''Caseodus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of eugeneodontid

holocephali Holocephali ("complete heads"), sometimes given the term Euchondrocephali, is a subclass of cartilaginous fish in the class Chondrichthyes. The earliest fossils are of teeth and come from the Devonian period. Little is known about these primit ...

an from the Carboniferous of the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

(

Illinois Illinois ( ) is a state in the Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolitan areas include, Peoria and Roc ...

Indiana Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th ...

Kansas Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to ...

South Dakota South Dakota (; Sioux language, Sioux: , ) is a U.S. state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota people, Lakota and Dakota peo ...

) and the

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tota ...

(

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost Provinces and territories of Canada, province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include ...

). It was of medium size, measuring in length.

Eugeneodontida The Eugeneodontida is an extinct and poorly known order of Chondrichthyes, cartilaginous fishes. They possessed "tooth-whorls" on the symphysis of either the lower or both jaws and pectoral fins supported by long radials. They probably lacked pel ...

are an extinct

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ...

Chondrichthyes Chondrichthyes (; ) is a class that contains the cartilaginous fishes that have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fishes'', which have skeletons primarily composed of bone tissu ...

. They are characterized by the presence of tooth whorls. They include iconic genera, such as ''

Helicoprion ''Helicoprion'' is an extinct genus of shark-like eugeneodont fish. Almost all fossil specimens are of spirally arranged clusters of the individuals' teeth, called "tooth whorls", which in life were embedded in the lower jaw. As with most exti ...

'' ("buzz-saw shark"), ''

Ornithoprion ''Ornithoprion'' is an extinct genus of eugeneodont holocephalan closely related to '' Caseodus.'' It lived in the Moscovian Moscovian may refer to: *An inhabitant of Moscow, the capital of Russia *Something of, from, or related to Moscow ...

'', ''

Edestus ''Edestus'' is an extinct genus of edestoid cartilaginous fish known from the Late Carboniferous (Pennsylvanian) of the United Kingdom, Russia, and the United States. Most remains consist of isolated curved blades or "whorls" that are studded wi ...

'' or ''

Fadenia ''Fadenia'' is an extinct genus of eugeneodontid holocephalian chondrichthyan from the Carboniferous Period of Missouri (United States), the Permian period of Greenland, and the Early Triassic epoch of Greenland and Sulphur Mountain Formati ...

''. ''Caseodus'' is one of the few eugeneodontid genera that survived the end-Permian mass extinction event. It is one of the last surviving genera of this clade. ''Caseodus'' is named after the late paleoichthyologist Gerard Case.

References

* Caseodontidae Prehistoric cartilaginous fish genera Carboniferous cartilaginous fish Triassic cartilaginous fish Fossils of Canada {{Triassic-fish-stub