Adnatoceras

Adnatoceras; Temporal range: Middle Devonian - Pennsylvanian
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	Nautiloidea
Order:	Pseudorthocerida
Family:	Spyroceratidae
Genus:	Adnatoceras; Flower, 1935

Adnatoceras is a genus of mid Devonian to Pennsylvanian orthoconic nautiloid cephalopods included in the pseudorthocerid family Spyroceratidae, characterized by tubular, straight-sided, siphuncle segments that expand abruptly at the septal foremen. In some species the siphuncle segments become more ovoid in the later grow stages. The name Adnatoceas comes from the wide area of contact, or adnation, between the connecting ring and flared out brim of the septal neck.[1]

References

Walter C. Sweet (1964). "Nautiloidea- Orthocerida". In Raymond C. Moore (ed.). Treatise on Invertebrate Paleontology, Part K. Geological Society of America and University of Kansas Press. p. K246.

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[1] Walter C. Sweet (1964). "Nautiloidea- Orthocerida". In Raymond C. Moore (ed.). Treatise on Invertebrate Paleontology, Part K. Geological Society of America and University of Kansas Press. p. K246.