Shelbyoceras

Shelbyoceras is a genus of Cambrian monoplacophora which was one of the genera mistaken for a cephalopod, since the characteristics differentiating monoplacophora from cephalopods are few. Shelbyoceras was reclassified based on a depressed groove that forms a band around the shell, which is similar to a feature seen in Hypseloconus^[2] (with whom it may be synonymous).^[3] The septa in this genus are either closely or irregularly spaced.^[2]

Shelbyoceras
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Monoplacophora
Order:	†Archinacelloidea
Family:	†Shelbyoceridae
Genus:	†Shelbyoceras Ulrich & Foerste, 1931
Type species
Shelbyoceras robustum Ulrich & Foerste, 1936
Species
S. bigpineyensis Stinchcomb, 1986[1] S. buttsi Ulrich et al., 1943 S. robustum Ulrich & Foerste, 1936 S. unguliforme Ulrich et al., 1943

References

1. Stinchcomb, B. L. (1986). "New Monoplacophora (Mollusca) from Late Cambrian and Early Ordovician of Missouri". Journal of Paleontology. 60 (3): 606–626. doi:10.1017/s0022336000022149.
2. Stinchcomb, B. L. (1980). "New Information on Late Cambrian Monoplacophora Hypseloconus and Shelbyoceras (Mollusca)". Journal of Paleontology. 54 (1). Paleontological Society: 45–49. doi:10.2307/1304159. JSTOR 1304159.
3. Stinchcomb, B. L.; Echols, D. J. (1966). "Missouri Upper Cambrian Monoplacophora Previously Considered Cephalopods". Journal of Paleontology. 40 (3): 647–650. doi:10.2307/1301748. JSTOR 1301748.