Figure 15. Tree of life. Modified from Cracraft, J. and M. J. Donoghue. 2004. Assembling the tree of life: where we stand at the beginning of the 21st century. In J. Cracraft and M. J. Donoghue, eds. Assembling the tree of life (pp. 553-561). New York: Oxford University Press. Courtesy of J. L. Cracraft and M.J. Donoghue.