Landeroceras

Landeroceras Temporal range: M -?U Ordovician
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	Nautiloidea
Order:	†Discosorida
Family:	†Cyrtogomphoceratidae
Genus:	†Landeroceras Foerste, 1935

Landeroceras is a genus of 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. Connecting rings are thick, septal necks cyrochoanitic to recumbent, bullettes markedly swollen.

Landeroceras is at the end of a small offshoot within the discosorid family Cyrtogomphoceratidae that also includes Cyrtogomphoceras, and not in the line which gave rise to the Phragmoceratidae.

References

• Flower, R H and Teichert, C., 1957. The Cephalopod Order Discosorida. University of Kansas Paleontological Contributions. Mollusca, Article 6, pp 1–144.
• Teichert C. 1964. Nautiloidea -Discosorida, Treatise on Invertebrate Paleontology, Part K. Teichert and Moore eds.