''Ptycholepis'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of prehistoric

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

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, tear ...

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

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

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

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

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 251.9 Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which ...

), ''

Ardoreosomus ''Ardoreosomus'' (meaning: "tropical body") is an extinct genus of marine 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. ...

'' (

Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...

, United States; Early Triassic), ''

Boreosomus ''Boreosomus'' (meaning: " boreal body") is an extinct genus of Triassic marine ray-finned fish. It was first described from the Arctic island of Spitsbergen (Svalbard, Norway), hence its genus name, but was later also discovered in other parts ...

'' (global, Early Triassic), '' Chungkingichthys'' (China, Early Triassic) 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 {{ ...

'' (China, Early Triassic). A typical feature of this family is the

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

, 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. File:Ptycholepis_bollensis.png, Life restoration

References

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