The timing and phylogenetic hierarchy of early placental mammal divergences was
determined based on combined DNA sequence analysis of 18 gene segments (9779 bp)
from 64 species. Using rooted and unrooted phylogenies derived from distinct theoretical
approaches, strong support for the divergence of four principal clades of eutherian mammals
was achieved. Minimum divergence dates of the earliest nodes in the placental mammal
phylogeny were estimated with a quartet-based maximum-likelihood method that …