''Perleidus'' 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 ...

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 ...

from the

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 ...

period. Fossils have been found in the

Middle Triassic In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided in chronostratigraphy. The Middle Triassic spans the time between Ma and ...

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...

Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...

, and

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 ...

. The inclusion of

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 ...

species in the genus ''Perleidus'' was questioned.

Ecology

''Perleidus'' was a marine predatory fish, about in length. Its jaws hung vertically under the braincase, allowing them to open wide, a feature it shared with the earlier

palaeonisciform The Palaeonisciformes (Palaeoniscida) are an extinct order of early ray-finned fishes ( Actinopterygii). Palaeonisciformes ''sensu lato'' first appeared in the fossil record in the Late Silurian and last appeared in the Late Cretaceous. The na ...

fish, from which it may have been descended. Unlike those earlier fish, however, ''Perleidus'' and its relatives had highly flexible dorsal and

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 ...

s, with a reduced number of fin rays. This would have made the fish more agile in the water.

Classification

The genus ''Perleidus'' currently comprises two species: ''P. altolepis'' (

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * Ty ...

) and ''P. sinensis''. The type species was originally described as ''

Semionotus ''Semionotus'' (from el, σημιον , 'mark' and el, νῶτος , 'back') is an extinct genus of ray-finned fish found throughout Northern Pangaea ( North America and Europe) during the late Triassic, becoming extinct in the Early Jurassic ...

altolepis'' by Wilhelm Deecke. The genus ''Perleidus'' was later erected for this species, named after the comune (municipality) of

Perledo Perledo (Comasco, Lecchese: ) is a ''comune'' (municipality) in the Province of Lecco in the Italian region Lombardy, located about north of Milan and about northwest of Lecco. As of 31 December 2004, it had a population of 900 and an area of . ...

in the

Province of Lecco The Province of Lecco ( it, provincia di Lecco; Lecchese: ) is a Provinces of Italy, province in the Lombardy region of Italy. Its capital is the city of Lecco. As of 2017, the province had a population of 337,211 on a surface of divided into ...

Lombardy Lombardy ( it, Lombardia, Lombard language, Lombard: ''Lombardia'' or ''Lumbardia' '') is an administrative regions of Italy, region of Italy that covers ; it is located in the northern-central part of the country and has a population of about 10 ...

, northern Italy. Several species from the

were subsequently referred to the genus ''Perleidus'' based on superficial resemblances. In 2017, a new genus, '' Teffichthys'', was erected for Early Triassic species of "''Perleidus''". ''Perleidus'' is the name giving taxon for 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 ...

Perleididae Perleidiformes are an extinct order (biology), order of prehistoric ray-finned fish from the Triassic period (geology), period Although numerous Triassic taxa have been referred to Perleidiformes, which ones should be included for it to form a mo ...

and the

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 d ...

Perleidiformes Perleidiformes are an extinct order of prehistoric ray-finned fish from the Triassic period Although numerous Triassic taxa have been referred to Perleidiformes, which ones should be included for it to form a monophyletic group is a matter of on ...

References

Prehistoric neopterygii Prehistoric ray-finned fish genera Triassic bony fish Triassic fish of Asia Triassic fish of Europe {{paleo-rayfinned-fish-stub