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73-576: See text Polypterus is a genus of freshwater fish in the bichir family ( Polypteridae ) of order Polypteriformes . The type species is the Nile bichir ( P. bichir ). Fish in this genus live in various areas in Africa . Polypterus is the only known vertebrate to have lungs , but no trachea . The etymology of the genus name derives from a combination of the Greek prefix πολυ-, poly- (many) and

146-412: A lower jaw . The jaw is derived from the most anterior two pharyngeal arches supporting the gills, and usually bears numerous teeth . The skull of the last common ancestor of today's jawed vertebrates is assumed to have resembled sharks. It is thought that the original selective advantages offered by the jaw were not related to feeding, but to increases in respiration efficiency. The jaws were used in

219-413: A basal ray-finned fish: Ancient establishment of the consensus vertebrate gene order . Genetics 144:1165-1180, cited by Hall Patterson C. (1982). Morphology and interrelationships of primitive actinopterygian fishes . American Zoologist 22: 241-260, cited by Hall. Romer, A S. (1946). The early evolution of fishes , Quarterly Review of Biology 21: 33-69, cited by Hall Genus The composition of

292-426: A bony shield) [REDACTED] Jawed vertebrates → continued in section below Conodonts resembled primitive jawless eels. They appeared 520 Ma ago and were wiped out 200 Ma ago. Initially they were known only from tooth-like microfossils called conodont elements . These "teeth" have been variously interpreted as filter-feeding apparatuses or as a "grasping and crushing array". Conodonts ranged in length from

365-692: A centimetre to the 40 cm Promissum . Their large eyes had a lateral position, which makes a predatory role unlikely. The preserved musculature hints that some conodonts ( Promissum at least) were efficient cruisers but incapable of bursts of speed. In 2012 researchers classified the conodonts in the phylum Chordata on the basis of their fins with fin rays, chevron -shaped muscles and notochord . Some researchers see them as vertebrates similar in appearance to modern hagfish and lampreys , though phylogenetic analysis suggests that they are more derived than either of these groups. Ostracoderms ( lit. 'shell-skinned') are armoured jawless fish of

438-641: A coral-like sea squirt (a tunicate ), whose larvae resemble early fish in important ways. The first ancestors of fish may have kept the larval form into adulthood , as some sea squirts do today, although this path cannot be proven. Vertebrates , in other words the first fish , originated about 530 million years ago during the Cambrian explosion , which saw the rise in animal diversity. The first ancestors of fish, or animals that were probably closely related to fish, were Haikouichthys and Myllokunmingia . These two genera all appeared around 530 Mya . Unlike

511-466: A fish or an amphibian, and if it were to be classified as a fish, it was unclear whether it ought to be regarded as an Actinopterygian, Chondrichthyan, or Sarcopterygian. Around the time following its initial discovery, some entertained the idea of Polypterus as a living fossil representing the "missing link" between fishes and tetrapods, illustrating a transitional form at the midpoint between finned and limbed vertebrates. In 1861, Thomas Huxley created

584-407: A genus is determined by taxonomists . The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: Moreover, genera should be composed of phylogenetic units of

657-591: A group of armoured fish that dominated much of the late Silurian , and the rise of the first labyrinthodonts , transitional between fish and amphibians . The colonisation of new niches resulted in diversification of body plans and sometimes an increase in size. The Devonian period (395 to 345 Mya) brought in such giants as the placoderm Dunkleosteus , which could grow up to seven meters long, and early air-breathing fish that could remain on land for extended periods. Among this latter group were ancestral amphibians . The reptiles appeared from labyrinthodonts in

730-471: A jawed mouth ; but it is unclear if the advantage of a hinged jaw is greater biting force, improved respiration, or a combination of factors. Fish, like many other organisms, have been greatly affected by extinction events throughout natural history. The earliest ones, the Ordovician–Silurian extinction events , led to the loss of many species. The Late Devonian extinction led to the extinction of

803-643: A later homonym of a validly published name is a nomen illegitimum or nom. illeg. ; for a full list refer to the International Code of Nomenclature for algae, fungi, and plants and the work cited above by Hawksworth, 2010. In place of the "valid taxon" in zoology, the nearest equivalent in botany is " correct name " or "current name" which can, again, differ or change with alternative taxonomic treatments or new information that results in previously accepted genera being combined or split. Prokaryote and virus codes of nomenclature also exist which serve as

