Boreoeutheria

Boreoeutheria Temporal range: Early Paleocene - Holocene, 65–0 Ma PreЄ Є O S D C P T J K Pg N
European mole (Talpa europaea)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Class:	Mammalia
Clade:	Exafroplacentalia
Magnorder:	Boreoeutheria
Subgroups
Laurasiatheria Euarchontoglires

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 suggests 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 cat, dog, mouse, rabbit, 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

• Magnorder Boreoeutheria
  • Superorder Euarchontoglires (Supraprimates)
    • Clade Euarchonta
      • Order Scandentia: treeshrews (Southeast Asia)
      • Clade Primatomorpha
        • Order Dermoptera: flying lemurs or colugos (Southeast Asia)
        • Order Primates: lemurs, bushbabies, monkeys, apes (cosmopolitan)
    • Clade Glires
      • Order Lagomorpha: pikas, rabbits, hares (Eurasia, Africa, Americas)
      • Order Rodentia: rodents (cosmopolitan)
  • Superorder Laurasiatheria
    • Clade Eulipotyphla
      • Order Erinaceomorpha: hedgehogs and gymnures (Eurasia, Africa, extinct in North America)
      • Order Soricomorpha: moles, shrews, solenodons (Eurasia, Africa, North America, northern South America)
    • Clade Cetartiodactyla
      • Order Cetacea: whales, dolphins and porpoises (cosmopolitan in seas)
      • Order Artiodactyla: even-toed ungulates, including pigs, hippopotamus, camels, giraffe, deer, antelope, cattle, sheep, goats (cosmopolitan)
    • Order Chiroptera: bats (cosmopolitan)
    • Clade Zooamata
      • Order Perissodactyla: odd-toed ungulates, including horses, donkeys, zebras, tapirs, and rhinoceroses (cosmopolitan)
      • Clade Ferae
        • Order Pholidota: pangolins or scaly anteaters (Africa, South and Southeast Asia)
        • Order Carnivora: carnivorans (cosmopolitan)

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. 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 534665. 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

• Waddell, PJ; Kishino, H; Ota, R (2001). "A phylogenetic foundation for comparative mammalian genomics". Genome Inform Ser Workshop Genome Inform 12: 141–154.
• Murphy, William J.; Eizirik, Eduardo; Springer, Mark S.; et al. (2001). "Resolution of the Early Placental Mammal Radiation Using Bayesian Phylogenetics". Science 294 (5550): 2348–2351. doi:10.1126/science.1067179. PMID 11743200.
• Kriegs; Ole, Jan; Churakov, Gennady; Kiefmann, Martin; Jordan, Ursula; Brosius, Juergen; Schmitz, Juergen (2006). "Retroposed Elements as Archives for the Evolutionary History of Placental Mammals". PLoS Biol 4 (4): e91. doi:10.1371/journal.pbio.0040091. PMC 1395351. PMID 16515367.
• Blanchette, M; Green, ED; Miller, W; Haussler, D (Dec 2004). "Reconstructing large regions of an ancestral mammalian genome in silico". Genome Res 14 (12): 2412–23. doi:10.1101/gr.2800104. PMC 534665. PMID 15574820.
• Ma, J; Zhang, L; Suh, BB; Raney, BJ; Burhans, RC; Kent, WJ; Blanchette, M; Haussler, D; Miller, W (Dec 2006). "Reconstructing contiguous regions of an ancestral genome". Genome Res 16 (12): 1557–65. doi:10.1101/gr.5383506. PMC 1665639. PMID 16983148.

External links

• Resolving the Family Tree of Placental Mammals
• Wired article: Bringing Back the Brontosaurus April 2006.