''Cenoceras'' is an extinct genus within the
cephalopod
A cephalopod is any member of the molluscan class Cephalopoda ( Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, ...
mollusc family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Nautilidae, which in turn makes up part of the superfamily
Nautilaceae. This genus has been described by Hyatt in 1884. The
type species
In 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 species that contains the biological type specimen( ...
is ''Cenoceras intermedium'' (Sowerby).
Species
*''
Cenoceras boreale'' †
Dagys and Sobolev 1988
*''
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 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 ...
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 of the Upper Triassic Series (or earliest age of the Late Triassic Epoch). It lasted from 237 to 227 million years ago (Ma). The Carnian is preceded by the Ladinian and is followe ...
age to the Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations ...
, Callovian
In the geologic timescale, the Callovian is an age and stage in the Middle Jurassic, lasting between 166.1 ± 4.0 Ma (million years ago) and 163.5 ± 4.0 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, 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
Prehistoric nautiloid genera
Late Triassic first appearances
Middle Jurassic extinctions
Prehistoric cephalopods of Europe
{{paleo-Nautiloidea-stub