Pseudorthoceratidae

Extinct family of molluscs

Pseudorthoceratidae Temporal range: Ordovician
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Order:	†Pseudorthocerida
Family:	†Pseudorthoceratidae Flower and Caster, 1935

Pseudorthoceratidae is an extinct family of actively mobile aquatic carnivorous cephalopods belonging to the subclass Orthoceratoidea endemic to what would be North America, Asia, and Europe during the Silurian living from 460.5—251 Ma, existing for approximately 209.5 million years.^[1]

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

Taxonomy

Pseudorthoceratidae was named by Flower and Caster (1935). It was assigned to Pseudorthocerataceae by Sweet (1964) and Teichert et al. (1964); to Orthocerida by Frey (1995); and to Pseudorthocerida by Barskov (1968) and Kröger (2008).^[2]^[3]^[4]

References

^ PaleoBiology Database: Pseudorthoceratidae, basic info
^ W. C. Sweet. 1964. Nautiloidea–Orthocerida. In C. Teichert et al. (ed.), Treatise on Invertebrate Paleontology (K) Mollusca 3 216-261
^ C. Teichert, B. Kummel, W.C. Sweet, H.B. Stenzel, W.M. Furnish, B.F. Glenister, H.K. Erben, R.C. Moore, and D.E. Nodine Zeller. 1964. Cephalopoda - general features - Endoceratoidea - Actinoceratoidea - Nautiloidea - Bactritoidea. Treatise on Invertebrate Paleontology K(3):1-519.
^ B. Kröger. 2008. Nautiloids before and during the ammonoid origin in a Siluro–Devonian section of the Tafilalt (Morocco). Special Papers in Palaeontology 79:1-110.

Notable fossil cephalopods (listed by first occurrence)

Cenozoic

The belemnite-cuttlefish-like Belosaepia

Evolution of
cephalopods

Mesozoic

Advanced nautiloids Nautilaceae True ammonites
Early coleoids Muensterelloidea Proteroctopus Styletoctopus Keuppia Palaeoctopus Paleocirroteuthis Vampyronassa
Ceratitid ammonoids late Nautilida
Advanced belemnoids Diplobelids: Diplobelus Belemnites: Belemnites Belemnopsis Belemnotheutis

Palaeozoic

Earliest unambiguous cephalopods: Plectronocerida: Plectronoceras, Monoplacophora-like form: Knightoconus? First appearance of long-lasting lineages Goniatite and ceratite ammonoids Probable coleoid ancestor Bactritida Early coleoids: Jeletzkya?, Gordoniconus, Syllipsimopodi Earliest belemnoids: Aulacocerids Phragmoteuthids
Early forms the earliest cephalopod group Ellesmerocerida Orthocones: Endocerida, Orthocerida, Actinocerida Brevicones: Ascocerida, Oncocerida Earliest coiled cephalopods: Tarphycerida Spirulid?: Shimanskya