Trigonoceratidae
| Trigonoceratidae Temporal range: L Carb (Miss) - L Perm |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | Nautiloidea |
| Order: | Nautilida |
| Superfamily: | Trigonocerataceae |
| Family: |
Trigonoceratidae Hyatt, 1884 |
| Genera | |
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The Trigonoceratidae is a family of coiled nautiloid cephalopods that lived during the period from the Early Carboniferous (Mississippian) to the Early Permian.
Trigonoceratidae comprise members of the order Nautilida characterized by a loosely coiled to evolute shell generally bearing longitudinal ribs or ridges with a whorl section that is oval to subquadrate and varying from compressed (squeezed) to depressed (flattened). (Kummel 1964)
The Trigonoceratidae along with four other related families are combined in the Superfamily Trigonocerataceae in the Treatise,(ibid Kummel) a superfamily. They are also the Triboloceratidae (Flower and Kummel,1950) which form the Tribolocerataceae within the Centroceratina of the Osnovy according to Shimansky. The Trigonocerataceae and Centroceratina are essentially equivalent as are the Trigonoceratidae and Triboloceratidae.
The Trigonerceratidae were derived from the core Centroceratidae (basis for the name Centroceratina) early in the Mississippian along with the longer lived Grypoceratidae. Of the five families of the Trigonocerataceae, the Trigonoceratidae was defined first, by Hyatt in 1884, hence the choice of name.
Seventeen trigonoceratid genera are listed in the Treatise. All but one are found in the Lower Carboniferous of Europe and equivalent Mississippian of North America.(ibid Kummel)
Mississippian Genera from North America alone
Mississippian Genera from North America and Europe ( L Carb)
Mississippian (L Carb) Genera from Europe
Lower Permian Central Asia
Trigonoceras, type genus, named by Hyatt, 1844, is unique among the Trigonoceratidae in the Treatise. It is the only genus included that has a subtriangular whorl section consisting of a broad concave venter and narrow dorsum. The remaining can be divided on the basis of shell morphology into those that are smooth, at least on the outer whorl, those with numerous equal longitudinal ribs or lirae, and those with prominent longitudinal ridges separated by wide grooves or sulci.(ibid Kummel)
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