Pseudorthocerida

Systematic Paleontology Class Cephalopoda Subclass Nautiloidea Order Pseudorthocerida

The Pseudorthocerida, named by Barskov, 1968, is an order of essentially Paleozoic nautiloids with generally straight, elongate shells similar to the Orthocerida but differing in the details of the siphuncle.

In the more recent perspective the Pseudorthocerida is said to include five families, the Carbactinoceratidae, Pseudactinoceratidae, Pseudorthoceratidae, Spyroceratidae, and Trematoceratidae. This differs from an earlier perspective in which the Pseudorthocerida is subdivided into just the Pseudorthoceratidae and Spyroceratidae.

References Walter C. Sweet, 1964. Nautiloidea --Orthocerida. Treatise on Invertebrate Paleontology, Part K. Pseudorthocerida in BioLib.cz