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876-446: A living stem actinopterygian." Research is ongoing. Most of the conclusions drawn by Kerr from Budgett's specimens have been confirmed, but many questions remain. Polypterus has rarely been bred in captivity. The first success was that of Polypterus senegalus by Arnoult in 1964, a species spawned repeatedly since (see Hartl, 1981; Bartsch and Gemballa, 1992; Bartsch et al., 1997 and Schugardt, 1997). Shortly after Arnoult's success,

949-621: A long time and redescribed as new by a range of subsequent workers, or if a range of genera previously considered separate taxa have subsequently been consolidated into one. For example, the World Register of Marine Species presently lists 8 genus-level synonyms for the sperm whale genus Physeter Linnaeus, 1758, and 13 for the bivalve genus Pecten O.F. Müller, 1776. Within the same kingdom, one generic name can apply to one genus only. However, many names have been assigned (usually unintentionally) to two or more different genera. For example,

1022-500: A rapid intake of air through the spiracle. The air is nearly sufficient to fill the lungs. This is followed by one cycle of buccal (mouth) pumping, which "tops off" the lungs, with the surplus air from the buccal pumping process discharged through the pharynx . According to one hypothesis, Devonian tetrapods may have inhaled in this way. Polypterus was discovered, described, and named in 1802 by Étienne Geoffroy Saint-Hilaire . Naturalists were initially unsure whether to regard it as

1095-409: A reference for designating currently accepted genus names as opposed to others which may be either reduced to synonymy, or, in the case of prokaryotes, relegated to a status of "names without standing in prokaryotic nomenclature". An available (zoological) or validly published (botanical) name that has been historically applied to a genus but is not regarded as the accepted (current/valid) name for

1168-404: A second species, Polypterus ornatipinnis , was spawned by Armbrust for the first time (1966 and 1973) and bred subsequently by Azuma in 1986; Wolf, 1992; Bartsch and Britz, 1996. The third species successfully spawned in captivity was Polypterus endlicheri by Azuma in 1995. Zoo Basel have been successful in breeding Polypterus in captivity. In December 2005, several eggs were laid, and at

1241-427: A taxon; however, the names published in suppressed works are made unavailable via the relevant Opinion dealing with the work in question. In botany, similar concepts exist but with different labels. The botanical equivalent of zoology's "available name" is a validly published name . An invalidly published name is a nomen invalidum or nom. inval. ; a rejected name is a nomen rejiciendum or nom. rej. ;

1314-455: A total of c. 520,000 published names (including synonyms) as at end 2019, increasing at some 2,500 published generic names per year. "Official" registers of taxon names at all ranks, including genera, exist for a few groups only such as viruses and prokaryotes, while for others there are compendia with no "official" standing such as Index Fungorum for fungi, Index Nominum Algarum and AlgaeBase for algae, Index Nominum Genericorum and

1387-799: Is a continuation of the cladogram in the section above. (†=extinct) † Placodermi (armoured fish) [REDACTED] Acanthodians and Chondrichthyes (cartilaginous fish) [REDACTED] [REDACTED] Actinopterygii (ray-finned fish), dominant class of fish today [REDACTED] ?† Onychodontiformes (lobe-finned) [REDACTED] Actinistia (coelacanths) [REDACTED] † Porolepiformes (lobe-finned) [REDACTED] Dipnoi (lungfish) [REDACTED] † Rhizodontimorpha (predatory lobe-finned) [REDACTED] † Tristichopteridae ( tetrapodomorphs ) [REDACTED] Tetrapods (four-legged animals) [REDACTED] Placoderms, class Placodermi ('plate-skinned'), are extinct armoured prehistoric fish, which appeared about 430 Ma in

1460-551: Is a heavy one, and even today many a text continues to cite Polypterus as a crossopterygian and it is so described in many a classroom, although students of fish evolution have realized the falsity of this position for many years. ... Polypterus ... is not a crossopterygian, but an actinopterygian, and hence can tell us nothing about crossopterygian anatomy and embryology." Hall (2001), relying on Patterson (1982) and Noack et al. (1996), writes, "Phylogenetic analyses using both morphological and molecular data affirm Polypterus as

