Echinoencrinitidae

Belongs within: Glyptocystitida. 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. Small-mouthed cystoids Published 11 September 2023 Imagine yourself swimming through oceans of the early Ordovician. You’re in what will eventually become the Baltic Sea, though it currently… Continue reading Echinoencrinitidae

Pentremitida

Belongs within: Blastoidea. The Pentremitida are a lineage of spiraculate blastoids with typically four spiracles and an anispiracle. Characters (from Waters & Horowitz 1993): Pyriform to godoniform theca; four spiracles (may be split by septum) and an anispiracle; deltoid faces in most genera; lancets partially to completely exposed. <==Pentremitida |–HyperoblastidaeWM03 | |–Conuloblastus malladai (Etheridge &… Continue reading Pentremitida

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). A beginner’s guide to blastoids Published 20 February 2010 No, not that. These (photo by DanielCD): Blastoids… Continue reading Blastoidea

Astrocrinidae

Belongs within: Blastoidea. The Astrocrinidae are a Devonian to Permian group of blastoids. The genera Astrocrinus and Tripoblastus are believed to have been free-living, sitting directly on the sea floor without an attaching stalk (Waters et al. 2003). Characters (from Beaver et al. 1967): Theca with eight spiracular slits along margins of ambulacra; anal side… Continue reading Astrocrinidae

Troosticrinidae

Belongs within: Blastoidea. The Troosticrinidae is a Silurian to Lower Carboniferous group of blastoids characterised by having an elongate conical or obconical theca with five paired spiracles around the mouth (Beaver et al. 1967). Beaver et al. (1967) suggested that this family is paraphyletic with regard to Diploblastidae (with a globular theca and five paired… Continue reading Troosticrinidae

Codasteridae

Belongs within: Blastoidea. The Codasteridae are a Devonian to Permian group of blastoids with eight hydrospire fields. Characters (from Beaver et al. 1967): Theca with eight exposed or constricted hydrospire fields; hydrospire slits lacking on anal side. <==Codasteridae [Angioblastidae] |–Emuhablastus Waters, Maples et al. 2003WM03 | `–*E. planus Waters, Maples et al. 2003WM03 |–Heteroschisma Wachsmuth… Continue reading Codasteridae

Glyptocystitida

Belongs within: Dichoporita.Contains: Rhipidocystidae, Callocystitidae, Echinoencrinitidae, Cheirocrinidae. The Glyptocystitida are a Lower Ordovician to Upper Devonian group of cystoids in which the pore groups have well-exposed openings. Characters (from Kesling 1967): Theca in most genera composed of four BB, five ILL, five LL, five RR, and five OO, though plate O1 is tripartite in many… Continue reading Glyptocystitida

Dichoporita

Belongs within: Pelmatozoa.Contains: Glyptocystitida, 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 Glyptocystitida and Hemicosmitida have thecae with plates arranged in regular… Continue reading Dichoporita

Callocystitidae

Belongs within: Glyptocystitida. The Callocystitidae are a group of Upper Ordovician to Upper Devonian cystoids distinguished from related groups by their particularly long ambulacra. Callocystitids: ambulacra advancement and rhomb reduction Published 10 January 2012 The Palaeozoic echinoderms included many distinctive groups that have no close relatives among the modern fauna: blastoids, cornutes, solutes, ctenocystoids… to… Continue reading Callocystitidae