''Diademoceras'' is a genus of

nautiloid Nautiloids are a group of marine cephalopods ( Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and ''Allonautilus''. Fossil nautiloids are diverse and speciose, with over 2,500 recorded species ...

cephalopods from the middle

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...

of North America, named by Rousseau Flower in 1945. The genus is a tainoceratacean included in the nautilid family

Rutoceratidae Rutoceratidae is a family of prototypical nautilids, derived probably from either Brevicoceratidae or Acleistoceratidae of the order Oncocerida early in the Devonian. Rutoceratidae comprise a family within the oncocerid superfamily Tainoceratac ...

. The shell of ''Diademoceras'' is gyroconic, of no more than two whorls, coiled such that whorls do not touch. Whorls are broad, section depressed, sides converge ventrally meeting at a well developed keel. Ornamentation consists of a series of spines on either side as well as transverse striae which form a well developed hyponomic sinus (for the funnel) on the venter. Sutures are straight across the venter, but form a broad shallow lobe on the dorsum. The siphuncle is close to the venter, composed of straight and empty segments, i.e. orthochoanitic.

References

* Bernhard Kummel 1964. Nautiloidea-Nautilida Treatise on Invertebrate Paleontology. Geological Society of America and University of Kansas Press. Prehistoric nautiloid genera {{paleo-nautiloidea-stub