A flatfish is a member of the ray-finned demersal fish suborder Pleuronectoidei, also called the Heterosomata. In many species, both eyes lie on one side of the head, one or the other migrating through or around the head during development. Some species face their left sides upward, some face their right sides upward, and others face either side upward. The most primitive members of the group, the threadfins, do not resemble the flatfish but are their closest relatives. Many important food fish are in this order, including the flounders, soles, turbot, plaice, and halibut. Some flatfish can

camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...

themselves on the ocean floor.

Taxonomy

Due to their highly distinctive morphology, flatfishes were previously treated as belonging to their own order, Pleuronectiformes. However, more recent taxonomic studies have found them to group within a diverse group of nektonic marine fishes known as the

Carangiformes Carangiformes is a large, diverse order of ray-finned fishes within the clade Percomorpha. It is part of a sister clade to the Ovalentaria, alongside its sister group, the Anabantaria (including Anabantiformes and Synbranchiformes). The Cara ...

, which also includes jacks and billfish. Specifically, flatfish are most closely related to the threadfins, which are now also placed in the suborder Pleuronectoidei. Together, the group is most closely related to the archerfish and beachsalmons within Toxotoidei. Due to this, they are now treated as a suborder of the Carangiformes. Over 800 described species are placed into 16 families. When they were treated as an order, the flatfishes are divided into two suborders, Psettodoidei and Pleuronectoidei, with > 99% of the species diversity found within the Pleuronectoidei. The largest families are Soleidae, Bothidae and Cynoglossidae with more than 150 species each. There also exist two monotypic families ( Paralichthodidae and Oncopteridae). Some families are the results of relatively recent splits. For example, the Achiridae were classified as a subfamily of Soleidae in the past, and the Samaridae were considered a subfamily of the Pleuronectidae.Randall, J. E. (2007). ''Reef and Shore Fishes of the Hawaiian Islands.'' Cooper, J.A.; and Chapleau, F. (1998). ''Monophyly and intrarelationships of the family Pleuronectidae (Pleuronectiformes), with a revised classification.'' Fish. Bull. 96 (4): 686–726. The families Paralichthodidae, Poecilopsettidae, and Rhombosoleidae were also traditionally treated as subfamilies of Pleuronectidae, but are now recognised as families in their own right. The Paralichthyidae has long been indicated to be paraphyletic, with the formal description of Cyclopsettidae in 2019 resulting in the split of this family as well. The

taxonomy image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...

of some groups is in need of a review. The last

monograph A monograph is generally a long-form work on one (usually scholarly) subject, or one aspect of a subject, typically created by a single author or artist (or, sometimes, by two or more authors). Traditionally it is in written form and published a ...

covering the entire order was John Roxborough Norman's ''Monograph of the Flatfishes'' published in 1934. In particular, '' Tephrinectes sinensis'' may represent a family-level lineage and requires further evaluation e.g. New species are described with some regularity and

undescribed species In taxonomy, an undescribed taxon is a taxon (for example, a species) that has been discovered, but not yet formally described and named. The various Nomenclature Codes specify the requirements for a new taxon to be validly described and named. U ...

likely remain.

Hybrids

Hybrids are well known in flatfishes. The Pleuronectidae have the largest number of reported hybrids of marine fishes.Garrett, D.L.; Pietsch, T.W.; Utter, F.M.; and Hauser, L. (2007). ''The Hybrid Sole Inopsetta ischyra (Teleostei: Pleuronectiformes: Pleuronectidae): Hybrid or Biological Species?'' American Fisheries Society 136: 460–468 Two of the most famous intergeneric hybrids are between the European plaice (''Pleuronectes platessa'') and European flounder (''Platichthys flesus'') in the

Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by the countries of Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden, and the North European Plain, North and Central European Plain regions. It is the ...

, and between the English sole (''Parophrys vetulus'') and starry flounder (''Platichthys stellatus'') in

Puget Sound Puget Sound ( ; ) is a complex estuary, estuarine system of interconnected Marine habitat, marine waterways and basins located on the northwest coast of the U.S. state of Washington (state), Washington. As a part of the Salish Sea, the sound ...

