Scientists have discovered the remains of a monster flying squirrel with a 5ft wingspan in their latest excavation.
Relics of the giant rodent were found in the caves located in the Land of the Leopard National Park near Vladivostok in east Russia.
Experts analysed the 30,000-year-old remains including the teeth and bones from the squirrel's upper jaw and believed the animal could glide around 170ft (51 metres).
Professor Mikhail Tiunov, of the Russian Far Eastern Institute of Biology and Soil Science, said the extinct animal is a previously unknown species.
He said: "Despite the significant amount of paleontological research in neighbouring China, their specialists did not discover bone remains of this giant flying squirrel species.
"It means that either it just has not been found there yet, or that it didn't live there."
More remnants of the monster squirrel were located inside the Tetyukhinskaya cave in the north of Primorsky region.
Modern day flying squirrels tend to live in isolated and unconnected areas and the same may have been true in prehistoric times, he surmised.
"Perhaps this is exactly how they lived in the past, and that the habitat of this particular species was limited by the territory of modern Primorsky region." he was quoted as saying in The Siberian Times .
"Just like modern-day giant flying squirrels, their newly-discovered relatives fed on insects, fruit and leaves, even though their bone structure was quite different.
A scientific report in the new discovery was published in the Palaeoworld journal.
By contrast the modern-day Japanese giant flying squirrel which measures two feet from the top of its head to the tip of its tail, has a wingspan of just over 18 inches and weighs up to five pounds.
