This article is about the taxonomic grouping of related organisms. It is not to be confused with the ecological grouping of unrelated plant taxa in phytosociology.
The class as a distinct rank of biological classification having its own distinctive name (and not just called a top-level genus(genus summum)) was first introduced by the FrenchbotanistJoseph Pitton de Tournefort in his classification of plants that appeared in his Eléments de botanique, 1694.
Insofar as a general definition of a class is available, it has historically been conceived as embracing taxa that combine a distinct grade of organization—i.e. a 'level of complexity', measured in terms of how differentiated their organ systems are into distinct regions or sub-organs—with a distinct type of construction, which is to say a particular layout of organ systems.[2] This said, the composition of each class is ultimately determined by the subjective judgment of taxonomists.
In the first edition of his Systema Naturae (1735),[3]Carl Linnaeus divided all three of his kingdoms of nature (minerals, plants, and animals) into classes. Only in the animal kingdom are Linnaeus's classes similar to the classes used today; his classes and orders of plants were never intended to represent natural groups, but rather to provide a convenient "artificial key" according to his Systema Sexuale, largely based on the arrangement of flowers. In botany, classes are now rarely discussed. Since the first publication of the APG system in 1998, which proposed a taxonomy of the flowering plants up to the level of orders, many sources have preferred to treat ranks higher than orders as informal clades. Where formal ranks have been assigned, the ranks have been reduced to a very much lower level, e.g. class Equisitopsida for the land plants, with the major divisions within the class assigned to subclasses and superorders.[4]
The class was considered the highest level of the taxonomic hierarchy until George Cuvier's embranchements, first called Phyla by Ernst Haeckel,[5] were introduced in the early nineteenth century.
Subdivisionsedit
As with the other principal ranks, classes can be grouped and subdivided.[b]
^"Class". Biology Articles, Tutorials & Dictionary Online. 23 July 2021.
^Huxley, Thomas Henry (1853). Henfrey, Arthur (ed.). Scientific memoirs, selected from the transactions of foreign academies of science, and from foreign journals. Natural history. Taylor and Francis. doi:10.5962/bhl.title.28029.
^Mayr E. (1982). The Growth of Biological Thought. Cambridge: The Belknap Press of Harvard University Press. ISBN0-674-36446-5
^Chase, Mark W. & Reveal, James L. (2009), "A phylogenetic classification of the land plants to accompany APG III", Botanical Journal of the Linnean Society, 161 (2): 122–127, doi:10.1111/j.1095-8339.2009.01002.x
^Collins, A.G., Valentine, J.W. (2001). "Defining phyla: evolutionary pathways to metazoan body plans" 2020-04-27 at the Wayback Machine. Evol. Dev. 3: 432–442.
^Classification according to Systema Naturae 2000, which conflicts with Wikipedia's classification. "The Taxonomicon: Neornithes". Retrieved 3 December 2010.
February 15, 2024
class, biology, other, uses, class, disambiguation, this, article, about, taxonomic, grouping, related, organisms, confused, with, ecological, grouping, unrelated, plant, taxa, phytosociology, ranked, biological, classification, class, latin, classis, taxonomi. For other uses see Class disambiguation This article is about the taxonomic grouping of related organisms It is not to be confused with the ecological grouping of unrelated plant taxa in phytosociology It is the 4th ranked In biological classification class Latin classis is a taxonomic rank as well as a taxonomic unit a taxon in that rank It is a group of related taxonomic orders a Other well known ranks in descending order of size are life domain kingdom phylum order family genus and species with class ranking between phylum and order 1 The hierarchy of biological classification s eight major taxonomic ranks A phylum contains one or more classes Intermediate minor rankings are not shown Contents 1 History 2 Subdivisions 3 See also 4 Explanatory notes 5 ReferencesHistory editThe class as a distinct rank of biological classification having its own distinctive name and not just called a top level genus genus summum was first introduced by the French botanist Joseph Pitton de Tournefort in his classification of plants that appeared in his Elements de botanique 1694 Insofar as a general definition of a class is available it has historically been conceived as embracing taxa that combine a distinct grade of organization i e a level of complexity measured in terms of how differentiated their organ systems are into distinct regions or sub organs with a distinct type of construction which is to say a particular layout of organ systems 2 This said the composition of each class is ultimately determined by the subjective judgment of taxonomists In the first edition of his Systema Naturae 1735 3 Carl Linnaeus divided all three of his kingdoms of nature minerals plants and animals into classes Only in the animal kingdom are Linnaeus s classes similar to the classes used today his classes and orders of plants were never intended to represent natural groups but rather to provide a convenient artificial key according to his Systema Sexuale largely based on the arrangement of flowers In botany classes are now rarely discussed Since the first publication of the APG system in 1998 which proposed a taxonomy of the flowering plants up to the level of orders many sources have preferred to treat ranks higher than orders as informal clades Where formal ranks have been assigned the ranks have been reduced to a very much lower level e g class Equisitopsida for the land plants with the major divisions within the class assigned to subclasses and superorders 4 The class was considered the highest level of the taxonomic hierarchy until George Cuvier s embranchements first called Phyla by Ernst Haeckel 5 were introduced in the early nineteenth century Subdivisions editAs with the other principal ranks classes can be grouped and subdivided b Name Meaning of prefix Example 1 Example 2 Example 3 6 Example 4Superclass super above TetrapodaClass Mammalia Maxillopoda Sauropsida DiplopodaSubclass sub under Theria Thecostraca Avialae ChilognathaInfraclass infra below Cirripedia Aves HelminthomorphaSubterclass subter below underneath ColobognathaParvclass parvus small unimportant Neornithes See also edit nbsp Biology portalCladistics List of animal classes Phylogenetics Systematics TaxonomyExplanatory notes edit When the term denotes taxonomic units the plural is classes Latin classes Not all ranks are used in every taxon References edit Class Biology Articles Tutorials amp Dictionary Online 23 July 2021 Huxley Thomas Henry 1853 Henfrey Arthur ed Scientific memoirs selected from the transactions of foreign academies of science and from foreign journals Natural history Taylor and Francis doi 10 5962 bhl title 28029 Mayr E 1982 The Growth of Biological Thought Cambridge The Belknap Press of Harvard University Press ISBN 0 674 36446 5 Chase Mark W amp Reveal James L 2009 A phylogenetic classification of the land plants to accompany APG III Botanical Journal of the Linnean Society 161 2 122 127 doi 10 1111 j 1095 8339 2009 01002 x Collins A G Valentine J W 2001 Defining phyla evolutionary pathways to metazoan body plans Archived 2020 04 27 at the Wayback Machine Evol Dev 3 432 442 Classification according to Systema Naturae 2000 which conflicts with Wikipedia s classification The Taxonomicon Neornithes Retrieved 3 December 2010 Retrieved from https en wikipedia org w index php title Class biology amp oldid 1205910370, wikipedia, wiki, book, books, library,
