Scientists have completed an 'autopsy' - or rather a necropsy, which is an autopsy for animals - on a 9,300 year-old bison.
The incredible discovery of the remarkably intact animal was made back in July 2011, but now scientists have taken a look inside.
And they have revealed the 'mummy' has a complete brain, heart, blood vessels and digestive system.
The most complete frozen mummy of a steppe bison, an extinct bison found on steppes throughout Europe, Central Asia, Beringia, and North America, was found in the Yana-Indigirka Lowland in the Sakha Republic, Siberia.
A necropsy was performed to learn about how this animal lived and died at the end of the Ice Age.
It showed the animal had a relatively normal anatomy with no obvious cause of death.
However, the lack of fat around the abdomen of the animal suggests it may have died from starvation.
'This is a very rare find,' Dr Olga Potapova from the Mammoth Site of Hot Springs in South Dakota told MailOnline.
'It is one out of three relatively complete steppe bison mummies that exist in the world, and it is the most complete out of those three.
'The body is in excellent condition. Normally, we find the mummies that are significantly damaged by predators in the past, or by modern arctic foxes and others, as soon as mummies are thawed out from the permafrost.
'Such processess happen very quickly, and a mummy that thaws out during summer may be gone in a few months forever.
Dr Potapova adds that the bison belongs to an extinct species that was found in the early Holocene epoch - 9,000 to 12,000 years ago.
She says there are very few records from species at the start of this epoch, known as the Pleistocene-Holocene boundary.
'This mummy gives us an opportunity to look beyond what for most of the paleontologists impossible to dream of - the opportunity to study genetics and morphology of preserved organs of this animal,' she said.
From the necropsy the scientists discovered that the brain appears to be complete, although it has shrunk to 36 per cent of its original volume.
However it had retained the bulbs, nerves and even medulla oblongata that once allowed the animal to think.
Organs in the throat such as the trachea appeared to be close to their normal sizes, as did the heart, blood vessels, stomach and penis.
Some parts of the animal were significantly shrunk though, including the lungs, liver and left testicle.
And, as mentioned, the lack of fat in the abdomen and neck suggested it died of starvation.
'The Yukagir bison mummy became the third find out of four now known complete mummies of this species discovered in the world, and one out of two adult specimens that are being kept preserved with internal organs and stored in frozen conditions,' said Dr Potapova in a separate statement.
%2Bwas%2Bdiscovered%2Bin%2BJuly%2B2011%2Bin%2Ba%2Bremote%2Bpart%2Bof%2BRussia%2C%2Bbut%2Bscientists%2Bhave%2Bnow%2Bperformed%2Ba%2Bnecropsy%2Brevealing%2Bit%2Bto%2Bhave%2Ba%2Bcomplete%2Bbrain%2C.jpg "9.300 year old bison found in Siberia: Mammal still has a complete brain, heart and digestive system")
'The next steps to be done include further examination of the bison's gross anatomy, and other detailed studies on its histology, parasites, and bones and teeth.
'We expect that the results of these studies will reveal not only the cause of death of this particular specimen, but also might shed light on the species behavior and causes of its extinction.'
Dr Evgeny Maschenkofrom the Palaeontological Institue in Moscow, added: 'The exclusively good preservation of the Yukagir bison mummy allows direct anatomical comparisons with modern species of Bison and cattle, as well as with extinct species of bison that were gone at the Pleistocene-Holocene boundary.'
The creature was found perfectly preserved in July 2011 in the Sakha Republic, also known as Yakutia, where woolly mammoth remains have previously been found.
Its body became visible after part of the shore collapsed into the water.
'The discovery has an enormous value for scientists since it is the best preserved bison ever found,' said Dr Albert Protopopov, chief of the Mammoth Fauna Research Department of the Yakutian Academy of Sciences, back in March.
He told The Siberian Times: 'We have ascertained that the bison lived 9,000 years ago, at the very beginning of the Holocene epoch and died aged approximately four.
'By that time, many mammoths had died here, but the bison still lived.'
'The careful and thorough examination we have begun will give us answers to many questions, first of all as to why did the bison die out'.
Scientists from the Yakutian Academy of Sciences, the Institute of Geology of Diamond and Precious Metals, Yakutsk Agricultural Research Institute and the Agricultural Academy of Yakutsk carried out the full anatomic necropsy , which involves removing and describing every organ as well as conducting microbiological and genetic tests and looking for parasites.
They were joined by the Russian Academy of Sciences and Mammoth Research Centre experts from the US.
American scientists have long been studying bison living in North America and hope to compare them to the animal's Yakutian relatives.
The scientists hope to map a model of an ancient pasture by studying remains of the foods in the bison's digestive organs and to publish their research next year.
Yevgeniy Maschenko, senior researcher at the Mammals Laboratory of the Russian Academy of Science Palaeontology Institute, said in March: 'This is the first study of an ancient mammal for the last 20 years.
'We have a team of experts from various fields. We are keen to learn the animal's morphology.
'All its internal organs will be weighed and described. All tissue samples will be taken. Any morphology study [the structure of an animal] is connected to the study of animal's adaptation to his environment and in this particular case to study the palae-ecology will be very interesting.
He said that histology samples - the samples showing the microscopic anatomy of cells and tissues of the animal - will prove the most interesting, as they will be the first chance scientists have to studying parasites attached to ancient bison.
'Perhaps they didn't preserve, but we will find their DNA and the traces of their activity,' he said.
'By performing biochemical tests and then comparing them by identical tests of currently living worms we will be able to find out what kind of parasites lived 9,000 years ago.
'This will be done thanks to a new technology aimed at studying invertebrates' DNA. It will be used for the first time on the extinct animal'.
Music : On The Ground by Kevin MacLeod
Source : DailyMail , Siberian Times , Live Science
