Boreoeutheria

Boreoeutheria
Temporal range: Early Paleocene - Holocene, 65–0 Ma
European mole (Talpa europaea)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Clade: Exafroplacentalia
Magnorder: Boreoeutheria
Subgroups

Boreoeutheria (synonymous with Boreotheria) (Greek: βόρειο "north" + ευ "good" + θεριό "beast") is a clade (magnorder) of placental mammals that is composed of the sister taxa Laurasiatheria (most hoofed mammals, most pawed carnivores, and several other groups) and Euarchontoglires (Supraprimates). It is now well supported by DNA sequence analyses, as well as retrotransposon presence or absence data.

The earliest known fossils belonging to this group date to about 65 million years ago, shortly after the K-Pg extinction event, though molecular data suggest they may have originated earlier, during the Cretaceous period.[1]

With the exception of rhinoceroses and cetaceans, male members of the clade share the distinction of external testicles.

Boreoeutherian ancestor

The common ancestor of Boreoeutheria lived between 100 and 80 million years ago. The boreoeutherian ancestor gave rise to species as diverse as giraffe, dog, mouse, bat, whale and humans. The concept of boreoeutherian ancestor was first proposed in 2004 in the journal Genome Research.[2][3] The genome sequence of the boreoeutherian ancestor can be computationally predicted with high accuracy. It is estimated to contain three billion base pairs.[2]

Classification

Class Mammalia

Cladogram

Eutheria  

Afrotheria


  Exafroplacentalia  

Xenarthra


  Boreoeutheria  
   

Laurasiatheria


   

Euarchontoglires





Notes

While it is agreed that the cetaceans evolved within artiodactyls, much of the branching order within Laurasiatheria is not yet well resolved. In particular, the most difficult order to place definitively has been and still is Perissodactyla: Their placement within Zooamata is controversial.

One study has suggested that the carnivores, cetaceans, chiroptera and ungulates form an ancient clade.[4] This is supported by another study that suggests that Eulipotyphla are the earliest diverging clade within the Laurasiatheria.[5]

References

  1. ↑ 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. doi:10.1126/science.1229237. PMID 23393258.
  2. 1 2 John Roach (January 25, 2005). "Scientists Recreate Genome of Ancient Human Ancestor". National Geographic. Retrieved 14 Feb 2015.
  3. ↑ Mathieu Blanchette, Eric D. Green, Webb Miller, David Haussler (2004). "Reconstructing large regions of an ancestral mammalian genome in silico". Genome Research. 14: 2412–2423. doi:10.1101/gr.2800104. PMC 534665Freely accessible. PMID 15574820. Retrieved 14 Feb 2015.
  4. ↑ Tsagkogeorga, G; Parker, J; Stupka, E; Cotton, JA; Rossiter, SJ (2013). "Phylogenomic analyses elucidate the evolutionary relationships of bats". Curr Biol. 23: 2262–2267. doi:10.1016/j.cub.2013.09.014. PMID 24184098.
  5. ↑ Morgan, CC; Foster, PG; Webb, AE; Pisani, D; McInerney, JO; O'Connell, MJ (2013). "Heterogeneous models place the root of the placental mammal phylogeny". Mol Biol Evol. 30 (9): 2145–256. doi:10.1093/molbev/mst117.

Additional references

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