Dalen said the cubs were initially thought to be siblings, but further analysis revealed the better preserved of the cubs, dubbed Sparta by researchers, is about 28,000 years old, while the other cub, named Boris, was determined to be 43,448 years old using radio carbon dating.
"Sparta is probably the best preserved Ice Age animal ever found, and is more or less undamaged apart from the fur being a bit ruffled. She even had the whiskers preserved. Boris is a bit more damaged, but still pretty good," Dalen said in a news release from Stockholm University.
Dalen's team, who published their research in the journal Quaternary, determined the cubs were each about 1 to 2 two months old when they died. They said there were no signs of them being killed by predators.
"Given their preservation they must have been buried very quickly. So maybe they died in a mudslide, or fell into a crack in the permafrost," Dalen said. "Permafrost forms large cracks due to seasonal thawing and freezing."
The researchers said the cubs had similar, but not identical, coats to African lion cubs. The team suggested the long thick fur undercoat of the cave lions may have been an adaptation spurred by the cold climate.
Dalen said her team is aiming to sequence Sparta's DNA to reveal the evolutionary history of the cave lion.