Paraphragmitidae is an extinct family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of actively mobile aquatic

Aquatic animal

An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...

 carnivorous cephalapods belonging to the subclass

Class (biology)

In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...

 Orthoceratoidea

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...

 endemic to what would be Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

 and Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 during the Silurian

Silurian

The Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443.7 ± 1.5 Mya , to the beginning of the Devonian Period, about 416.0 ± 2.8 Mya . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...

 living from 436—418.7 mya, existing for approximately .

In life, these animals may have been similar to the modern squid

Squid

Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...

, except for the long shell. The internal structure of the shell consists of concavo-convex chambers linked by a centrally-placed tube called a siphuncle

Siphuncle

The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and Spirula...

.

Taxonomy

The Paraphragmitidae was named and defined by Flower (1950) as containing annulated orthocone

Orthocone

An orthocone is a usually long straight shell of a nautiloid cephalopod. During the 18th and 19th centuries, all shells of this type were named Orthoceras, but it is now known that many groups of nautiloids developed or retained this type of shell....

s and cyrtocones included in the Michelinoceratida. Walter Sweet, (in Teichert et al 1964), included them in the Orthocerataceae

Orthocerataceae

The Orthocerataceae is a superfamily of orthocerid cephalopods that lived from the late Early Ordovician to the Early Cretaceous., but is no longer in general use....

, one of two superfamilies then of the Orthocerida (=Michelinocerida) . With the recognition of the Pseudorthocerida

Pseudorthocerida

Pseudorthocerida are generally straight longiconic nautiloids with a subcentral to marginal cyrtochoanitic siphuncle composed of variably expanded segments which may contain internal deposits that may develop into a continuous parietal lining.. Cameral deposits are common and concentrated ventrally...

as a separate order the two superfamilies became obsolete leaving the Paraphragmitidae simply an orthocerid family .