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The Euarchonta are a proposed grandorder of mammals containing four orders: the Scandentia or treeshrews, the Dermoptera or colugos, the extinct Plesiadapiformes, and the Primates.

Euarchonts
Temporal range: Paleocene - Holocene, 65–0 Ma
Euarchonta.jpg
Euarchonts: upper left: Plesiadapis, upper right: northern treeshrew, lower left: Sunda flying lemur and lower right: yellow baboon
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Superorder: Euarchontoglires
Grandorder: Euarchonta
Subgroups

Scandentia
Primatomorpha

The term "Euarchonta" (Waddell et al. 1999, meaning "true ancestors") appeared in 1999, when molecular evidence suggested that the morphology-based Archonta should be trimmed down to exclude Chiroptera (Waddell et al. 1999b). Further DNA sequence analyses (Madsen et al. 2001, Murphy et al., 2001 Waddell et al. 2001) supported the Euarchonta hypothesis. Despite multiple papers pointing out that some mitochondrial sequences showed unusual properties (particularly murid rodents and hedgehogs) and were likely distorting the overall tree (Sullivan and Swofford 1997, Waddell et al. 1999c), and despite Waddell et al. (2001) showing near total congruence of mtDNA-based and nuclear-based trees when such sequences were excluded, some authors continued to produce misleading trees (Arnason et al., 2002). A study investigating retrotransposon presence/absence data has claimed strong support for Euarchonta (Kriegs et al., 2007). Some interpretations of the molecular data link Primates and Dermoptera in a clade (mirorder) known as Primatomorpha, which is the sister of Scandentia. In some, the Dermoptera are a member of the primates rather than a sister group. Other interpretations link the Dermoptera and Scandentia together in a group called Sundatheria as the sister group of the primates.

Euarchonta and Glires together form the Euarchontoglires, one of the four Eutherian clades.

The current hypothesis, based on molecular clock evidence, suggests that the Euarchonta arose in the Cretaceous period, about 88 million years ago, and diverged 86.2 million years ago into the groups of tree shrews and Primatomorpha. The latter diverged prior to 79.6 million years into the orders of Primates and Dermoptera.[1] The earliest fossil species often ascribed to Euarchonta (Purgatorius coracis) dates to the early Paleocene, 65 million years ago,[2] but it appears to have been a non-placental eutherian.[3] Although it is known that Scandentia is one of the most basal Euarchontoglire clades, the exact phylogenetic position is not yet considered resolved, and it may be a sister of Glires, Primatomorpha or Dermoptera or to all other Euarchontoglires.[4][5][6][7]

Euarchontoglires
Glires

Rodentia (rodents)



Lagomorpha (rabbits, hares, pikas)



Euarchonta

Scandentia (treeshrews)


Primatomorpha

Dermoptera (colugos)




Primates (†Plesiadapiformes, Strepsirrhini, Haplorrhini)






ReferencesEdit

  1. ^ Jan E. Janecka, Webb Miller, Thomas H. Pringle, Frank Wiens, Annette Zitzmann, Kristofer M. Helgen, Mark S. Springer und William J. Murphy: Molecular and Genomic Data Identify the Closest Living Relative of Primates. In: Science. 318. 2007, 792-794 (PDF 384 KB)
  2. ^ O'Leary, M. A., Bloch, J. I., Flynn, J. J., Gaudin, T. J., Giallombardo, A., Giannini, N. P., ... & Cirranello, A. L. (2013). The placental mammal ancestor and the post–K-Pg radiation of placentals. Science, 339(6120): 662-667.
  3. ^ Halliday, T. J. D., Upchurch, P. and Goswami, A. "Resolving the relationships of Paleocene placental mammals" Biological Reviews. (2015). | doi = 10.1111/brv.12242
  4. ^ Foley, Nicole M.; Springer, Mark S.; Teeling, Emma C. (2016-07-19). "Mammal madness: is the mammal tree of life not yet resolved?". Phil. Trans. R. Soc. B. 371 (1699): 20150140. doi:10.1098/rstb.2015.0140. ISSN 0962-8436. PMC 4920340 . PMID 27325836. 
  5. ^ Kumar, Vikas; Hallström, Björn M.; Janke, Axel (2013-04-01). "Coalescent-Based Genome Analyses Resolve the Early Branches of the Euarchontoglires". PLOS ONE. 8 (4): e60019. doi:10.1371/journal.pone.0060019. ISSN 1932-6203. PMC 3613385 . PMID 23560065. 
  6. ^ Zhou, Xuming; Sun, Fengming; Xu, Shixia; Yang, Guang; Li, Ming (2015-03-01). "The position of tree shrews in the mammalian tree: Comparing multi-gene analyses with phylogenomic results leaves monophyly of Euarchonta doubtful". Integrative Zoology. 10 (2): 186–198. doi:10.1111/1749-4877.12116. ISSN 1749-4877. 
  7. ^ Meredith, Robert W.; Janečka, Jan E.; Gatesy, John; Ryder, Oliver A.; Fisher, Colleen A.; Teeling, Emma C.; Goodbla, Alisha; Eizirik, Eduardo; Simão, Taiz L. L. (2011-10-28). "Impacts of the Cretaceous Terrestrial Revolution and KPg Extinction on Mammal Diversification". Science. 334 (6055): 521–524. doi:10.1126/science.1211028. ISSN 0036-8075. PMID 21940861. 
  • Waddell, P.J., Y. Cao, M. Hasegawa, and D.P. Mindell. 1999a. Assessing the Cretaceous superordinal divergence times within birds and placental mammals using whole mitochondrial protein sequences and an extended statistical framework. Systematic Biology 48: 119-137.[1]
  • Waddell, P.J., N. Okada, and Hasegawa. 1999b. Towards resolving the interordinal relationships of placental mammals. Systematic Biology 48: 1-5. [2]
  • Madsen, O., Scally, M., Douady, C.J., Kao, D.J., DeBry, R.W.,

Adkins, R., Amrine, H.M., Stanhope, M.J., de Jong, W.W., Springer, M.S., 2001. Parallel adaptive radiations in two major clades of placental mammals. Nature 409, 610–614.[3]

  • Murphy W. J., E. Eizirik, W. E. Johnson, Y. P. Zhang, O. A. Ryder, S. J. O'Brien, 2001a. Molecular phylogenetics and the origins of placental mammals Nature 409:614-618. [4]
  • Waddell, P.J., H. Kishino, and R. Ota. 2001. A phylogenetic foundation for comparative mammalian genomics. Genome Informatics Series 12: 141-154. [5]
  • Sullivan, J., and D. L. Swofford. 1997. Are guinea pigs rodents? The importance of adequate models in molecular phylogenetics. J. Mammal. Evol. 4:77–86 [6]
  • Waddell, P. J., Y. Cao, J. Hauf, and M. Hasegawa. 1999c. Using novel phylogenetic methods to evaluate mammalian mtDNA, including AA invariant sites-LogDet plus site stripping, to detect internal conflicts in the data, with special reference to the position of hedgehog, armadillo, and elephant. Systematic Biology 48: 31-53.[7]
  • Ulfur Arnason, et al. 2002. Mammalian mitogenomic relationships and the root of the eutherian tree. Proceedings of the National Academy of Sciences 99: 8151-8156. [8]
  • Jan Ole Kriegs, Gennady Churakov, Jerzy Jurka, Jürgen Brosius, and Jürgen Schmitz (2007) Evolutionary history of 7SL RNA-derived SINEs in Supraprimates. Trends in Genetics 23 (4): 158-161 doi:10.1016/j.tig.2007.02.002 (PDF version [9])

External linksEdit