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Weighing up to 7,700 pounds, Elasmotherium sibiricum– an extinct hairy rhinoceros known as the "Siberian unicorn" – would have disappeared 200 000 years ago. An updated fossil record suggests that this formidable species still existed about 39,000 years ago and that the ice age conditions, not the human hunters, contributed to its demise.
Paleontologists know about 250 species of rhinoceros, only five of which still exist today. Among the most spectacular of these rhinos was Elasmotherium sibiricum– the Siberian unicorn. For the Neanderthals and the modern humans who lived next door to this huge creature from Eastern Europe and Central Asia and perhaps hunted it, this show must have been impressive and deeply intimidating. Fossil evidence suggests Elasmotherium weighed more than 3.5 tons, was covered with a thick layer of hair and sported a horn of biblical portions, up to 1 meter long.
As impressive as it may be, Siberian unicorns have finally disappeared. Previous fossil dating suggested an expiration date between 200,000 and 100,000 years ago, well before the large-scale extinction of the Late Quaternary megafauna, which began about 40,000 years ago. A new study published this week in Nature Ecology & Evolution now offers a more reliable estimate, dating from the disappearance of Elasmotherium at one point between 39,000 and 35,000 years. The extinction of Siberian unicorns can henceforth be linked to the megafauna extinction of the Quaternary, event that saw the end of the woolly mammoth, Irish elk and saber-toothed cat.
In their new study, led by Adrian Lister of the Natural History Museum in London, the researchers said: "No absolute dating, genetic analysis or quantitative ecological assessment of this species. [had] companies', which explains why the estimate of prior extinguishing was so remote. The new study addresses these gaps and includes the use of up-to-date fossil dating techniques.
For the study, an international team of researchers from the United Kingdom, the Netherlands and Russia closely examined 23 Elasmotherium specimens, including a virgin skull preserved at the Museum of Natural History. An improved radiocarbon dating technique has led to the revision of extinction dates; many samples were covered with preservation materials, which required careful preparation for carbon dating.
"Some of the samples we studied were very contaminated, which made radiocarbon dating difficult," said Thibaut Devièse, a researcher at Oxford School of Archeology and co-author of the study. "For this reason, we have used a new method of extracting a single amino acid collagen from the bone to ensure extremely accurate results."
In addition, the researchers were able, for the first time, to extract the DNA from the database. Elasmotherium fossils. The ensuing genetic analysis showed that Siberian unicorns were separating from modern rhinos about 43 million years ago, "settling a debate based on fossil evidence and confirming that the two lineages had diverged from each other. the Eocene, "wrote the researchers. These rhinos are the latest species of a "very distinct and ancient lineage", according to research.
Siberian unicorns cohabited with anatomically modern humans and Neanderthals. The fact that some old hominids might have been feeding on these oversized rhinos is not as outrageous as it sounds. The first humans, probably a form of Homo erectus, hunted rhinos in the Philippines about 700,000 years ago. But while rhinoceroses were on the menu of hominids, this new research suggests that climate change, not hunters, was responsible for ElasmotheriumDisappearance.
As we now know from new research, these rhinos lived in the ice age just prior to the last glacial maximum, the stage when ice sheets covered their largest area about 26,500 years ago. The Earth has been subject to dramatic climatic changes during this period, causing drought, desertification, falling sea levels and constant encroachment of glaciers. These climatic disturbances have been fatal to many species, Elasmotherium among them.
For the Siberian unicorn, this meant a loss of habitat and, therefore, the disappearance of an essential food source, as the new study assumes. In experiments, Lister and his colleagues analyzed the stable isotope ratios of fossilized rhinoceros teeth. The researchers sought to establish a link between various plants and the levels of carbon and nitrogen isotopes in their teeth. This analysis revealed that Siberian unicorns lived in an arid steppe environment where they nibbled hard, dry grasses. Rhinos, with their highly specialized lifestyle in pasture and their naturally low population, have not been able to adapt quickly enough to rapidly changing conditions, the study says.
A changing climate, not human beings, was therefore responsible for the disappearance of E. sibiricum. Interestingly, this is a conclusion that is consistent with similar but unrelated research in which scientists claim that humans were not responsible for many megafaunal extinctions of the ice age. Unfortunately, the same can not be said of the current sixth mass extinction, which is certainly our fault.
[Nature Ecology & Evolution]
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