Blastozoa

Troosticrinidae

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

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

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

Protocrinitida

Belongs within: Diploporita. The Glyptosphaeritida are a group of Lower Ordovician to Middle Silurian cystoids bearing radial ambulacra with alternating lateral branches. Members include the Dactylocystidae, with an ovate to pear-shaped theca bearing long, straight ambulacra with brachioles at the end of short, regularly alternating branches (Kesling 1967). Characters (Kesling 1967): Diplopore-bearing cystoids with globular,… Continue reading Protocrinitida

Echinoencrinitidae

Belongs within: Cheirocrinidae.Contains: Callocystitidae. The Echinoencrinitidae are a group of Lower Ordovician to Upper Silurian cystoids with a generally distinctly shaped theca, with short ambulacra and a protruding periproct. Inclusion of the Scoliocystinae, possessing advanced disjunct pectinirhombs with vestibule rims, in the Echinoencrinitidae has been subject to debate (Paul & Rozhnov 2016). Small-mouthed cystoids Published… Continue reading Echinoencrinitidae

Glyptocystitoida

Belongs within: Dichoporita.Contains: Rhipidocystidae, Cheirocrinidae. The Glyptocystitida are a Lower Ordovician to Upper Devonian group of cystoids in which the pore groups often have well-exposed openings. These pore groups, known as pectinirhombs, have historically been considered diagnostic of the group but have been shown to be absent in some genera (Paul & Rozhnov 2016). Characters… Continue reading Glyptocystitoida