. The offspring of the latter species pair is popularly known as the hybrid sole and was initially believed to be a valid species in its own right.

Distribution

Flatfishes are found in oceans worldwide, ranging from the

Arctic The Arctic (; . ) is the polar regions of Earth, polar region of Earth that surrounds the North Pole, lying within the Arctic Circle. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway ( ...

, through the tropics, to

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

. Species diversity is centered in the Indo-West Pacific and declines following both latitudinal and longitudinal gradients away from the Indo-West Pacific. Most species are found in depths between 0 and , but a few have been recorded from depths in excess of . None have been confirmed from the abyssal or hadal zones. An observation of a flatfish from the Bathyscaphe Trieste at the bottom of the

Mariana Trench The Mariana Trench is an oceanic trench located in the western Pacific Ocean, about east of the Mariana Islands; it is the deep sea, deepest oceanic trench on Earth. It is crescent-shaped and measures about in length and in width. The maxi ...

at a depth of almost has been questioned by fish experts, and recent authorities do not recognize it as valid. Among the deepwater species, '' Symphurus thermophilus'' lives congregating around "ponds" of sulphur at hydrothermal vents on the seafloor. No other flatfish is known from hydrothermal vents. Many species will enter brackish or fresh water, and a smaller number of soles (families Achiridae and Soleidae) and tonguefish ( Cynoglossidae) are entirely restricted to fresh water.

Characteristics

The most obvious characteristic of the flatfish is its

asymmetry Asymmetry is the absence of, or a violation of, symmetry (the property of an object being invariant to a transformation, such as reflection). Symmetry is an important property of both physical and abstract systems and it may be displayed in pre ...

, with both eyes lying on the same side of the head in the adult fish. In some families, the eyes are usually on the right side of the body (dextral or right-eyed flatfish), and in others, they are usually on the left (sinistral or left-eyed flatfish). The primitive spiny turbots include equal numbers of right- and left-sided individuals, and are generally less asymmetrical than the other families. Other distinguishing features of the order are the presence of protrusible eyes, another adaptation to living on the

seabed The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as seabeds. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...

( benthos), and the extension of the dorsal fin onto the head. Polynemus paradiseus Ford 42

The most basal members of the group, the threadfins, do not closely resemble the flatfishes. The surface of the fish facing away from the sea floor is pigmented, often serving to

the fish, but sometimes with striking coloured patterns. Some flatfishes are also able to change their pigmentation to match the background, in a manner similar to some

cephalopods A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

. The side of the body without the eyes, facing the seabed, is usually colourless or very pale. In general, flatfishes rely on their camouflage for avoiding predators, but some have aposematic traits such as conspicuous eyespots (e.g., '' Microchirus ocellatus'') and several small tropical species (at least '' Aseraggodes'', '' Pardachirus'' and '' Zebrias'') are poisonous. Juveniles of '' Soleichthys maculosus''

mimic In evolutionary biology, mimicry is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of the same species. In the simples ...

toxic flatworms of the genus '' Pseudobiceros'' in both colours and swimming mode. Conversely, a few

octopus An octopus (: octopuses or octopodes) is a soft-bodied, eight-limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like oth ...

species have been reported to mimic flatfishes in colours, shape and swimming mode. The flounders and spiny turbots eat smaller fish, and have well-developed teeth. They sometimes seek prey in the midwater, away from the bottom, and show fewer extreme adaptations than other families. The soles, by contrast, are almost exclusively bottom-dwellers, and feed on invertebrates. They show a more extreme asymmetry, and may lack teeth on one side of the jaw. Flatfishes range in size from '' Tarphops oligolepis'', measuring about in length, and weighing , to the Atlantic halibut, at and .

Species and species groups

* Brill * Dab * Sanddab * Flounder * Halibut * Megrim * Plaice * Sole * Tonguefish * Turbot

Reproduction

Flatfishes lay eggs that hatch into larvae resembling typical, symmetrical, fish. These are initially elongated, but quickly develop into a more rounded form. The larvae typically have protective spines on the head, over the gills, and in the pelvic and pectoral fins. They also possess a

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ (anatomy), organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift ...

