The specimen was carbon dated and found to be 18,000 years old, but looks and feels like a “very recently dead animal”.
Researchers in Stockholm found the puppy in summer 2018 in a remote part of northeast Siberia, about two hours from the nearest town of Belaya Gora.
The male puppy appears to have been just two months old when it died, and lay undisturbed in permafrost until last year, reported the Siberian Times.
The specimen remains in Russia, but researchers Love Dalen and Dace Stanton, 34, brought its rib back to Sweden to study.
Dalen, a professor of evolutionary genetics, said: “I had assumed that what we’d find was that this was a wolf. But we recently got our first round of results on the genome and we can’t say if it’s a dog or a wolf. We should be able to – it should be easy.
“So this could be a very early modern wolf or very early dog, or a late Pleistocene (Ice Age) wolf,” he added. “If it turns out to be a dog I would say it is the earliest confirmed dog.”
Samples from the puppy were sent to the Swedish Centre for Palaeogenetics, which has the largest DNA bank of canines from around the world, but they were still not able to determine its species.
The puppy, affectionately named Drogo, has milk teeth, thick fur, claws, and even eyelashes intact.
The only sign of significant decomposition was a part of the spine that had been exposed, baring its ribs.
Further analysis and genome sequencing will be carried out to find out where to place Drogo on the canine evolutionary scale.