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According to a study published today in Nature Ecology & Evolution, a mysterious species of giant rhinoceros, called the Siberian unicorn because of its huge single horn, has survived in the west of Russia up to only 36,000 years ago. This date of extinction means that the last days of the Siberian unicorn were shared with the early modern humans and the Neanderthals.
Previously, we knew little about the creature that would have disappeared for more than 200 000 years. But genetic badysis and radiocarbon dating have begun to reveal many aspects of its way of life and its extinction.
A key finding is that the Siberian unicorn did not go extinct because of modern hunting, or even the peak of the last ice age that began about 25,000 years ago.
Instead, he succumbed to a more subtle climate change that has reduced grazing from Eastern Europe to China.
Our new findings show that the Siberian unicorn was dependent on these grbadlands and, unlike other species in the region such as the saiga antelope, was not able to adapt to the change.
The "Siberian unicorn"
The Siberian unicorn (Elasmotherium) had a single large horn, estimated to be one meter long. It was one of the many rhinoceros species that existed in the past.
In addition to the extinct woolly rhinoceros (which are still found as frozen mummies), there are five species of live rhinoceros. All these creatures now have problems, including the white rhinoceros (almost threatened), the Java rhinoceros (critically endangered) and the Sumatran rhinoceros (critically endangered).
The loss of the Siberian unicorn provides a valuable case study showing the low resilience of rhinos to environmental changes.
The animal we worked on was found in modern Russia, but its range also extends to areas that now include Kazakhstan, Mongolia and northern China, where he lives. a steppe-like habitat, dominated by grbades and herbs.
The Siberian unicorn shared this environment with the saiga antelope and other species of the Ice Age, notably the woolly rhinoceros and the mammoth.
But most evidence to date suggests that the Siberian unicorn went extinct 200,000 years ago, while the woolly rhinoceros and the mammoth died about 13,000 and 4,000 years ago, respectively.
So why did the Siberian unicorn get extinct while other species that lived in the same habitat have survived for thousands of years or, like the saiga, still survive today? ; hui?
An adult saiga antelope flees after being released in the Sharga Nature Reserve in Mongolia in 2006.
Gun
Some unconfirmed evidence has recently suggested that the Siberian unicorn has survived until today closer to the present, much like the woolly rhinoceros. So we studied 23 animal bone samples kept in museum collections in Russia and the United Kingdom.
Instead of 200,000 years, a new dating revealed that the Siberian unicorn was actually extinct just 36,000 years ago.
We then examined how it could have been extinguished at this point.
Climate change seems to be a likely candidate – but 36,000 years ago, well before the climax of the Ice Age, which occurred 20,000 to 25,000 years ago.
But this date corresponds to the moment of a pronounced shift to cooler summers in Northern Europe and Asia. This seasonal change has reduced the density of grbades and grbades and increased the number of tundra plant species such as mosses and lichens.
A vulnerable specialist
So, why did a climate change 36,000 years ago extinguish the Siberian unicorn, but not the woolly rhinoceros or the saiga?
To answer this question, our study was inspired by fossil bones of the unicorn, woolly rhinoceros and Siberian saiga and examined the nitrogen and carbon they contain – differences in these elements reflect the diet. food of an animal.
We found that before 36,000 years ago, the Siberian saiga and unicorn behaved the same way, feeding almost exclusively on grbad. After that moment, carbon and nitrogen in the saiga bones showed a major dietary change towards other types of plants.
But going from a grbad-based diet has proved too difficult for the Siberian unicorn, with its specially folded and wear-resistant teeth and its low head in height, at the same time. height of the grbad. Family members such as the woolly rhinoceros have always eaten a more balanced range of plants and are far less affected by a change in habitat.
It is important to note that the climate change that led to the extinction of the Siberian unicorn was actually much less pronounced than that of the ice age that followed. Or the changes we will face in the near future.
The story of the Siberian unicorn reminds us that even subtle changes in plant distribution can have devastating effects on large animal species.
It is disturbing to note that this poses a serious risk to many animals, such as the surviving cousins of the Siberian unicorn, which, thanks to humans, already have a very restricted range.
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