Body-plan evolution in the Bilateria: early antero-posterior patterning and the deuterostome-protostome dichotomy

Recent molecular analyses reveal common themes in early antero-posterior patterning in the four major groups of invertebrate deuterostomes and vertebrates in spite of large differences in the mode of gastrulation. Comparisons with Drosophila and Cnidarians suggest a scheme for evolution of the Bilaterian body plan and emphasize the pressing need for similar studies in a wider variety of organisms, especially more basal protostomes.