Main animal groups are noted at the right. Names diverging at each node are morphological or body form names. Note that the animal traits key to distinguishing the groups and body forms are not shown. Ancestral protist Animals Multicellularity Eumetazoa Parazoa Bilateria Radiata Deuterostomes Protostomes Ecdysozoa Lophotrochozoa Chordates Echinoderms Arthropods Roundworms Annelids Mollusks Flatworms Cnidarians Sponges If an animal researcher reproduces this evolutionary tree, but rotates the body form and animal groups, showing the deuterostomes beneath the protostomes, the interpretation of common ancestry and divergence among the body forms and animal groups will completely change.