Exafroplacentalia
Exafroplacentalia or Notolegia is a clade of placental mammals proposed in 2001 on the basis of molecular research.
Exafroplacentalia places Xenarthra as a sister group to the Boreoeutheria, thus making Afrotheria a primitive group of placental mammals.
Classification
However, this classification makes the autapomorphy dubious: it is hard to classify a group by the absence of a feature. Hence, several alternative hypotheses can be considered.Alternative hypotheses
One alternative hypothesis is the Epitheria hypothesis:Another alternative hypothesis is the Atlantogenata hypothesis:
Updated analysis of transposable element insertions around the time of divergence strongly supports the fourth hypothesis of a near-concomitant origin of the three superorders of mammals: