''Discosorus'', a genus of the

Discosorida Discosorida are an order of cephalopods that lived from the beginning of the Middle Ordovician, through the Silurian, and into the Devonian. Discosorids are unique in the structure and formation of the siphuncle, the tube that runs through an ...

and member of the family

Discosoridae Discosoridae comprise a family of endogastric discosorids, (Cephalopoda, Nautiloidea), with endocones in the siphuncle, ranging from the Middle Silurian to Middle Devonian. Shell morphology The shell in the Discosoridae is conical, expanding va ...

. Not to be confused with ''

Discoceras ''Discoceras'' is an extinct marine cephalopod mollusk, a member of the Trocholitidae in the Tarphycerida. It is distinct from '' Discosorus'', It is characterized by closely coiled, gradually expanding shells with a subquadrate cross section, ...

''. ''Discosorus'' consists of rapidly expanding endogastric brevicones, mostly known from isolated

siphuncle The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and ...

s composed of broadly expanded segments that increase rapidly in size. Septal necks are recumbent, connecting rings thin, bullettes small. The siphuncle interior is occupied by endocones produced by layered annular deposits expanded back toward the apex, leaving a central tube running down the middle. The short phragmocone is poorly known. ''Discosorus'' is found in the Middle

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...

of eastern and arctic North America and as part of the Discosoratidae is derived from the

Lowoceratidae The Lowoceratidae is a small family of discosorids, early nautiloid cephalopods, from the Middle Silurian in which the characteristic bullette is found only in early growth stages. Lowoceratids were first found in Southampton Island in the Ca ...

which forms a link in the Early Silurian from the Late Ordovician exogastric ''

Faberoceras ''Faberoceras'' is an extinct genus of prehistoric 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 naut ...

'' of the

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 ...

References

*Discosorus, pK336 in Vol K of the

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ...

in the section on the Discosoridae, pp K335 -K338 in the Chapter on the Discosorida by Curt Teichert starting on page K320 {{Taxonbar, from=Q5281711 Discosorida Prehistoric nautiloid genera Silurian cephalopods Silurian cephalopods of North America Paleozoic life of Nunavut Paleozoic life of Quebec

See also

References