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Norops (clade)
Norops is a clade of 169 species of polychrotid lizards within the genus ''Anolis''. Evidence for the clade's recognition stems from the fact that all of its designated species possess sufficient differences in morphology, especially in the structure and design of tail vertebrae, to suggest a deep divergence from the rest of ''Anolis''. The exact position of ''Norops'' and other distinct species groups within ''Anolis'', either as clades or as genera, has been a subject of ongoing debate among anole scientists, however the description of ''Norops'' and other clades as genera is rapidly losing support within the scientific community; however, it is unclear as to whether this debate will ever be completely resolved.
== Taxonomic Status ==
In Richard E. Etheridge's original 1959 publication he recognized ''Anolis'' as an extremely diverse genus, and also recognized ten other genera including ''Norops'', however he ultimately concluded that only four of these genera were morphologically unusual enough to warrant separation from ''Anolis''.〔Etheridge, R. (“1959”, 1960) ''The Relationships of the Anoles (Reptilia: Sauria: Iguanidae): An Interpretation Based on Skeletal Morphology''. PhD. Dissertation, University of Michigan, Ann Arbor, 236 pp.〕 Thus Etheridge concluded that the rest of the genera were simply deeply divergent groups of ''Anolis'' that were still firmly nestled within the genus. However the most recognized part of Etheridge's publication was his proposal to split ''Anolis'' into alpha and beta series based on morphological differences in caudal vertebrae.〔
In a 1986 publication Craig Guyer and Jay Savage applied the genus name ''Norops'' to Etheridge's beta anoles and also divided the rest of Anolis into four other genera. This proposal has been mostly rejected by the anole community as ''Norops'' was one of only a few of these genera proven to be monophyletic. During the 1990s and early 2000s some biologists working in Central America also began assigning certain species in Etheridge’s beta section of ''Anolis'' into ''Norops''. Though ''Norops'' is usually proposed as a separate genus from ''Anolis'' the name ''Norops'' was originally treated by Kristen. E. Nicholson (2002) as a name for a clade of lizards nestled within the genus Anolis, but distinct in terms of certain aspects of skeletal morphology which differentiate them from all other anoles. Ironically Nicholson is also the first author of a 2012 publication proposing the split of ''Anolis'' into several genera. The classification of ''Norops'' as a clade is often preferred by the scientific community as classification of ''Norops'' as a genus separate from ''Anolis'' would necessitate the designation of several other species formerly placed in ''Anolis'' into newly created genera (as proposed by Guyer and Savage (1986) and Nicholson (2012)), several of which have proven to be paraphyletic; however the separation of ''Anolis'' into several distinct but interrelated clades would make anole classification easier without necessitating the creation of several new genera. This was also part of the reason why Etheridge left his beta anoles within the genus ''Anolis'' even though he recognized that there were some differences between the two groups. There is still much debate regarding the placement of ''Norops'' and other distinct groups within ''Anolis''. In December 2012 the online website (The Reptile Database ) revised their classification of ''Anolis'' and followed Nicholson in splitting the genus into eight new genera; however all the new genera were grouped back into ''Anolis'' in April 2013.
''Norops'' continues to be recognized as a genus by workers in Central America 〔 However, it is universally rejected by West Indian workers. These differences may be due to the fact the mainland fauna is dominated by only two deeply divergent clades (''Norops'' and ''Dactyloa'' in Guyer and Savage's terminology), whereas the West Indian radiation is much more taxonomically diverse, and relationships less certain.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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