Tienoceras

Tienoceras
Tienoceras
Temporal range: Permian
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Nautiloidea
Order: Orthocerida?
Family: undetermined
Genus: Tienoceras
Chao (1954)

Tienocerasis an extinct orthoceratoid genus from the Permian of China (Hunan). Orthoceratoids are slender conical or near cylindrial, orthoconic, nautiloid cephalopods from the Paleozoic. Nautiloids, which include a number of different extinct orders, were far more divers and numerous in the past, but are represented today by only two closely related genera.

Teinoceras is represented by a smooth orthocone that enlargens slightly with growth and that has a lenticular cross section. The middle of the dorsum and venter (top and bottom) are flattened or depressed and the dorsolateral and ventrolateral areas have longitudinal depressions. Sutures have mid dorsal, mid ventral, and sharp lateral lobes separated by narrow ventrolateral and dorsolateral saddles. The siphuncle, which is small, runs through the middle.

The exact relationship of Tienoceras within the orthoceratoids is unknown.


References

  • Sepkoski, J.J. Jr. 2002. A compendium of fossil marine animal genera. Bulletins of American Paleontology 363: 1560. [1]