Boreoeutheria

Boreoeutheria (synonymous with Boreotheria) (from Greek Βορέας, Boreas 'the greek god of north wind', εὐ-, eu- 'good, right' and θηρίον, thēríon 'beast' hence 'northern true beasts') is a clade (magnorder) of placental mammals which is composed of the sister taxa Laurasiatheria (most hoofed mammals, most pawed carnivores, and several other groups) and Euarchontoglires (Supraprimates). It is now well supported by DNA sequence analyses, as well as retrotransposon presence or absence data. Placental mammals outside of this clade are the clades Xenarthra (sloths and their close relatives) and Afrotheria (elephants and their close relatives). The earliest known fossils belonging to this group date to about 65 million years ago, shortly after the K-Pg extinction event, though molecular data suggest they may have originated earlier, during the Cretaceous period. With a few exceptions male animals in the clade have a scrotum. The sub-clade Scrotifera was named after this feature. The common ancestor of Boreoeutheria lived between 100 and 80 million years ago. The boreoeutherian ancestor gave rise to species as diverse as giraffes, dogs, mice, bats, whales, and humans. The concept of a boreoeutherian ancestor was first proposed in 2004 in the journal Genome Research. The paper's authors claimed that the genome sequence of the boreoeutherian ancestor could be computationally predicted with 98% accuracy, but would 'take a few years and a lot of money'. It is estimated to contain three billion base pairs. Other studies have placed the common ancestor at closer to 65 million years ago. Class Mammalia The weakly favoured cladogram favours Boreoeutheria as a basal Eutherian clade as sister to the Atlantogenata.