''Bickmorites'' is an extinct

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 speci ...

cephalopod A cephalopod is any member of the molluscan class Cephalopoda ( Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, ...

genus known from the upper Ordovician to the middle Silurian of North America and northern Europe (Norway). ''Bickmorites'' has a gyroconic shell, coiled such that whorls are not in contact, although close. The surface is strongly ribbed; ribs slant dorso-ventrally toward the apex. The siphuncle is narrow, located slightly ventral of the center. Septal necks are straight, making the siphuncle orthochoanitic. ''Bickmorites'' seems to bridge the temporal gap between the Upper Ordovivian barrandeoceratid '' Antiplectoceras'' and the Middle Silurian barrandoeceratids ''

Gasconsoceras ''Gasconsoceras'' is a genus of nautiloid cephalopods belonging to the tarphyceroid family Barrandeoceratidae, known from Middle Silurian marine strata in Quebec Quebec ( ; )According to the Canadian government, ''Québec'' (with the ac ...

'', ''

Laureloceras ''Laureloceras'' is a genus of the tarphycerid family Plectoceratidae that lived during the Middle Silurian in what is now North America. The shell of ''Laureloceras'' is a smooth, slender, compressed cyrtocone or gyrocone with the venter more n ...

'', and ''

Savageoceras The genus ''Savageoceras'' is a barrandeoceratid first known from the Middle Silurian of Illinois consisting of rapidly enlarging, depressed cyrtocones with a trapezoidal section; ventral side wider and flatter than dorsal; sides converging on ...

''.

References

* Walter C. Sweet, 1964. Naautiloidea-Barrandeocerida. Treatise on Invertebrate Paleongology, Part K. Geological Society of America.
Bickmorites
in Fossilworks gateway, Prehistoric nautiloid genera Late Ordovician first appearances Silurian extinctions Paleozoic life of Manitoba {{paleo-nautiloid-stub

See also

References