Working in northeastern Siberia, researchers describe a complete bison cadaver that’s literally been frozen in time for the last 9,300 years. Like many other charismatic megafauna featured in ancient cave art, the steppe bison (Bison priscus) went extinct at the end of the Ice Age around 11,000 years ago.

This four-year-old male was discovered in mid-August of 2011 by members of the Yukagir tribal community during their traditional summer activities on the shore of Lake Chukchalakh in the Yana-Indigirka Lowland of Yakutia, Russia. Members of the Yukagir found two other frozen corpses in this permafrost graveyard as well: a young woolly mammoth (Mammuthus primigenius) from the Late Pleistocene and a wild horse (Equus sp.) from the Holocene, like the bison.

The Yukagir bison mummy is the most complete one ever found: 100 percent, they say, including the snout, the tips of the ears, the tail, and everything in between. Until this find, just a couple other permafrost bison mummies have been described, including “Blue Babe” from Alaska and the "Mylakhchin bison" from Yakutia. This mummy is also “one out of two adult specimens that are being kept preserved with internal organs and stored in frozen conditions,” Natalia Serduk of the Russian Academy of Sciences says in a news release.

Its brain, heart, blood vessels, genitalia, and digestive system (complete with stomach and intestinal contents) are still intact, though some have shrunk over time. His age was based on an examination of incisor eruption and wear; he likely weighed between 500 and 600 kilograms, and the distance between the horns tips is an impressive 75 centimeters.

A necropsy revealed relatively normal anatomy with no obvious cause of death. Although, the lack of fat around the animal’s abdomen suggests it could have died from starvation. The absence of damage from predators supports a natural cause of death, and so does the position it was locked in. The bison mummy was found in a "sleeping pose"—legs tucked under the belly, neck stretched out, head lowered to the ground—a typical position for ungulates who died naturally.

"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,” says Evgeny Maschenko from the Paleontological Institute in Moscow. Next, the team plan to examine the bison mummy’s genetics, tissue and cells, parasites, bones, and teeth. These results might disclose a cause of death and reveal more about their behavior and maybe why they went extinct.

The preliminary analyses of the three frozen mummies were published in Integrative Zoology. This new work was presented at the annual Society of Vertebrate Paleontology meeting this week in Berlin and will be published in the Journal of Vertebrate Paleontology.

Image: G.G. Boeskorov et al., Integrative Zoology 2014 / International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd