Figure 1.

Predicted events leading to the proposed ancestral marsupial and eutherian karyotypes. Chromosomes have been color-coded to reflect their homology to human chromosomes. Chromosome fusions followed by inversions resulted in a 2n = 14 marsupial ancestral karyotype [14] whereas a series of intrachromosomal rearrangements followed by fissions and fusions resulted in the predicted 2n = 42 ancestral eutherian karyotypes [18].