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34-458: The Argentiniformes / ɑːr dʒ ə n ˈ t ɪ n ɪ f ɔːr m iː z / is an order of marine ray-finned fish whose distinctness was recognized only fairly recently. In former times, they were included in the Osmeriformes (typical smelt and allies) as suborder Argentinoidei . That term refers only to the suborder of marine smelts and barreleyes in the classification used here, with

68-713: A monophyletic group. The order Salmoniformes first appeared during the Santonian and Campanian stages of the Late Cretaceous , and is most closely related to pike and mudminnows in the order Esociformes , to the extent that some authors have grouped the Esociformes within the Salmoniformes. Although it is assumed that salmon and pike diverged from one another during the Cretaceous, no definitive salmonids appear before

102-405: A physoclistous gas bladder when present, or they lack it entirely. In suborder Alepocephaloidei the swim bladder is completely absent. The hypaxial muscle is unusually extended to forward at its upper end and attaches to the neurocranium below the spine , perhaps to snap the upper part of the skull down when catching prey. The primordial ligament attaches posteriorly on the upper surface of

136-423: A closer examination of the salmonid genome, and has allowed for a more precise dating of the whole-genome duplication of the group, that places the latest possible date for the event at 88 million years ago. This more precise dating and examination of the salmonid whole-genome duplication event has allowed more speculation on the radiation of species within the group. Historically, the whole-genome duplication event

170-478: A different position. There are no hard rules that a taxonomist needs to follow in describing or recognizing an order. Some taxa are accepted almost universally, while others are recognized only rarely. The name of an order is usually written with a capital letter. For some groups of organisms, their orders may follow consistent naming schemes . Orders of plants , fungi , and algae use the suffix -ales (e.g. Dictyotales ). Orders of birds and fishes use

204-568: A single row of sharp teeth . Although the smallest salmonid species is just 13 cm (5.1 in) long for adults, most salmonids are much larger, with the largest reaching 2 m (6 ft 7 in). All salmonids are migratory fish that spawn in the shallow gravel beds of freshwater headstreams , spend the growing juvenile years in rivers , creeks , small lakes and wetlands , but migrate downstream upon maturity and spend most of their adult lives at much larger waterbodies. Many salmonid species are euryhaline and migrate to

238-651: Is an archaic salmonid, representing an important stage in salmonid evolution. Fossil scales of coregonines are known from the Late Eocene or Early Oligocene of California. A gap appears in the salmonine fossil record after E. driftwoodensis until about 7 million years ago ( mya ), in the Late Miocene , when trout-like fossils appear in Idaho , in the Clarkia Lake beds . Several of these species appear to be Oncorhynchus —

272-524: Is so, it would probably require either inclusion of the supposed superorders " Cyclosquamata " and " Stenopterygii " in the Protacanthopterygii, or if the unranked clade name Euteleostei is used for this entire group restricting the Protacanthopterygii to the Osmeriformes and either Esociformes or Salmoniformes and establishing a monotypic superorder for the other of the two latter orders. Given

306-401: Is the fourth of its kind to happen in the evolutionary lineage of the salmonids, with two having occurred commonly to all bony vertebrates, and another specifically in the teleost fishes. Extant salmonids all show evidence of partial tetraploidy, as studies show the genome has undergone selection to regain a diploid state. Work done in the rainbow trout ( Onchorhynchus mykiss ) has shown that

340-628: The Prodromus Systematis Naturalis Regni Vegetabilis of Augustin Pyramus de Candolle and the Genera Plantarum of Bentham & Hooker, it indicated taxa that are now given the rank of family (see ordo naturalis , ' natural order '). In French botanical publications, from Michel Adanson 's Familles naturelles des plantes (1763) and until the end of the 19th century, the word famille (plural: familles )

374-575: The Eocene . The Salmonidae first appear in the fossil record in the Early Eocene with Eosalmo driftwoodensis , a stem- salmonine , which was first described from fossils found at Driftwood Creek , central British Columbia , and has been recovered from most sites in the Eocene Okanagan Highlands . This genus shares traits found in all three subfamily lineages. Hence, E. driftwoodensis

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408-521: The Pattersonellidae , but more recent studies have found them to be basal euteleosts . The Argentiniformes are smallish silvery or dark and generally bathypelagic ocean fishes. Some Argentinoidei have an adipose fin , which is – unusually for Protacanthopterygii to which they belong – missing in the rest of the order. The dorsal fin is located in the second half of the body. Teeth are absent in almost all. Suborder Argentinoidei have

