The Nautilaceae is one of five superfamilies that make up the 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...

 according to Bernard Kummel (1964), and the only one that survived past the Triassic

Triassic

The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

. The Nautilaceae comprise six families: Nautilidae, Paracenoceratidae, Pseudonautilidae

Pseudonautilidae

The Pseudonautilidae is a family of Jurassic and Lower Cretaceous cephalopods belonging to the same major group as modern Nautilus, the Nautilaceae, but forming a different branch from the Nautilidae...

, Cymatoceratidae

Cymatoceratidae

The Cymatoceratidae is a family of Mesozoic and early Cenozoic nautiloid cephalopods and the most abundant of this kind in the Cretaceous. They are characterized by ribbed, generally involute shells of varied form - coiled such that the outer whorl envelops the previous, as with Nautilus, and...

, Hercoglossidae

Hercoglossidae

Hercoglossidae was established by Spath in 1927 for smooth, involute nautiloids characterized by a suture with differentiated elements, known from the Upper Jurassic to the Oligocene. Hercoglossids make up part of the Nautilid superfamily Nautilaceae. Four genera are described in the Treatise...

, and Aturiidae

Aturiidae

The Aturiidae constitutes a family of Paleocene to Miocene nautilids , established by Campman in 1857 for Aturia Bronn, 1838, and are included in the superfamily Nautilaceae in Kümmel 1964....

. Shimanskiy (1957) separated the Paracenoceratidae and Pseudonautilidae from his near equivalent Nautilina

Nautilina

The Nautilina is the last suborder of the Nautilida and the only nautiloids living since the end of the Triassic. The Nautilina, proposed by Shimanskiy, is basically the Nautilaceae of Kummel, 1964, defined by Furnish and Glenister, but differs in omitting two families, the Paracenoceratidae and...

 and added them to the Lyroceratina, expanding the equivalent Clydonautilaceae

Clydonautilaceae

The Clydonautilaceae is a superfamily within the nautiloid order Nautilida characterized by smooth, generally globular, shells with nearly straight sutures, in early forms but developing highly differentiated sutures in some later forms...

 and bringing it into the Jurassic. The Nautilaceae are represented by Nautilus

Nautilus

Nautilus is the common name of marine creatures of cephalopod family Nautilidae, the sole extant family of the superfamily Nautilaceae and of its smaller but near equal suborder, Nautilina. It comprises six living species in two genera, the type of which is the genus Nautilus...

and Allonautilus

Allonautilus

The genus Allonautilus contains two species of nautiluses, which differ significantly in terms of morphology from those placed in the sister taxon Nautilus. Allonautilus is now thought to be a descendant of Nautilus and the latter paraphyletic.-External links:*...

, genera included in the Nautilidae.

Species in the Nautilaceae are generally smooth and involute with straight to strongly sinuous sutures and a small siphuncle. Some groups have sinuous plications or ribs

The Nautilaceae began in the Late Triassic with Cenoceras

Cenoceras

The genus Cenoceras is a member of the Nautilidae, which in turn makes up part of the superfamily Nautilaceae.Cenoceras is variable in form, depending on species; ranges from evolute to involute, compressed lenticular to globose with rounded to flattened venter and flanks. The suture generally has...

, a golublar to discoidal genus derived from the Syringonautilidae and possibly from Syringonautilus. Cenoceras, the earliest member of the Nautilaceae and Nautilidae, is the only nautiloid known to have crossed the upper Triassic boundary and the only one known from the Lower Jurassic

All six families of the Nautilaceae, except for the Aturiidae (Aturia), are derived from the Cenoceras complex in the Middle Jurassic or from Eutrephoceras which immediately followed. The Cenozoic Aturia seems sufficiently derived to warrant familial distinction from its source, the Hercoglossidae.

References

• Kummel B. 1964. Nautiloidea-Nautilida; Treatise on Invertebrate Paleontology Part K, Teichert & Moore (eds) Geological Society of America and University of Kansas Press.