''Boreosomus'' (meaning: "

boreal Boreal may refer to: Climatology and geography *Boreal (age), the first climatic phase of the Blytt-Sernander sequence of northern Europe, during the Holocene epoch *Boreal climate, a climate characterized by long winters and short, cool to mild ...

body") is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

. It was first described from the Arctic island of

Spitsbergen Spitsbergen (; formerly known as West Spitsbergen; Norwegian: ''Vest Spitsbergen'' or ''Vestspitsbergen'' , also sometimes spelled Spitzbergen) is the largest and the only permanently populated island of the Svalbard archipelago in northern Norw ...

(

Svalbard Svalbard ( , ), also known as Spitsbergen, or Spitzbergen, is a Norwegian archipelago in the Arctic Ocean. North of mainland Europe, it is about midway between the northern coast of Norway and the North Pole. The islands of the group range ...

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...

), but was later also discovered in other parts of the world. ''Boreosomus'' belongs to the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Ptycholepidae (= Boreosomidae/Chungkingichthyidae). Other genera of this family are '' Acrorhabdus'' (

), ''

Ardoreosomus ''Ardoreosomus'' (meaning: "tropical body") is an extinct genus of ray-finned fish. It was described from the Induan aged Candelaria Formation of Nevada, United States, which was located near the equator during the Early Triassic epoch. It con ...

'' (

Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...

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 states, a federal district, five major unincorporated territorie ...

), '' Chungkingichthys'' (

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

), '' Ptycholepis'' (global) and ''

Yuchoulepis ''Yuchoulepis'' is an extinct genus of prehistoric Actinopterygii, ray-finned fish. See also * Prehistoric fish * List of prehistoric bony fish References External links Bony fish in the online Sepkoski Database
Ptycholepiformes {{ ...

'' (

Description

The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''Boreosomus arcticus'' (= ''Acrolepis arctica'' Woodward, 1912). A characteristic feature of this family is the

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

, which inserts at the level of the pelvic fins in the middle portion of the body. Most contemporary ray-fins have their dorsal fin in a more posterior position, often opposite to the

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

. Also typical for ptycholepids are the somewhat rectangular, horizontally arranged suborbital bones.

Fossil record

''Boreosomus'' had a worldwide distribution during 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 un ...

. Fossils of ''Boreosomus'' were found, apart from Spitsbergen, in

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

, China, Spain, Svalbard and Jan Mayen, United States and

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 tot ...

Species

Species within this genus include: * †'' Boreosomus arcticus'' (Woodward, 1912) 'Acrolepis_arctica''_Woodward_1912.html" ;"title="Acrolepis.html" ;"title="'Acrolepis">'Acrolepis arctica'' Woodward 1912">Acrolepis.html" ;"title="'Acrolepis">'Acrolepis arctica'' Woodward 1912(

) * †''Boreosomus gillioti'' (Priem, 1924) [''Diaphorognathus gillioti'' (Priem 1924); ''Gyrolepis gillioti'' Priem 1924] * †''Boreosomus merlei'' Beltan, 1957 * †'' Boreosomus piveteaui'' Stensiö, 1921 * †'' Boreosomus reuterskioeldi'' Stensiö, 1921 * †'' Boreosomus scaber'' Stensiö, 1921

References

Prehistoric ray-finned fish genera Palaeonisciformes {{Triassic-fish-stub