The beardfishes consist of a single extant

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 ...

, ''

Polymixia ''Polymixia'' is the only extant taxon, extant genus of the Order (biology), order Beardfish, Polymixiiformes and family Polymixiidae. It contains 10 species, all of which live in deepwater marine environments. They are found in tropical and subt ...

'', of deep-sea marine

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 ...

named for their pair of long

hyoid The hyoid-bone (lingual-bone or tongue-bone) () is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid-cartilage. At rest, it lies between the base of the mandible and the third cervical verte ...

barbel Barbel may refer to: *Barbel (anatomy), a whisker-like organ near the mouth found in some fish (notably catfish, loaches and cyprinids) and turtles *Barbel (fish), a common name for certain species of fish **''Barbus barbus'', a species of cyprini ...

s. They are classified in their own order Polymixiiformes . But as Nelson says, "few groups have been shifted back and forth as frequently as this one, and they were recently added to Paracanthoptergii". For instance, they have previously been classified as belonging to the

Beryciformes The Beryciformes are a poorly-understood Order (biology), order of carnivorous ray-finned fishes consisting of 7 families, 30 genera, and 161 species. They feed on small fish and invertebrates. Beyond this, little is known about the biology of m ...

, and are presently considered either paracanthopterygians or the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

acanthopterygians Acanthopterygii (meaning "spiny-finned one") is a superorder of bony fishes in the class Actinopterygii. Members of this superorder are sometimes called ray-finned fishes for the characteristic sharp, bony rays in their fins; however this name ...

. They are of little economic importance. They are found in tropical and subtropical waters of the

Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

, Indian and western

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

. They are bottom-dwelling fish, found down to about depth. Most are relatively small fish, although one species, ''

Polymixia berndti ''Polymixia berndti'' is a species of beardfish found in the Indian and Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north ...

'', is over in length. The earliest body fossils are from the Late

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

Lebanon Lebanon, officially the Republic of Lebanon, is a country in the Levant region of West Asia. Situated at the crossroads of the Mediterranean Basin and the Arabian Peninsula, it is bordered by Syria to the north and east, Israel to the south ...

, of the genus ''

Pycnosteroides ''Pycnosteroides'' is an extinct genus of prehistoric bony fish that lived during the upper Cenomanian. See also * Prehistoric fish * List of prehistoric bony fish This list of prehistoric bony fish is an attempt to create a comprehensive li ...

''. However, tentative earlier records are known from distinctive fossil

otoliths An otolith (, ' ear + , ', a stone), also called otoconium, statolith, or statoconium, is a calcium carbonate structure in the saccule or utricle of the inner ear, specifically in the vestibular system of vertebrates. The saccule and utricle, i ...

from the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

(

Albian The Albian is both an age (geology), age of the geologic timescale and a stage (stratigraphy), stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early Cretaceous, Early/Lower Cretaceous epoch (geology), Epoch/s ...

) of Texas, USA. Many different fossil families and genera are known from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

and early

Cenozoic The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three g ...

, in contrast to the relatively few surviving species in a single genus. Extant beardfish can thus be considered " living fossils".

Classification

* Order Polymixiiformes Rosen & Patterson, 1969 ** Genus ?†'' Allocyclostoma'' Schwarzhans, Stringer & Welton, 2022 nowiki/>otolith">otolith.html" ;"title="nowiki/>otolith">nowiki/>otolithref name=":2" /> ***†''A. alienus'' Schwarzhans, Stringer & Welton, 2022 ** Genus †''Cumbaaichthys'' Murray 2016 *** †''Cumbaaichthys oxyrhynchus'' Murray 2016 **Genus †''Severnichthys'' Stringer & Schwarzhans, 2021 [otolith] ***†''S. beauryi'' (Schwarzhans, 2010) ***†''S. bourdoni'' Stringer & Schwarzhans, 2021 **Genus ?†''

Texoma Texoma is an interstate region in the United States, split between Oklahoma and Texas. The name is a portmanteau of Texas and Oklahoma. Businesses use the term in their names to describe their intended service area. This includes 8 counties with ...

'' Schwarzhans, Stringer & Welton, 2022 tolithref name=":2" /> ***†''T. cyclogaster'' Schwarzhans, Stringer & Welton, 2022 ** Family † Boreiohydriidae Murray & Cumbaa 2013 *** Genus †'' Boreiohydrias'' Murray & Cumbaa 2013 **** †''Boreiohydrias dayi'' Murray & Cumbaa 2013 ** Family † Dalmatichthyidae Radovčić 1975 *** Genus †'' Dalmatichthys'' Radovčić 1975 **** †''Dalmatichthys malezi'' Radovčić 1975 ** Family † Digoriidae Bannikov 1985 *** Genus †'' Digoria'' Daniltshenko, 1980 **** †''Digoria ambigua'' Daniltshenko, 1980 ** Family † Dinopterygidae Jordan, 1923 *** Genus †'' Dinopteryx'' Woodward, 1901 **** †''Dinopteryx spinosus'' (Davis, 1887) ** Family

Polymixiidae The beardfishes consist of a single extant genus, ''Polymixia'', of deep-sea marine ray-finned fish named for their pair of long hyoid barbel (anatomy), barbels. They are classified in their own order Polymixiiformes . But as Nelson says, "few g ...

