Linnean taxonomy

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* Classis ("Class") - subdivisions of the above, in the animal kingdom six were recognized (mammals, birds, amphibians, fish, insects, and worms)  
* Classis ("Class") - subdivisions of the above, in the animal kingdom six were recognized (mammals, birds, amphibians, fish, insects, and worms)  
* Ordo ("Order") - further subdivision of the above - the class Mammalia has eight  
* Ordo ("Order") - further subdivision of the above - the class Mammalia has eight  
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* Genus - further subdivisions of the order - in the mammalian order Primates there are four. e.g. Homo  
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* Genus - further subdivisions of the order - in the mammalian order Primates there are four. e.g. ''Homo''
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* Species - subdivisions of genus, e.g. Homo sapiens.  
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* Species - subdivisions of genus, e.g. ''Homo sapiens''.  
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* Varietas ("Variety") - species variant, e.g. Homo sapiens europaeus.  
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* Varietas ("Variety") - species variant, e.g. ''Homo sapiens europaeus''.  
As can be seen, Linneus wrote in Latin, the standard intellectual language of the time.  His hierarchical system still reflected the old medieval feudalistic worldview ("Order" for example referred to an order of monks).  And concepts like evolution were alien to him.  For Linneus and his contemporaries, the world and all it's creatures was created once and for all, by the Judaeo-Christian  God.  Nevertheless this basic formula, as set out in the 10th edition of his Systema Naturae, published in 1758, was and still is considered the foundation of all modern taxonomy (at least until the cladists came along!)
As can be seen, Linneus wrote in Latin, the standard intellectual language of the time.  His hierarchical system still reflected the old medieval feudalistic worldview ("Order" for example referred to an order of monks).  And concepts like evolution were alien to him.  For Linneus and his contemporaries, the world and all it's creatures was created once and for all, by the Judaeo-Christian  God.  Nevertheless this basic formula, as set out in the 10th edition of his Systema Naturae, published in 1758, was and still is considered the foundation of all modern taxonomy (at least until the cladists came along!)
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The formal international agreement on names, ranks, and so on, is laid out in the [[International Code of Zoological Nomenclature]], the [[International Code of Botanical Nomenclature]], and the [[Bacteriological Code of Nomenclature]].  These set guidelines and publish a reports containing the rules of nomenclature.  For example, the Law of Priority (Article 25) says that if a genus or species has been accidentally given two names, only the earlier one is valid.  The later name becomes a "junior synonym".  This is the case even when it is better known (or more evocative).  To give a famous illustration, the Jurassic dinosaur ''Brontosaurus'', named by the 19th century American paleontologist Othniel C. Marsh in 1879, was later found to be the same animal as ''Apatosaurus'', which was actually named by the same guy two years previously (this was during the great dinosaur rush when Marsh and his rival Edward Drinker Cope were engaged in a bitter feud to see who could discover the most prehistoric animals!).  Therefore ''Apatosaurus'' is the correct name, even though "thunder lizard" (''Brontosaurus'') would seem more appropriate than "deceptive lizard" (''Apatosaurus''), and even though the later name honors the same man (maverick paleontologist Dr Bob Bakker has suggested using ''Brontosaurus'' anyway!).  A similar thing happened with ''Eohippus'' ("dawn horse") and ''Hyracotherium'' ("hyrax beast").  The better known, more appropriate name was later fond to be describe the same animal as had been previously named.  In some cases things are not so clear cut, and a ruling from the Commission in charge of these things is necessary to decide which name to use.
The formal international agreement on names, ranks, and so on, is laid out in the [[International Code of Zoological Nomenclature]], the [[International Code of Botanical Nomenclature]], and the [[Bacteriological Code of Nomenclature]].  These set guidelines and publish a reports containing the rules of nomenclature.  For example, the Law of Priority (Article 25) says that if a genus or species has been accidentally given two names, only the earlier one is valid.  The later name becomes a "junior synonym".  This is the case even when it is better known (or more evocative).  To give a famous illustration, the Jurassic dinosaur ''Brontosaurus'', named by the 19th century American paleontologist Othniel C. Marsh in 1879, was later found to be the same animal as ''Apatosaurus'', which was actually named by the same guy two years previously (this was during the great dinosaur rush when Marsh and his rival Edward Drinker Cope were engaged in a bitter feud to see who could discover the most prehistoric animals!).  