1533-575: Is based on studies by Philippe Janvier and others for the Tree of Life Web Project . (†=group is extinct) Hyperoartia (lampreys) [REDACTED] ?† Euconodonta (eel-like animals) † Pteraspidomorphi (jawless fish) [REDACTED] ?† Thelodonti (jawless fish with scales) [REDACTED] ?† Anaspida [REDACTED] † Galeaspida (jawless fish with bone head shields) ?† Pituriaspida (armoured jawless fish with large rostrums) † Osteostraci (bony armoured jawless fish with heads covered with

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1606-596: Is discouraged by both the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi, and plants , there are some five thousand such names in use in more than one kingdom. For instance, A list of generic homonyms (with their authorities), including both available (validly published) and selected unavailable names, has been compiled by the Interim Register of Marine and Nonmarine Genera (IRMNG). The type genus forms

1679-460: Is somewhat arbitrary. Although all species within a genus are supposed to be "similar", there are no objective criteria for grouping species into genera. There is much debate among zoologists about whether enormous, species-rich genera should be maintained, as it is extremely difficult to come up with identification keys or even character sets that distinguish all species. Hence, many taxonomists argue in favor of breaking down large genera. For instance,

1752-474: Is the type species , and the generic name is permanently associated with the type specimen of its type species. Should the specimen turn out to be assignable to another genus, the generic name linked to it becomes a junior synonym and the remaining taxa in the former genus need to be reassessed. In zoological usage, taxonomic names, including those of genera, are classified as "available" or "unavailable". Available names are those published in accordance with

1825-648: The Cyclostomata , which includes the extant hagfish , and this group may have split early on from other agnathans. The earliest jawed vertebrates probably developed during the late Ordovician period. They are first represented in the fossil record from the Silurian by two groups of fish: the armoured fish known as placoderms , which evolved from the ostracoderms; and the Acanthodii (or spiny sharks). The jawed fish that are still extant in modern days also appeared during

1898-621: The International Code of Zoological Nomenclature ; the earliest such name for any taxon (for example, a genus) should then be selected as the " valid " (i.e., current or accepted) name for the taxon in question. Consequently, there will be more available names than valid names at any point in time; which names are currently in use depending on the judgement of taxonomists in either combining taxa described under multiple names, or splitting taxa which may bring available names previously treated as synonyms back into use. "Unavailable" names in zoology comprise names that either were not published according to

1971-799: The International Plant Names Index for plants in general, and ferns through angiosperms, respectively, and Nomenclator Zoologicus and the Index to Organism Names for zoological names. Totals for both "all names" and estimates for "accepted names" as held in the Interim Register of Marine and Nonmarine Genera (IRMNG) are broken down further in the publication by Rees et al., 2020 cited above. The accepted names estimates are as follows, broken down by kingdom: The cited ranges of uncertainty arise because IRMNG lists "uncertain" names (not researched therein) in addition to known "accepted" names;

2044-611: The Ordovician period (500–430 Mya ). The first jawed vertebrates appeared in the late Ordovician and became common in the Devonian , often known as the "Age of Fishes". The two groups of bony fish , the Actinopterygii and Sarcopterygii , evolved and became common. The Devonian saw the demise of virtually all jawless fish, save for lampreys and hagfish, as well as the Placodermi ,

2117-688: The Paleozoic . The term does not often appear in classifications today because the taxon is paraphyletic or polyphyletic , and has no phylogenetic meaning. However, the term is still used informally to group together the armoured jawless fish. The ostracoderm armour consisted of 3–5 mm polygonal plates that shielded the head and gills, and then overlapped further down the body like scales. The eyes were particularly shielded. Earlier chordates used their gills for both respiration and feeding, whereas ostracoderms used their gills for respiration only. They had up to eight separate pharyngeal gill pouches along

2190-547: The bony fish and hence to the tetrapods (including humans)—are known from the Middle Ordovician , and by the Late Silurian the agnathans had reached the high point of their evolution. Most of the ostracoderms, such as thelodonts , osteostracans and galeaspids , were more closely related to the gnathostomes than to the surviving agnathans, known as cyclostomes. Cyclostomes apparently split from other agnathans before

2263-575: The buccal pump (observable in modern fish and amphibians ) that pumps water across the gills of fish or air into the lungs in the case of amphibians. Over evolutionary time the more familiar use of jaws (to humans) in feeding was selected for and became a very important function in vertebrates. Many teleost fish have substantially modified their jaws for suction feeding and jaw protrusion , resulting in highly complex jaws with dozens of bones involved. Jawed vertebrates and jawed fish evolved from earlier jawless fish. The cladogram for jawed vertebrates

