Subvestinautilus is an evolute koninckioceratid

Koninckioceratidae

The Koninckioceratidae comprise a collection of nautilid genera, typically with more or less evolute shells with depressed whorl sections, that are combined as a family within the Tainocerataceae...

 genus, order Nautilida

Nautilida

The Nautilida constitute a large and diverse order of generally coiled nautiloid cephalopods that began in the mid Paleozoic and continues to the present with a single family, the Nautilidae which includes two genera, Nautilus and Allonautilus, with six species...

, with a depressed, trapezoidal whorl section. The venter is broadly rounded, ventrolateral shoulders sharply rounded, flanks flattened and converging toward a narrow rounded dorsum. In early growth stages a keel forms on the umbilical shoulder which becomes rounded or marked by a longitudal rib at maturity . The suture has a broadly rounded ventral lobe and a deeper lateral lobe.

Subvestinautilus, named by Turner, 1954, has been found in the Lower Carboniferous of Ireland and the Isle of Man.

References

• Bernhard Kummel, 1964. Nautiloidea-Nautilida. Treatise on Invertebrate Paleontology, Part K. Geological Soc. of America and University of Kansas press. Teichert and Moore (eds)
• Koninckioceratidae-Paleodb