| Wutinoceras Temporal range: early Middle Ordovician (Whiterockian) | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | Nautiloidea |
| Order: | † Actinocerida |
| Family: | † Wutinoceratidae |
| Genus: | † Wutinoceras Flower (1957,emend) |
Wutinoceras is a genus of now extinct nautiloid cephalopods of the Wutinoceratidae family. It exhibits orthoconic actinocerids with ventral siphuncles composed of broadly expanded segments. [1] [2]
Wutinoceras, as with its family the Wutinoceratidae, has a reticulated canal system within the siphuncle, distinguishing it from later forms with arcuate canal systems. Septal necks, components of the siphuncle that project from the back side of the septa, are cyrtochoanitic (outwardly curved) and may be recumbent. Connecting rings are thick, reflective of the ancestral form.
The three varieties of Wutinoceras are based on the form of the siphuncle, and each contains a number of species. These have not been ascribed to subgenera. They include those with broad segments and strongly recumbent brims to the septal necks; those with large segments and rings free ventrally; and those with small segments in which the brims on the dorsal side are sometimes free. [2] The genotype Wutinoceras foerste, which comes from northeast China (Manchuria), is of the second variety.
Wutinoceras species of the broad-segment variety are found in Newfoundland, Oklahoma, and Tasmania; those of the large-segment variety are found in Utah, Nevada, Newfoundland, and Manchuria. Those of the small-segment variety have only been found in Nevada. [2] unless new species described [3] from elsewhere can be included.
Wutinoceras may have its origin in the primitive actinocerid Georgina from the upper Lower Ordovician of Northern Australia and east Asia [4] although its exact ancestor remains elusive. Wutinoceras was once thought to be derived from Polydesmia [1] from northern China, which was later) [3] found to come from beds that overlie those with Wutinoceras, thereby precluding the possibility.
Wutinoceras gave rise to Cyrtonybyoceras with the development of a curved, cyrtoconic shell and to Adamsoceras with the development of a more narrow siphuncle. [1] [2] Wutinoceras is also the ancestor of the Armenoceratidae which gave rise in the later Middle Ordovician to Actinoceras and Gonioceras
The Ellesmerocerida is an order of primitive cephalopods belonging to the subclass Nautiloidea with a widespread distribution that lived during the Late Cambrian and Ordovician.
Actinoceras is the principal and root genus of the Actinoceratidae, a major family in the Actinocerida, that lived during the Middle and Late Ordovician. It is an extinct genus of nautiloid cephalopod that thrived in the warm waters of the United States during the Paleozoic era.
Ormoceras is an actinocerid nautiloid genus and type for the family Ormoceratidae, found in North America from the late Chazyan through the early Cincinnatian of the Middle and Upper Ordovician, but which continued through the Devonian worldwide.
Lambeoceras is a genus of large actinocerids with a convexly lenticular cross section from the Upper Ordovician of North America and the sole representative of the family Lambeoceratidae.
Armenoceras is a genus of actinocerid nautiloid cephalopods whose fossils ranged from the late Whiterockian Stage in the early Middle Ordovician, through the remainder of the period and on into the Upper Silurian. It is the type genus of the family Armenoceratidae.
Bathmoceras is a primitive cephalopod genus from the Middle and Upper Ordovician, type for the family Bathmoceratidae, order Ellesmerocerida.
Adamsoceras is a genus of actinocerids of the family Wutinoceratidae, with spheroidal siphuncle segments like Ormoceras, but having a reticular canal system like Wutinoceras. Adamsoceras has a slender, gently expanding, orthoconic shell that is slightly broader than high, i.e. depressed, with close spaced septa that form ventral lobes and a siphuncle that is near the ventral margin.
Gonioceras is an extinct genus of actinocerid nautiloidean cephalopods typified by a broad, low shell; flattened ventrally, convexly rounded dorsally; top and bottom meeting at an acute angle along the sides. In most the shell is rather thin, especially along the lateral portion. The aperture is contracted. Sutures from broad ventral and dorsal lobes, more narrowly rounded ventro-lateral and dorso-lateral saddles, and sharp pointed lateral lobes; more complex than in later Lambeoceras. The siphuncle is typically subcentral but may be closer to the venter; armenocerid in form with short segments and very short brims and containing a straight endosiphuncular canal system.
Cyrtonybyoceras is a genus of slightly exogastric members of the Wutinoceratidae, a family of actinocerids and probably derived from an earlier Wutinoceras. The shell of Cyrtonybyoceras is curved slightly upwardly and is slightly compressed. Sutures slope toward the aperture, from the dorsum to the venter. The siphuncle is ventral but not marginal, in general form like that of Nybyoceras. Upper and lower septal necks are recumbent or narrowly free. The canal system is reticular, characteristic of the Wutinoceratidae.
The Actinocerida are an order of generally straight, medium to large cephalopods that lived during the early and middle Paleozoic, distinguished by a siphuncle composed of expanded segments that extend into the adjacent chambers, in which deposits formed within contain a system of radial canals and a narrow space along the inner side of the connecting ring known as a paraspatium. Septal necks are generally short and cyrtochoanitic, some being recumbent, some hook shaped. Most grew to lengths of about 60 to 90 cm but some, like the Huroniidae of the Silurian grew significantly larger.
Dawsonoceratidae is an extinct family of orthoconic nautiloid cephalopods that lived in what would be North America and Europe from the Late Ordovician through the Middle Devonian from about 480–390 mya, existing for approximately 90 million years.
Rhabdiferoceras is an extinct genus of orthocerids belonging to the Baltoceratidae that lived in what would be North America during the Cassinian Stage at the end of the Early Ordovician, existing for approximately two million years from about 474 -472 mya.
Sactoceras is an extinct nautiloid cephalopod that lived during the Ordovician and Silurian in what would become North America, Europe, and Asia.
The Wutinoceratidae are a family of early actinocerids defined by Shimazu and Obata in 1938 for actinocerids with thick connecting rings and a complex irregular canal system. Actinocerids are generally straight shelled nautiloid cephalopods with a siphuncle composed of expanded segments, typically with thin connecting rings, in which the internal deposits are penetrated by a system of canals.
The Actinoceriatidae are a family of actinocerids named by Saemann in 1853 for those that grew to have large shells with blunt apices and large siphuncles with widely expanded segments and a generally arcuate endosiphucular canal system. Their range is from the upper Middle Ordovician to the Lower Silurian. Actinocerids are generally straight-shelled nautiloid cephalopods with a siphuncle composed of expanded segments, typically with thin connecting rings, in which the internal deposits are penetrated by a system of canals
The Armenoceratidae are a family of early Paleozoic nautiloid cephalopods belonging to the order Actinocerida.
Nybyoceras is an actinocerid genus assigned to the Armenoceratidae and similar to Armenoceras except for having a siphuncle close to the ventral side of the shell.
Macroloxoceras is a large pseuorthocerid from the upper Devonian of Central Colorado and Southern New Mexico with features resembling those found in actinocerids. Pseudorthocerids and actinocerids are extinct nautiloid cephalopods, generally with long straight shells and expanded siphuncle segments filled with organic deposits.
Protcycloceratidae is an extinct family of slender, commonly annulate, members of the cephalopod order Ellesmerocerida that lived during the Early Ordovician.
Eothinoceratidae is a family of Lower Ordovician nautiloid cephalopods included in the Ellesmerocerida originally established for the genus Eothinoceras.