The Exafroplacentalia ("ex afro"; "placentalia" = all placentalia except the Afrotheria ) are a group within the higher mammals (Eutheria). In 2001 they were described as taxon (subcohort) on the basis of genetic investigations and include the Xenarthra in addition to the Boreoeutheria ( Euarchontoglires and Laurasiatheria ) . They are often not explicitly mentioned in systematic representations of mammals.
The current data allow extrapolation based on the molecular clock that the exafroplacentalia originated in the Cretaceous period about 110–115 million years ago and already split into the groups of Xenarthra and Boreoeutheria 105 million years ago. The latter divided 100 million years ago into the superordinates of the Euarchontoglires and the Laurasiatheria.
Systematics
The following cladogram shows the systematic position of the exafroplacentalia:
One variant positions the secondary animals as the most original group at the base of the higher mammals and thus as the sister group of all other taxa, which in this case are summarized as Epitheria . This variant is proposed both molecularly and morphologically, based on the structure of the inner ear.
A third theory finally summarizes the Afrotheria and the secondary articulated animals as a taxon called Atlantogenata and contrasts this with the Boreoeutheria.
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