Russian scientists believe two ancient lion cubs dug from the Siberian permafrost are likely to show traces of the world's oldest mother's milk.
Frozen for at least 12,000 years, they have "reason to believe" the carcasses of the extinct predators contain breast milk dating back to prehistoric times.
An autopsy on one of the infant big cats will take place in the city of Yakutsk later this year with the "hope" of confirming the sensational discovery.
The cubs were originally found in November, 2015.
"Experts do not want to draw premature conclusions but they have 'reason to believe' that the well-preserved innards of two cave lion cubs - one of which will be subjected to an autopsy, the other preserved for future study - contains an opaque white fluid that will prove to be from an extinct lactating lioness," reported The Siberian Times.
The other cub will be kept in the hope that future scientific advances will allow experts to understand more about a species that was once present on the Eurasian land mass from the UK to the extreme east of Russia.
The cubs were dug last year from their icy grave "complete with all their body parts: fur, ears, soft tissue and even whiskers", said Dr Albert Protopopov, head of the mammoth fauna studies department of the Yakutian Academy of Sciences.
It was recently reported that South Korean cloning guru Hwang Woo-suk took samples from the cub that will be subjected to the autopsy.
He is also hoping to clone the extinct woolly mammoth.
Skin and muscle tissue was extracted from the ancient creature's remains, aiming to find living cells, which could trigger research aiming to bring the extinct cave lions back to life.
A sudden summer rise - then fall - in the level of the Uyandina River led to cracks appearing and local worker Yakov Androsov spotted an ice lens with the lion cubs inside.
Dr Protopopov said last year when he unveiled the animals to the media: "Comparing with modern lion cubs, we think that these two were very small, maybe a week or two old.
"The eyes were not quite open, they have baby teeth and not all had appeared."
He thinks they may have perished after the lioness hid her cubs in a cave to protect them from hungry lions.
Cave lions - Panthera spelaea (Goldfuss) - lived during Middle and Late Pleistocene times on the Eurasian continent, from the British Isles to Chukotka in the extreme east of Russia, and they also roamed Alaska and northwestern Canada.
Research on the two cubs could help to explain why the species died out, since the animal had few predators, was smaller than herbivores, and was not prone to getting bogged down in swamps, as did woolly mammoths and rhinos.