Cyrtobaltoceras is an extinct cephalopod genus known from the upper Lower Ordovician Fort Cassin Formation at Valcour, N.Y. that's included in the Nautiloid family Baltoceratidae

Baltoceratidae

Baltoceratidae is an extinct family of orthoconic cephalopods belonging to the subclass Nautiloidea endemic to what would be Asia, Australia, Europe, North America, and South America during the Ordovician living from about 480–460 mya, existing for approximately .-Taxonomy:Baltoceratidae was...

Taxonomy

Cyrtobaltoceras was named by Flower (1964 who then assigned it to the Baltoceratidae which at that time was included in the Ellesmerocerida

Ellesmerocerida

The Ellesmerocerida is a order of primitive cephalopods belonging to the subclass Nautiloidea with a widespread distribution that lived during the Late Cambrian and Ordovician.-Morphology:...

. The Baltoceratidae, along with included genera, has since been moved to the Orthocerida.

Morphology

The genotype, Cyrobaltoceras gracile Flower, is based on a small, slender, incomplete, 25 mm long shell with a slight exogastric curvature. Sutures form lobes across the ventral side but go transversely striaight across the dorsum. The siphuncle is proportionally large, almost half the shell diameter in width, and lies against the ventral margin.

Retention

The holotype of Cyrtobaltoceras gracile , Reusseau Flower's no. 341, is housed in the paleontological collection of the New Mexico Museum of Natural History and Science in Albuquerque, N.M (U.S.A)

References

• Fossils (Smithsonian Handbooks) by David Ward