Epitheria

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Epitheria
Fossil range: early Late Cretaceous - Recent

Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Subclass:	Theria
Infraclass:	Eutheria
(unranked)	Epitheria

Orders and Clades

Superorder Afrotheria:
- Afrosoricida (Golden mole and tenrec)
- Macroscelidea (Elephant shrew)
- Tubulidentata (Aardvark)
- Hyracoidea (Hyrax)
- Proboscidea (Elephant)
- Sirenia (Manatee, Dugong)
Superorder Laurasiatheria:
- Chiroptera (Bats)
- Insectivora (Shrews, Moles)
- Cetacea (Whale, dolphin)
- Artiodactyla (Ruminants et al)
- Perissodactyla(Horse et al.)
- Pholidota (Scaly Anteater)
- Carnivora (Carnivores)
Superorder Euarchontoglires:
- Rodentia (Rodents)
- Lagomorpha (Rabbits, etc.)
- Dermoptera (Flying Lemur)
- Scandentia (Tree Shrew)
- Primates

Epitherians comprise all the eutherian 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.

Monophyly of Epitheria has been challenged by molecular phylogenetic studies (Springer et al., 2004), but Kriegs et al., 2006, and Svartman et al. 2006 found evidence for the clade based on a set of retroposons shared by all its members (presence/absence data).

Epitheres appeared in the early part of the Late Cretaceous age. Before the end of the Mesozoic Era, ancestral forms of most of the living orders (such as the ungulates and the insectivores) had already appeared. After the extinction of non-avian dinosaurs (in the Early Paleocene), the epitheres' diversity exploded, and by the end of the Eocene, all living orders of the infraclass Epitheria had appeared. Epitheres are one of the most successful groups of animals.

[edit] References

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.[1]
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. (pdf version)