Only adult cave bear bones have been found until now.
Reindeer hunters in Siberia have unearthed the remains of an extinct ice age beast: a mummified cave bear — the only adult of its species ever discovered that still has intact soft tissues, including its fur and even its black nose, according to news reports.
The hunters found the cave bear (Ursus spelaeus) mummy on Bolshoy Lyakhovsky island, in the East Siberian Sea. Meanwhile, on the mainland in the Republic of Sakha (also known as Yakutia), another group discovered the mummy of a cave bear cub, according to a statement from the North-Eastern Federal University (NEFU) in Yakutsk.
“This is the first and only find of its kind — a whole bear carcass with soft tissues,” Lena Grigorieva, a molecular paleontologist at NEFU, said in the statement, referring to the mummy found on Bolshoy Lyakhovsky island. “It is completely preserved, with all internal organs in place”
Until the adult cave bear mummy was discovered, “only skulls and bones were found,” Grigorieva said. “This find is of great importance for the whole world.”
Unlike many of today’s bears, which are omnivorous, cave bears likely didn’t eat meat (except for maybe the occasional scavenging of other dead cave bears), making them largely vegetation-eating machines. These bears must have eaten a lot, because they were huge — up to 11.5 feet (3.5 meters) tall when they reared up on their hind legs, according to Ars Technica. Although most cave bears likely weighed about 1,100 lbs. (500 kilograms), some weighed as much as 3,300 lbs. (1,500 kg), according to a 2018 study in the journal PLOS One. That’s way more than their closest living relatives, the brown bear (U. arctos) and the polar bear (U. maritimus).
After living in Eurasia since at least 300,000 years ago, cave bears mysteriously went extinct about 25,000 to 20,000 years ago, during the Last Glacial Maximum. Humans likely hunted the bears to extinction, a 2019 study in the journal Scientific Reports found. (Many other big animals, known as megafauna, went extinct at the end of the Pleistocene epoch, 2.5 million to 11,700 years ago, but it’s still unclear whether the changing temperatures at the end of the last ice age or human interference played a larger role in their demise.)
Cave bears likely lived in Siberia during the Karaginsky interglacial (a warm period between colder glacial periods), meaning the adult and cub likely date to this time, between 39,500 and 22,000 years ago, according to NEFU.
“It is necessary to carry out radiocarbon analysis to determine the precise age of the bear,” Maxim Cheprasov, a senior researcher at the Mammoth Museum laboratory in Yakutsk, said in the statement.
The scientists have yet to examine the adult cave bear mummy in person, but the reindeer hunters have given them permission to do so, Cheprasov added.
As climate change melts the permafrost in Siberia, more of these ice age mummies will likely emerge. However, discovering, preserving and studying these mummies is a mammoth effort, and many of the mummies that go undetected will likely rot.
“For every one that they do recover, there are 10 if not 20 lost,” Daniel Fisher, a curator at the Museum of Paleontology at the University of Michigan, who wasn’t involved in the cave bear finding, previously told Live Science.