Strandoceras
Encyclopedia
Strandoceras is a stronly curved cyrtogomphoceratid
with a laterally compressed cross section from the middle and upper Ordovician
of Northern Europe
; 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
and very likely to Kiaeroceras and Cyrtogomphoceras, which in turn gave rise to Landeroceras
, within the Cyrtogomphoceratidae
Cyrtogomphoceratidae
The Cyrtogomphoceratidae is a family in the cephalopod order Discosorida that comprises genera commonly with compressed, endogastrically curved shells. Siphuncles lie close to the venral side, segments are broadly inflated, connecting rings thick and apically expanded thick bullettes. Chambers are...
with a laterally compressed cross section from the middle and upper 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...
of Northern Europe
Northern Europe
Northern Europe is the northern part or region of Europe. Northern Europe typically refers to the seven countries in the northern part of the European subcontinent which includes Denmark, Estonia, Latvia, Lithuania, Norway, Finland and Sweden...
; 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
Phragmoceratidae
The Phragmoceratidae is a family of extinct nautiloid cephalopods from the Order Discosorida that lived during the latter part of the Silurian...
and very likely to Kiaeroceras and Cyrtogomphoceras, which in turn gave rise to Landeroceras
Landeroceras
Landeroceras is a straight shelled cyrtogomphoceratid from the Middle Ordovician Big Horn dolomite of Wyoming.The shell of Landeroceras is a subcylindrical brevicone with the siphuncle on one side, determined as ventral. Siphuncle segments are short and well expanded into the chambers...
, within the Cyrtogomphoceratidae
Cyrtogomphoceratidae
The Cyrtogomphoceratidae is a family in the cephalopod order Discosorida that comprises genera commonly with compressed, endogastrically curved shells. Siphuncles lie close to the venral side, segments are broadly inflated, connecting rings thick and apically expanded thick bullettes. Chambers are...
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.