, and do not dwell on the bottom, instead dispersing from their hatching grounds as

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

. The length of the planktonic stage varies between different types of flatfishes, but eventually they begin to metamorphose into the adult form. One of the eyes migrates across the top of the head and onto the other side of the body, leaving the fish blind on one side. The larva also loses its swim bladder and spines, and sinks to the bottom, laying its blind side on the underlying surface.

Origin and evolution

Scientists have been proposing since the 1910s that flatfishes evolved from percoid ancestors.Regan C.T. (1910). "The origin and evolution of the Teleostean fishes of the order Heterosomata". ''Annals and Magazine of Natural History'' 6(35): p. 484-496
doi.org/10.1080/00222931008692879
/ref> There has been some disagreement whether they are a monophyletic group. Some palaeontologists think that some percomorph groups other than flatfishes were "experimenting" with head asymmetry during the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

, and certain molecular studies conclude that the primitive family of Psettodidae evolved their flat bodies and asymmetrical head independently of other flatfish groups.Campbell M.A., Chen W-J. & López J.A. (2013). "Are flatfishes (Pleuronectiformes) monophyletic?". ''Molecular Phylogenetics and Evolution'' 69(3): p. 664-673
doi.org/10.1016/j.ympev.2013.07.011
/ref>Campbell M.A., López J.A., Satoh T.P., Chen W-J. & Miya M. (2014). "Mitochondrial genomic investigation of flatfish monophyly". ''Gene'' 551(2): p. 176-182
doi.org/10.1016/j.gene.2014.08.053
/ref> Many scientists, however, argue that pleuronectiformes are

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

.Duarte-Ribeiro E, Rosas-Puchuri U, Friedman M, Woodruff G.C., Hughes L.C., Carpenter K.E., White W.T., Pogonoski J.J., Westneat M, Diaz de Astarloa J.M., Williams J.T., Santos M.D., Domínguez-Domínguez O, Ortí G, Arcila D & Betancur-R R. (2024). "Phylogenomic and comparative genomic analyses support a single evolutionary origin of flatfish asymmetry". ''Nature Genetics'' 56: p. 1069-1072
doi.org/10.1038/s41588-024-01784-w
/ref> The fossil record indicates that flatfishes might have been present before the

, based on fossil

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

s resembling those of modern pleuronectiforms dating back to the Thanetian and

Ypresian In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...

stages (57-53 million years ago).Schwarzhans W. (1999). "A comparative morphological treatise of recent and fossil otoliths of the order Pleuronectiformes". ''Piscium Catalogus. Otolithi Piscium 2''. doi:10.13140/2.1.1725.5043 Flatfishes have been cited as dramatic examples of evolutionary adaptation.

Richard Dawkins Richard Dawkins (born 26 March 1941) is a British evolutionary biology, evolutionary biologist, zoologist, science communicator and author. He is an Oxford fellow, emeritus fellow of New College, Oxford, and was Simonyi Professor for the Publ ...

, in '' The Blind Watchmaker'', explains the flatfishes' evolutionary history thus:

...bony fish as a rule have a marked tendency to be flattened in a vertical direction.... It was natural, therefore, that when the ancestors of latfishtook to the sea bottom, they should have lain on one ''side''.... But this raised the problem that one eye was always looking down into the sand and was effectively useless. In evolution this problem was solved by the lower eye 'moving' round to the upper side.

