For more than seven decades, they sat in a university museum as prized specimens: two ancient bones that appeared to belong to the world's youngest woolly mammoths ever discovered. Then scientists ran a DNA test, and the fossils told an entirely different story.
The fossilised remains aren't mammoth bones at all.
They belong to two different species of whale, somehow ending up more than 400 kilometres (250 miles) inland from the nearest Alaskan coastline, according to ScienceAlert.
Which raises an obvious question: how on earth did whale bones end up there?
Archaeologist Otto Geist found the bones during a 1951 expedition through Alaska's interior, just north of Fairbanks. The two epiphyseal plates, essentially the connectors between spine bones, were massive. Combined with their location in the prehistoric Beringia region, a mammoth identification seemed certain.
He donated them to the University of Alaska Museum of the North, where they joined roughly 1,500 other mammoth fossils.
Radiocarbon Dating Raises Red Flags
The museum's Adopt-a-Mammoth programme, which partners with Colossal Biosciences, recently enabled researchers to radiocarbon-date the fossils. Lead researcher Matthew Wooller from the University of Alaska Fairbanks got a shock when the results came back.
The carbon isotopes suggested the bones were only 2,000 to 3,000 years old.
Woolly mammoths are believed to have gone extinct roughly 13,000 years ago, with only isolated populations surviving until about 4,000 years ago on remote islands near Alaska and Russia, according to Discover Magazine. Finding mammoths thousands of years younger would have rewritten the extinction timeline completely.
'I was pretty much gobsmacked,' Wooller told the University of Alaska Fairbanks. 'But then the rational science side of my brain kicked in - we've got to do more forensic work here.'
'Mammoth fossils dating to the Late Holocene from interior Alaska would have been an astounding finding: the youngest mammoth fossil ever recorded,' Wooller and his team wrote in their peer-reviewed paper published in the Journal of Quaternary Science.
Chemical Clues Point to Marine Origins
Before rewriting mammoth extinction timelines, researchers decided to verify the species identification. That's when chemical analysis revealed something odd.
The bones showed unusually high levels of nitrogen-15 and carbon-13 isotopes, according to the study. Grass-eating land mammals don't carry these chemical signatures. Marine creatures do.
No eastern Beringian mammoth has ever tested this way. The deep Alaskan interior isn't exactly teeming with seafood.
'This was our first indication that the specimens were likely from a marine environment,' the researchers explained in the paper.
DNA Reveals Stunning Identity Switch
Both mammoth and whale experts agreed they couldn't identify the specimens by appearance alone, per the research. They needed ancient DNA.
The bones were too degraded for nuclear DNA extraction, but the team managed to recover mitochondrial DNA. When they compared it with reference samples, the truth emerged: one bone belonged to a Northern Pacific Right whale, the other to a Common Minke whale.
'Here we had two whale specimens - not just that, but two separate species of whale,' Wooller said. 'It just kept getting weirder and weirder.'
It's easy to see why they were confused.
Whale and mammoth vertebral connectors look remarkably alike - both have a spongy texture and distinctive plate-like shape. Patrick Druckenmiller, who worked alongside Wooller, noted that the original misidentification made complete sense given the bones' appearance and their discovery location deep in mainland Alaska.
The 250-Mile Mystery
Which brings us back to the central question: how did whale bones wind up more than 400 kilometres (250 miles) from the sea?
Researchers floated several theories. Predators like wolves or bears might have dragged the bones inland. Ancient whales could have swum up the Tanana or Yukon rivers, though this seems unlikely given how massive these whale species are and how small Alaska's inland waterways tend to be.
Druckenmiller suggested ancient humans may have transported them. 'It might have been used as a plate, a platter, or for carving, but the bone hasn't been modified,' he noted in a university press statement.
The most likely culprit? A museum mix-up.
On the same day that fossils from Dome City were processed, specimens from Alaska's west coast were also catalogued, per researchers. A label switch could easily have happened during the rush.
'Ultimately, this may never be completely resolved,' Wooller and his team wrote. 'However, this effort has successfully ruled these specimens out as contenders for the last mammoths.'
The hunt for the youngest mammoth fossil goes on. Evidence indicates mammoths lived on St. Paul Island in Alaska until about 5,600 years ago, whilst fossils from Wrangel Island in Russia date to approximately 4,000 years ago, according to the University of Alaska Fairbanks.
