i. s.: Laubeocrinus Waagen & Jahn 1899U78b | `–*L. barrandei Waagen & Jahn 1899U78b |–PhysetocrininaeU78b | |–Physetocrinus Meek & Worthen… Continue reading Actinocrinitidae
Articulata
Belongs within: Dendrocrinida.Contains: Ampelocrinidae, Corythocrinidae, Cyrtocrinidia, Holopodinidia, Isocrinidae, Hyocrinidae, Apiocrinitidae, Millericrinidae, Bourgueticrinidae, Bathycrinidae, Pentacrinitidae, Comatulidia, Roveacrinidae, Somphocrinidae, Saccocomidae. The Articulata are a group of crinoids with a flexible tegmen known from the Lower Triassic to the present, including all living members of the crinoids (Wienberg Rasmussen 1978). In the Comatulida, feather stars, the larval column… Continue reading Articulata
Texacrinacea
Belongs within: Dendrocrinida. The Texacrinacea are a group of long-armed crinoids with a tall, slender crown known from the Carboniferous and Permian periods (Moore et al. 1978). The month’s edition of Gigantic Asses Published 27 October 2025 Echinoderm anatomy is weird. And crinoids are arguably the weirdest of the bunch (among living classes, at least).… Continue reading Texacrinacea
Heterocrinidae
Belongs within: Inadunata. Fateful symmetry Published 13 September 2024 I’ll admit straight up: echinoderms confound me. The study of fossil echinoderms often hinges on describing the arrangement of plates making up the stereo, and the terminology used to describe said plates is often beyond me. As a result, this major lineage of marine animals leaves… Continue reading Heterocrinidae
Stephanocrinidae
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 of any type, with… Continue reading Stephanocrinidae
Hemistreptocrinida
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 of three or more circlets of plates which are only slightly offset rather than alternating; anal plates absent;… Continue reading Hemistreptocrinida
Homocrinidae
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 C and D radials. Homocrinidae [Homocrinacea, Homocrinicae,… Continue reading Homocrinidae