If this is starting to sound a bit confusing, the biologists have a very simple explanation for the divergence and resulting evolutionary tree. The relationships which evolved closely parallel the movement of continental land masses during geologic time. That's why Springer named one group Afrotheria for its African origins and another Laurasiatheria after the land mass which gave rise to North America, Europe and Asia. One in the southern hemisphere and the other in the northern hemisphere. On the classic trees, the northern and southern groups are mixed up.
Geological evidence supports the phylogenies as well.
Mammals first appeared in the fossil record about the time continents were splitting apart. This would give the different groups separate evolutionary histories, which is documented in the DNA analyses. We're not the first to see these relationships, but the evidence really hammers home the point that there is a group from Africa that is closely related. Funding was provided by the National Science Foundation and the European Commission's Training and Mobility of Researchers program.