''Strandoceras'' is a strongly curved cyrtogomphoceratid with a laterally compressed cross section from the middle and upper Ordovician of

Northern Europe The northern region of Europe has several definitions. A restrictive definition may describe Northern Europe as being roughly north of the southern coast of the Baltic Sea, which is about 54th parallel north, 54°N, or may be based on other g ...

; Estonia, Norway, the U.K. The body chamber of ''Stradoceras'' is straighter and more slender than the chambered phragmocone; the venter narrowly rounded with a shallow hyponomic sinus; the aperture open, sutures with shallow lateral lobes. The siphuncle is close to the venter which is on the inside, endogastric curvature. Segments are large and broadly rounded; connecting rings thick, bullettes large. ''Strandoceras'' gave rise to the

Phragmoceratidae The Phragmoceratidae is a family of extinct nautiloid cephalopods from the Order Discosorida that lived during the latter part of the Silurian. Diagnosis Phragmoceratids are characterized by generally compressed, upwardly curved endogastric sh ...

and very likely to '' Kiaeroceras'' and '' Cyrtogomphoceras'', which in turn gave rise to '' Landeroceras'', within the

Cyrtogomphoceratidae 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 th ...

References

* Flower, R H and Teichert, C; 1957. The Cephalopod Order Discosorida. University of Kansas Paleontological Contributions. Mollusca, Article 6, pp 1–144. * Teicher, C. 1964. Nautiloidea-Discosorida. Treatise on Invertebrate Paleontology, Part K. Teichert and Moore, eds. {{Taxonbar, from=Q7621294 Discosorida Prehistoric nautiloid genera Middle Ordovician first appearances Late Ordovician extinctions