Ancient tusk found 150 miles from land, 10,000 feet deep

Ayoung female mammoth was wandering long ago near what would become the Central Coast of California, when her life came to an untimely end. Although she died on land, her massive body found its way into the Pacific Ocean. Carried by currents, her remains drifted more than 150 miles from shore before settling 10,000 feet beneath the water’s surface on the side of a seamount. There she sat for millenniums, her existence known to no one.

However, that all changed in 2019 when scientists from the Monterey Bay Aquarium Research Institute stumbled upon one of her tusks while using remotely operated vehicles to search for new deep-sea species off the coast of Monterey, Calif. “We were just flying along and I look down and see it and go ‘that’s a tusk,’” said Randy Prickett, a senior ROV pilot at the institute. Not everyone believed him at first, but Prickett was able to convince his colleagues to go in for a closer look. “I said ‘if we don’t grab this right now you’ll regret it.’” The crew attempted to collect the mysterious object. To their dismay, the tip of the scimitar-shaped specimen broke off. They picked up the small piece and left the rest behind.

It wasn’t until the scientists examined the fragment that they were sure that what they had stumbled upon was indeed a tusk. But from what animal and what time period was still unknown.

The discovery of such a specimen in the deep sea is unusual. Tusks and other skeletal remains of prehistoric creatures are usually found deep underground or encased in permafrost near the Arctic Circle. Although some specimens have been found in shallow waters in Western Europe’s North Sea, the remains of a mammoth, or any ancient mammal for that matter, have never been found in waters so deep.

Steven H.D. Haddock, a marine biologist at the institute who led the 2019 survey, usually focuses on bioluminescence and the ecology of gelatinous deep-sea organisms. But he couldn’t resist the allure of this scientific stumper. So he put together a team of scientists from the institute, the University of California, Santa Cruz and the University of Michigan to solve the mystery.

Preliminary research by Dr. Haddock’s colleagues presented the possibility that this wasn’t just any mammoth — instead, it might have been one that died during the Lower Paleolithic, an era that lasted 2.7 million through 200,000 years ago and from which well-preserved specimens are sparse.

Further study of this specimen may help answer long-held questions about the evolution of mammoths in North America. The discovery also suggests that the ocean floor could be covered in paleontological treasures that will add to our knowledge of the deep past. But before the team could really advance the science, they’d have to head back out to sea to collect the rest of the tusk. Along for the ride were Daniel Fisher, a paleontologist and Katherine L Moon, a post-doctoral researcher who studies the DNA of ancient animals. The tusk had been found and recovered in just under two hours. Dr Fisher used a wire saw to slice a chunk of the tusk off, allowing Dr Moon to sample its innermost tissue. She said she hoped this sample contained more mammoth DNA than was recovered from the sampling of the tusk’s tip two years ago — enough to determine the species of mammoth that ended up in this watery grave, as well as its lineage.