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2336-844: The evolution of species . No one had studied the embryology of Polypterus . Someone who could do this might prove the "missing link" theory and be greatly honoured, but it could be a dangerous quest. The only breeding Polypterus specimens were in swampy parts of African rivers. Africa was a turbulent place and swamps were rich breeding grounds for mosquitoes carrying malaria . Two men, Nathan Harrington and John Samuel Budgett , attempted to answer this question by making repeated expeditions to Africa. Harrington failed on his first attempt in 1898 and died early on his second in 1899 before he could reach his destination. Budgett failed in 1898/9, 1900, and 1902. He finally succeeded in 1903, but died of blackwater fever shortly after his return to England. He left excellent samples and drawings, but his only writing

2409-419: The nomenclature codes , which allow each species a single unique name that, for animals (including protists ), plants (also including algae and fungi ) and prokaryotes ( bacteria and archaea ), is Latin and binomial in form; this contrasts with common or vernacular names , which are non-standardized, can be non-unique, and typically also vary by country and language of usage. Except for viruses ,

2482-404: The platypus belongs to the genus Ornithorhynchus although George Shaw named it Platypus in 1799 (these two names are thus synonyms ) . However, the name Platypus had already been given to a group of ambrosia beetles by Johann Friedrich Wilhelm Herbst in 1793. A name that means two different things is a homonym . Since beetles and platypuses are both members of the kingdom Animalia,

2555-427: The 1830s. He had a hard time classifying them as they did not resemble any living creature. He compared them at first with extant armored fish such as catfish and sturgeons but later, realizing that they had no movable jaws, classified them in 1844 into a new group "ostracoderms". Ostracoderms existed in two major groups, the more primitive heterostracans and the cephalaspids . Later, about 420 million years ago,

2628-462: The Devonian being known as the age of fishes . It was from the lobe-finned fish that the tetrapods evolved, the four-limbed vertebrates, represented today by amphibians , reptiles , mammals , and birds . Transitional tetrapods first appeared during the early Devonian, and by the late Devonian the first tetrapods appeared. The diversity of jawed vertebrates may indicate the evolutionary advantage of

2701-583: The Early to Middle Silurian. They were mostly wiped out during the Late Devonian extinction event, 378 Ma, though some survived and made a slight recovery in diversity during the Famennian epoch before dying out entirely at the close of the Devonian, 360 mya; they are ultimately ancestral to modern gnathostome vertebrates. Their head and thorax were covered with massive and often ornamented armoured plates. The rest of

2774-469: The University of Cambridge: Being a Collection of His Zoological Papers, together with a Biographical Sketch by A . E. Shipley, F.R.S., and Contributions by Richard Assheton, Edward J.Bles , Edward T. Browne, J. Herbert Budgett and J. Graham Kerr. Cambridge (UK): Cambridge University Press. Noack K, Zardoya R, Meyer A. 1996. The complete mitochondrial DNA sequence of the bichir ( Polypterus ornatipinnis ),

2847-442: The base for higher taxonomic ranks, such as the family name Canidae ("Canids") based on Canis . However, this does not typically ascend more than one or two levels: the order to which dogs and wolves belong is Carnivora ("Carnivores"). The numbers of either accepted, or all published genus names is not known precisely; Rees et al., 2020 estimate that approximately 310,000 accepted names (valid taxa) may exist, out of

2920-700: The beginning of 2006, six young hatched. Within two months, they reached 10 cm (about 4 in). In 2014 researchers at McGill University (published in the journal Nature) turned to Polypterus to help show what might have happened when fish first attempted to walk out of the water. The team of researchers raised juvenile Polypterus on land for nearly a year, with the aim of revealing how these 'terrestrialized' fish looked and moved differently. "Polypterus" . Integrated Taxonomic Information System . Retrieved 4 May 2005 . Froese, Rainer ; Pauly, Daniel (eds.). "Species in genus Polypterus " . FishBase . May 2005 version. Goodrich, E. S. (1908). On

