Sarcopterygii or the lobe-finned fishes ( coelacanths and

lungfish Lungfish are freshwater vertebrates belonging to the order Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, i ...

es) were usually classified as either a class or a subclass of

Osteichthyes Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilage ...

based on the traditional

Linnaean classification Linnaean taxonomy can mean either of two related concepts: # The particular form of Taxonomy (biology), biological classification (taxonomy) set up by Carl Linnaeus, as set forth in his ''Systema Naturae'' (1735) and subsequent works. In the ta ...

. Identification of the group is based on several characteristics, such as the presence of fleshy, lobed, paired fins, which are joined to the body by a single bone.

Taxonomic and fossil history

The properties defining the sarcopterygians are in contrast to the other group of bony fish, the

Actinopterygii 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 h ...

, which have ray-fins made of bony rods, called '' lepidotrichia''. These two bony fish groups were classified together as Osteichthyes at one time, the whole combined group was seen as the sister group to the

tetrapod Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids (pelycosaurs, extinct theraps ...

s (

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

s, and

amphibian Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...

s). The extensive fossil record and numerous morphological and molecular studies have shown, however, that lungfish and some fossil lobe-finned fish are more closely related to tetrapods than they are to coelacanths; as a result tetrapods are nested within Sarcopterygii. This abides to cladistics in that in order for a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

to be monophyletic, it must have an ancestral species and all descendants of that common ancestor based on shared characteristics. As such mammals, birds and reptiles, and amphibians are highly derived lobe-finned fish despite looking nothing like the standard sarcopterygian anatomically speaking.

Current taxonomy

The list below shows the taxonomy of the extant members of class Sarcopterygii at the

ordinal level Level of measurement or scale of measure is a classification that describes the nature of information within the values assigned to variables. Psychologist Stanley Smith Stevens developed the best-known classification with four levels, or scal ...

. While this does reflect the evolutionary relationships within the group, it also retains the rankings seen in the Linnaean classification as suggested by some scientists. The evolutionary sequences are based from current phylogenetic work on the various subclades. Class Sarcopterygii Romer, 1955 *Subclass Actinistia Cope, 1871 **Order

Coelacanthiformes The coelacanths ( ) are fish belonging to the order Actinistia that includes two extant species in the genus ''Latimeria'': the West Indian Ocean coelacanth (''Latimeria chalumnae''), primarily found near the Comoro Islands off the east coast ...

Berg, 1937 *Subclass

Rhipidistia Rhipidistia, also known as Dipnotetrapodomorpha, is a clade of lobe-finned fishes which includes the tetrapods and lungfishes. Rhipidistia formerly referred to a subgroup of Sarcopterygii consisting of the Porolepiformes and Osteolepiformes, a d ...

Cope, 1871 **Infraclass

Dipnoi Lungfish are freshwater vertebrates belonging to the order Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, i ...

Müller, 1844 ***Order

Ceratodontiformes Ceratodontoidei is a suborder of lungfish that is defined as "the clade including all taxa more closely related to ''Lepidosiren'', '' Neoceratodus'' and '' Gnathorhiza'' than to '' Uronemus'', '' Conchopoma'' and ''Sagenodus''". Members of this ...

Berg, 1940 ***Order

Lepidosireniformes Lev Berg Lev Semyonovich Berg, also known as Leo S. Berg (russian: Лев Семёнович Берг; 14 March 1876 – 24 December 1950) was a leading Russian geographer, biologist and ichthyologist who served as President of the Soviet Geogra ...

Müller, 1844 **Infraclass Tetrapoda Goodrich, 1930 ***Parvclass

Lissamphibia The Lissamphibia is a group of tetrapods that includes all modern amphibians. Lissamphibians consist of three living groups: the Salientia (frogs, toads, and their extinct relatives), the Caudata (salamanders, newts, and their extinct relatives), ...

Haeckel, 1866 ****Order Apoda Oppel, 1811 ****Order Urodela Duméril, 1806 ****Order Anura Duméril, 1806 ***Parvclass Sauria Macartney, 1802 ****Cohort

Lepidosauria The Lepidosauria (, from Greek meaning ''scaled lizards'') is a subclass or superorder of reptiles, containing the orders Squamata and Rhynchocephalia. Squamata includes snakes, lizards, and amphisbaenians. Squamata contains over 9,000 species, m ...

Haeckel, 1866 *****Order

Rhynchocephalia Rhynchocephalia (; ) is an order of lizard-like reptiles that includes only one living species, the tuatara (''Sphenodon punctatus'') of New Zealand. Despite its current lack of diversity, during the Mesozoic rhynchocephalians were a diverse g ...

Günther, 1867 *****Order

Squamata Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest order of reptiles, comprising lizards, snakes, and amphisbaenians (worm lizards), which are collectively known as squamates or scaled reptiles. With over 10,900 species, ...

Oppel, 1811 ****Cohort

Testudinata Testudinata is the group of all tetrapods with a true turtle shell. It includes both modern turtles (Testudines) and many of their extinct, shelled relatives (stem-turtles). Though it was first coined as the group containing turtles by Jacob The ...

Klein, 1760 *****Order

Testudines Turtles are an order (biology), order of reptiles known as Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) an ...

Batsch, 1788 ****Cohort Archosauria Cope, 1869 *****Order Crocodylia Owen, 1842 *****Subcohort

Aves Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

Linnaeus, 1758 ******Infracohort

Palaeognathae Palaeognathae (; ) is a infraclass of birds, called paleognaths, within the class Aves of the clade Archosauria. It is one of the two extant infraclasses of birds, the other being Neognathae, both of which form Neornithes. Palaeognathae contai ...

Pycraft, 1900 *******Order Struthioniformes Latham, 1790 *******Order Rheiformes Forbes, 1884 *******Order Tinamiformes Huxley, 1872 *******†Order

Dinornithiformes Moa are extinct giant flightless birds native to New Zealand. The term has also come to be used for chicken in many Polynesian cultures and is found in the names of many chicken recipes, such as Kale moa and Moa Samoa. Moa or MOA may also refer ...

Bonaparte, 1853 *******†Order Aepyornithiformes Newton, 1884 *******Order

Apterygiformes Kiwi ( ) are flightless birds endemic to New Zealand of the order Apterygiformes. The five extant species fall into the family Apterygidae () and genus ''Apteryx'' (). Approximately the size of a domestic chicken, kiwi are by far the smallest ...

Haeckel, 1866 *******Order Casuariiformes Sclater 1880 ******Infracohort

Neognathae Neognathae (; ) is a infraclass of birds, called neognaths, within the class Aves of the clade Archosauria. Neognathae includes the majority of living birds; the exceptions being the tinamous and the flightless ratites, which belong instead to ...

Pycraft, 1900 *******Section Galloanserae Sclater, 1880 ********Order

Anseriformes Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which in ...

Wagler, 1831 ********Order

Galliformes Galliformes is an order of heavy-bodied ground-feeding birds that includes turkeys, chickens, quail, and other landfowl. Gallinaceous birds, as they are called, are important in their ecosystems as seed dispersers and predators, and are often ...

Temminck, 1820 *******Section

Neoaves Neoaves is a clade that consists of all modern birds (Neornithes or Aves) with the exception of Paleognathae (ratites and kin) and Galloanserae (ducks, chickens and kin). Almost 95% of the roughly 10,000 known species of extant birds belong to ...

Sibley et al., 1988 ********Subsection

Mirandornithes Mirandornithes () is a clade that consists of flamingos and grebes. Many scholars use the term Phoenicopterimorphae for the superorder containing flamingoes and grebes. Determining the relationships of both groups has been problematic. Flamingos ...

Sangster, 2005 *********Order Phoenicopteriformes Fürbringer, 1888 *********Order Podicipediformes Fürbringer, 1888 ********Subdivision

Gruimorphae Gruimorphae is a clade of birds that contains the orders Charadriiformes (plovers, gulls, and allies) and Gruiformes (cranes and rails) identified by molecular analysis. This grouping has had historical support, as various charadriiform families ...

Bonaparte, 1854 *********Order

Gruiformes The Gruiformes are an order (biology), order containing a considerable number of living and extinct bird family (biology), families, with a widespread geographical diversity. Gruiform means "crane-like". Traditionally, a number of wading and t ...

Bonaparte, 1854 *********Order

Charadriiformes Charadriiformes (, from ''Charadrius'', the type genus of family Charadriidae) is a diverse order of small to medium-large birds. It includes about 390 species and has members in all parts of the world. Most charadriiform birds live near water an ...

