†Strepsodiscus is an extinct genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of very primitive snail

Snail

Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...

-like mollusc from the early part of the Late Cambrian (Dresbachian

Dresbachian

The Dresbachian is the lower stage of the Late or Upper Cambrian Period in North America, equivalent to the Chinese Guzhangian which spans about 4 million years, from...

 Age) of North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. The coiled, slightly asymmetrical shell is about 3 cm in height.

Bouchet & Rocroi (2005) divide the Bellerophontoidea into 8 families listed Paleozoic molluscs with isostrophically coiled shells of uncertain position within Mollusca (Gastropoda or Monoplacophora)

Knight, et al., 1960 included it within the Cyrtolitidae, a paraphyletic or polyphyletic assemblage of proto-Gastropods and Tergomyan molluscs. Strepsodiscus may be too primitive to be a true gastropod.

Species

Species within the genus Strepsodiscus are as follows: http://paleobackup.nceas.ucsb.edu:8090/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=68880

• Strepsodiscus major
• S. minutissimus
• S. paucivoluta
• S. splettstoesseri
• S. strongi

External links

• Strepsodiscus - Palaeos

• A possible reference: http://jpaleontol.geoscienceworld.org/cgi/content/abstract/59/3/733

• Info at Paleobiology Database: http://paleobackup.nceas.ucsb.edu:8090/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=68880