442-415: The biomass transfer provided by their mass migration from oceanic to inland waterbodies. Current salmonids comprise three main clades taxonomically treated as subfamilies : Coregoninae ( freshwater whitefishes ), Thymallinae ( graylings ), and Salmoninae ( trout , salmon , char , taimens and lenoks ). Generally, all three lineages are accepted to allocate a suite of derived traits indicating

476-423: The coronoid process . The autopalatine is peculiarly expanded to above and below at its caudal end, and like in some Otocephala , the caudal part of the mesethmoid appears compressed when seen from above. As in many other teleosts , the autopterotic and dermopterotic bones are not fused together. The most distinctive characteristic, however, is the crumenal organ, also called epibranchial organ. This consists of

510-683: The sea or brackish estuaries as soon as they approach adulthood, returning to the upper streams only to reproduce. Such sea-run life cycle is described as anadromous , and other freshwater salmonids that migrate purely between lakes and rivers are considered potamodromous . Salmonids are carnivorous predators of the middle food chain , feeding on smaller fish, crustaceans , aquatic insects and larvae , tadpoles and sometimes fish eggs (even those of their own kind), and in turn being preyed upon by larger predators. Many species of salmonids are thus considered keystone organisms important for both freshwater and terrestrial ecosystems due to

544-461: The slickheads and allies being the Alepocephaloidei. These suborders were treated as superfamilies Argentinoidea and Alepocephaloidea, respectively, when the present group was still included in the Osmeriformes. They contain six or seven families with almost 60 genera and at least 228 species . A common name for the group is marine smelts and allies , but this is rather misleading since

578-550: The subarctic and cool temperate waters of the Northern Hemisphere . The Atlantic salmon ( Salmo salar ), whose Latin name became that of its genus Salmo , is also the eponym of the family and order names. Salmonids have a relatively primitive appearance among teleost fish, with the pelvic fins being placed far back, and an adipose fin towards the rear of the back. They have slender bodies with rounded scales and forked tail fins , and their mouths contain

612-618: The " freshwater " smelts of the Osmeridae also live predominantly in the ocean . The earliest fossil argentiniform remains are otoliths of indeterminate argentinids from the Barremian Kimigahama Formation of Japan. Later otoliths are known of other indeterminate taxa and Argentina itself from the Late Cretaceous ( Maastrichtian ) of the United States and Germany. A fossil family that might belong in this order are

646-684: The Latin suffix -iformes meaning 'having the form of' (e.g. Passeriformes ), but orders of mammals and invertebrates are not so consistent (e.g. Artiodactyla , Actiniaria , Primates ). For some clades covered by the International Code of Zoological Nomenclature , several additional classifications are sometimes used, although not all of these are officially recognized. In their 1997 classification of mammals , McKenna and Bell used two extra levels between superorder and order: grandorder and mirorder . Michael Novacek (1986) inserted them at

680-508: The Pliocene. Suggestions have gone back as far as the Early Miocene (about 20 mya). Based on the most current evidence, salmonids diverged from the rest of teleost fish no later than 88 million years ago, during the late Cretaceous . This divergence was marked by a whole-genome duplication event in the ancestral salmonid, where the diploid ancestor became tetraploid . This duplication

714-490: The additional cartilage and gill rakers on the fifth ceratobranchial, which is found in other teleosts, too, but not as well-developed as in the present order. The treatment of the Argentiniformes as distinct order follows the discovery that they are by no means as closely related to the Osmeriformes as was long believed. In fact, they may actually be the most basal lineage of the living Protacanthopterygii. If this

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748-583: The current genus for Pacific salmon and Pacific trout. The presence of these species so far inland established that Oncorhynchus was not only present in the Pacific drainages before the beginning of the Pliocene (~5–6 mya), but also that rainbow and cutthroat trout , and Pacific salmon lineages had diverged before the beginning of the Pliocene. Consequently, the split between Oncorhynchus and Salmo (Atlantic salmon and European trout) must have occurred well before

782-468: The ending -anae that was initiated by Armen Takhtajan 's publications from 1966 onwards. The order as a distinct rank of biological classification having its own distinctive name (and not just called a higher genus ( genus summum )) was first introduced by the German botanist Augustus Quirinus Rivinus in his classification of plants that appeared in a series of treatises in the 1690s. Carl Linnaeus

