Great question! Whales are so obviously water creatures, right? We've all seen pictures of whales washed up on the beach and it's quite clear that whales aren't well adapted to terrestrial (land) habitats. So, what evidence is there for the idea that whales "once walked on land?"

The answer is actually very simple. Whales never walked on land! Rather, the ancestor to whales walked on land. This is an important difference. You see, whales are mammals. They are closely related to other animals with hair - horses, dogs, monkeys, rats and even humans. But, millions of years ago whales as we know them today did not exist - they had not yet evolved. Instead, there was a kind of mammal with four legs that roamed the earth above water. These animals were well adapted for living on the land; they could breath the air, walk on land and capture food just as other mammals can. These were the ancestors to whales.

It is thought that over time, these four-legged creatures began to spend a lot of time in the water, probably fishing for food. Over thousands of generations, these land-based creatures began to change in ways that helped them live more easily in the water. One of the most obvious changes was the loss of legs and the addition of a powerful tail for swimming. As time progressed, these animals became more fish-like and less mammal-like. These fish-like mammals are what we now call Whales. So, again, whales themselves never walked on land. The ancestors to whales, a primitive mammal, walked on land.

Now, how do we know that whales had ancestors that walked on land? There are many reasons why we know this is true, but one of the most compelling lines of evidence is that whales have a pelvis. Animals that walk on land have a pelvis which is an important structure to which legs attach. Except for whales, animals that live in the water don't have a pelvis. Why? Because there's no need to have legs for walking if you live in the water. The reason why whales have a pelvis is because they are descendent from animals that walked on land - the ancestors to whales were terrestrial! Whales don't use their pelvis anymore.

So, we know whales had ancestors that walked on the land because they have a pelvis - a feature common to all walking mammals - which used only for terrestrial purposes. Now you might ask yourself, what is the name of this whale-like ancestor that walked on land? What did it look like? You may find the answer to this question at this web site:

http://library.advanced.org/17963/evolution.html

by studying the morphology and anatomy of fossil bones, it is possible to follow a transition from legs to strong flippers.This change occurred over a long time period...perhaps 20 to 30 million years. In fact the most distant relative of the modern whale may be the Hippo.you can learn more about this subject in the library. one place to look id for a book on vertebrate zoology and paleontology.

It is pretty impossible to imagine whales walking on land. In fact scientists don't think they ever did. What we think is that their distant ancestors did. The earliest mammals were terrestrial (land) animals. Since whales are mammals, we think they must have descended from land mammals too. (What is a mammal?)

The earliest known whale-like fossils were found in Pakistan. (Take a look at a map to find Pakistan. Why would we find whale-like things here?) The fossils seem to be about 45-50 million years old. The discoverers think that these animals lived part of their lives on land and part of their lives in water. Can you think of another type of mammal that lives like this? These early animals were only about 3 meters long. Other fossilized bones were found of animals that scientist think lived about 40 million years ago. They were shaped a lot more like our modern whales, but might have still come on shore to give birth. As you probably know, there are lots of different kinds of whales now. Most of these species probably evolved in the last 2-30 million years ago. Another interesting bit of evidence that suggests whales descended from land animals is the fact that they still have a tiny pelvis and thigh bone (femur). In a 19 m long finback whale, the pelvis is only 41 cm long and the thigh bone is only 4 cm long. How tall are you in meters? How long is your thigh?

Thanks for asking,