An international group of scientists is studying two well-preserved cave lion cubs found in Siberian permafrost.

Love Dalen, a professor at the Centre for Palaeogenetics in Stockholm and one of the authors of a study on the cubs, has described one of them, a female lion nicknamed Sparta, as "probably the best preserved Ice Age animal ever found," according to Reuters.

The second cub, known as Boris, was found on the same river in the Siberian region of Yakutia in 2017. He is a bit more damaged, but in a pretty good condition, too, Dalen said.

Sparta was discovered in 2018 and she is about 27,962 years old, according to the study published in the Quaternary research journal.

Boris is believed to have been a cub 43,000 years ago – both of the animals were not older than two months when they died, another author of the study, Valeri Plotnikov, told Reuters.

Such findings are "unique," Plotnikov said.

But the melting of the permafrost in Siberia exposes more and more of ancient soil formed during the last ice age, when large herbivores such as mammoths and bison roamed Siberia's huge landmass.