The scientists have moved it back to their laboratory without cleaning it to ensure there is no deterioration before it is properly examined. Picture: Sergey Fyodorov/NEFU

Scientists may also have discovered telltale signs of human activity in the same remote site as they seek to research the theory that these canines were tamed by ancient man.

The latest pre-historic 'puppy carcass', caked in mud, is entirely intact, said Sergei Fedorov, head of exhibitions at the Mammoth Museum in Yakutsk, who led the field trip to this dog necropolis in the Ust-Yansky district of the Sakha Republic - also known as Yakutia - on a steep bank of River Syalakh. Its owners might have been woolly mammoth hunters, it is believed.

'The condition of our new find is perfect,' he said. 'It is preserved from nose to tail, including the hair. You can see the hair on the paw on the picture.' The scientists have moved it back to their laboratory without cleaning it to ensure there is no deterioration before it is properly examined.

Four years ago, at the same spot, brothers Yury and Igor Gorokhov along with friend Aiaal Tomsky - all mammoth bone hunters - found the first ancient puppies, believed to be a three month old female, its bones, heart, lungs and stomach intact. Both puppies were sealed in the permafrost which led to them being mummified. They died in a landslide close to the river, it is thought.

Scientists came back here this summer in search of evidence of ancient human activity, but found an unexpected bonus. 'The find of the new remains was pure luck,' said research fellow Fedorov. 'We had no inkling we would get it. But having worked there for a full hour, at the beginning of the second hour, some two metres away from the first find, and down the rock, we saw the front paws and the head.'

The second puppy was found on the steep bank of River Syalakh in the Ust-Yana region of Yakutia, also known as the Sakha Republic. Pictures: Google maps, Sergey Fyodorov/NEFU

The surface layer had slipped in the past four years and it is likely the permafrost tomb of the second puppy was in exactly the same place as the first. This means it is likely the second puppy was a relative, even a sibling, of the first. 'The body of the puppy was found on 13 August not far from Tumat village during our expedition,' he said.

The aim of this summer's expedition 'was to search for the traces of human activity there, to seek evidence that the first puppy was a dog tamed by ancient people.' In other words, to find evidence of the owners of what is known as Tumat Dog.

'We invited the archaeologist Alexander Kandyba, from the Institute of Archeology and Ethnography, at the Siberian Branch of the Russian Academy of Sciences, to take part in our expedition. He obtained some tools made of bone, and the bones of animal with traces of butchering and of fire.'

It is too early to confirm that this links the puppies to the humans, showing these as 12,400 year old pets. 'Alexander needs to study the finds thoroughly to be sure that the bones have traces left by human activity,' he said.

On the 'new' puppy, he said: 'We decided to take the carcass (back to Yakutsk) encased in soil, not cleaning it, in one piece. It will help to save the environment of the remains for further research. We plan to study microorganisms in the soil that covers the carcass. Some parasites might be preserved, which will also give us useful information.'

'It is preserved from nose to tail, including the hair. You can see the hair on the paw on the picture.' Pictures: Sergey Fyodorov/NEFU

Further work will be undertaken on the puppies in October in joint research with scientists from Belgium. 'We plan to finish the 'post-mortem' of the first puppy, found in 2011, to dissect its stomach, and conduct the 'post-mortem' of our new find.'

DNA tests on the first puppy showed it to be a dog, rather than a wolf, but the Russian scientists plan more work to confirm this since the genetic make-up of these ancient animals is very similar.

In August 2014, Dr Mietje Germonpre, from the palaeontology department of the Royal Belgian Institute of Natural Sciences, travelled to Yakutsk to see the remains of the first puppy.

She told Yakutsk Vecherny at the time: 'After studying the mummy and looking at the measurements of the skulls belonging to ancient dogs and wolves, I can say this find is unique. It's amazing. In other museums around the world you will only find the remains of adult dogs, but this is a puppy.

'Also all external signs and scan results indicate that it is a primitive dog, and at the moment it is the most ancient one found in northern Siberia. The oldest dog remains were found in the Goya cave in Belgium, and were 36,500 years old, and there are many finds dating to about 26,000 years ago - but they are not so well preserved. Here we see the skin and hair and even the internal organs survived.'

During the post-mortem of the first puppy at Yakutsk, experts found parts of the dog's insides intact, including remains of the heart, liver, lungs, and part of the intestine as well as the stomach, complete with its contents. Pictures: NEFU

The Belgian said the animal is the 'oldest mummified dog in the world' and said scientists hope it will help chart the ancestry to today's domesticated canines. It could be that it belonged to an early domestic breed that lived with the people of Central Asia and went on to settle in the American continent.

'There are two main theories,' said Dr Germonpre. 'The first is that dogs arrived near sites where humans lived and picked up the scraps and gradually they co-existed. The second version talks about the active involvement of man, where the people themselves were the initiator of the relationship, and brought the puppies to their home and trained them. The data that I have accumulated speaks in favour of the latter theory. Now we can get more arguments.'

During the post-mortem at Yakutsk, experts found parts of the dog's insides intact, including remains of the heart, liver, lungs, and part of the intestine as well as the stomach, complete with its contents.

What intrigued them most was that two pieces of twig, about one centimetre in length, were found inside the stomach. One theory is that as the puppy fell to its death from the landslide it attempted to grab onto nearby plants with its mouth.