''Gomphoceras'' is a questionable nautiloid cephalopod genus assigned to the

Oncocerida The Oncocerida comprise a diverse group of generally small nautiloid cephalopods known from the Middle Ordovician to the Mississippian (early Carboniferous; one possible member is known from the Early Permian), in which the connecting rings are t ...

. The family to which it might belong is undetermined. ''Gomphoceras'', named by Sowerby in 1839, is generally short but rapidly expanding, straight to slightly endogastric, with a gibbous body chamber such that all sides are convex. The aperture as vertically transverse, with a hyponomic sinus on a low spout-like process and a larger rounded dorsal sinus connetected above. ''

Tetrameroceras ''Tetrameroceras'' is a genus of short, essentially straight, breviconic, nautiloid cephalopods from the middle and Upper Silurian of Europe and North America included in the oncocerid family Hemiphragmoceraidae. The body chamber is inflated, dor ...

'' and ''

Trimeroceras ''Trimeroceras'' is a genus of straight oncocerid (Nautilodea, Cephalopoda) from the Silurian ( Telychian to Ludlow) of Europe, China, and North America. Originally classified as a part of '' Gomphoceras'', it is now type for the Trimeroceratid ...

'', both oncocerids, are similar in general form, but have more complex apertures.

References

* Oncocerida Paleozoic cephalopods of Europe Paleozoic life of Manitoba Bertie Formation Silurian cephalopods {{paleo-cephalopod-stub