In the traditional morphological phylogeny (a), the phylum platyhelminthes is depicted as a sister taxon to the rest of the protostome phyla and as having diverged earlier from the lineage that led to the rest of the protostomes. in the molecular phylogeny, which was made using analysis of dna sequences, (b), platyhelminthes is depicted as one of several phyla that make up the lophotrochozoa group. what probably led to this change?