New study suggests whales & dolphins may be related to Hippos.
I've always had a special fondness for hippos. Or "River Horse" as the Greeks* called them. Ever since my mother explained to me why I'd never be as slender or athletic as my cousins. "Honey," she said.... "some people are built like gazelles. Long legs, no curves, no boobs. They're born to run and love to run. We, on the other hand are built more like hippos. It's hard to get into jogging when your boobs smack you in the face at every step." (don't tell me about athletic bra's. Even if they come big enough they just create a more unified mass to bounce around). And lest you think Mom was insulting me, let me make it clear that Hippos are about the cutest thing you've ever seen in their native element. The moral of the story... everybody's beautiful when they find their place in life.
*If you think this is an unlikely pairing you should remember that Poseidon was both the Greek god of the rivers & oceans and the creator of the horse, whose shape he often took in myth.