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.

Strepsodiscus Temporal range: Late Cambrian PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda (?)
Order:	†Bellerophontida
Family:	†Tropidodiscidae
Genus:	†Strepsodiscus

Bouchet & Rocroi (2005)^[1] 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