Natural Trap Cave: Ice Age bones, modern science and a lifeline to Lovell

Falling 100 feet down into a dark cave is (almost) never a good thing.

It is easy to imagine: a mountain lion sprinting after an antelope at 45 mph, both animals cresting a low rise. The antelope, eyes locked on the ground, darts sharply at the last instant. The lion, focused only on its prey, misses the turn and plunges into darkness, dropping nearly 100 feet. It crashes onto a mound of sand and bone. Stunned and broken, it struggles to rise, then falls still.

Scenes like this played out often 25,000 years ago in the sand hills near today’s Wyoming–Montana border northeast of Lovell. Predators and prey alike vanished into the abyss, their remains accumulating for millennia. Today, those bones tell a story few places on Earth can match.

I spoke last week with Dr. Julie Meachen, lead paleontologist and a professor at Des Moines University about Wyoming’s Natural Trap Cave, a dark hole in the ground that holds not only Ice Age skeletons but also one of the richest caches of ancient DNA ever found.

A cave with a past

From the surface, the Natural Trap Cave looks like nothing more than a wind-blown opening nestled into the sandhills. But the drop is 100 feet. For Ice Age animals it meant sudden death; for scientists, it means a window into deep time. Bones have piled inside for at least 100,000 years, the freshest near the top, mammoths and ancient horses buried far below. Digging downward is like peeling back layers of history.

Local cavers knew of the site in the 1950s and ’60s, and scientific work began in 1971 under archaeologist Lawrence Loendorf and paleontologist Larry Martin. That effort slowed in the mid-1980s, and the Bureau of Land Management sealed the opening with a heavy steel grate to keep out both people and livestock. For three decades the cave sat untouched.

That changed in 2014, when a new team led by Meachen trained in rope systems, secured permits and once again lowered themselves into the pit. Work takes place during a narrow summer window, usually just a few weeks in July.

“That’s the one time we know there won’t be snow on the mountain,” Meachen said.

Crews camp nearby, rappel daily and spend six-hour shifts digging, hauling and recording finds.

“It’s physical and dirty,” she admitted. “You lie in that cold dirt, and it pulls the warmth right out of you.”

That chill is exactly what makes the cave so rare. Unlike most fossil sites in the lower 48, Natural Trap Cave preserves ancient DNA. Year-round, the cave is a near constant 48 degrees, cold, humid and dark. Bones don’t dry out; decay slows; genetic material survives. In other words, the cave doesn’t just keep bones, it keeps their stories.

What the bones tell us

The fossil list reads like an Ice Age roster: bighorn sheep, elk, deer, bears, rabbits, snakes, birds and even camels. Horses are especially common, with hundreds of specimens from two extinct species: the stilt-legged Harrington hippus and a western horse related to modern Equus. Both vanished about 11,000 years ago in the great Pleistocene extinction.

Meachen believes that early humans likely hunted the horses to extinction, viewing them not as candidates for domestication but as a convenient food source.

Large predators are plentiful, too, including American lions and the so-called North American “cheetah-like” cat.

“We’ve found lots of cats, maybe a hundred,” Meachen said. Scientists still debate its name, since it isn’t quite like Africa’s cheetah but still a runner built for rougher terrain and longer pursuits.

The discovery raises new puzzles. Why did this cat vanish, especially when humans were unlikely to have hunted it? Did antelope evolve to outmaneuver their predator, or did climate and habitat shifts tip the balance? Meachem and her colleagues are hoping to discover the answer.

Mammoths are also part of the cave’s record.

“We pulled a mammoth this year,” Meachen noted.

Many large animals date to about 30,000 years ago, near the height of the last Ice Age. Others endured until roughly 12,000 years ago, when North America lost much of its megafauna. Why? Likely a combination of changing climate and human impact.

“It probably was a mix of several things,” she said.

Science, community and continuity

Despite decades of effort, most of Natural Trap Cave remains untouched.

“It’s a 50-by-50-foot pit and we’ve gone down maybe 10 feet,” Meachen explained. “We’ve excavated one percent, maybe.”

Each bucket of soil is hauled out by pulley and sifted piece by piece. Volunteers from caving groups in Wyoming, Montana and Utah make the work possible.

The cave also touches the present. Before the grate was installed in the 1970s, livestock and wildlife sometimes fell in. Even now, smaller animals, snakes, rabbits and mice occasionally drop through the opening. One rabbit, Meachen laughed, startled the crew mid-dig.

Through it all, the lifeline has been the town of Lovell.

“Lovell is our support place,” she said. “Water, showers, groceries, hardware, lunch, ice — we get almost everything there.” 

Dr. Meachen was pleased to get the chance to thank all the people here for the support they’ve had over the years.

Looking ahead

What becomes of the bones once they leave the cave? All specimens are curated at the University of Wyoming Geological Museum, where they join one of the state’s most significant fossil collections. A dedicated Natural Trap Cave exhibit is still in the works, while researchers continue publishing new findings.

The cave is far from giving up all its secrets. For now, it remains a place where Ice Age drama, modern science and community ties meet at the edge of a dark Wyoming hole.

If you plan to drive to the site, be sure you have a high-clearance four-wheel-drive vehicle. Take the first left after crossing the Big Horn River causeway; from there it’s about 10 miles. You can find it on Google Maps as ‘Natural Trap Cave,’ and there are signs along the way.