2993-666: The body was scaled or naked, depending on the species. The armour shield was articulated, with the head armour hinged to the thoracic armour. This allowed placoderms to lift their heads, unlike ostracoderms. Placoderms were the first jawed fish; their jaws likely evolved from the first of their gill arches. The chart on the right shows the rise and demise of the separate placoderm lineages: Acanthothoraci , Rhenanida , Antiarchi , Petalichthyidae , Ptyctodontida and Arthrodira . Spiny sharks, class Acanthodii , are extinct fish that share features with both bony and cartilaginous fish, though ultimately more closely related to and ancestral to

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3066-444: The early Cambrian Maotianshan shales of China : Haikouichthys and Myllokunmingia . They have been tentatively assigned to Agnatha by Janvier. A third possible agnathan from the same region is Haikouella . Many Ordovician , Silurian and Devonian agnathians were armoured with heavy, bony, and often elaborately sculpted, plates derived from mineralized scales. The first armoured agnathans—the ostracoderms , precursors to

3139-501: The evolution of dentine and bone, which are present in many fossil agnathans, including conodonts . Agnathans declined in the Devonian and never recovered. The agnathans as a whole are paraphyletic , because most extinct agnathans belong to the stem group of the gnathostomes, the jawed fish that evolved from them. Molecular data, both from rRNA and from mtDNA strongly supports the theory that living agnathans, known as cyclostomes , are monophyletic . In phylogenetic taxonomy ,

3212-465: The first craniates and vertebrates . The first fish lineages belong to the Agnatha , or jawless fish. Early examples include Haikouichthys . During the late Cambrian , eel-like jawless fish called the conodonts , and small mostly armoured fish known as ostracoderms , first appeared. Most jawless fish are now extinct; but the extant lampreys may approximate ancient pre-jawed fish. Lampreys belong to

3285-446: The form "author, year" in zoology, and "standard abbreviated author name" in botany. Thus in the examples above, the genus Canis would be cited in full as " Canis Linnaeus, 1758" (zoological usage), while Hibiscus , also first established by Linnaeus but in 1753, is simply " Hibiscus L." (botanical usage). Each genus should have a designated type , although in practice there is a backlog of older names without one. In zoology, this

3358-727: The generic name (or its abbreviated form) still forms the leading portion of the scientific name, for example, Canis lupus lupus for the Eurasian wolf subspecies, or as a botanical example, Hibiscus arnottianus ssp. immaculatus . Also, as visible in the above examples, the Latinised portions of the scientific names of genera and their included species (and infraspecies, where applicable) are, by convention, written in italics . The scientific names of virus species are descriptive, not binomial in form, and may or may not incorporate an indication of their containing genus; for example,

3431-470: The jaw itself and the hyoid arch, respectively. The hyoid system suspends the jaw from the braincase of the skull, permitting great mobility of the jaws. Already long assumed to be a paraphyletic assemblage leading to more derived gnathostomes, the discovery of Entelognathus suggests that placoderms are directly ancestral to modern bony fish. As in most vertebrates , fish jaws are bony or cartilaginous and oppose vertically, comprising an upper jaw and

3504-492: The jawed fish evolved from one of the ostracoderms. After the appearance of jawed fish, most ostracoderm species underwent a decline, and the last ostracoderms became extinct at the end of the Devonian period . The vertebrate jaw probably originally evolved in the Silurian period and appeared in the Placoderm fish , which further diversified in the Devonian . The two most anterior pharyngeal arches are thought to have become

3577-489: The land also. Jawless fish belong to the superclass Agnatha in the phylum Chordata , subphylum Vertebrata . Agnatha means 'un-jawed, without jaws' (from Ancient Greek ). It excludes all vertebrates with jaws, known as gnathostomes . Although a minor element of modern marine fauna , jawless fish were prominent among the early fish in the early Paleozoic . Two types of Early Cambrian animal which apparently had fins, vertebrate musculature, and gills are known from

3650-628: The largest component, with 23,236 ± 5,379 accepted genus names, of which 20,845 ± 4,494 are angiosperms (superclass Angiospermae). By comparison, the 2018 annual edition of the Catalogue of Life (estimated >90% complete, for extant species in the main) contains currently 175,363 "accepted" genus names for 1,744,204 living and 59,284 extinct species, also including genus names only (no species) for some groups. The number of species in genera varies considerably among taxonomic groups. For instance, among (non-avian) reptiles , which have about 1180 genera,

