Winnipegoceras is an extinct nautiloid genus from the Ordovician

Ordovician

The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...

 belonging to the Order Discosorida

Discosorida

Discosorida is a unique 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 and connects the chambers in cephalopods, which unlike...

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Phylogeny

Winnipegoceras is included in the discosorid family Westonoceratidae and is derived from Westonoceras

Westonoceras

Westonoceras is an extinct nautiloid genus from the Discosorida that lived during the Middle and Late Ordovician that has been found in North America, Greenland, and Northern Europe...

. Westonoceratidae have mostly medium to large, compressed, exogastric shells with moderately sized siphuncle

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 Spirula...

s composed of short folded back septal necks and generally thin connecting rings with swollen bullettes and which contain internal linings. (Flower & Teichert 1957; Teichert 1964)

Description

Winnipegoceras, named by Foerste (1922) for fossils found near Winnipeg in Manitoba, Canada, is known by it large, slender, compressed, strongly curved exogastric shells; long slender body chamber and siphuncle that is slightly removed from the venter which is the outer, longitudinally convex margin. Siphuncle segments are strongly narrowed at the septal foremina, bullettes swollen, parietal and other internal deposits rarely preserved. (ibid)

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
  Treatise on Invertebrate Paleontology
  The Treatise on Invertebrate Paleontology 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 covering every phylum, class, order, family, and genus of fossil and...
  
   Part K(3), R.C.Moore (ed), Univ.Kans.press.

See also

• List of nautiloids
• Sepkoski, J.J. Jr. 2002. A compendium of fossil marine animal genera. Sepkoski's Online Genus Database (CEPHALOPODA)