Initial attempts at classifying and ordering organisms (plants and animals) were presumably set forth in prehistoric times by hunter-gatherers, as suggested by the fairly sophisticated folk taxonomies. Much later, Aristotle, and later still, European scientists, likeMagnol,[2]Tournefort[3] andCarl Linnaeus'ssystem inSystema Naturae, 10th edition (1758),[4], as well as an unpublished work byBernard andAntoine Laurent de Jussieu, contributed to this field. The idea of a unit-based system of biological classification was first made widely available in 1805 in the introduction ofJean-Baptiste Lamarck'sFlore françoise, andAugustin Pyramus de Candolle'sPrincipes élémentaires de botanique. Lamarck set out a system for the "natural classification" of plants. Since then,systematists continue to construct accurate classifications encompassing the diversity of life; today, a "good" or "useful" taxon is commonly taken to be one that reflectsevolutionary relationships.[note 1]
Many modern systematists, such as advocates ofphylogenetic nomenclature, usecladistic methods that require taxa to bemonophyletic (all descendants of some ancestor). Therefore, their basic unit, theclade, is equivalent to the taxon, assuming that taxa should reflect evolutionary relationships. Similarly, among those contemporary taxonomists working with the traditional Linnean (binomial) nomenclature, few propose taxa they know to beparaphyletic.[5] An example of a long-established taxon that is not also a clade is theclassReptilia, the reptiles; birds and mammals are the descendants of animals traditionally classed as reptiles, but neither is included in the Reptilia (birds are traditionally placed in the classAves, and mammals in the classMammalia).[6]
A taxonomic unit, whether named or not: i.e. a population, or group of populations of organisms which are usually inferred to be phylogenetically related and which have characters in common which differentiate (q.v.) the unit (e.g. a geographic population, a genus, a family, an order) from other such units. A taxon encompasses all included taxa of lower rank (q.v.) and individual organisms. [...]"
A taxon can be assigned ataxonomic rank, usually (but not necessarily) when it is given a formal name.[citation needed]
"Phylum" applies formally to any biologicaldomain, but traditionally it was always used for animals, whereas "division" was traditionally often used forplants,fungi, etc.[citation needed]
A prefix is used to indicate a ranking of lesser importance. The prefixsuper- indicates a rank above, the prefixsub- indicates a rank below. Inzoology, the prefixinfra- indicates a rank belowsub-. For instance, among the additional ranks ofclass are superclass, subclass and infraclass.[citation needed]
Rank is relative, and restricted to a particular systematic schema. For example,liverworts have been grouped, in various systems of classification, as a family, order, class, or division (phylum). The use of a narrow set of ranks is challenged by users ofcladistics; for example, the mere 10 ranks traditionally used between animal families (governed by theInternational Code of Zoological Nomenclature (ICZN)) and animal phyla (usually the highest relevant rank in taxonomic work) often cannot adequately represent the evolutionary history as more about a lineage'sphylogeny becomes known.[citation needed]
In addition, the class rank is quite often not an evolutionary but aphenetic orparaphyletic group and as opposed to those ranks governed by the ICZN (family-level, genus-level andspecies-level taxa), can usually not be made monophyletic by exchanging the taxa contained therein. This has given rise tophylogenetic taxonomy and the ongoing development of thePhyloCode, which has been proposed as a new alternative to replace Linnean classification and govern the application of names toclades. Many cladists do not see any need to depart from traditional nomenclature as governed by the ICZN,International Code of Nomenclature for algae, fungi, and plants, etc.[citation needed]
^Romer, A. S. (1970) [1949].The Vertebrate Body (4th ed.). W.B. Saunders.
^Sylvain Adnet;Brigitte Senut; Thierry Tortosa; Romain Amiot, Julien Claude, Sébastien Clausen, Anne-Laure Decombeix, Vincent Fernandez, Grégoire Métais, Brigitte Meyer-Berthaud, Serge Muller (25 September 2013).Principes de paléontologie. Dunod. p. 122.ISBN978-2-10-070313-5.La taxinomie s'enrichit avec l'invenition du mot «taxon» par Adolf Meyer-Abich, naturaliste allemand, dans sa Logik der morphologie, im Rahmen einer Logik der gesamten Biologie (1926) [Translation: Taxonomy is enriched by the invention of the word "taxon" by Adolf Meyer-Abich, German naturalist, in his Logik der morphologie, im Rahmen einer Logik der gesamten Biologie (1926).]{{cite book}}: CS1 maint: multiple names: authors list (link)
