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 Temporal range: Late Cretaceous - Recent
| |
|---|---|
| |
| |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Clade: | Eutheria |
| Infraclass: | Placentalia |
| Clade: | Epitheria |
| Orders and Clades | |
| |
Epitheria like 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 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 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 and Boreoeutheria.[6]
Alternative hypotheses
editAlternative hypotheses place either Atlantogenata and Boreoeutheria, or Afrotheria and Exafroplacentalia (Notolegia) at the base of the tree:
One Bayesian analysis places the root between 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 Mammal Ancestor and the Post-K-Pg Radiation of Placentals". Science. 339 (6120): 662–667. Bibcode:2013Sci...339..662O. doi:10.1126/science.1229237. hdl:11336/7302. ISSN 0036-8075. PMID 23393258. S2CID 206544776.
- ^ For example: Springer, M. (2004). "Molecules consolidate the placental mammal tree". Trends in Ecology & Evolution. 19 (8): 430–438. doi:10.1016/j.tree.2004.05.006. PMID 16701301.
- ^ Kriegs, Jan Ole; Churakov, Gennady; Kiefmann, Martin; Jordan, Ursula; Brosius, Jürgen; Schmitz, Jürgen (2006). "Retroposed Elements as Archives for the Evolutionary History of Placental Mammals". PLOS Biology. 4 (4): e91. doi:10.1371/journal.pbio.0040091. PMC 1395351. PMID 16515367.
- ^ Nishihara, Hidenori; Maruyama, Shigenori; Okada, Norihiro (2009). "Retroposon analysis and recent geological data suggest near-simultaneous divergence of the three superorders of mammals". Proceedings of the National Academy of Sciences. 106 (13): 5235–5240. Bibcode:2009PNAS..106.5235N. doi:10.1073/pnas.0809297106. PMC 2655268. PMID 19286970.
- ^ Churakov, Gennady; Kriegs, Jan Ole; Baertsch, Robert; Zemann, Anja; Brosius, Jürgen; Schmitz, Jürgen (2009). "Mosaic retroposon insertion patterns in placental mammals". Genome Research. 19 (5): 868–875. doi:10.1101/gr.090647.108. PMC 2675975. PMID 19261842.
- ^ Song, Sen; Liu, Liang; Edwards, Scott V.; Wu, Shaoyuan (2012). "Resolving conflict in eutherian mammal phylogeny using phylogenomics and the multispecies coalescent model". Proceedings of the National Academy of Sciences. 109 (37): 14942–14947. Bibcode:2012PNAS..10914942S. doi:10.1073/pnas.1211733109. PMC 3443116. PMID 22930817.
- ^ Morgan, CC; Foster, PG; Webb, AE; Pisani, D; McInerney, JO; O'Connell, MJ (2013). "Heterogeneous models place the root of the placental mammal phylogeny". Molecular Biology and Evolution. 30 (9): 2145–256. doi:10.1093/molbev/mst117. PMC 3748356. PMID 23813979.
External links
edit- Gross, Liza (2006). "Resolving the Family Tree of Placental Mammals". PLOS Biology. 4 (4): e111. doi:10.1371/journal.pbio.0040111. PMC 1395350. PMID 20076552.
- Waddell, P. J.; Kishino, H.; Ota, R. (2001). "A phylogenetic foundation for comparative mammalian genomics". Genome Informatics. 12: 141–154. PMID 11791233. Archived from the original on 2010-04-23.
- 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. Bibcode:2003PNAS..100.1056S. doi:10.1073/pnas.0334222100. PMC 298725. PMID 12552136.
- 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. Bibcode:2006PNAS..103.3203W. doi:10.1073/pnas.0511344103. PMC 1413940. PMID 16492730.
- Nikolaev, Sergey; Montoya-Burgos, Juan I.; Margulies, Elliott H.; Program, Nisc Comparative Sequencing; 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. S2CID 1982092.
- Churakov, Gennady; Kriegs, Jan Ole; Baertsch, Robert; Zemann, Anja; Brosius, Jürgen; Schmitz, Jürgen (2009). "Mosaic retroposon insertion patterns in placental mammals". Genome Research. 19 (5): 868–875. doi:10.1101/gr.090647.108. PMC 2675975. PMID 19261842.