Therefore ''Apatosaurus'' is the correct name, even though "thunder lizard" (''Brontosaurus'') would seem more appropriate than "deceptive lizard" (''Apatosaurus''), and even though the later name honors the same man (maverick paleontologist Dr Bob Bakker has suggested using ''Brontosaurus'' anyway!).  A similar thing happened with ''Eohippus'' ("dawn horse") and ''Hyracotherium'' ("hyrax beast").  The better known, more appropriate name was later fond to be describe the same animal as had been previously named.  In some cases things are not so clear cut, and a ruling from the Commission in charge of these things is necessary to decide which name to use.
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The complete scientific name includes genus and species, the name of the scientist who first described the species in a scientific journal deemed valid for taxonomic purposes, and the year that the paper was published.  By convention that the genus and species are written in italics (or, where that is not possible, underlined, or even _underlined ascii wise_).  The generic name is always capitalized, the trivial or species name is not.  So we have (to use the above illustration) Apatosaurus ajax Marsh, 1877
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The complete scientific name includes genus and species, the name of the scientist who first described the species in a scientific journal deemed valid for taxonomic purposes, and the year that the paper was published.  By convention that the genus and species are written in italics (or, where that is not possible, underlined, or even _underlined ascii wise_).  The generic name is always capitalized, the trivial or species name is not.  So we have (to use the above illustration) ''Apatosaurus ajax'' Marsh, 1877
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When a species is placed in a genus different to the one originally named, then the discoverer's name is placed in brackets, even when it is the same guy who named both.  So Brontosaurus excelsus Marsh, 1879 becomes Apatosaurus excelsus (Marsh, 1879)
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When a species is placed in a genus different to the one originally named, then the discoverer's name is placed in brackets, even when it is the same guy who named both.  So ''Brontosaurus excelsus'' Marsh, 1879 becomes ''Apatosaurus excelsus'' (Marsh, 1879)
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The generic name can be abbreviated to a single capital letter, as in  A. ajax.  However just using the generic name alone refers to all species included in that genus, in this case Apatosaurus includes the species A. ajax, A. excelsus and A. louisae.
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The generic name can be abbreviated to a single capital letter, as in  ''A. ajax''.  However just using the generic name alone refers to all species included in that genus, in this case ''Apatosaurus'' includes the species ''A. ajax'', ''A. excelsus'' and ''A. louisae''.
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When a new genus is described, it is based on a particular species (i.e. nomenclature-wise the taxonomic hierarchy works from species up, not from kingdom down) which becomes the type species of that genus.  So A. ajax is the type species of Apatasaurus.
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When a new genus is described, it is based on a particular species (i.e. nomenclature-wise the taxonomic hierarchy works from species up, not from kingdom down) which becomes the type species of that genus.  So ''A. ajax'' is the type species of ''Apatosaurus''.
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Sometimes a species is deemed too different to belong in the genus it was formally placed in, and so becomes the type species of a new genus.  So Apatasaurus alenquerensis de Lapparent & Zbyszewski, 1957 was recently made the type species for the genus Lourinhasaurus, hence Lourinhasaurus alenquerensis (de Lapparent & Zbyszewski, 1957).  Of course whether a species should be retained in a former genus or placed in a new one is often an arbitrary choice, which brings us to the battle between the splitters and the lumpers.
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Sometimes a species is deemed too different to belong in the genus it was formally placed in, and so becomes the type species of a new genus.  So ''Apatosaurus alenquerensis'' de Lapparent & Zbyszewski, 1957 was recently made the type species for the genus ''Lourinhasaurus'', hence ''Lourinhasaurus alenquerensis'' (de Lapparent & Zbyszewski, 1957).  Of course whether a species should be retained in a former genus or placed in a new one is often an arbitrary choice, which brings us to the battle between the splitters and the lumpers.
==Infra-orders and superfamilies==
==Infra-orders and superfamilies==

Revision as of 20:10, 6 October 2006

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