Strepsodiscus

Strepsodiscus is an extinct genus of very primitive fossil snail-like molluscs from the early part of the Late Cambrian (Dresbachian Age) of North America. The coiled, slightly asymmetrical shells are about 3 cm in height. It is not known whether these are shells of gastropods (sea snails) or monoplacophorans, which are more primitive mollusks.

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 this genus 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:


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