Gill 1862 erycopsidae Regan 1911; Dalmatichthyidae Radovčić 1975; Omosomopsidae Gaudant 1978; Homonotichthyidae Whitley 1933*** Genus †'' Apricenaichthys'' Taverne 2011 **** †''Apricenaichthys italicus'' *** Genus †'' Berycopsia'' Radovčić 1975 **** †''Berycopsia inopinnata'' Radovčić 1975 *** Genus †'' Berycopsis'' Dixon 1850 'Platycormus'' von der Marck 1900">Platycormus.html" ;"title="'Platycormus">'Platycormus'' von der Marck 1900**** †''B. elegans'' Dixon 1850 [''Platycormus elegans'' (Dixon 1850)] **** †''B. germana'' (Agassiz 1839) [''Beryx germanus'' Agassiz 1839; ''Platycormus germanus'' (Agassiz 1839)] **** †''B. pulcher'' Bannikov & Bacchia 2004 ***Genus †'' Cowetaichthys'' Schwarzhans, Huddleston & Takeuchi, 2018 tolith****†''C. alabamae'' Schwarzhans, Huddleston & Takeuchi, 2018 ****†''C. beauryi'' (Schwarzhans, 2010) ****†''C. carnevalei'' Schwarzhans & Stringer, 2020 ****†''C. groenlandicus'' (Schwarzhans, 2004) ****†''C. harderi'' (Schwarzhans, 2003) ****†''C. lamberi'' Schwarzhans, Huddleston & Takeuchi, 2018 *** Genus †'' Homonotichthys'' Whitley 1933 **** †''H. dorsalis'' (Dixon 1850) 'Homonotus dorsalis'' Dixon 1850**** †''H. elegans'' (Dixon 1850) 'Homonotus elegans'' Dixon 1850**** †''H. rotundus'' (Woodward 1902) 'Homonotus rotundus'' Woodward 1902***Genus †'' Namicauda'' Schwarzhans, Ohe & Ando, 2017 tolith****†''Namicauda pulvinata'' Schwarzhans, Ohe & Ando, 2017 *** Genus †'' Omosoma'' Costa 1857 **** †''O. garretti'' Bardack 1976 **** †''O. pulchellum'' Davis 1887 **** †''O. sahelalmae'' Costa 1857 **** †''O. tselfatense'' Gaudant 1978 *** Genus †''

Omosomopsis ''Omosomopsis'' is a genus of prehistoric ray-finned fish from the Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata f ...

'' Gaudant 1978 **** †''Omosomopsis sima'' (Arambourg 1954) Gaudant 1978 *** Genus †'' Parapolymixia'' David 1946 **** †''Parapolymixia californica'' David 1946 *** Genus †'' Pycnosterinx'' Heckel 1849 'Imogaster'' Costa 1857">Imogaster.html" ;"title="'Imogaster">'Imogaster'' Costa 1857 **** †''P. discoides'' Heckel 1849 **** †''P. dorsalis'' Pictet 1850 **** †''P. heckelii'' Pictet 1850 **** †''P. latus'' Davis 1887 **** †''P. russeggeri'' Heckel 1849 [''Homonotus pulcher'' Davis 1886] *** Genus ''

'' Lowe 1836 'Dinemus'' Poey 1860; ''Nemobrama">Dinemus.html" ;"title="'Dinemus">'Dinemus'' Poey 1860; ''Nemobrama'' Valenciennes 1860 non Jordan, Evermann & Clark 1930] **** ''Polymixia berndti, P. berndti'' Gilbert 1905 (Pacific beardfish) **** ''Polymixia busakhini, P. busakhini'' Kotlyar 1993 (Busakhin's beardfish) **** ''Polymixia carmenae, P. carmenae'' Caixeta, Oliveira & de Melo, 2024 (Brazilian beardfish) **** '' Polymixia fusca, P. fusca'' Kotthaus 1970 **** †?'' P. harderi'' (Schwarzhans 2003) tolithref> **** '' P. hollisterae'' Grande & Wilson, 2021 (Bermuda beardfish) **** '' P. japonica'' Günther 1877 (Silver eye) **** '' P. longispina'' Deng, Xiong & Zhan 1983 'Polymixia kawadae'' Okamura & Ema 1985**** '' P. lowei'' Günther 1859 (Beardfish) **** '' P. nobilis'' Lowe 1838 'Nemobrama webbii'' Valenciennes 1837; ''Dinemus venustus'' Poey 1860; ''Polymixia nobilis virginica'' Nichols & Firth 1936(Stout beardfish) **** †'' P. polita'' Schwarzhans 2012 tolith**** '' P. salagomeziensis'' Kotlyar 1991 **** '' P. sazonovi'' Kotlyar 1992 **** '' P. yuri'' Kotlyar 1982 Eocene fish from the Fur Formation

