''Simardoceras'' is a genus in the discosorid (nautiloid cephalopod) family

Westonoceratidae Westonoceratidae are exogastric, mostly compressed, Discosorida of moderate size from the Middle Ordovician to the Lower Silurian. The siphuncle is typically close to the convexly curved outer margin of the phragmocone – the chambered part o ...

from the Middle Ordovician of Quebec. The shell of ''Simardoceras'' is a moderately expanding exogastric cyrtocone, said to resemble a rather large ''

Oncoceras ''Oncoceras'' is a genus of oncocerids, family Oncoceratidae from the middle and upper Ordovician of North America and Europe. The shell, or conch, of ''Oncoceras'' is relatively short, a curved, compressed brevicone with a maximum width in the ...

'', but with a siphuncle that is definitely discosorid. The venter is almost uniformly convex in longitudinal profile. The dorsal profile changes from concave in the apical portion to straight, then slightly convex at the front of the phragmocone and back of the body chamber, the concave again near the aperture. The siphuncle is ventral. Segments are subquadrate in outline and are longer than broad. Connecting rings are thick. Although ''Simardoceras'' somewhat resembles ''

Winnipegoceras ''Winnipegoceras'' is an extinct nautiloid genus from the Ordovician belonging to the Order Discosorida. Phylogeny ''Winnipegoceras'' is included in the discosorid family Westonoceratidae and is derived from '' Westonoceras''. Westonoceratidae ...

'' is the form of its siphuncle, it differs in its very broad cross section. The slender siphuncle segments also distinguish it from the apparently more closely related ''

Sinclairoceras ''Sinclairoceras'' is a nautiloid cephalopod in the discosorid family Westonoceratidae from the Middle Ordovician Simard Limestone of Quebec Quebec ( ; )According to the Canadian government, ''Québec'' (with the acute accent) is th ...

'' and from its apparent derivative ''

Reedsoceras ''Reedsoceras'' is a genus of large discosorids (Nautiloidea) in the family Westonoceratidae from the middle and upper Ordovician of North America. ''Reedsoceras'' was named as a genus characterized by rapidly expanding exogastric cyrtocones wi ...

''. ''Sinclairoceras'', ''Simardoceras'', and ''Reedsoceras'' are found in beds of Black River age (Middle Ordovician) and seem to be closely related, and may even form a phylogenetic (evolutionary) series.

References

* Flower, R.H. and Curt Teichert, 1957. The Cephalopod Order Discosorida. University of Kansas Paleontological Contributions, Mollusca, Article 6. July 1957 * Teichert, C 1964. Nautiloidea -Discosorida. Treatise on Invertebrate Paleontology Part K. Geological Soc of America and Univ. Kansas Press {{Taxonbar, from=Q7517379 Ordovician cephalopods of North America Discosorida Prehistoric nautiloid genera Ordovician cephalopods