With a huge horn rising several feet from the top of their skulls, it is easy to see how their fossilised remains could have been mistaken for the skeletons of the now mythical unicorns.

But it seems a giant species of rhinoceros, thought to have died out in Siberia 350,000 years ago may have actually clung on long enough to really enter into human legend.

Scientists claim to have discovered evidence the giant Elasmotherium sibiricum, or Siberian Unicorn as it is known locally, may have survived in part of Kazakhstan until 26,000 years ago.

The Siberian rhinoceros, Elasmotherium sibiricum (artist's impression pictured), is nicknamed the Siberian Unicorn due to the huge horn it is thought to have had on its head. Scientists previously thought it died out 350,000 years ago, but a new discovery suggests they survived in some areas until 26,000 years ago

This last refuge in south western Siberia could have allowed the strange creatures, which would have grown to the size of mammoths weighing up to five tons, to have encountered humans.

Early humans began spreading across Asia more than 50,000 years ago and probably moved into Siberia at least 35,000 years ago.

CURSE OF THE LAST SURVIVORS The last Siberian rhinos that managed to cling on in Kazakhstan for more than 320,000 years after the rest of its species are thought to have died out, were not the only survivors from the ice age to have outlived their relatives. Scientists have discovered evidence that woolly mammoths, though to have been wiped out by a combination of human hunting and climate change around 12,000 years ago, clung on for thousands of years on a remote Arctic Island. Mammoth bones have been discovered on Wrangle Island, off the north coast of Russia, that are just 5,000 years old. It suggests the animals were able to live here, cut off from the rest of the world for longer than the rest of their species. However, this had a devastating impact on their genetic make up as their population became increasingly inbred. This left them less able to adapt and caused their numbers to dwindle further until they eventually disappeared. Advertisement

Dr Andrei Shpanski, a palaeontologist at the Tomsk State University, who led the new research, said: 'Most likely, the south of Western Siberia was a refúgium, where this rhino persevered the longest in comparison with the rest of its range.

'There is another possibility that it could migrate and dwell for a while in the more southern areas.'

The researchers discovered fragments of the giant Siberian rhinoceros skull near the village of Kozhamazhar in the Pavlodar Priirtysh region of north east Kazakhstan.

It was discovered alongside the remains of prehistoric bioson and mammoth remains.

While Elasmotherium sibircum is thought to have spread widely across Siberia after it emerged around 2.6 million years ago, evidence suggests the majority of the species died out 350,000 years ago.

Its habitat was the vast territory from the Don River close to Voronezh in Russia, to the east of modern Kazakhstan.

Fossilislied remains suggest it would have reached around 15ft long (4.6 metres) and stood over 6ft tall (2 metres), making it one of the largest species of rhino to have ever lived.

It was certainly much larger than the woolly rhinos thought to have lived at around the same time.

Although no horns from the animals have been found, studies of the skulls show a bony lump that is thought to have supported a keratin horn much like those seen on modern rhinos in Africa.

The researchers analysed the skull fragments of a Siberian rhinoceros, Elasmotherium sibircum, found in the Pavlodar Priirtysh region Kazakhstan. Carbon dating revealed the fossil was just a little over 26,000 years old, meaning the animal had outlived others of its species by more than 320,000 years

Researchers discovered the fossils alongside those of other prehistoric mammals including bison and mammoths close to the village of Kozhamazhar in Pavlodar Priirtysh, north east Kazakhstan (pictured)

However, rather than sitting on the snout of the animal, the horn was positioned further back on top of its head.

Although no horns have been found for Elasmotherium sibircum, scientists have inferred they had them from skulls (horn reconstruction pictured at the Natural History Museum London)

Research on the skulls have suggested the horns could have grown to have a circumference of more than three feet and would have been several feet long.

Early palaeontologists who first put forward the idea that it had a horn also described how they had heard stories among the Tatars of Siberia about a unicorn with a horn so large it needed a sledge to transport it.

It is thought the animals may have used these enormous horns to drive away competitors and even sweeping snow from the grass in winter.

It also had long legs, which would have allowed the animal to gallop much like a horse rather than the lumbering trot seen in modern rhinos.

Using radio carbon dating Dr Shpanski and his colleagues, whose findings are published in the American Journal of Applied Science, used radio carbon dating to examine the skull fragments they discovered in Kazakhstan.

They discovered it was between 26,038 years old - making it remarkably young.

The skull was well preserved and while it bore some cracks, it showed no sign of gnawing of abrasion.

Dr Shpanski said: 'Most likely, it was a very large male of very large individual age.

'The dimensions of this rhino are the biggest of those described in the literature, and the proportions are typical.'

He added that it is likely that as the climate in Siberia changed, causing many Elasmotherium sibircum to die out, local conditions in Kazakhstan may have allowed them to survive.

It is not the first time scientists have discovered a last refuge of a giant ice age species thought to have died out long ago.

Woolly mammoths, which are widely thought to have died out 12,000 years ago may have survived until around 4,500 years ago on Wrangle Island in the Arctic Ocean north of Russia.

Dr Shpanski said: 'Our research makes adjustments in the understanding of the environmental conditions in the geologic time in general.

'Understanding of the past allows us to make more accurate predictions about natural processes in the near future - it also concerns climate change.'

The unicorn is a mythical being but some suggest there may have been extinct creatures that resembled the animal (illustrated). It is now thought to have been based on Elasmotherium