Uyan and Dina were clearly very young when they died. The pair of baby cave lions, entombed in ice at least 30,000 years ago in Yakutia, Russia, are preserved well enough to see that their eyes hadn't opened yet and their baby teeth hadn't begun to grow in. Staring into their tiny frozen faces, it's hard not to feel fascinated and sympathetic at the same time.

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Image: Vera Salnitskaya/Siberian Times

Scientists have been hard at work studying these cubs since their unveiling in 2015, and each examination brings new insights, including one of the latest announcements: these cubs might have been even younger – and their story more tragic – than researchers first suspected.

Recently, Japanese scientists scanned the ancient remains to look at the animals' stomachs, hoping to find clues to their diet. (Similar tests performed on another frozen baby, Lyuba the mammoth, have managed to reveal that her stomach contained her mom's milk and faeces.) The Japanese team, however, didn't find what they were looking for, according to Albert Protopopov of the Academy of Sciences of the Republic of Sakha (Yakutia).

"When the Japanese [researchers] performed a tomography scan, it became clear that [the cubs'] stomachs were empty," he told the The Siberian Times. "They did not even have time to try their mother's milk."

Based on their size and undeveloped features in comparison with modern-day African lions (the cave lion's closest living cousins), researchers originally estimated the cubs were one or two weeks old at the time of their death. But their hollow bellies now have Protopopov and colleagues wondering if they were perhaps much younger, maybe only one or two days old.

The cubs are thought to have died when their den collapsed, based in part on their crushed features and the soil trapped inside their digestive tracts. The possibility that they hadn't eaten raises the question of what happened to mom. Did she die before being able to care for her cubs? Had she simply left?

Answering questions about ancient animals is always a challenge because we often have only sparse clues to go on, but a new piece of the cave-lion story came along earlier this year: the discovery of another frozen baby cat from the same region, this one even more finely preserved than Uyan and Dina. The cub might help to shed more light on the lives (and deaths) of Ice Age cave lions ... unless it turns out to be a different cat altogether!

The newly discovered cave lion was found back in September, and its remains unveiled early last month.

Preserved baby animals don't always look quite like their parents, so deciphering their identities can be tricky. Although the newest kitty, unearthed with hair tousled and head resting on its paw, was originally announced as another cave lion, closer study of its body has researchers suspecting that it might be a different cat: a lynx.

The only other known lynx fossil from the region called Beringia – the vast area surrounding the ancient connection between North America and Asia – is just a single bone, so the newly unveiled remains represent an exciting possibility. "[T]he find of the complete mummy of this species would be very surprising and interesting," Olga Potapova of the Mammoth Site in Hot Springs, South Dakota told Live Science.

Based on the original identification of cave lion, researchers estimated that the animal was just one to two months old at the time of death. If the lynx hunch proves correct, however, it could push its age up to six months.

One thing the researchers definitely agree on is that the new cub has great hair. "The hide of the new mummy is just beautiful," Potapova said. "It has predominantly grey colouration flecked by black guard hairs. The hair on the head has many black spots."

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A replica of the cave-lion paintings from the Chauvet Cave in southern France. Prehistoric art like this tells us that male cave lions probably didn't have manes. Image: Claude Valette, Flickr

That "thick and beautiful" hair, Protopopov notes, offers a very rare opportunity for scientists to understand the colour of these prehistoric felines. We've learned quite a bit about the appearance of ancient animals from cave drawings made by their human neighbours – this is how, for example, we know that cave lions had no manes. But such paintings don't hold clues to colour. "Ancient people drew with ochre, so they could not reliably display shades [and] colours," Protopopov explained.

Many of the outstanding questions about these cats' lives and identities will certainly be resolved by examining that other exciting evidence that frozen bodies hold: DNA.

Although it's tempting here to jump straight to the idea of cloning extinct species (something that is currently not possible, and might never be), the much more informative use of such DNA is to help us tease out ancient relationships: genetic studies of cave lions recently revealed their close kinship to modern African lions, for example. And in the case of this latest frozen mystery, such genetic research could easily allow experts to distinguish a cave lion from a lynx.