Can you believe it? Whales not only have legs, but are also cousins ​​of hippos

Speaking of fish with legs, to be honest, the first thing that comes to my mind is this picture.

Mr. Jun, does the fish with legs you just mentioned look like this?

Emmmmmmm, let's get back to the point. Whether you believe it or not, I have to tell you categorically that whales did have legs for a period of time. (Whale: Oh, who doesn't have a dream of becoming a mermaid these days?) This matter has to start with evolution...

Although whales are a small branch in the biological evolution tree, they are very fascinating. Because it is actually a magical thing for whales to survive in the sea. If you don’t believe it, take a look at these little facts that are terrifying when you think about them carefully:

1. Whales are warm-blooded animals. You should know that warm-blooded fish are extremely rare in the ocean.

2. Whales have placentas, give birth to live young, and also feed their babies.

3. They live in water all year round, but have no gills and use two lungs to breathe.

4. There is no nose, but there is a stoma, which is divided into two nasal passages inside the head.

5. Whales have hair. (You never expected that I have more hair than programmers!)

Watson, did you find the blind spot? Yes, they are really similar to land animals! Therefore, scientists speculate that whales evolved from land quadrupeds.

Let’s first look at it from the perspective of anatomy, because on the surface it seems intuitive that whales are just ordinary big fish. If we want to understand more clearly, we have to peel off their “underwear”.

Look at the hands of whales. Why are they called hands? Because the bones of their flipper-shaped forelimbs have different functions, such as arms, wrists, and fingers.

Then please turn your attention to the strange little bone at the whale's tail.

No way, no way, this thing can't be a whale's leg

In the spirit of seeking truth and being pragmatic, I went back several generations of whales and found this guy - Basilosaurus . Because they still have small hind legs that have not completely degenerated, so we call it "calf whale" first.

They lived in the late Eocene epoch, 36 to 45 million years ago.

Its discovery clearly shows that whales evolved from terrestrial quadrupeds, because they are a species in the process of evolution.

Let's first look at photos of dolphins at different stages of development. We can see that as they age, the location of the dolphin's blowhole gradually grows from the middle of the face to the top of the head.

Then let's take a look at the skull of the calf whale. Its blowhole is not located on the top of the head like modern whales, nor is it located in the middle of the face like land animals, but right between the face and the head.

Left: Land mammals: Ridgeback whales Right: Modern whales

But these were not enough (yes, scientists thought so at the time), so everyone went through great pains to find the next witness near the top of the whale family tree - Maiacetus inuus (mother whale). Here we will simply call it "thigh whale".

I think I found the whale's leg! That's it!

When scientists first discovered them, they looked like prehistoric land animals, but strangely, all the skeletal fossils of the whale appeared in places rich in marine fossils, which once puzzled everyone.

But later, when similarities were discovered in the skulls of the hamstring whale and the calf whale, the truth gradually became clear.

Although fossils can provide a very intuitive view of the evolution of organisms that once existed, there are always some small troublemakers like the giant whale that blur the line between limbed land animals and fully aquatic creatures, which can easily lead to misjudgment.

Well, there is another top-secret weapon, called DNA, which is absolutely a good tool for tracing one's roots.

So the whale's DNA was compared with that of other species, and after the comparison, they discovered something wrong: the animal with the closest similarity to the whale's DNA was actually the hippopotamus!

Although this cannot prove that whales evolved from hippos, this information tells us that the ancestors of whales and hippos may be the same animal.

This makes sense for some of the strange things that happen to hippos, because hippos also have the same special-shaped ankle bones as whales .

Moreover, hippos, as land mammals, give birth to their young and even breastfeed in water .

So the question is, what do you think caused a part of the "common ancestor" of hippos and whales to choose to "run away from home" by going into the sea?