In the footsteps of the unicorn
The DNA of the "Siberian unicorn" told when and why it became extinct
Yulia Vorobyova, Vesti
Illustration by DiBgd/Wikimedia Commons.
The modern rhinoceros family has only five species, but in the past, at various evolutionary stages, it included up to 250 species. And one of the most mysterious for paleontologists is still the ancient rhinoceros Elasmotherium sibiricum, also known as the "Siberian unicorn".
It was believed that these amazing animals disappeared from 200 to 100 thousand years ago, but in recent years, researchers have found more and more evidence that in fact the "Siberian unicorn" was in no hurry to die out. Experts even suggest that representatives of this species caught ancient people.
In the course of the new work, an international team of researchers clarified not only the time of extinction of an unusual species, but also the causes of this sad process, and also deciphered the DNA of the "Siberian unicorn".
Paleontologists explain that E.sibiricum rhinos lived in the Eurasian steppes, that is, on the territory of modern Siberia, Kazakhstan, Mongolia, and Northern China. The animals weighed about 3.5 tons and were twice the size of modern rhinos.
The weight category of this species allows it to be attributed to representatives of megafauna. This group also includes mammoths, giant sloths, saber-toothed cats. The disappearance of all these creatures was one of the landmark events of the last glacial epoch.
"This "megafauna extermination event" ended about 40 thousand years ago. For this reason, the extinction of E.sibiricum, [which happened] 100 thousand years ago, was not considered part of this event," says Professor Adrian Lister from the Natural History Museum of Great Britain.
However, the new findings forced paleontologists to reconsider the established ideas. Over the past few years, 23 well-preserved specimens have been found, including the skull of the "Siberian unicorn". According to Lister, the age of the remains is about 39 thousand years, and in some cases, presumably, about 35 thousand years.
Photo by Igor Doronin/Kosintsev et al., 2018
The new findings allowed experts to collect more data about ancient creatures. Paleontologists believe that, despite their large size and outstanding shoulder hump, "Siberian unicorns" were able to develop great speed while running.
Judging by the anatomical characteristics, ancient rhinos lived on open grassy plains and, accordingly, fed mainly on grass. Their teeth look adapted for this kind of "grazing," Professor Lister explained.
After studying the isotopic signature of dental tissues, the team confirmed this. The researchers clarified that the "Siberian unicorns" preferred, apparently, hard and dry grass.
But the opinion about the behavioral features of the E.sibiricum species can be formed only by its descendants, scientists admit. Modern rhinos, as a rule, live alone and disperse throughout their range. Given that the habitat of the ancient species was relatively limited, it is likely that the populations of Siberian rhinos were very small.
Actually, this factor, along with the shortage of resources that arose due to climate change, seems to be the most likely cause of the rather rapid extinction of E.sibiricum.
The researchers note that it is unlikely that ancient people had anything to do with the disappearance of these creatures. Firstly, some of them, in particular, Neanderthals, were themselves "busy with extinction". Secondly, too many animal species have disappeared in a relatively short period of time to associate this with human activity. Thirdly, no archaeological evidence of Siberian rhinoceros hunting has been found.
Another important part of the work was to decipher the DNA of the "Siberian unicorn". This was done by specialists from the University of Adelaide in Australia. By the way, scientists managed to extract the DNA of this species from fossilized remains for the first time.
The new data helped to determine the exact place of E. sibiricum on the rhino family tree and to understand its kinship with other species.
As it turned out, the "split" into ancient and modern groups occurred about 43 million years ago. Co-author of the work, evolutionary biologist Kieren Mitchell, noted in a press release that the "Siberian unicorn" and the modern African white rhinoceros are even more distant relatives than humans and monkeys.
Moreover, it turned out that the Siberian rhinoceros was the last species from a very peculiar and very ancient line.
More about this work is described in an article published in the journal Nature Ecology & Evolution (Kosintsev et al., Evolution and extinction of the giant rhinoceros Elasmotherium sibiricum sheds light on late Quaternary megafaunal extinctions).
By the way, due to the growing problem of poaching today, rhinos are threatened with complete extinction. The rescue of one of the species – the northern white rhinoceros – was previously described in detail. There are only two infertile females of these animals left in the world, but experts still do not lose hope and rely on the latest reproductive technologies.
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