The exact relationships among these three lineages is currently a subject of debate, and four different hypotheses have been proposed with respect to which group is basal or diverged first from other placentals. These hypotheses are Atlantogenata (basal Boreoeutheria), Epitheria (basal Xenarthra), Exafroplacentalia (basal Afrotheria) and a hypothesis supporting a near simultaneous divergence. Estimates for the divergence times among these three placental groups range from 105 to 120 million years ago (MYA), depending on the type of DNA (e.g. nuclear or mitochondrial) and varying interpretations of paleogeographic data.