Huxley, 1867 ********Subsection

Columbaves Columbaves is a clade that contains Columbimorphae (pigeons, mesites, and sandgrouse) and Otidimorphae (bustards, cuckoos, and turacos) discovered by genomic analysis by Prum ''et al''. (2015).Prum, R. O. et al. A comprehensive phylogeny of birds ...

Prum et al., 2015 *********Order Musophagiformes Seebohm, 1890 *********Order Cuculiformes Wagler, 1830 *********Order Otidiformes Wagler, 1830 *********Order

Columbiformes Columbidae () is a bird family consisting of doves and pigeons. It is the only family in the order Columbiformes. These are stout-bodied birds with short necks and short slender bills that in some species feature fleshy ceres. They primarily ...

Latham, 1790 *********Order

Pterocliformes Sandgrouse is the common name for Pteroclidae , a family of sixteen species of bird, members of the order Pterocliformes . They are traditionally placed in two genera. The two central Asian species are classified as '' Syrrhaptes'' and the othe ...

Huxley, 1868 *********Order Mesitornithiformes Wetmore, 1960 ********Order Opisthocomiformes L'Herminier, 1837 ********Subsection Strisores Baird, 1858 *********Order Steatornithiformes Sharpe, 1891 *********Order Nyctibiiformes Sharpe, 1891 *********Order Caprimulgiformes Ridgway, 1881 *********Order Podargiformes Sharpe, 1891 *********Order Aegotheliformes Simonetta, 1967 *********Order Apodiformes Peters, 1940 ********Subsection

Ardeae Phaethoquornithes is a clade of birds that contains Eurypygimorphae and Aequornithes, found in 2014 by genome analysis. Members of Eurypygimorphae were originally classified in the obsolete group Metaves, and Aequornithes were classified as the s ...

Wagler, 1830 *********Order Phaethontiformes Sharpe, 1891 *********Order Eurypygiformes Fürbringer, 1888 *********Order

Gaviiformes Gaviiformes is an order of aquatic birds containing the loons or divers and their closest extinct relatives. Modern gaviiformes are found in many parts of North America and northern Eurasia (Europe, Asia and debatably Africa), though prehistori ...

Wetmore & Miller, 1926 *********Order Sphenisciformes Sharpe, 1891 *********Order

Procellariiformes Procellariiformes is an order of seabirds that comprises four families: the albatrosses, the petrels and shearwaters, and two families of storm petrels. Formerly called Tubinares and still called tubenoses in English, procellariiforms are of ...

Fürbringer, 1888 *********Order Ciconiiformes Bonaparte, 1854 *********Order Suliformes Sharpe, 1891 *********Order Pelecaniformes Sharpe, 1891 ********Subsection Telluraves Yuri et al., 2013 *********Division

Afroaves Afroaves is a clade of birds, consisting of the kingfishers and kin (Coraciiformes), woodpeckers and kin (Piciformes), hornbills and kin (Bucerotiformes), trogons (Trogoniformes), cuckoo roller ( Leptosomiformes), mousebirds ( Coliiformes), owls ...

Ericson, 2012 **********Order

Cathartiformes The order Cathartiformes of raptors or birds of prey includes the New World vultures and the now-extinct Teratornithidae. These raptors are classified by most taxonomic authorities in the order Accipitriformes (which includes the eagles and hawk ...

Coues, 1884 **********Order Accipitriformes Vieillot, 1816 **********Order Strigiformes Wagler, 1830 **********Order Coliiformes Murie, 1872 **********Order Leptosomiformes Sharpe, 1991 **********Order Trogoniformes AOU, 1886 **********Order Bucerotiformes Fürbringer, 1888 **********Order

Coraciiformes The Coraciiformes are a group of usually colourful birds including the kingfishers, the bee-eaters, the rollers, the motmots, and the todies. They generally have syndactyly, with three forward-pointing toes (and toes 3 & 4 fused at their base) ...

Forbes, 1884 **********Order Piciformes Meyer & Wolf, 1810 *********Division

Australaves Australaves is a recently defined clade of birds, consisting of the Eufalconimorphae (passerines, parrots and falcons) as well as the Cariamiformes (including seriemas and the extinct "terror birds").Prum, R.O. ''et al''. (2015A comprehensive ph ...