The origin of the unusual morphology of flatfishes was enigmatic up to the 2000s, and early researchers suggested that it came about as a result of saltation rather than gradual evolution through natural selection, because a partially migrated eye were considered to have been maladaptive. This started to change in 2008 with a study on the two fossil genera '' Amphistium'' and '' Heteronectes'', dated to about 50 million years ago. These genera retain primitive features not seen in modern types of flatfishes. In addition, their heads are less asymmetric than modern flatfishes, retaining one eye on each side of their heads, although the eye on one side is closer to the top of the head than on the other.Friedman M. (2008). "The evolutionary origin of flatfish asymmetry". ''Nature'' 454(7201): p. 209–212. doi:10.1038/nature07108 The more recently described fossil genera '' Quasinectes''Bannikov A.F. & Zorzin R (2019)
"A new genus and species of ''incertae sedis'' percomorph fish (Perciformes) from the Eocene of Bolca in northern Italy, and a new genus for ''Psettopsis latellai'' Bannikov, 2005"
''Studi e ricerche sui giacimenti terziari di Bolca'': p. 5-15. and '' Anorevus''Bannikov A.F. & Zorzin R. (2020)
"A new genus and species of percomorph fish ("stem pleuronectiform") from the Eocene of Bolca in northern Italy"
''Miscellanea Paleontologica'' 17: p. 5–14 have been proposed to show similar morphologies and have also been classified as "stem pleuronectiforms". Suchs findings lead Friedman to conclude that the evolution of flatfish morphology "happened gradually, in a way consistent with evolution via

natural selection Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the Heredity, heritable traits characteristic of a population over generation ...

—not suddenly, as researchers once had little choice but to believe." To explain the survival advantage of a partially migrated eye, it has been proposed that primitive flatfishes like ''Amphistium'' rested with the head propped up above the seafloor (a behaviour sometimes observed in modern flatfishes), enabling them to use their partially migrated eye to see things closer to the seafloor.Janvier P. (2008). "Squint of the fossil flatfish". ''Nature'' 454(7201): p. 169–170 While known basal genera like ''Amphistium'' and ''Heteronectes'' support a gradual acquisition of the flatfish morphology, they were probably not direct ancestors to living pleuronectiforms, as fossil evidence indicate that most flatfish lineages living today were present in the

and contemporaneous with them. It has been suggested that the more primitive forms were eventually outcompeted. File:Pleuronectes platessa.jpg, The European plaice is the principal commercial flatfish in Europe. File:Lined sole.jpg, American soles are found in both freshwater and marine environments of the Americas. File:Alaska 2007 071.jpg, Halibut are the largest of the flatfishes, and provide lucrative fisheries. File:Psetta maxima Luc Viatour.jpg, The turbot is a large, left-eyed flatfish found in sandy shallow coastal waters around Europe. File:Flatfish-lefteyed-flounder.jpg, Flatfish (left‐eyed flounder)

As food

Flatfish is considered a Whitefish because of the high concentration of oils within its liver. Its lean flesh makes for a unique flavor that differs from species to species. Methods of cooking include grilling, pan-frying, baking and deep-frying.

Timeline of genera

ImageSize = width:600px height:auto barincrement:15px PlotArea = left:10px bottom:50px top:10px right:10px Period = from:-65.5 till:15 TimeAxis = orientation:horizontal ScaleMajor = unit:year increment:5 start:-65.5 ScaleMinor = unit:year increment:1 start:-65.5 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:white value:black id:white value:white 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:NAM11 bar:NAM12 bar:NAM13 bar:NAM14 bar:NAM15 bar:NAM16 bar:NAM17 bar:NAM18 bar:NAM19 bar:NAM20 bar:NAM21 bar:NAM22 bar:NAM23 bar:NAM24 bar:NAM25 bar:NAM26 bar:NAM27 bar:NAM28 bar:NAM29 bar:NAM30 bar:NAM31 bar:NAM32 bar:NAM33 bar:NAM34 bar:NAM35 bar:NAM36 bar:NAM37 bar:NAM38 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: -65.5 till: -55.8 color:paleocene text:

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

from: -55.8 till: -33.9 color:eocene text:

from: -33.9 till: -23.03 color:oligocene text:

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

from: -23.03 till: -5.332 color:miocene text:

