Arionoceras

Arionoceras is an extinct orthocerid genus from the Middle and Upper Silurian, of Europe that is estimated to have lived from 422.9—418.1 mya, existing for approximately 4.8 million years.[1]

Arionoceras
Temporal range: M-USilurian
Scientific classification
Kingdom:
Animalia
Phylum:
Mollusca
Class:
Cephalopoda
Subclass:
Nautiloidea
Order:
Orthocerida
Family:
Arionoceratidae
Genus:
Arionoceras

Barskov (1966)

Taxonomy

Arionoceras was named by Barskov (1966) [2] and originally assigned to the Michelinoceratidae, but attributed by Serpagli and Gnoli (1977) -ibid to the Geisonoceratidae Zhuravleva (1959) "on the basis of the (admittedly irregular) occurrence of a lining-like endosiphucular deposit." Dzik (1984) assigned Arionoceras to the newly proposed Arionoceratidae as the type genus. Sepkoski (2002)[3] follows previous authors in putting Arionoceras in the Orthoceratida.

Morphology

Arionoceras has a straight or slightly curved shell with a circular or depressed cross section, smooth or transversely sculptured surface, and large apically pointed protoconch.[2] The siphuncle is central with very short suborthochoanitic septal necks and cylindrical connecting rings. Apical chambers in adults have cameral deposits.

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gollark: Or just, you know, metal but melted.
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References
  1. PaleoBiology Database: Arionoceras, basic info
  2. Some Remarks and Emendaation of the Family Arionoceratidae Dzik 1984 (Cephalopoda, Nautiloidea).
  3. J. J. Sepkoski. 2002. A compendium of fossil marine animal genera. Bulletins of American Paleontology 363:1-560
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