(ORDO NEWS) — At the end of the Devonian period (about 370 million years ago), fish-like vertebrates took their first hesitant steps on the shore – among them was the famous Tiktaalik.
It turned out that some of his relatives, meanwhile, chose not to risk it and continued to live in the water – like the new species just described, Qikiqtania wakei.
An important milestone in evolution was the emergence of life on land after a long existence exclusively in water. The development of the coast became massive only at the beginning of the Paleozoic era, although individual traces of life on land are ancient.
Among the “pioneers” of the new habitat were microbes, primitive spore plants and arthropods like crustaceans – it was they who became the basis of the first terrestrial ecosystems.
Vertebrates, meanwhile, were in no hurry to stick out of the warm seas. The first of them crawled ashore (where a whole company was already waiting for them) only at the end of the Devonian period.
These animals resembled fish with clumsy short legs and still spent most of their time in the water. But on the shore they turned out to be invincible predators and could literally afford to eat everything that moves.
Among them was Tiktaalik ( Tiktaalik rosea ), which gained great popularity due to its expressive appearance and funny name.
It is considered a transitional form from lobe-finned fish to four-legged vertebrates, which later conquered the entire land. Therefore, Tiktaalik and others like him are sometimes called fishapods – literally “fish legs”.
Yet the emergence of terrestrial vertebrates is still poorly understood, so that paleontologists continue to understand the ancestry of their primitive similarities.
Recently, a more thorough study of a previously found specimen (largely due to forced downtime during the pandemic) has made it possible to describe a new species from this group, Qikiqtania wakei.
The authors of the discovery (and at the same time a new article in Nature ) were Neil Shubin (Niel Shubin) and colleagues – almost 20 years ago, it was he who described Tiktaalik itself.
At first, the find was considered another representative of this species, namely, its immature individual. The researchers were busy doing routine CT scans of the “young Tiktaalik” when their lab was quarantined in the spring of 2020.
The interrupted scientists returned to the sample only in the summer, realizing that they should first remove some of the rock from it. This allowed us to get a better image and eventually open up a new view.
Kikiktania was three times smaller than Tiktaalik – only 75 centimeters versus 250 centimeters or more. But much more important was the lack of important devices for moving on land.
“The humerus is smooth and has the shape of a boomerang, and is also devoid of the parts necessary for repulsion from the ground (we are talking about outgrowths for attaching muscles. – Approx. ed.) This is something wonderful and unusual, which we have not yet encountered, ” Shubin explained .
In addition, the kickiktania had pectoral fins, which, together with the device of the forelimbs, makes it clear that we have a good swimmer in front of us, but he has nothing to do on the shore.
An unexpected discovery completed the picture of the evolution of the first terrestrial vertebrates. It turns out that not all “fishlegs” who had grown limbs immediately rushed to explore the land – some preferred the familiar and well-known aquatic environment to it.
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