Origin 
The next time you visit a farm, and see cows, horses or goats in the fields, you should think of whales. Why? Well, most scientists believe that these common farm animals are the whales’ closest relatives on land.  All are thought to have evolved from a common ancestor called a mesonychid, a small meat-eating animal which looked a bit like a wolf. About 50 million years ago, some mesonychids began to venture into the sea in search of food. Over millions of years, they slowly adapted to life in the water. Their bodies lost their hair and became more streamlined; they developed a thick layer of insulating blubber under the skin to keep them warm in cold water; their front legs were transformed into flippers, and their back legs disappeared, replaced by a powerful tail; their nostrils shifted to the top of their heads to make breathing at the ocean’s surface easier. By 25 million years ago, creatures resembling the whales of today were swimming around.