3723-555: The late Silurian: the Chondrichthyes (or cartilaginous fish) and the Osteichthyes (or bony fish). The bony fish evolved into two separate groups: the Actinopterygii (or ray-finned fish) and Sarcopterygii (which includes the lobe-finned fish). During the Devonian period a great increase in fish variety occurred, especially among the ostracoderms and placoderms, and also among the lobe-finned fish and early sharks. This has led to

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3796-545: The latter. Despite being called "spiny sharks", acanthodians predate sharks, though they gave rise to them. They evolved in the sea at the beginning of the Silurian period, some 50 million years before the first sharks appeared. Eventually competition from bony fish proved too much, and the spiny sharks died out in Permian times about 250 Ma. In form they resembled sharks, but their epidermis was covered with tiny rhomboid platelets like

3869-399: The lizard genus Anolis has been suggested to be broken down into 8 or so different genera which would bring its ~400 species to smaller, more manageable subsets. Fish evolution The evolution of fish began about 530 million years ago during the Cambrian explosion . It was during this time that the early chordates developed the skull and the vertebral column , leading to

3942-403: The most (>300) have only 1 species, ~360 have between 2 and 4 species, 260 have 5–10 species, ~200 have 11–50 species, and only 27 genera have more than 50 species. However, some insect genera such as the bee genera Lasioglossum and Andrena have over 1000 species each. The largest flowering plant genus, Astragalus , contains over 3,000 species. Which species are assigned to a genus

4015-428: The name could not be used for both. Johann Friedrich Blumenbach published the replacement name Ornithorhynchus in 1800. However, a genus in one kingdom is allowed to bear a scientific name that is in use as a generic name (or the name of a taxon in another rank) in a kingdom that is governed by a different nomenclature code. Names with the same form but applying to different taxa are called "homonyms". Although this

4088-519: The order Crossopterygii to house animals, fossil and living, that possessed lungs and fleshy pectoral fins with lobes. He placed Polypterus and Calamoichthys within this order, allocating them to a new tribe, Polypterini, which he created especially for them. The weight of Huxley's authority allowed this allocation to last in textbooks and lectures long after it had been disproved. In the 1870s and 1880s, Francis Balfour and his students had shown that embryology could help to answer questions about

4161-538: The ostracoderms and placoderms by the end of the Devonian, as well as other fish. The spiny sharks became extinct at the Permian–Triassic extinction event ; the conodonts became extinct at the Triassic–Jurassic extinction event . The Cretaceous–Paleogene extinction event , and the present day Holocene extinction , have also affected fish variety and fish stocks . Fish may have evolved from an animal similar to

4234-454: The other fauna that dominated the Cambrian, these groups had the basic vertebrate body plan : a notochord , rudimentary vertebrae, and a well-defined head and tail. All of these early vertebrates lacked jaws in the common sense and relied on filter feeding close to the seabed. These were followed by indisputable fossil vertebrates in the form of heavily armoured fish discovered in rocks from

4307-526: The provisions of the ICZN Code, e.g., incorrect original or subsequent spellings, names published only in a thesis, and generic names published after 1930 with no type species indicated. According to "Glossary" section of the zoological Code, suppressed names (per published "Opinions" of the International Commission of Zoological Nomenclature) remain available but cannot be used as the valid name for

4380-446: The relationships between animals are not typically divided into ranks, but illustrated as a nested "family tree" known as a cladogram . Phylogenetic groups are given definitions based on their relationship to one another, rather than purely on physical traits such as the presence of a backbone. This nesting pattern is often combined with traditional taxonomy, in a practice known as evolutionary taxonomy . The cladogram for jawless fish

4453-402: The root word πτερον, pteron (wing or fin) – "many fins". In shallow water, Polypterus inhales primarily through its spiracle (blowhole). Exhalation is powered by muscles in the torso. During exhalation, the bony scales in the upper chest become indented. When the muscles are relaxed, the bony scales spring back into position, generating negative pressure within the torso, resulting in

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4526-466: The same kind as other (analogous) genera. The term "genus" comes from Latin genus , a noun form cognate with gignere ('to bear; to give birth to'). The Swedish taxonomist Carl Linnaeus popularized its use in his 1753 Species Plantarum , but the French botanist Joseph Pitton de Tournefort (1656–1708) is considered "the founder of the modern concept of genera". The scientific name (or

