Why do manatees have toenails?

My daughter was just reading a book on manatees (which I knew nothing about other than what I saw at Sea World), and I was amazed at some of the interesting facts about them. It seems that they are incredibly similar to elephants in many, many ways, and even have vestigal toenails on their flippers! These little nails serve absolutely no purpose whatsoever.

One description is as follows:

The similarities between manatees and elephants are considerable: the toenails, teeth, digestive tract, prehensile mouth parts, skin, location of mammary glands, and hair are the most notable. The manatee's hind legs have been reabsorbed and only a cartilaginous structure remains.

All very odd, indeed, without evolution.

To believe that manatees did NOT share a common ancestor with elephants seems like "head in the sand" tactics.