Exafroplacentalia

Exafroplacentalia or Notolegia is a clade of placental mammals proposed in 2001 on the basis of molecular research.[1][2]

Exafroplacentalia Temporal range: Paleocene - Holocene, 65–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Infraclass:	Placentalia
Clade:	Exafroplacentalia Waddell et al, 2001
Orders and Clades
Superorder Xenarthra: Cingulata (Armadillos) Pilosa (Anteaters, sloths) Magnorder Boreoeutheria: Superorder Laurasiatheria: Eulipotyphla (Shrews, moles) Cetartiodactyla (Whales, dolphins, ruminants, etc.) Chiroptera (Bats) Perissodactyla (Horses, etc.) Pholidota (Pangolins) Carnivora (Carnivores) Superorder Euarchontoglires: Glires Rodentia (Rodents) Lagomorpha (Rabbits, etc.) Euarchonta Scandentia (Tree shrews) Primatomorpha Dermoptera (Flying lemurs) Primates

Exafroplacentalia places Xenarthra as a sister group to the Boreoeutheria (comprising Laurasiatheria and Euarchontoglires),[3] thus making Afrotheria a primitive group of placental mammals (the group name roughly means "those which are not African placentals").

Classification

Eutheria	Afrotheria     Exafroplacentalia     Xenarthra     Boreoeutheria       Laurasiatheria       Euarchontoglires

However, this classification makes the autapomorphy (character shared only among Exafroplacentalia) dubious: it is hard to classify a group by the absence of a feature (in this case "not coming from Africa").[4] Hence, several alternative hypotheses can be considered.

Alternative hypotheses

One alternative hypothesis is the Epitheria hypothesis:

Placentalia	Xenarthra   Epitheria   Afrotheria   Boreoeutheria   Euarchontoglires     Laurasiatheria

Another alternative hypothesis is the Atlantogenata hypothesis:

Eutheria	Atlantogenata   Xenarthra     Afrotheria     Boreoeutheria   Euarchontoglires     Laurasiatheria

Updated analysis of transposable element insertions around the time of divergence strongly supports the fourth hypothesis of a near-concomitant origin of the three superorders of mammals:[4]

Eutheria	Xenarthra     Afrotheria   Boreoeutheria   Euarchontoglires     Laurasiatheria

See also

• Epitheria
• Atlantogenata

References

1. Murphy, W.J., Pringle, T.H., Crider, T.A., Springer, M.S. & Miller, W. 2007. Using genomic data to unravel the root of the placental mammal phylogeny. Genome Research 17, pp.413-421.
2. Kriegs, J.O., Churakov, G., Kiefmann, M., Jordan, U., Brosius, J. & Schmitz, J. 2006. Retroposed elements as archives for the evolutionary history of placental mammals. Plos Biol 4, pp.e91.
3. Goloboff, Pablo A.; Catalano, Santiago A.; Mirande, J. Marcos; Szumik, Claudia A.; Arias, J. Salvador; Källersjö, Mari; Farris, James S. (2009). "Phylogenetic analysis of 73 060 taxa corroborates major eukaryotic groups". Cladistics. 25 (3): 211–230. doi:10.1111/j.1096-0031.2009.00255.x.
4. Nishihara, H., Maruyama, S. & Okada, N. 2009. Retroposon analysis and recent geological data suggest near-simultaneous divergence of the three superorders of placental mammals. PNAS 106: 5235-40.

Further reading

• Churakov, G.; Kriegs, J. O.; Baertsch, R.; Zemann, A.; Brosius, J. R.; Schmitz, J. R. (2009). "Mosaic retroposon insertion patterns in placental mammals". Genome Research. 19 (5): 868–875. doi:10.1101/gr.090647.108. PMC 2675975. PMID 19261842.
• Nikolaev, Sergey; Montoya-Burgos, Juan I.; Margulies, Elliott H.; NISC Comparative Sequencing Program; Rougemont, Jacques; Nyffeler, Bruno; Antonarakis, Stylianos E. (2007). "Early History of Mammals is Elucidated with the ENCODE Multiple Species Sequencing Data". PLoS Genetics. 3 (1): e2. doi:10.1371/journal.pgen.0030002. PMC 1761045. PMID 17206863.
• Springer, Mark S.; Murphy, William J.; Eizirik, Eduardo; O'Brien, Stephen J. (2003). "Placental mammal diversification and the Cretaceous–Tertiary boundary". Proceedings of the National Academy of Sciences. 100 (3): 1056–1061. doi:10.1073/pnas.0334222100. PMC 298725. PMID 12552136.
• Waddell, Peter J.; Kishino, Hirohisa; Ota, Rissa (2001). "A phylogenetic foundation for comparative mammalian genomics". Genome Informatics. 12: 141–154. PMID 11791233.
• Wildman, Derek E.; Chen, Caoyi; Erez, Offer; Grossman, Lawrence I.; Goodman, Morris; Romero, Roberto (2006). "Evolution of the mammalian placenta revealed by phylogenetic analysis". Proceedings of the National Academy of Sciences. 103 (9): 3203–3208. doi:10.1073/pnas.0511344103. PMC 1413940. PMID 16492730.