Boreosomus

Boreosomus (meaning: "boreal body") is an extinct genus of Triassic ray-finned fish. It was first described from the Arctic island of Spitsbergen (Svalbard, Norway), but was later also discovered in other parts of the world. Boreosomus had a worldwide distribution during the Early Triassic. Fossils of Boreosomus were found, apart from Spitsbergen, in Greenland, Madagascar and Canada.[2] The type species is Boreosomus arcticus (= Acrolepis arctica Woodward, 1912).

Boreosomus Temporal range:
Boreosomus slab and counterslab fossils at the Geological Museum in Copenhagen
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	†Palaeonisciformes[1]
Family:	†Ptycholepidae
Genus:	†Boreosomus Stensiö, 1921
Type species
†Acrolepis arctica Woodward, 1912
Other species
†B. gillioti (Priem, 1924) †B. merlei Beltan, 1957 †B. piveteaui Nielsen, 1942 †B. reuterskioldi Stensiö, 1921 †B. scaber Stensiö, 1921
Synonyms
Diaphorognathus Brough, 1933

Boreosomus gillioti: fossil mold and latex cast

Boreosomus belongs to the family Ptycholepidae (= Boreosomidae/Chungkingichthyidae). Other genera of this family are Acrorhabdus (Spitsbergen), Ardoreosomus (Nevada, United States), Chungkingichthys (China), Ptycholepis (global) and Yuchoulepis (China).[3] A characteristic feature of this family is the dorsal fin, 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. Also typical for ptycholepids are the somewhat rectangular, horizontally arranged suborbital bones.