Belongs within: Blastoidea. The Troosticrinidae are a Silurian to Lower Carboniferous family of blastoids characterised by having an elongate conical or obconical theca with five paired spiracles around the mouth (Beaver et al. 1967). The Silurian Troosticrinus has short, outwardly directed and slightly downward ambulacra margined by thin thecal plates (Beaver et al. 1967). Beaver et al. (1967) suggested… Continue reading Troosticrinidae
Category: Echinodermata
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
Mitrocystitida
Belongs within: Ankyroida. Mitrocystitida was identified by Parsley (1997) as a paraphyletic group with the Anomalocystitida and Lagynocystis nested within it. Members of this clade mostly have moderately to only slightly asymmetrical thecae (Ubaghs 1967). The basal ‘Mitrocystitida’ have two adorals and lack exothecal posterior processes (Ubaghs 1967). <==Mitrocystitida [Mitrocystida] | i. s.: Spermacystis Ubaghs… Continue reading Mitrocystitida
Blastoidea
Belongs within: Dichoporita.Contains: Pentremitida, Troosticrinidae, Astrocrinidae, Codasteridae, Orophocrinidae. The Blastoidea are a Silurian to Permian group of stalked echinoderms with a compact theca crowned, in life, with numerous brachioles (though these are often not preserved attached in fossils). They may be divided between the Fissiculata, with exposed hydrospire or spiracular slits, and the Spiraculata, with… Continue reading Blastoidea
Blastozoa
Belongs within: Echinodermata.Contains: Paracrinoidea, Dichoporita, Diploporita. The Blastozoa are a Palaeozoic group of mostly stalked echinoderms in which ambulacra overly or are embayed in the multiplated theca, supported biserial brachioles. <==BlastozoaGS20 |–Lepidocystidae [Imbricata, Lepidocystoidea]SW07 | |–Kinzercystis durhami Sprinkle 1973TG19, SG93 | `–Lepidocystis Foerste 1938GS20, K67 | `–*L. wanneri Foerste 1938D67 `–+–Gogia Walcott 1917GS20, U67 [incl. Eocrinus Jaekel… Continue reading Blastozoa
Astrocrinidae
Belongs within: Blastoidea. The Astrocrinidae are a Devonian to Permian group of blastoids with eight spiracular slits along the margins of the ambulacra, and no slits on the anal side (Beaver et al. 1967). The genera Astrocrinus and Tripoblastus are believed to have been free-living, sitting directly on the sea floor without an attaching stalk… Continue reading Astrocrinidae
Pentremitida
Belongs within: Blastoidea. The Pentremitida are a lineage of spiraculate blastoids with typically four spiracles and an anispiracle. Members include the Pentremitidae, in which spiracle margins are formed by ambulacral plates. Characters (Waters & Horowitz 1993): Pyriform to godoniform theca; four spiracles (may be split by septum) and an anispiracle; deltoid faces in most genera;… Continue reading Pentremitida
Dichoporita
Belongs within: Blastozoa.Contains: Glyptocystitoida, Blastoidea. The Dichoporita are a group of Lower Ordovician to Upper Devonian cystoids. Members of this group bear plates with pore groups crossing the plate boundaries, comprising tubes or folds running perpendicular to said boundaries (Jaekel 1918). Within the Dichoporita, the Hemicosmitida have thecae with plates arranged in regular circlets (Kesling… Continue reading Dichoporita