Whales (including dolphins and porpoises), pinnipeds (e.g., seals, sea lions and walruses) and sirenians (e.g. manatees) are all marine mammals with highly modi?ed limbs for swimming.  Are the limbs from these different taxa synapomorphies?  Explain..  Pleisomorphies?  Explain.   Note the current phylogeny of mammals in Figure 4.18 (Freeman and Herron 2007).  Pinnipeds are currently classi?ed with the carnivores.  If whales, pinnipeds and sirenians are classi?ed together based on their similar limbs the taxon would be what?  Explain.