Temporal range: Late Cretaceous - Recent
|Clockwise from the upper left: giraffe, golden crown fruit bat, lion, hedgehog|
Waddell et al. 1999 
Laurasiatheria is a large group of placental mammals believed to have originated on the northern supercontinent of Laurasia. It includes shrews, hedgehogs, pangolins, bats, whales, most hoofed mammals (such as hippopotamuses), and carnivorans, among others.
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 (or Supraprimates) with which it forms the clade Boreoeutheria. Laurasiatheria includes the following extant taxa:
There is still uncertainty regarding the phylogenetic tree for extant Laurasiatherians, primarily due to disagreement about the placement of Chiroptera and Perissodactyla. Based on morphological grounds, Chiroptera had long been classified in the superorder Archonta (e.g. along with treeshrews and the gliding colugos) until genetic research ruled that out and instead showed their kinship with the other Laurasiatherians. The studies conflicted in terms of the exact placement of Chiroptera however, with it being linked most closely to groups such as Eulipotyphla, Ferae or with Perissodactyla and Ferae in the Pegasoferae proposal. The most recent study (Zhou et al., 2011) found that "trees reconstructed [...] for the 1,608-gene data set fully support [...] a basal position for Eulipotyphla and a more apical position for Chiroptera" (see cladogram below) and concluded that "Pegasoferae [...] does not appear to be a natural group." The exact position of Perissodactyla remains less certain however, with some studies linking it with Ferae into a proposed clade Zooamata while others unite it with Cetartiodactyla into Euungulata, a clade of 'true ungulates'; Zhou et al. find better (but not full) support for the latter.
Laurasiatheria is also posited to include several extinct orders and superorders:
||This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. (February 2008)|
|Wikispecies has information related to: Laurasiatheria|
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