''Cenoceras'' (meaning "recent horn") is an extinct genus within the

cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Nautilidae A nautilus (; ) is any of the various species within the cephalopod family Nautilidae. This is the sole extant family of the superfamily Nautilaceae and the suborder Nautilina. It comprises nine living species in two genera, the type genus, ty ...

, which in turn makes up part of the superfamily

Nautilaceae The Nautilaceae form one of five superfamilies that make up the Nautilida according to Bernard Kummel (1964), and the only one that survived past the Triassic. The Nautilaceae comprise six families: Nautilidae, Paracenoceratidae, Pseudonautili ...

. This genus has been described by Hyatt in 1884. The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

is ''Cenoceras intermedium'', which was originally described by Sowerby 1816 as ''

Nautilus A nautilus (; ) is any of the various species within the cephalopod family Nautilidae. This is the sole extant family of the superfamily Nautilaceae and the suborder Nautilina. It comprises nine living species in two genera, the type genus, ty ...

intermedius''.

Species

*†''Cenoceras boreale'' Dagys and Sobolev 1988 *†''Cenoceras rumelangense'' Weis & Schweigert 2023 *†''Cenoceras trechmanni'' Kummel 1953

Description

Shells of these nektonic carnivores are 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 shallow ventral and lateral lobes. The location of the

siphuncle The siphuncle is a strand of biological tissue, tissue passing longitudinally through the mollusc shell, shell of a cephalopod mollusc. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the li ...

is variable, but never at an extreme ventral or dorsal position (Kümmel 1964, K449).

Fossil range

''Cenoceras'' has a fossil range from the

Upper Triassic The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch. T ...

Carnian The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227.3 ...

age to the

Middle Jurassic The Middle Jurassic is the second Epoch (geology), epoch of the Jurassic Period (geology), Period. It lasted from about 174.1 to 161.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relativel ...

Callovian In the geologic timescale, the Callovian is an age and stage in the Middle Jurassic, lasting between 165.3 ± 1.1 Ma (million years ago) and 161.5 ± 1.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the ...

age (from 235.0 to 163.5 Ma).The Paleobiology Database
/ref>Sepkoski, Jac
Sepkoski's Online Genus Database – Cephalopoda
/ref>

References

* Kümmel, B. 1964, Nauiloidea-Nautilida, in The

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology,'' published from 1953–2007 by the Geological Society of America and the University of Kansas, then 2009–present by the University of Kansas Paleontological Institute, is a definitive multi-authore ...

, Part K, Nautiloidea; Geological Society of America and University of Kansas Press. * Cyril Walker & David Ward (1993) - Fossielen: Sesam Natuur Handboeken, Bosch & Keuning, Baarn.

External links

Europeana
Prehistoric nautiloid genera Late Triassic first appearances Middle Jurassic extinctions Mesozoic cephalopods of Europe {{paleo-Nautiloidea-stub