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
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Placentalia
Clade: Exafroplacentalia
Waddell et al, 2001
Orders and Clades

Magnorder Boreoeutheria:

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

 
 
 
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See also

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
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