Parakionoceras is an extinct nautiloid that lived during the Silurian and Devonian in what is now Europe; included in the orthoceratoid

Orthoceratoidea

The Orthoceratoidea is a superorder , sometimes considered an infraclass or even a subclass, that comprizes nautiloid orders that have orthoconic to slightly cyrtoconic shells and central to subcentral siphuncles in which there may be internal deposits...

 family Kionoceratidae

Kionoceratidae

Kionoceratidae is a family in the Orthocerida, proposed by Hyatt in 1900 for genera characterized by prominent ornamentation in the form of longitudinal ribs, ridges, or lirae, or combinations thereof, sometimes with similar transverse ornament or faint transverse annulations.When Kionoceratidae...

 in the Treatise

Treatise on Invertebrate Paleontology

The Treatise on Invertebrate Paleontology published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and covering every phylum, class, order, family, and genus of fossil and...

part K, 1964 but removed to the Arionoceratidae in Kröger 2008.

Parakionoceras has a long, faintly curved, exogastric shell with relatively long camerae and straight transverse sutures. The surface is lined with sharp-edged longitudinal ribs separated by broader concave inner areas. The siphuncle is slightly eccentric; necks short and loxochoantitic, directed slightly inward; connecting rings slightly inflated. Cameral deposits well developed.

References

• Sweet, Walter C. 1964. Nautiloidea-Orthocerida. Treatise on Invertebrate Paleontology, Part K. Geological Soc of America, and Univ Kansas Press.
• Parakionoceras -Paleobio db