816-888: The field of zoology , the Linnaean orders were used more consistently. That is, the orders in the zoology part of the Systema Naturae refer to natural groups. Some of his ordinal names are still in use, e.g. Lepidoptera (moths and butterflies) and Diptera (flies, mosquitoes, midges, and gnats). In virology , the International Committee on Taxonomy of Viruses 's virus classification includes fifteen taxomomic ranks to be applied for viruses , viroids and satellite nucleic acids : realm , subrealm , kingdom , subkingdom, phylum , subphylum , class, subclass, order, suborder, family, subfamily , genus, subgenus , and species. There are currently fourteen viral orders, each ending in

850-449: The genome is still partially-tetraploid. Around half of the duplicated protein-coding genes have been deleted, but all apparent miRNA sequences still show full duplication, with potential to influence regulation of the rainbow trout's genome. This pattern of partial tetraploidy is thought to be reflected in the rest of extant salmonids. The first fossil species representing a true salmonid fish ( E. driftwoodensis ) does not appear until

884-427: The middle Eocene. This fossil already displays traits associated with extant salmonids, but as the genome of E. driftwoodensis cannot be sequenced, it cannot be confirmed if polyploidy was present in this animal at this point in time. This fossil is also significantly younger than the proposed salmonid divergence from the rest of the teleost fishes, and is the earliest confirmed salmonid currently known. This means that

918-434: The reluctance of modern zoologists to establish monotypic taxa if not absolutely necessary, the former treatment is probably preferable. The former classification of the Argentiniformes is: Order (biology) What does and does not belong to each order is determined by a taxonomist , as is whether a particular order should be recognized at all. Often there is no exact agreement, with different taxonomists each taking

952-441: The salmonids have a ghost lineage of approximately 33 million years. Given a lack of earlier transition fossils, and the inability to extract genomic data from specimens other than extant species, the dating of the whole-genome duplication event in salmonids was historically a very broad categorization of times, ranging from 25 to 100 million years in age. New advances in calibrated relaxed molecular clock analyses have allowed for

986-420: The same position. Michael Benton (2005) inserted them between superorder and magnorder instead. This position was adopted by Systema Naturae 2000 and others. In botany , the ranks of subclass and suborder are secondary ranks pre-defined as respectively above and below the rank of order. Any number of further ranks can be used as long as they are clearly defined. The superorder rank is commonly used, with

1020-672: The suffix -virales . Salmoniformes Salmonidae ( / s æ l ˈ m ɒ n ɪ d iː / , lit. "salmon-like") is a family of ray-finned fish that constitutes the only currently extant family in the order Salmoniformes ( / s æ l ˈ m ɒ n ɪ f ɔːr m iː z / , lit. "salmon-shaped"), consisting of 11 extant genera and over 200 species collectively known as " salmonids " or " salmonoids ". The family includes salmon (both Atlantic and Pacific species), trout (both ocean-going and landlocked), char , graylings , freshwater whitefishes , taimens and lenoks , all coldwater mid- level predatory fish that inhabit

1054-574: The word family ( familia ) was assigned to the rank indicated by the French famille , while order ( ordo ) was reserved for a higher rank, for what in the 19th century had often been named a cohors (plural cohortes ). Some of the plant families still retain the names of Linnaean "natural orders" or even the names of pre-Linnaean natural groups recognized by Linnaeus as orders in his natural classification (e.g. Palmae or Labiatae ). Such names are known as descriptive family names. In

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1088-543: Was the first to apply it consistently to the division of all three kingdoms of nature (then minerals , plants , and animals ) in his Systema Naturae (1735, 1st. Ed.). For plants, Linnaeus' orders in the Systema Naturae and the Species Plantarum were strictly artificial, introduced to subdivide the artificial classes into more comprehensible smaller groups. When the word ordo was first consistently used for natural units of plants, in 19th-century works such as

1122-609: Was thought to be the reason for the variation within Salmonidae. Current evidence done with molecular clock analyses revealed that much of the speciation of the group occurred during periods of intense climate change associated with the last ice ages, with especially high speciation rates being observed in salmonids that developed an anadromous lifestyle. Together with the closely related orders Esociformes ( pikes and mudminnows ), Osmeriformes ( true smelts ) and Argentiniformes ( marine smelts and barreleyes ), Salmoniformes comprise

1156-540: Was used as a French equivalent for this Latin ordo . This equivalence was explicitly stated in the Alphonse Pyramus de Candolle 's Lois de la nomenclature botanique (1868), the precursor of the currently used International Code of Nomenclature for algae, fungi, and plants . In the first international Rules of botanical nomenclature from the International Botanical Congress of 1905,

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