Figure 1.

Three phylogenetic hypotheses for the root of theeutherian tree. (a) Tree 1: basal Afrotheria. (b) Tree 2: basal Xenarthra. (c) Tree 3: basal Boreotheria, or Afrotheria/Xenarthra clade. The phylogenetic relationships within Boreotheria (cow, dog, mouse, rat, human, chimpanzee, and macaque) are fixed in this study.