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

from: -5.332 till: -2.588 color:pliocene text: Plio. from: -2.588 till: -0.0117 color:pleistocene text: Pleist. from: -0.0117 till: 0 color:holocene text: H. bar:eratop 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:eocene bar:NAM1 from:-55.8 till:-33.9 text: Amphistium color:eocene bar:NAM2 from:-55.8 till:-33.9 text: Eobothus color:eocene bar:NAM3 from:-55.8 till:-33.9 text: Eobuglossus color:eocene bar:NAM4 from:-55.8 till:-33.9 text: Imhoffius color:eocene bar:NAM5 from:-55.8 till:-33.9 text: Joleaudichthys color:eocene bar:NAM6 from:-55.8 till:-33.9 text: Turahbuglossus color:eocene bar:NAM7 from:-55.8 till:0 text: Scophthalmus color:eocene bar:NAM8 from:-55.8 till:0 text: Citharus color:eocene bar:NAM9 from:-55.8 till:0 text: Psettodes color:eocene bar:NAM10 from:-37.2 till:0 text: Arnoglossus color:oligocene bar:NAM11 from:-33.9 till:0 text: Bothus color:oligocene bar:NAM12 from:-33.9 till:0 text: Monolene color:oligocene bar:NAM13 from:-33.9 till:0 text: Solea color:oligocene bar:NAM14 from:-28.4 till:0 text: Buglossidium color:oligocene bar:NAM15 from:-28.4 till:0 text: Hippoglossoides color:oligocene bar:NAM16 from:-28.4 till:0 text: Lepidorhombus color:miocene bar:NAM17 from:-23.03 till:0 text: Dicologoglossa color:miocene bar:NAM18 from:-23.03 till:0 text: Paraplagusia color:miocene bar:NAM19 from:-23.03 till:0 text: Platichthys color:miocene bar:NAM20 from:-15.97 till:0 text: Achiurus color:miocene bar:NAM21 from:-15.97 till:0 text: Microchirus color:miocene bar:NAM22 from:-15.97 till:0 text: Microstomus color:miocene bar:NAM23 from:-11.608 till:-5.332 text: Evesthes color:miocene bar:NAM24 from:-11.608 till:0 text: Citharichthys color:miocene bar:NAM25 from:-11.608 till:0 text:

Monochirus ''Monochirus'' is a genus of small soles. It contains two species; one from the northeast Atlantic and Mediterranean, and the second from the South China Sea. Species There are currently two recognized species in this genus: * '' Monochirus hi ...

color:miocene bar:NAM26 from:-11.608 till:0 text: Paralichthys color:miocene bar:NAM27 from:-11.608 till:0 text: Pleuronichthys color:pliocene bar:NAM28 from:-5.332 till:0 text: Atheresthes color:pliocene bar:NAM29 from:-5.332 till:0 text:

Clidoderma ''Clidoderma'' is a genus of righteye flounders containing one extant species and two described fossil species from Japan. Fossil species Two fossil species are known from the Miocene of Japan. ''Clidoderma chitaensis, C. chitaensis'' Ohe & K ...

color:pliocene bar:NAM30 from:-5.332 till:0 text: Glyptocephalus color:pliocene bar:NAM31 from:-5.332 till:0 text: Limanda color:pliocene bar:NAM32 from:-5.332 till:0 text: Lyopsetta color:pliocene bar:NAM33 from:-5.332 till:0 text: Pegusa color:pleistocene bar:NAM34 from:-2.588 till:-0.0117 text: Chibapsetta color:pleistocene bar:NAM35 from:-2.588 till:0 text: Eopsetta color:pleistocene bar:NAM36 from:-2.588 till:0 text: Isopsetta color:pleistocene bar:NAM37 from:-2.588 till:0 text: Parophrys color:pleistocene bar:NAM38 from:-2.588 till:0 text: Symphurus PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25 bar:period from: -65.5 till: -55.8 color:paleocene text:

from: -55.8 till: -33.9 color:eocene text:

from: -33.9 till: -23.03 color:oligocene text:

from: -23.03 till: -5.332 color:miocene text:

from: -5.332 till: -2.588 color:pliocene text: Plio. from: -2.588 till: -0.0117 color:pleistocene text: Pleist. from: -0.0117 till: 0 color:holocene text: H. bar:era 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

External links

Information on Canadian fisheries of plaice
{{Authority control Commercial fish Articles which contain graphical timelines Extant Paleocene first appearances Asymmetry