The Nautilitoidea is a superorder within the subclass Nautiloidea, comprising the phylogenetically related Nautilida, Oncocerida, and Tarphycerida. The superorder has its roots in the

Bassleroceratidae The Bassleroceratidae is a family of gradually expanding, smooth ellesmerocerids with a slight to moderate exogastric curvature, subcircular to strongly compressed cross section, and ventral orthochaonitc siphuncle. The ventral side is typicall ...

, the ancestral family of the Tarphycerida, sometimes included in the Ellesmerocerida. The Bassleroceratidae also gave rise to the Granciloceratidae, the ancestral family of the Oncocerida, which in turn gave rise to the Nautilida, which includes the

Nautilidae The nautilus (, ) is a pelagic marine mollusc of the cephalopod family Nautilidae. The nautilus is the sole extant family of the superfamily Nautilaceae and of its smaller but near equal suborder, Nautilina. It comprises six living species in t ...

which includes the living '' Nautilus''. By having the ancestral Bassleroceratidae in the Tarphycerida, the Nautilitoidea becomes

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

. With the Bassleroceratidae in the Ellesmerocerida, the Tarphycerida becomes distinct from the oncocerid-nautilid lineage, making the Nautilitoidea polyphyletic.

References

* Wade, M. 1988. Nautiloids and their descendants: cephalopod classification in 1986. Memoir 44, pp 15–25; New Mexico Bureau of Mines and Mineral Resources, Socorro, NM ''See also'' * Bernhard. Nautiloidea - Nautilida, Treatise on Invertebrate Paleontology Part K. Geological Soc of America and Univ of Kansas Press, R.C. Moore (Ed) 1964. *Furnish & Glenister. Nautiloidea - Tarphycerida ''ibid'' *Sweet, W. C. Nautiloidea - Barrandeocerida ''ibid'' *Sweet, W. C. Nautilodiea - Oncocerida ''ibid'' {{Taxonbar, from=Q6981503 Nautiloids Protostome superorders