Evolution sometimes turns back how fish from land returned to the water

(ORDO NEWS) — All animals, as we know, once came out of the sea. In particular, all vertebrates are descendants of fish, which began to emerge on land approximately 360 million years ago. According to scientists, outwardly they resembled modern lungfish and coelacanths.

The former have both lungs and gills, while the latter have fins that look like paws. All of them belong to the ancient group of lobe-finned fish, which were the first to come out of the water onto the shore.

Moreover, scientists even managed to find the remains of transitional species, which made it possible to draw some conclusions about the evolution of these creatures. As it turned out, they not only evolved into full-fledged land animals, but sometimes returned to the water and became fish again.

A new kind of prehistoric fish

Earlier, we talked about the fish Elpistostege watsoni, in which the bones of the phalanges of the fingers were found in the pectoral fins.

They were not yet well developed, as in land animals, however, they are evidence of how fish began to adapt to land. According to scientists, Elpistostege watsoni is a relative of the Taktaaliks, the most famous transitional creatures in science.

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The coelacanth belongs to an ancient species of lobe-finned fish that first came to land

The Taktaalik fossil was discovered in 2004 in Canada at the Taktaalik site. Next to her, scientists discovered the fossils of another interesting creature. It included the upper and lower jaws, parts of the neck and scales. In addition, the humerus and pectoral fin-blade are perfectly preserved.

The presence of scales suggested that the fossils also belong to an ancient fish. However, all attention at that time was focused on taktaalik, so the other find was forgotten for a long time. But after 15 years, scientists still engaged in the study of fossils, and made an interesting discovery.

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Taktaalik site in Canada where scientists found fossils of prehistoric fish in 2004

It turned out that in front of them was the fish Qikiqtania wakei, still unknown to science. She received this name in honor of the administrative Eskimo region of Kikiktani.

The fish was much smaller than Tiktaalik – about 70 centimeters. For comparison, Tiktaalik grew in length over 2.5 meters. But the most important thing is that kickiktania has taken a different evolutionary path of development.

How did the body structure of the fish that came out on land change?

Fish with the usual body structure, adapted to life in the water, of course, could not live on land. Therefore, the shape and number of bones changed in the creatures that went ashore, the structure of the fins changed – joints appeared and muscles changed.

I must say that the muscles themselves, for obvious reasons, scientists cannot study. However, by the characteristic protrusions on the bones, one can understand how they were attached and located.

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Tiktaalik is an intermediate species between water and land

According to such characteristic features, scientists easily distinguish completely land creatures that recently emerged from the water from those that continued to live in the water.

After studying the fossils of Qikiqtania wakei, scientists came to the conclusion that this fish was not land, at the same time it was different from aquatic.

Can evolution turn back?

As researchers from the University of Chicago report in the journal Nature, there are no joints and muscles on the forearm of a fish designed for walking on land.

The fin-blade was more suitable for rowing them in the water, but at the same time it was very different from the usual fin of fish and looked more like the paws of an animal. You can learn more about the fossils of Kikiktania in this video.


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