Examining Organisms to Prove the Evolution of Whales
Whales and their ancestors have been around for millions of years! It is very surprising that a mammal who gives birth to live young, is warm blooded, and breaths air through its lungs evolved to live completely under water.
The following are ancestors of this amazing creature:
- Pakicetus-- (50 mya) Wolf sized organism that lived near water and ate from the sea.
- Ambulocetus-- (49 mya) Its name means "walking whale that swims." The name refers to the fact that this animal spent a lot of time on both land and water.
- Kutchicetus-- (43-46 mya) A smaller whale ancestor that spent lots of its time diving.
- Rodhocetus-- (48-40 mya) Had much smaller rear limbs than previous ancestors.
- Dorudon-- (40 mya) Primitive whale about 5 meters long! Major size increase.
- Odontocetes-- (34 mya) Known as "toothed whales."
*Note: mya means million years ago.
See images of some of these ancestors below:
Modern Toothed Whale
- skull shape
- limb shape
- spine shape
- rib cage
Analyses of skeleton fossils also showed scientists that some of these organisms could walk on land and swim by pushing back their hind feet and undulating their tails, like otters do today.
Vestigial or remnant bones, such as the hip bone found in modern whales, are also proof of once having had legs! Notice the hip bones of the modern whale in the image above.
Examine the fossil records below to see if you can find similarities in bone structures, too!
Click to Watch Whale Evolution Animation
Holt Science and Technology Life Science Textbook