***Genus †'' Polyspinatus'' Schrøder, Rasmussen, Møller & Carnevale, 2022 ****†''Polyspinatus fluere'' Schrøder, Rasmussen, Møller & Carnevale, 2022 **Family † Pycnosteroididae Patterson, 1964 ***Genus †'' Magrebichthys'' Murray & Wilson 2014 **** †''Magrebichthys nelsoni'' Murray & Wilson 2014 ***Genus †''

'' Woodward, 1942 ****†''Pycnosteroides levispinosus'' (Hay, 1903)

Timeline of genera

ImageSize = width:1000px height:auto barincrement:15px PlotArea = left:10px bottom:50px top:10px right:10px Period = from:-145.5 till:10 TimeAxis = orientation:horizontal ScaleMajor = unit:year increment:10 start:-145.5 ScaleMinor = unit:year increment:1 start:-145.5 TimeAxis = orientation:hor AlignBars = justify Colors = #legends id:CAR value:claret id:ANK value:rgb(0.4,0.3,0.196) id:HER value:teal id:HAD value:green id:OMN value:blue id:black value:black id:white value:white id:cretaceous value:rgb(0.5,0.78,0.31) id:earlycretaceous value:rgb(0.63,0.78,0.65) id:latecretaceous value:rgb(0.74,0.82,0.37) id:cenozoic value:rgb(0.54,0.54,0.258) id:paleogene value:rgb(0.99,0.6,0.32) id:paleocene value:rgb(0.99,0.65,0.37) id:eocene value:rgb(0.99,0.71,0.42) id:oligocene value:rgb(0.99,0.75,0.48) id:neogene value:rgb(0.999999,0.9,0.1) id:miocene value:rgb(0.999999,0.999999,0) id:pliocene value:rgb(0.97,0.98,0.68) id:quaternary value:rgb(0.98,0.98,0.5) id:pleistocene value:rgb(0.999999,0.95,0.68) id:holocene value:rgb(0.999,0.95,0.88) BarData= bar:eratop bar:space bar:periodtop bar:space bar:NAM1 bar:NAM2 bar:NAM3 bar:NAM4 bar:NAM5 bar:NAM6 bar:NAM7 bar:NAM8 bar:NAM9 bar:NAM10 bar:space bar:period bar:space bar:era PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25 shift:(7,-4) bar:periodtop from: -145.5 till: -99.6 color:earlycretaceous text:

Early Early may refer to: Places in the United States * Early, Iowa, a city * Early, Texas, a city * Early Branch, a stream in Missouri * Early County, Georgia * Fort Early, Georgia, an early 19th century fort Music * Early B, stage name of Jamaican d ...

from: -99.6 till: -65.5 color:latecretaceous text:

Late Late or LATE may refer to: Everyday usage * Tardy, or late, not being on time * Late (or the late) may refer to a person who is dead Music * ''Late'' (The 77s album), 2000 * Late (Alvin Batiste album), 1993 * Late!, a pseudonym used by Dave Groh ...

from: -65.5 till: -55.8 color:paleocene text: Paleo. from: -55.8 till: -33.9 color:eocene text: Eo. from: -33.9 till: -23.03 color:oligocene text: Oligo. from: -23.03 till: -5.332 color:miocene text: Mio. from: -5.332 till: -2.588 color:pliocene text: Pl. from: -2.588 till: -0.0117 color:pleistocene text: Pl. from: -0.0117 till: 0 color:holocene text: H. bar:eratop from: -145.5 till: -65.5 color:cretaceous text:

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

from: -65.5 till: -23.03 color:paleogene text:

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

from: -23.03 till: -2.588 color:neogene text:

Neogene The Neogene ( ,) is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period million years ago. It is the second period of th ...

from: -2.588 till: 0 color:quaternary text: Q. PlotData= align:left fontsize:M mark:(line,white) width:5 anchor:till align:left color:latecretaceous bar:NAM1 from:-99.6 till:-97.6 text: Aipichthyoides color:latecretaceous bar:NAM2 from:-99.6 till:-97.6 text: Aipichthys color:latecretaceous bar:NAM3 from:-99.6 till:-97.6 text: Paraipichthys color:latecretaceous bar:NAM4 from:-99.6 till:-93.5 text: Homonotichthys color:latecretaceous bar:NAM5 from:-99.6 till:-70.6 text: Omosoma color:latecretaceous bar:NAM6 from:-99.6 till:-70.6 text: Berycopsis color:latecretaceous bar:NAM7 from:-93.5 till:-89.3 text: Berycopsia color:latecretaceous bar:NAM8 from:-89.3 till:-65.5 text: Dalmatichthys color:latecretaceous bar:NAM9 from:-85.8 till:-83.5 text: Pycnosterinx color:eocene bar:NAM10 from:-37.2 till:0 text:

PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25 bar:period from: -145.5 till: -99.6 color:earlycretaceous text:

from: -99.6 till: -65.5 color:latecretaceous text:

from: -65.5 till: -23.03 color:paleogene text:

from: -23.03 till: -2.588 color:neogene text:

from: -2.588 till: 0 color:quaternary text: Q.

References

* {{Taxonbar, from1=Q1922429, from2=Q3907757 Fish of Hawaii Extant Cenomanian first appearances