Laurasiatheria Gill, 1872
Laurasiatheria is a large group of placental mammals. It includes bats, whales, most hoofed mammals, and carnivorans, among other mammals.
Laurasiatheria was discovered on the basis of the similar gene sequences shared by the mammals belonging to it. No anatomical features have yet been found that unite the group. Laurasiatheria is a clade usually discussed without a Linnaean rank, but has been assigned the rank of cohort or magnorder, and superorder. The Laurasiatheria clade is based on DNA sequence analyses and retrotransposon presence/absence data. The name comes from the theory that these mammals evolved on the supercontinent of Laurasia, after it split from Gondwana when Pangaea broke up. It is a sister group to Euarchontoglires (Supraprimates) and Afrotheria. It includes the following extant orders:
* Erinaceomorpha: hedgehogs and gymnures
Within the Laurasiatheria, the Erinaceomorpha appears to be the most divergent branch. Some studies link the Perissodactyla and Ferae in a clade Zooamata; others link Perissodactyla and Cetartiodactyla in a clade of true ungulates . Neither clade is well supported.
Laurasiatheria is also posited to include several extinct orders and superorders:
1. ^ Waddell, Peter J., Okada, Norihiro, & Hasegawa, Masami (1999). "Towards resolving the interordinal relationships of placental mammals". Systematic Biology 48 (1): 1–5. doi:10.1093/sysbio/48.1.1. http://www.deer.rr.ualberta.ca/library/taxonomy/reading.pdf. Retrieved 2009-10-26.
Source: Wikispecies, Wikipedia: All text is available under the terms of the GNU Free Documentation License