Helcionopsis | |
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Drawing of dorsal view of the shell of Helcionopsis radiatum . Head region is on the left. | |
Drawing of lateral view of the shell of Helcionopsis radiatum . Head region is on the left. | |
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Mollusca |
(unranked): | Monoplacophora |
Class: | Tergomya |
Order: | Tryblidiida |
Family: | † Tryblidiidae |
Genus: | † Helcionopsis Ulrich & Scofield, 1897 [1] |
Helcionopsis is an extinct genus of paleozoic monoplacophoran in the family Tryblidiidae.
The generic name is from the external resemblance which the genus bear to the recent species of the genus Helcion in family Patellidae. [1]
Species in the genus Helcionopsis include: [2]
General form and position of apex is as in Tryblidium , from which Helcionopsis differ in having the surface marked by fine radiating striae. [1] Muscular scars of this genus Helcionopsis unknown in 1897, when the genus was described. [1]
Endocerida is an extinct nautiloid order, a group of cephalopods from the Lower Paleozoic with cone-like deposits in its siphuncle.
John William Salter was an English naturalist, geologist, and palaeontologist.
The Bellerophontidae are an extinct family of specialized globose bellerophontids, Paleozoic and early Triassic mollusks of the class Gastropoda.
Cameroceras is a genus of extinct, giant orthoconic cephalopod that lived mainly during the Ordovician period. It first appears during the middle Ordovician, around 470 million years ago, and was a fairly common component of the fauna in some places during the period, inhabiting the shallow seas of Laurentia, Baltica and Siberia. Its diversity and abundance became severely reduced following the Ordovician–Silurian extinction events, and the last remnants of the genus went extinct sometime during the Wenlock.
Nanno is an Endocerid, named by Clarke in 1894 for the apical end of an endocerid from the Trenton Limestone of New York state that has the basic description of the nanno type. It is possibly the senior synonym for Proterovaginoceras. As a valid genus, Nanno is included in the Endoceratidae but the nanno type apex may be found in other families.
Pomatiopsidae is a family of small, mainly freshwater snails, that have gills and an operculum, aquatic gastropod mollusks in the superfamily Truncatelloidea.
Bellerophontoidea, common name "bellerophonts", is a superfamily of extinct planospirally-coiled globose molluscs. This superfamily is generally included within the Gastropoda, but may instead be a group of monoplacophorans. The taxon first appeared late in the Cambrian and continued until late in the Triassic.
Coreospiridae is an extinct family of Paleozoic molluscs of uncertain position taxonomically. They might be snails (Gastropoda), Helcionelloida, or they might be Monoplacophora.
†Archinacellidae is an extinct family of paleozoic molluscs of uncertain position.
Bucaniidae is an extinct family of Paleozoic molluscs of uncertain position possibly being either gastropods or monoplacophorans in the superfamily Bellerophontoidea. The family lived from the Lower Ordovician to the Devonian and have shells in which the apertural margins tend to flare. Most genera have a slit and selenizone, others some modification of this feature.
Sinuitidae is an extinct family of Paleozoic molluscs of uncertain position. They had isostrophically coiled shells.
Craspedostomatidae is an extinct taxonomic family of fossil sea snails, marine, gastropod mollusks in the clade Neritimorpha.
Pilina unguis is an extinct species of Paleozoic Silurian monoplacophoran. It was first named as Tryblidium unguis and described by Gustaf Lindström in Latin from the Silurian deposits of Gotland in Sweden, in 1880.
Pilina is an extinct genus of paleozoic monoplacophorans in the family Tryblidiidae.
Tryblidiidae is an extinct family of paleozoic monoplacophorans in the superfamily Tryblidioidea.
Helcionopsis radiatum is an extinct species of paleozoic monoplacophoran in the family Tryblidiidae.
Helcionopsis striata is an extinct species of paleozoic monoplacophoran in the family Tryblidiidae.
Helcionopsis subcarinata is an extinct species of paleozoic monoplacophoran in the family Tryblidiidae.
Similodonta is an extinct genus of early bivalve in the extinct family Praenuculidae. The genus is one of eleven genera in the subfamily Praenuculinae. Similodonta is known from Middle Ordovician through Middle Silurian fossils found in Europe and North America. The genus currently contains eight accepted species, Similodonta ceryx, Similodonta collina, Similodonta djupvikensis, Similodonta magna, Similodonta recurva, Similodonta spjeldnaesi, Similodonta wahli and the type species Similodonta similis.
Phragmolites is an extinct genus of molluscs in the family Bucaniidae, paleozoic molluscs of uncertain position possibly being either Gastropods or Monoplacophorans in the superfamily Bellerophontoidea.
This article incorporates public domain text from reference. [1]