<p><strong>Fig. 6.4.</strong> Generalized phylogenetic tree diagram of extant mammals. Groups containing marine mammal species are indicated by asterisks. Monotremes are shaded red. Marsupials are shaded blue. Placentals are shaded yellow.</p>

Fig. 6.4. Generalized phylogenetic tree diagram of extant mammals. Groups containing marine mammal species are indicated by asterisks. Monotremes are shaded red. Marsupials are shaded blue. Placentals are shaded yellow.

Image by David Lin, adapted from Fred Hsu, Wikimedia Commons