Radiata
Radiata Temporal range: Ediacaran – Present
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Louis Agassiz in 1870, with drawings of animals then considered Radiates | |
Scientific classification | |
Kingdom: | |
Subkingdom: | |
(unranked): | Radiata
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Radiata or Radiates is a historical taxonomic rank that was used to classify
monophyletic group under current views of animal phylogeny. The similarities once offered in justification of the taxon, such as radial symmetry, are now taken to be the result of either incorrect evaluations by early researchers or convergent evolution, rather than an indication of a common ancestor. Because of this, the term is used mostly in a historical context.[1]
In the early 19th century,
Zoophytes).[2] Thomas Cavalier-Smith, in 1983, redefined Radiata as a subkingdom consisting of Myxozoa, Placozoa, Cnidaria and Ctenophora.[3] Lynn Margulis and K. V. Schwartz later redefined Radiata in their Five Kingdom classification, this time including only Cnidaria and Ctenophora.[4] This definition is similar to the historical descriptor Coelenterata, which has also been proposed as a group encompassing Cnidaria and Ctenophora.[5][6]
Although
larvae, and are now in the Bilateria. Ctenophores exhibit biradial or rotational symmetry, defined by tentacular and pharyngeal axes, on which two anal canals are located in two diametrically opposed quadrants.[7] Some species within the cnidarian class Anthozoa are bilaterally symmetric (For example, Nematostella vectensis). It has been suggested that bilateral symmetry may have evolved before the split between Cnidaria and Bilateria, and that the radially symmetrical cnidarians have secondarily evolved radial symmetry, meaning the bilaterality in cnidarian species like N. vectensis has a primary origin.[8]
The differing definitions assigned by zoologists are listed in the table.
Author | Work | Date | Name of group | Taxa included | Level of group |
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Cuvier | Le Règne Animal[2] | 1817 | Zoophytes (Radiata in English translations) |
Embranchement (1 of 4)
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Cavalier-Smith | "A 6-kingdom classification and a unified phylogeny"[3] | 1983 | Radiata | Myxozoa, Placozoa, Cnidaria, Ctenophora | Subkingdom
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Margulis, Schwartz |
Five Kingdoms[4] | 1988 | Radiata | Cnidaria, Ctenophora | Subkingdom
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Philippe et al. | "Phylogenomics Revives Traditional Views on Deep Animal Relationships"[5] | 2009 | Coelenterata | Cnidaria, Ctenophora | Proposed clade |
References
Wikispecies has information related to Radiata.
- ISBN 0080100791.
- ^ a b Cuvier, Georges (1817). Le Règne Animal Distribué Selon son Organisation, pour Servir de Base à l'Histoire Naturelle des Animaux et d'Introduction à l'Anatomie Comparée. Paris: Déterville.
- ^ ISBN 3110086603.
- ^ ISBN 0716730278.
- ^ S2CID 15282843.
- PMID 25840473.
- PMID 12220977.
- S2CID 21555976.