Ericson, 2012 **********Order

Cariamiformes Cariamiformes (or Cariamae) is an order of primarily flightless birds that has existed for over 60 million years. The group includes the family Cariamidae (seriemas) and the extinct families Phorusrhacidae, Bathornithidae, Idiornithidae and Ame ...

Fürbringer, 1888 **********Order Falconiformes Sharpe, 1874 **********Order Psittaciformes Wagler, 1830 **********Order Passeriformes Linnaeus, 1758 ***Parvclass

Mammalia Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur o ...

Linnaeus, 1758 ****Order Monotremata Bonaparte, 1837 ****Supercohort

Theria Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes. Ch ...

Parker & Haswell, 1897 *****Cohort Marsupialia Illiger, 1811 ******Order Didelphimorphia Gill, 1872 ******Order

Paucituberculata Paucituberculata is an order of South American marsupials. Although currently represented only by the seven living species of shrew opossums, this order was formerly much more diverse, with more than 60 extinct species named from the fossil reco ...

Trouessart, 1898 ******Subcohort

Australidelphia Australidelphia is the superorder that contains roughly three-quarters of all marsupials, including all those native to Australasia and a single species — the monito del monte — from South America. All other American marsupials are members of ...

Szalay, 1982 *******Order Microbiotheria Ameghino, 1889 *******Order Diprotodontia Owen, 1866 *******Order

Notoryctemorphia Notoryctidae is a family of mammals, allying several extant and fossil species of Australia. The group appear to have diverged from other marsupials at an early stage and are highly specialised to foraging through loose sand; the unusual feature ...

Kirsch, 1977 *******Order

Dasyuromorphia Dasyuromorphia (, meaning "hairy tail" in Greek) is an order comprising most of the Australian carnivorous marsupials, including quolls, dunnarts, the numbat, the Tasmanian devil, and the thylacine. In Australia, the exceptions include the omn ...

Gill, 1872 *******Order

Peramelemorphia The Order (biology), order Peramelemorphia includes the bandicoots and bilby, bilbies; it equates approximately to the mainstream of marsupial omnivores. All members of the order are endemic to the twin land masses of Australia-New Guinea and mo ...

Ameghino, 1889 *****Cohort

Placentalia Placental mammals (infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguished ...

Owen, 1837 ******Subcohort Atlantogenata Waddell, Okada & Hasegawa, 1999 *******Infracohort Xenarthra Cope, 1889 ********Order Cingulata Illiger, 1811 ********Order Pilosa Flower, 1883 *******Infracohort Afrotheria Stanhope et al., 1998 ********Order

Afrosoricida The order Afrosoricida (a Latin-Greek compound name which means "looking like African shrews") contains the golden moles of Southern Africa, the otter shrews of equatorial Africa and the tenrecs of Madagascar. These three families of small mamma ...

Stanhope et al., 1998 ********Order Macroscelidea Butler, 1956 ********Order Tubulidentata Huxley, 1872 ********Order Hyracoidea Huxley, 1869 ********Order Sirenia Illiger, 1811 ********Order

Proboscidea The Proboscidea (; , ) are a taxonomic order of afrotherian mammals containing one living family (Elephantidae) and several extinct families. First described by J. Illiger in 1811, it encompasses the elephants and their close relatives. From ...

Illiger, 1810 ******Subcohort Boreoeutheria Springer & de Jong, 2001 *******Infracohort Laurasiatheria Waddell, Okada & Hasegawa, 1999 ********Order Eulipotyphla Douady et al., 2002 ********Order Chiroptera Blumenbach, 1779 ********Order Pholidota Weber, 1904 ********Order

Carnivora Carnivora is a Clade, monophyletic order of Placentalia, placental mammals consisting of the most recent common ancestor of all felidae, cat-like and canidae, dog-like animals, and all descendants of that ancestor. Members of this group are f ...

Bowdich, 1821 ********Order Perissodactyla Owen, 1848 ********Order Artiodactyla Owen, 1848 *******Infracohort Euarchontoglires Murphy et al., 2001 ********Order Lagomorpha Brandt, 1855 ********Order

Rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...

ia Bowdich, 1821 ********Order Scandentia Wagner, 1855 ********Order Dermoptera Illiger, 1811 ********Order

Primates Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including huma ...

Linnaeus, 1758

References

{{Reflist, 25em Lobe-finned fish Fish classes

Taxonomic and fossil history

Current taxonomy

See also

References