''Ptycholepis'' 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 prehistoric

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 h ...

having the head and opercular bones ornamented with ridges of ganoin, minute

teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, te ...

, and thick scales (which are much longer than deep and are grooved longitudinally on the outer side). ''Ptycholepis'' belongs to the

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

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

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 N ...

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 ...

), '' Ardoreosomus'' (

Nevada Nevada ( ; ) is a state in the 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. Nevada is the 7th-most extensive, ...

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 ...

;

), ''

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'' b ...

'' (global,

), '' Chungkingichthys'' ( China,

) and '' Yuchoulepis'' ( China,

). A typical 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 c ...

, which inserts at the level of the pelvic fins in the front part of the body. Other characters include the striated skull bones and scales, and the small teeth. File:Ptycholepis bollensis.jpg, ''Ptycholepis bollensis'' File:Ptycholepis bollensis - Holzmaden.jpg, ''Ptycholepis bollensis'' File:Ptycholepis bollensis - Lyme Regis.jpg, ''Ptycholepis'' sp.

References

Paleobiology Database entry
Prehistoric ray-finned fish genera {{Jurassic-fish-stub

See also

References