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Mesoceras is a mid Silurian discosorid from central Europe named by Barrande in 1877, with a short, anteriorly contracted body chamber and an aperture that is a long transverse slit.. The cross section is slightly oval with the dorso-ventral dimension slightly less than the lateral. Sutures are straight and transverse, the siphuncle is subcentral.
Franklinoceras is an extinct gensu of cephalopods from the nautiloid order, Discosorida. Nautiloids comprise a subclass of shelled cephalopods that were once diverse and numerous but are now represented by only a handful of species.
Pancornus is an extinct genus from the nautiloid order Discosorida that lived during the Late Devonian. Pancornus was named by F.A. Zhuravleva in 1972, and is contemporary with other late discosorids such as Parevlanoceras and Raphanites.
Antigyroceras is a genus of nautiloids in the order Discosorida, known from central Asia, that lived during Late Silurian and Early Devonian times. It is contemporary with the discosorid Endoplectoceras.
Winnipegoceras is an extinct nautiloid genus from the Ordovician belonging to the Order Discosorida.
Selenoceras is an extinct genus of nautiloids, named by Zhuravleva in 1972, assigned to the Discosorida. Discosorids constitute an order of shelled cephalopods with siphuncle segments that are zoned longitudinally and connecting rings that typically wrap around the septal necks, re-enforcing the septal perforations. Discosorids ranged from the Middle Ordovician possibly to the Upper Devonian.
Hemiphragmoceratidae is a family of endogastrically brevconic oncocerids characterized by elaborately visored apertures in which the hyponomic sinus in mature specimens is on a spout-like process and there may be lateral and dorsal salients.. Shells are compressed with the apical portion curved and the anterior straight. Siphucles are nummuloideal with expanded spheroidal segments and continuously actinosiphonate interiors.
The Cyrtogomphoceratidae are a family in the cephalopod order Discosorida that comprises genera commonly with compressed, endogastrically curved shells. Siphuncles lie close to the ventral side, segments are broadly inflated, connecting rings thick and apically expanded thick bullettes. Chambers are short, separated by shallow, dish shaped septa. Apertures are generally simple.
Burenoceras is a genus of small, even tiny, Gasconadian cyrtoconic ellesmeroceratids in which the phragmocone—the chambered portion—is shorter that the living chamber.
Westonoceratidae are exogastric, mostly compressed, Discosorida of moderate size from the Middle Ordovician to the Lower Silurian.
Teichertoceras is a discosorid genus in the family Westonoceratidae characterized by an endogastric curvature to the early portion of the phragmocone.
Reedsoceras is a genus of large discosorids (Nautiloidea) in the family Westonoceratidae from the middle and upper Ordovician of North America.
Simardoceras is a genus in the discosorid family Westonoceratidae from the Middle Ordovician of Quebec.
Sinclairoceras is a nautiloid cephalopod in the discosorid family Westonoceratidae from the Middle Ordovician Simard Limestone of Quebec. The shell is laterally compressed, upwardly curved, and short; an exogastric brevicone with the venter narrowly and dorsum broadly rounded. The dorsum, at the upper surface, is only slightly concave longitudinally. The venter, at the lower surface, is more strongly convex longitudinally, drawing away from the dorsum and forming a hump at the anterior end of the phragmocone where Sinclairoceras reaches its greatest width.
Discosoridae comprise a family of endogastric discosorids, with endocones in the siphuncle, ranging from the Middle Silurian to Middle Devonian.
Jaregoceras is a genus of nautiloids from the Upper Devonian discosorid that probably belongs to the family Discosoridae.
Kadaroceras is a genus of discosorids from the Devonian, named by Zhuravleva, 1972, possibly a member of the Discosoridae. Discosorids are nautiloid cephalopods generally characterized by inflated siphuncle segments that expand into the chambers and by connecting rings that vary in composition along their length.
Karadzharoceras is a genus of discosorids from the Devonian, named by Zhuravleva in 1972, possibly a member of the Discosoridae. Discosorids are nautiloid cephalopods generally characterized by inflated siphuncle segments that expand into the chambers and by connecting rings that vary in composition along their length. Kadaroceras and Katageioceras are related genera.
Lavaloceras is a genus of middle Ordivician discosorids included in the Westonoceratidae. The shell as nearly straight, with a slight exogastic curvature, and is rather short, breviconic.
Paldoceras is a genus of nautiloid cephalopods found in the middle Ordovician of Estonia and Sweden, included in the discosorid family Apocrinoceratidae. Two species are recognized; Paldoceras paldiskense found northwest of Paldiski in northern Estonia and Paldoceras neptunsakerense found on Öland Island, Sweden.
References
- Manjoceras, Fossilworks entry.
- Curt Teichert, 1964, Nautiloidea-Discosorids. Treatise on Invertebrate Paleontology, Part K. Geological Society of America.
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