'The latest lion cub is unique in that it has a completely preserved hairline.' Picture: The Siberian Times

Scientists have revealed the shocking truth about the two cubs Uyan and Dina found in Yakutia in 2015 which could be used in a Jurassic Park-style experiment to revive the lost species.

Research on the unique sibling pair has been conducted in Japan, the US and Germany, said Dr Albert Protopopov, head of the department for the study of mammoth fauna, Academy of Sciences of the Republic of Sakha (Yakutia).

Hopes had been high that the little lions, members of a species that were once the largest big cats on the planet, had traces of mother's milk in their well preserved stomachs.

But it is now established that the tiny animals, pictured here, died before getting the opportunity to feed from their mother.

It is now established that the tiny animals, pictured here, died before getting the opportunity to feed from their mother. Picture: The Siberian Times

It raises the possibility that they were abandoned at birth in Pleistocene times. Or that the cubs perished because their mother died.

Another possibility is that the prehistoric kittens were buried perhaps in a landslide. Certainly, specks of soil have been found in their food tracts, Dr Protopopov.

'We examined and measured the lions, recently conducting tomographic studies.

'At first we thought that they were two or three weeks old, but now we are inclined to think that they are only one or two days old - they died soon after birth.

'When the Japanese performed a tomography scan, it became clear that their stomachs were empty. They did not even have time to try their mother's milk.

Dr Albert Protopopov, head of the department for the study of mammoth fauna, Academy of Sciences of the Republic of Sakha (Yakutia). Picture: The Siberian Times

'Most likely they were buried by soil, as there are soil particles in their food tract.'

Another older cub, found this year and revealed to the world last month, shows another intriguing truth about this extinct species.

This cub died at the age of between one and two months old up to 50,000 years ago on the bank of Tirekhtykh River, in the Abyisky district of Yakutia.

Analysis is only now beginning on it, but the cub's colouring indicates that the species - known until these discoveries only by skeletons was an unexpected colour compared with modern-day big cats.

'The latest lion cub is unique in that it has a completely preserved hairline,' he said.

'And if the kittens found two years ago were covered in a cub fluff two years ago, this new one has a thick and beautiful hair, and there are spinous hairs.

Excited scientists unveiled the discovery - its facial features clearly visible - in Yakutsk today. Picture: Anastasiya Koryakina

'We will finally be able to find out what the cave lions really looked like. This opportunity was not previously available, because we found only skeletal remains.'

And their colour?

'Most likely they were smoky grey. Previously, scientists judged the look of the lions from the drawings ancient man left in caves.'

Indeed, this gave rise to a misnomer about this species, whose bones were also found in caves. In fact, the animals lived in the open spaces of Eurasia.

'Ancient people drew with ocher, so they could not reliably display shades, colours. And it is interesting that there is not a single drawing on which the cave lion would be depicted with a mane.'

Earlier examination of Uyan and Dina indicates that they had shorter tails than modern lions.

Another intriguing fact about the cave lions is that they appear to have much in common with tigers as well as lions.

Panel of the Lions in Chauvet Cave. Picture: John Robinson

'Some scientists believe that morphologically cave lions are close not only to modern African lions, but also tigers,' he said. 'This opinion, for example, was held by the Soviet paleontologist Nikolai Vereshchagin.

'He called them 'tigerlions'.'

Cave lions - Panthera spelaea (Goldfuss) - lived during Middle and Late Pleistocene times from Britain to the Chukotka in the extreme east of Russia.

They also roamed Alaska and northwestern Canada. Scientists have predicted that the carcass finds will assist in reviving the extinct species in future.