4599-458: The scales of holosteans ( gars , bowfins ). Cartilaginous fish, class Chondrichthyes , consisting of sharks , rays and chimaeras , appeared by about 395 million years ago, in the Middle Devonian , evolving from acanthodians. The class contains the subclasses Holocephali ( chimaeras ) and Elasmobranchii ( sharks and rays ). The radiation of elasmobranches in the chart on the right

4672-408: The scientific epithet) of a genus is also called the generic name ; in modern style guides and science, it is always capitalised. It plays a fundamental role in binomial nomenclature , the system of naming organisms , where it is combined with the scientific name of a species : see Botanical name and Specific name (zoology) . The rules for the scientific names of organisms are laid down in

4745-430: The side of the head, which were permanently open with no protective operculum . Unlike invertebrates that use ciliated motion to move food, ostracoderms used their muscular pharynx to create a suction that pulled small and slow-moving prey into their mouths. The first fossil fish that were discovered were ostracoderms. The Swiss anatomist Louis Agassiz received some fossils of bony armored fish from Scotland in

4818-497: The specific name particular to the wolf. A botanical example would be Hibiscus arnottianus , a particular species of the genus Hibiscus native to Hawaii. The specific name is written in lower-case and may be followed by subspecies names in zoology or a variety of infraspecific names in botany . When the generic name is already known from context, it may be shortened to its initial letter, for example, C. lupus in place of Canis lupus . Where species are further subdivided,

4891-412: The standard format for a species name comprises the generic name, indicating the genus to which the species belongs, followed by the specific epithet, which (within that genus) is unique to the species. For example, the gray wolf 's scientific name is Canis lupus , with Canis ( Latin for 'dog') being the generic name shared by the wolf's close relatives and lupus (Latin for 'wolf') being

4964-539: The subsequent Carboniferous period. The anapsid and synapsid amniotas were common during the late Paleozoic , while the diapsids became dominant during the Mesozoic . In the sea, the bony fish became dominant. The later radiations, such as those of fish in the Silurian and Devonian periods, involved fewer taxa, mainly with very similar body plans. The first animals to venture onto dry land were arthropods . Some fish had lungs and strong, bony fins and could crawl onto

5037-621: The systematic position of Polypterus. Report of the 77th Meeting of the British Association for the Advancement of Science (1907): 545-546. Quoted by Hall Hall, B. K. (2001) John Samuel Budgett (1872-1904): In Pursuit of Polypterus , BioScience, Vol. 51, No. 5 (May, 2001), pp. 399–407 Kerr, J.G. (1907), The development of Polypterus senegalus Cuv. , Pages 195-290 in Kerr, J.G., (ed. 1907), The Work of John Samuel Budgett, Balfour Student of

5110-403: The taxon is termed a synonym ; some authors also include unavailable names in lists of synonyms as well as available names, such as misspellings, names previously published without fulfilling all of the requirements of the relevant nomenclatural code, and rejected or suppressed names. A particular genus name may have zero to many synonyms, the latter case generally if the genus has been known for

5183-566: The values quoted are the mean of "accepted" names alone (all "uncertain" names treated as unaccepted) and "accepted + uncertain" names (all "uncertain" names treated as accepted), with the associated range of uncertainty indicating these two extremes. Within Animalia, the largest phylum is Arthropoda , with 151,697 ± 33,160 accepted genus names, of which 114,387 ± 27,654 are insects (class Insecta). Within Plantae, Tracheophyta (vascular plants) make up

5256-429: The virus species " Salmonid herpesvirus 1 ", " Salmonid herpesvirus 2 " and " Salmonid herpesvirus 3 " are all within the genus Salmonivirus ; however, the genus to which the species with the formal names " Everglades virus " and " Ross River virus " are assigned is Alphavirus . As with scientific names at other ranks, in all groups other than viruses, names of genera may be cited with their authorities, typically in

5329-538: Was a diary. Consequently, his results on Polypterus were written up and published by his friend John Graham Kerr . Drawing on this work, in 1907, E. S. Goodrich reported to the British Association the then current state of evidence 'against' Polypterus being a crossopterygian, placing it within the palaeoniscids , the most primitive actinopterygians . Much later, in 1946, Romer confirmed this view, but he also wrote, "The weight of Huxley's [1861] opinion

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