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Monstrous rhino ‘unicorn’ species survived for longer than previously thought.
What’s four metres long, 2.5 metres high, weighs 3.5 tonnes and has a preposterously large horn in the middle of its face? A really massive unicorn, that’s what.
So unicorns really existed?
Dubbed the ‘Siberian unicorn’, details of the life, history and extinction of a spectacular species of an extinct member of the rhinoceros family, Elasmotherium sibiricum, were uncovered in 2018 by Adrian Lister of London’s Natural History Museum, Pavel Kosintsev of the Russian Academy of Sciences and a team of researchers.
E. sibiricum is known as the Siberian unicorn because of its unusually large horn. It was the largest rhinoceros of the Quaternary period – which ran from roughly 2.5 million to 12 thousand years ago.
Despite its huge size it was lithe and seemed adapted to running across its homelands of central Asia: Kazakhstan, western and central Russia, Ukraine, Azerbaijan and Uzbekistan, and possible areas of Mongolia and China.
When did the Siberian unicorn live?
DNA analyses of collagen extracted from the bones of a fossil showed that the Siberian Unicorn belonged to a sister taxon to Rhinocerotinae, the group to which all modern rhinoceros belong. The two were thought to have split about thirty-five million years ago, but may even have been as late as forty-seven million years ago.
The unicorn might not be very old at all, and might have still been kicking until 39,000 years ago. This places its extinction ‘firmly within the late Quaternary extinction event’, between 50,000 and four thousand years ago, in which nearly half of Eurasian mammalian megafauna died out. Interestingly, this adds to the evidence of the decline of megafauna just before the ice sheets of the last ice age reached their maximum extension.
And this might help us to understand the reasons for the unicorn’s demise.
The shape of, and the isotopes within, the remains of E. sibiricum suggest that it found its home in herb- and grass-covered steppes, with an extreme adaptation for feeding close to the ground. Perhaps it dug up vegetation up to consume it roots and all.
However, starting about 35 thousand years ago, as the deep cold extended further south, the steppe became more like tundra, denying the unicorn its primary food source, and this was perhaps a decisive factor in its extinction.
The researchers also speculated that humans might have had something to do with it, although they acknowledge a dearth of supporting evidence.
‘The extinction of E. sibiricum,’ they write, ‘could in theory have been exacerbated by human hunting pressure, given the replacement of H. neanderthalensis by H. sapiens in Eurasia around 45–40 [thousand years ago]’.
Stephen Fleischfresser is a lecturer at the University of Melbourne’s Trinity College and holds a PhD in the History and Philosophy of Science.