| Nautilina | |
|---|---|
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | Nautiloidea |
| Order: | Nautilida |
| Suborder: | Nautilina Shimanskiy, 1957 |
| Families | |
TheNautilina is the last suborder of theNautilida and the onlynautiloids living since the end of theTriassic. The Nautilina, proposed by Shimanskiy, is basically theNautilaceae of Kummel, 1964, defined byFurnish and Glenister, but differs in omitting two families, theParacenoceratidae andPseudonautilidae which instead are placed in theLiroceratina.
The Nautilina are derived from theSyringonautilidae, a family in theCentroceratina (Trigonocerataceae), in theLate Triassic and consists of four families, the Nautilidae,Cymatoceratidae, Herocoglossidae, andAturiidae. The Nautilidae, which is the root stock of the suborder, includes the livingNautilus.
The Nautilidae areinvolute or slightly evolute and generally smooth with straight to sinuous sutures. The Cymatoceratidae, which are the most common of the Cretaceous nautiloids, are strongly ribbed. The Hercoglossidae are smooth but withdifferentiated sutures, in some with deep lateral lobes and well-developed saddles. The Aturiidae (Aturia) is similar to the Hercoglossidae except for being more discoidal and having a more complex suture and subdorsalsiphuncle.
The Nautilidae gave rise to the Cymatoceratidae and Hercoglossidae during theJurassic while the Herocoglossidae became ancestral to the Aturiidae near the beginning of theCenozoic. The Cymatoceratidae and Hercoglossidae became extinct near the end of thePaleogene while the Aturiidae reached into theNeogene. Only the Nautilidae remain.