Manatees and Hippos

While at the zoo on Tuesday, I recorded this movie of a hippo swimming on my Droid*.

As I watched the big, grey beast go swimming by, I was struck by how much its appearance and manners resembled a manatee. I looked them up on the Interweb Tubes only to discover they aren't very closely related at all. It has to do with skeletal structure, something obscured by all that flesh on both of them.

Hippos (order Artiodactyla)

Despite their physical resemblance to pigs and other terrestrial even-toed ungulates, their closest living relatives are cetaceans (whales, porpoises, etc.) from which they diverged about 55 million years ago.

Manatees (order Sirenia)

Manatees comprise three of the four living species in the order Sirenia. The 4th is the Eastern Hemisphere's dugong. The Sirenia are thought to have evolved from four-legged land mammals over 60 million years ago, with the closest living relatives being the Proboscidea (elephants) and Hyracoidea (hyraxes).

The taxonomical proximity (say that three times fast) seems backwards from appearances. Hippos are most closely related to whales while manatees are most closely related to elephants. Wild.

* - To be clear, I recorded the movie on my Droid, the hippo was not swimming on my Droid. While my Droid is incredibly capable, I don't think it can be used as a flotation device for hippos. Of course, experimentation may prove otherwise, but I remain skeptical.