Scientists have found new evidence that could explain more precisely why the wooly mammoth went extinct more than 10,000 years ago.

According to the Los Angeles Times, an unusual cervical rib bone at the base of the neck was associated with abnormal development issues. The bone is not dangerous itself, but is known to cause early death even in humans.

The researchers published a new study in the journal PeerJ Tuesday. They discovered this peculiar bone was 10 times more common in mammoths from the Late Pleistocene period than they are in elephants today.

"It had aroused our curiosity to find two cervical vertebrae, with large articulation facets for ribs, in the mammoth samples recently dredged from the North Sea," study lead author Jelle Reumer, a paleontologist at Utrecht University and director of the Natural History Museum Rotterdam, said in a press release. "We knew these were just about the last mammoths living there, so we suspected something was happening. Our work now shows that there was indeed a problem in this population."

The researchers found three of the bone samples to be from the part of the neck just above where the spine connects to the ribs. Two of them were later found to have been connected directly to the ribs.

The researchers also compared the ancient mammoth bones to modern Asian and African elephants. Of the 28 examined, only one had a cervical rib bone.

Since the mammoths were so much more likely to have this bone, the researchers concluded the bone was a leading cause in extinction. Not only was the bone causing death, but it was irregularly large, which likely caused even more health complications.

"A combination of inbreeding and harsh conditions may be the most likely explanation for the extremely high incidence of cervical ribs," the research team reported in the study. "[The mammoth's vulnerability] may well have contributed to the eventual extinction of the woolly mammoths."