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48-588: 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

96-413: 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

144-466: 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

192-407: 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

240-651: 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

288-446: 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,

336-628: 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,

384-500: 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

432-409: 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

480-404: 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

528-427: 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. ;

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576-455: 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

624-551: 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

672-612: 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

720-460: 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,

768-474: 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

816-836: The American Philosophical Society . In 1954 Romer was awarded the Mary Clark Thompson Medal from the National Academy of Sciences , of which he was a member. He was awarded the academy's Daniel Giraud Elliot Medal in 1956. In 1961, Romer received the Golden Plate Award of the American Academy of Achievement . Romer was a keen practical student of vertebrate evolution. Comparing facts from paleontology , comparative anatomy , and embryology , he taught

864-621: 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

912-824: 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;

960-844: 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

1008-419: 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 ,

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1056-404: 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,

1104-475: 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 ),

1152-442: 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

1200-447: The basic structural and functional changes that happened during the evolution of fishes to ancestral terrestrial vertebrates and from these to all other tetrapods . He always emphasized the evolutionary significance of the relationship between form and function of animals and their environment. Through his textbook Vertebrate Paleontology , Romer laid the foundation for the traditional classification of vertebrates. He drew together

1248-700: 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

1296-446: 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

1344-737: 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,

1392-633: 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,

1440-463: 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. Alfred Romer Alfred Sherwood Romer (December 28, 1894 – November 5, 1973) was an American paleontologist and biologist and a specialist in vertebrate evolution . Alfred Romer was born in White Plains , New York,

1488-403: 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

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1536-428: 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

1584-519: 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

1632-541: 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

1680-402: 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

1728-470: 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

1776-408: 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

1824-414: The son of Harry Houston Romer and his wife, Evalyn Sherwood. He was educated at White Plains High School. He studied at Amherst College for his Bachelor of Science Honours degree in biology, then at Columbia University for an M.Sc. in biology and a doctorate in zoology in 1921. Romer joined the department of geology and paleontology at the University of Chicago as an associate professor in 1923. He

1872-497: 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,

1920-412: 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

1968-640: 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

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2016-403: 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

2064-444: The then widely scattered taxonomy of the different vertebrate groups and combined them into a single scheme, emphasizing orderliness and overview. Based on his research into early amphibians, he reorganised the labyrinthodontians . Romer's classification has been followed by many subsequent authors, notably Robert L. Carroll , and is still in use. In honor of Alfred Romer, several taxonomic patronyms were given in animals: Romer

2112-576: 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

2160-429: 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

2208-547: 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

2256-463: Was an active researcher and teacher. His collecting program added important Paleozoic specimens to Chicago's Walker Museum of Paleontology. In 1934 he was appointed professor of biology at Harvard University . In 1946, he became director of the Harvard Museum of Comparative Zoology (MCZ). Romer was elected to the American Academy of Arts and Sciences in 1937. In 1951, he was elected to

2304-469: Was the first to recognise the gap in the fossil record between the tetrapods of the Devonian and the later Carboniferous period, a gap that has borne the name Romer's gap since 1995. A romerogram, also called spindle diagram, or bubble diagram, is a diagram popularised by Alfred Romer. It represents taxonomic diversity (horizontal width) against geological time (vertical axis) in order to reflect

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