| Rhabdiferoceras Temporal range: | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Order: | † Orthocerida |
| Family: | † Baltoceratidae |
| Genus: | † Rhabdiferoceras Flower (1964) |
| Species | |
| |
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. [1]
Rhabdiferoceras was named by Flower (1964). Its type is Rhabdiferoceras annuliferum. It was assigned to Baltoceratidae by Flower (1964) and Hook and Flower (1977). [2] [3]
Rhabdiferoceras is a rod-bearing baltoceratid with undulations on the dorsal side of the ventral siphuncular rod that correspond to the segments of the siphuncle. Septal necks are very short, connecting rings are layered and are slightly expanded and gently convex from the outside. The genotype, Rhadiferoceras annuliferum Flower is known only from sectioning a limestone block, presumed to be of Cassinian age from the Pogonip Group from the northern end of the Ely Springs Range, Nevada. [2] The siphuncle is rather large, in proportion, and slightly removed from the venter, considered a baltoceratid aspect.
We can only guess at what the animal may have been like or as to its habits. As an orthocerid it may have had 8 or 10 long arms or tentacles projecting from its head, as found in modern squids, belemnites, and indicated for Upper Ordovician Orthonybyoceras and Silurian Michelinoceras .
Orthocerida, also known as the Michelinocerida, is an order of extinct orthoceratoid cephalopods that lived from the Early Ordovician possibly to the Late Triassic. A fossil found in the Caucasus suggests they may even have survived until the Early Cretaceous, and the Eocene fossil Antarcticeras is sometimes considered a descendant of the orthocerids although this is disputed. They were most common however from the Ordovician to the Devonian.
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.
Baltoceras is a member of the Ellesmerocerida, included in the family, Baltoceratidae. The shell of Baltoceras is slender with a subcircular cross section, straight transverse sutures, and a large siphuncle in contact with the venter. Septal necks are short but not vestigial; connecting rings are thick; endosiphonal organic deposits are unknown.
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.
The Ellesmeroceratidae constitute a family within the cephalopod order Ellesmerocerida. They lived from the Upper Cambrian to the Lower Ordovician. They are characterized by straight and endogastric shells, often laterally compressed, so the dorso-ventral dimension is slightly greater than the lateral, with close spaced sutures having shallow lateral lobes and a generally large tubular ventro-marginal siphuncle with concave segments and irregularly spaced diaphragms. Connecting rings are thick and layered, externally straight but thickening inwardly with the maximum near the middle of the segment so as to leave concave depressions on internal siphuncle molds. Septal necks are typically orthochoanitic but vary in length from almost absent (achoanitic) to reaching halfway to the previous septum (hemichoanitic) and may even slope inwardly (loxochoanitic).
Wardoceras is an extinct nautiloid genus from the late Early Ordovician of Western Utah, assigned to the orthocerid family, Michelinoceratidae
Baltoceratidae is an extinct family of orthoconic cephalopods belonging to the subclass Nautiloidea endemic to what would be Asia, Australia, Europe, North America, and South America during the Ordovician living from about 480–460 mya, existing for approximately 20 million years.
Geisonoceratidae is an extinct family of orthoceroid cephalopods endemic to what would be Asia, Europe, and North America from the Middle Ordovician to the Middle Devonian living from about 470—380 mya, existing for approximately 90 million years. With the possible addition of an Early Cretaceous orthocerid from the western Caucasus the range of this group increases dramatically to some 350 million years, thus making it one of the longest lived families of the Nautiloidea.
Endorioceras is an extinct genus of actively mobile carnivorous cephalopod of the family Baltoceratidae that lived in what would be North America during the Ordovician from 490–479 mya, existing for approximately 11 million years.
Rioceras is an extinct genus of orthocerid cephalopods of the family Baltoceratidae that lived in what would be North America during the Early Ordovician from 480—472 mya, existing for approximately 8 million years.
Microbaltoceras is an extinct genus of the cephalopod family Baltoceratidae that lived in what would be North America during the Early Ordovician. It was named by Rousseau Flower (1964) and assigned by him to the Baltoceratidae. The type species is Microbaltoceras minore which was found in the Threadgill Member of the Tanyard Formation in Gillespie County, Texas, USA.
Tajaroceras is an extinct slender cephalopod from the uppermost Lower Ordovician of western North America, belonging to the Orthocerid family Troedssonellidae.
Troedssonellidae is a family of orthoceroid cephalopods from the Ordovician, derived from rod-bearing Baltoceratidae, that have a continuous lining within the siphuncle that resembles very thin and slender endocones. Shells are generally slender and orthoconic. The siphuncle is central or subcentral, composed of straight or slightly expanded segments. Septal necks generally short and connecting rings are thin. Thin cameral deposits are known, which along with the position of the siphuncle and thin connecting rings distinguishes them from the endocerids in which they have been included.
Rangeroceras is an extinct orthoceratoid cephalopod genus that lived in what is now western North America during the latter part of the Early Ordovician.
Veneficoceras is a genus of the rod-bearing Baltoceratidae, an extinct cephalopod family with characteristics of the orthoceratoid Dissidocerida, found in Cassinianage, Lower Ordovician, limestone in western Utah.
Rangeroceratidae is a family of orthoceroid cephalopods known from the late Early Ordovician in eastern North America and Great Britain, included in the order Dissidocerida. The family was named by Evans, 2005, and contains three genera: Rangeroceras, Anrangeroceras, and Cyclorageroceras.
The Sactorthoceratidae comprise Orthocerataceaen genera with a subcentral suborthochoanitic siphuncle composed of slightly expanded segments and free of organic deposits. The camerae (chambers) of the phragmocone likewise have organic deposits that are typically retarded or sparse.
Cartersoceras is a genus of nautiloid cephalopods placed in the Orthocerid family Baltoceratidae, established by Rousseau Flower (1964), for species formally included in part in Murrayoceras, and in part in "Sacotoceras". This group is typical of Murrayoceras in all features except that the siphuncle segments are convex in outline. It is known from the Middle Ordovician of the eastern United States.
Murrayoceras is a nautilid cephalopod included in the orthocerid family Baltoceratidae, widespread in the Middle Ordovician of North America, characterized by a depressed orthoconic shell with a subtriangular cross section and flattened venter and a proportionally large ventral siphuncle, 0.15 to 0.3 the dorso-ventral shell diameter. Septa are close spaced with sutures forming broad lobes on the upper flanks and ventral surface.
Cyclostomiceratidae is an extinct family of Early Ordovician, (Cassinian), ellesmerocerid cephalopods characterized by short, essentially straight shells, a fairly rapidly expanding phragmocone and a ventral siphuncle in which septal necks are almost non-existent and connecting rings are thick and layered. As typical of the Ellesmerocerida, chambers are short, septa close spaced.
