Parouse.com
 Parouse.com



Epitherians comprise all the placental mammals except the Xenarthra. They are primarily characterized by having a stirrup-shaped stapes in the middle ear, which allows for passage of a blood vessel. This is in contrast to the column-shaped stapes found in marsupials, monotremes, and xenarthrans. They are also characterized by having a shorter fibula relative to the tibia. Epitheria — like Xenarthra
Xenarthra
and Afrotheria — originated after the K-Pg boundary 66 million years ago, with the placental diversification occurring within the first hundred thousand years after the K-Pg event and the first modern placental orders began appearing 2–3 million years later.[1] Epitheres are one of the most successful groups of animals. The monophyly of Epitheria
Epitheria
has been challenged by molecular phylogenetic studies.[2] While preliminary analysis of a set of retroposons shared by both Afrotheria, and Boreoeutheria (presence/absence data) supported the Epitheria
Epitheria
clade,[3] more extensive analysis of such transposable element insertions around the time of the divergence of Xenarthra, Afrotheria, and Boreoeutheria strongly support the hypothesis of a near-concomitant origin (trifurcation) of these three superorders of mammals.[4][5] Another analysis suggests that the root of this clade lies between the Atlantogenata
Atlantogenata
and Boreoeutheria.[6]

Placentalia  

Xenarthra

  Epitheria  

Afrotheria

  Boreoeutheria  

Euarchontoglires

Laurasiatheria

Alternative hypotheses[edit] Alternative hypotheses place either Atlantogenata
Atlantogenata
and Boreoeutheria, or Afrotheria
Afrotheria
and Exafroplacentalia
Exafroplacentalia
(Notolegia) at the base of the tree:

Placentalia  

  Atlantogenata  

Xenarthra

Afrotheria

  Boreoeutheria  

Euarchontoglires

Laurasiatheria

Placentalia  

Afrotheria

  Exafroplacentalia  

Xenarthra

  Boreoeutheria  

Euarchontoglires

Laurasiatheria

One Bayesian analysis places the root between Atlantogenata
Atlantogenata
and Boreoeutheria.[7] References[edit]

^ O'Leary, M. A.; Bloch, J. I.; Flynn, J. J.; Gaudin, T. J.; Giallombardo, A.; Giannini, N. P.; Goldberg, S. L.; Kraatz, B. P.; Luo, Z.-X.; Meng, J.; Ni, X.; Novacek, M. J.; Perini, F. A.; Randall, Z. S.; Rougier, G. W.; Sargis, E. J.; Silcox, M. T.; Simmons, N. B.; Spaulding, M.; Velazco, P. M.; Weksler, M.; Wible, J. R.; Cirranello, A. L. (2013). "The Placental
Placental
Mammal
Mammal
Ancestor and the Post-K-Pg Radiation of Placentals". Science. 339 (6120): 662–667. doi:10.1126/science.1229237. ISSN 0036-8075. PMID 23393258.  ^ For example: Springer, Mark S., Michael J. Stanhope, Ole Madsen, and Wilfried W. de Jong. 2004. Molecules consolidate the placental mammal tree" Trends in Ecology and Evolution 19:430–438. ^ Kriegs, Jan Ole, Gennady Churakov, Martin Kiefmann, Ursula Jordan, Juergen Brosius, and Juergen Schmitz. (2006) Retroposed Elements as archives for the evolutionary history of placental mammals" PLoS Biol 4(4) e91. ^ Nishihara, H., Maruyama, S. & Okada, N. 2009. Retroposon analysis and recent geological data suggest near-simultaneous divergence of these three superorders of mammals. PNAS 106: 5235-40. ^ Churakov, G., Kriegs, J.O., Baertsch, R., Zemann, A., Brosius, J. & Schmitz, J. 2009. Mosaic retroposon insertion patterns in placental mammals. Genome Research 19: 868-75. ^ Song S, Liu L, Edwards SV, Wu S (2012) Resolving conflict in eutherian mammal phylogeny using phylogenomics and the multispecies coalescent model. Proc Natl Acad Sci USA ^ 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. 

External links[edit]

Summary of molecular support for Epitheria Waddell PJ, Kishino H, Ota R. 2001. A phylogenetic foundation for comparative mammalian genomics. Genome Inform Ser Workshop Genome Inform 12: 141–154 Mark S. Springer, William J. Murphy, Eduardo Eizirik, and Stephen J. O'Brien (Edited by Morris Goodman). 2002 Placental
Placental
mammal diversification and the Cretaceous-Tertiary boundary Wildman D.E.; Chen C.; Erez O.; Grossman L.I.; Goodman M.; Romero R. 2006. Evolution of the mammalian placenta revealed by phylogenetic analysis" PNAS 103 (9) 3203–3208 Nikolaev, S., Montoya-Burgos, J.I., Margulies, E.H., Rougemont, J., Nyffeler, B., Antonarakis, S.E. 2007. Early history of mammals is elucidated with the ENCODE multiple species sequencing data" PLoS Genet 3:e2, doi:10.1371/journal.pgen.0030002. Gennady Churakov, Jan Ole Kriegs, Robert Baertsch, Anja Zemann, Jürgen Brosius, Jürgen Schmitz. 2008. Mosaic retroposon insertion patterns in placental mammals

Taxon identifiers

Wd: Q2475989 E