''Cheirolepis'' (from , 'hand' and 'scale') is an extinct genus of marine and freshwater

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 ...

that lived in the

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

period of Europe and North America. It is the only genus yet known within the family Cheirolepididae and the order Cheirolepidiformes. It was among the most basal of the Devonian actinopterygians and is considered the first to possess the "standard" dermal cranial bones seen in later actinopterygians. ''Cheirolepis'' was a predatory freshwater and estuarine animal about long. It had a streamlined body with small, triangular

ganoid scale A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as w ...

s similar to those of the

Acanthodii Acanthodii or acanthodians is an extinct class of gnathostomes (jawed fishes). They are currently considered to represent a paraphyletic grade of various fish lineages basal to extant Chondrichthyes, which includes living sharks, rays, and ...

. These scales had a basic structure typical of many early osteichthyans, with a superficial of ganoine overlying

dentine Dentin ( ) (American English) or dentine ( or ) (British English) () is a calcified tissue of the body and, along with enamel, cementum, and pulp, is one of the four major components of teeth. It is usually covered by enamel on the crown ...

, and a basal plate of

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

. ''Cheirolepis'' had well-developed fins which gave it speed and stability, and was probably an active predator. Based on the size of its eyes, it hunted by sight. ''Cheirolepiss jaws, lined with sharp

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 ...

, could be opened very wide, allowing it to swallow prey two thirds of its own size.

Species

The following species are known: * ''C. aleshkai'' Plax, 2020 - Middle Devonian (

Eifelian The Eifelian is the first of two faunal stages in the Middle Devonian Epoch. It lasted from 393.3 ± 1.2 million years ago to 387.7 ± 0.8 million years ago. It was preceded by the Emsian Stage and followed by the Givetian Stage. North American ...

) of

Belarus Belarus, officially the Republic of Belarus, is a landlocked country in Eastern Europe. It is bordered by Russia to the east and northeast, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the northwest. Belarus spans an a ...

* ''C. bychovensis'' Plax, 2022 - Middle Devonian (

Emsian The Emsian is one of three faunal stages in the Early Devonian Epoch. It lasted from 410.62 ±1.95 million years ago to 393.47 ±0.99 million years ago. It was preceded by the Pragian Stage and followed by the Eifelian Stage. It is named after ...

& Eifelian) of Belarus * ''C. canadensis'' Whiteaves, 1881 - Late Devonian (

Frasnian The Frasnian is one of two faunal stages in the Late Devonian Period. It lasted from million years ago to million years ago. It was preceded by the Givetian Stage and followed by the Famennian Stage. Major reef-building was under way during ...

) of Miguasha,

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

* ''C. gaugeri'' Gross, 1973 - Middle Devonian (Givetian) of Belarus &

Estonia Estonia, officially the Republic of Estonia, is a country in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea across from Sweden, to the south by Latvia, and to the east by Ru ...

* ''C. gracilis'' Gross, 1973 - Emsian & Eifelian of Belarus & Estonia * ''C. jonesi'' Newman, Burrow, den Blaauwen & Giles, 2021 - Givetian of

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 ...

Svalbard Svalbard ( , ), previously known as Spitsbergen or Spitzbergen, is a Norway, Norwegian archipelago that lies at the convergence of the Arctic Ocean with the Atlantic Ocean. North of continental Europe, mainland Europe, it lies about midway be ...

* ''C. trailli''

Agassiz Jean Louis Rodolphe Agassiz ( ; ) FRS (For) FRSE (May 28, 1807 – December 14, 1873) was a Swiss-born American biologist and geologist who is recognized as a scholar of Earth's natural history. Spending his early life in Switzerland, he recei ...

, 1835 (

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

) - Middle Devonian (Eifelian &

Givetian The Givetian is one of two faunal stages in the Middle Devonian Period. It lasted from million years ago to million years ago. It was preceded by the Eifelian Stage and followed by the Frasnian Stage. It is named after the town of Givet in ...

) of

Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...

* ''C. schultzei'' Arratia & Cloutier, 2004 - Middle Devonian (Givetian) of

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 ...

, USAArratia, G. and Cloutier, R. (2004). A new cheirolepidid fish from the Middle-Upper Devonian of Red Hill, Nevada, USA. ''In:'' Arratia, G., Wilson, M. V. H. and Cloutier, B., eds., ''Recent Advances in the Origin and Early Radiation of Vertebrates''. Verlag Dr. Friedrich Pfeil. München, Germany. pp. 583-598. ''C. schultzei'' is known from Red Hill, Nevada deposited during the Mid-Late Devonian boundary. The specimen from which this species was named, consisting of scales and a lower jaw, was originally referred to ''C. canadensis''. Many species, including ''C. aleshkai'',''C. bychovensis'', ''C. gracilis'' & ''C. gaugeri'' are only known from isolated scales. The species ''C. sinualis'' from Belarus is considered a ''

nomen nudum In Taxonomy (biology), taxonomy, a ''nomen nudum'' ('naked name'; plural ''nomina nuda'') is a designation which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published ...

''. The species ''C. cummingae'' Agassiz, 1845, ''C. macrocephalus'' M'Coy 1848, & ''C. uragus'' Agassiz, 1835 are considered conspecific with ''C. trailli'' Cheirolepis canadensis

References

External links

''Cheirolepis''
at

Palaeos Palaeos.com is a web site on biology, paleontology, phylogeny and geology and which covers the history of Earth. The site is well respected and has been used as a reference by professional paleontologists such as Michael J. Benton, the professor of ...

{{Taxonbar, from1=Q149446, from2=Q19817097, from3=Q19817098 † Prehistoric ray-finned fish genera Middle Devonian ray-finned fish Late Devonian ray-finned fish Devonian fish of North America Devonian fish of Europe Emsian genera Eifelian life Givetian life Frasnian extinctions Fossils of Scotland Fossils of Belarus Fossils of Estonia Fossils of Canada Fossils of Svalbard Fossils of Nevada Taxa named by Louis Agassiz Fossil taxa described in 1835