Secrets of the Trap Cave

Scientists from across the nation converge on ‘important’ site outside of Lovell

Posted 7/22/21

For the past 50 years, scientists have been coming to Big Horn County to study remains of exotic creatures that died horrific deaths. Diverse species like lion, cheetah, giant bears, mammoth, camels, …

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Secrets of the Trap Cave

Scientists from across the nation converge on ‘important’ site outside of Lovell


For the past 50 years, scientists have been coming to Big Horn County to study remains of exotic creatures that died horrific deaths. Diverse species like lion, cheetah, giant bears, mammoth, camels, prehistoric horses and even giant lemmings all share one thing in common; they all met their end in Wyoming’s Natural Trap Cave.

The cave is unique in that the 15-foot wide entrance to the 82-foot-deep sinkhole-type pit is virtually impossible to see until it’s directly underfoot. Most of the history uncovered by the teams of scientists ranges from the end of the Ice Age about 11,500 years ago to more than 250,000 years.

Located on Bureau of Land Management land near Bighorn Lake, the cave became a deadly trap for thousands of prehistoric animals that either fell to their deaths or survived the fall only to find no escaping a slow death in the chilly tomb. Since researchers at the University of Kansas first studied the cave in the 1970s and excavations since have revealed tens of thousands of specimens, mostly from extinct animals buried beneath sediment in the dusty tomb.

Now, scientists from California, Georgia, Texas, Michigan, Wisconsin, Wyoming, Florida and Iowa are participating in a study led by Julie Meachen, vertebrate paleontologist and associate professor of anatomy at Des Moines University in Iowa, and Jenny McGuire, assistant professor of biological, earth and atmospheric sciences at Georgia Tech. They’re collecting evidence of the effects of climate change through specimens both large and small, and the changing plantlife that grew in the area. 

The team isn’t stopping there, either: They’re also looking at the creatures that currently exist in the region, comparing how they’ve changed based on long-term climate conditions.

“Looking at [the specimens] through time gives us an idea of how aridity and drying in today’s climate will affect modern mammals,” Meachen said. 

The scientists are keen to study arthropods, like scorpions, reptiles, rodents and mammals, predators and prey. Specialists are eager to get their hands on the sometimes dangerous creatures, willing to search every crack and crevice in the land near the cave, which is just outside the Bighorn Canyon National Recreation Area. There are many, due to the cave’s unique location.


A cool experience

During the Ice Age, two large glaciers covered most of the land north of what is now Wyoming. The huge sheets of ice expanded and contracted, depending on the climate. As they withdrew, a gateway opened for animals from Europe and Asia to enter the territory that later became the Lower 48 states. Meachen theorizes that the gateway led directly to the Big Horn Basin — more specifically to the trap cave.

“All the species here basically have a direct line from Europe and Eurasia, all the way into North America,” she said. “The Natural Trap Cave is the gateway to the Lower 48, in the Pleistocene [period].”

The unique cave has just the right combination of temperature and dryness to preserve not only intact fossils, but also DNA.

“We really want to look at the teeth of large mammals,” Meachen said. “The tooth enamel of large mammals gives a good signal of what they ate, what the water cycles were like when they were alive, how they responded to water and the lack or glut of water.”

Working in the cave isn’t easy. First, team members are trained in climbing techniques under the direction of safety director Juan Laden, of Lander. Everyone entering the cave needs to be able to both drop 82 feet into the cave and pull themselves out on their own.

They spend the entire day working in chilly temperatures. While the world above them was scorching hot during this year’s field season, most researchers were forced to wear coats in the cave. Team members, meanwhile, spend hours in the heat, pulling buckets of material to the surface. The scientists then ascend from the giant cavity, going from the “refrigerator” to the shocking heat on ground level. The rest of the day is spent discussing the day’s finds while hiding in the shade. 

Teams camp at the site, enduring the dusty work and heat without showers for days. Rain turned the area into a muddy mess several times and high winds collapsed tents and tore through the thin material of canopies that shaded gathering and dining areas. They live and work together for 24 hours a day in what most would call misery.

But it has brought them together like a family.

“We’re not just collaborators. We’re friends,” Meachen said.

The work is slow, but with each new find scientists are rewarded for their persistence and spirits are lifted. Bonnie Smith, a Park County archaeologist volunteering to assist in the work, found fossils from a wolf and prehistoric horse on her first trip into the cave. The excitement was almost overwhelming, Smith said as she joined the roundtable discussions under the canopy.

“It’s so frigging cool,” she said in her excitement before going into scientific details.


A changing climate

It’s a dry year. Most of the West is experiencing severe drought. The southern reaches of Bighorn Lake are now dry, the only water being the shallow creek bed that supplies the lake with water each year. It was a constant reminder of the work at hand for McGuire, of Georgia Tech.

“Our goal here is to understand how different periods of more or less arid climates have affected the community composition and what it means for species living on the landscape,” McGuire said, adding, “We want to know if life here gets totally decimated when there’s a drought and which species becoming more abundant.”

To study the current conditions, trap lines are run through the night and checked each morning. Ben Shipley, a biogeographer from Georgia Tech, wakes before most in camp and does a series of long hikes to check the live traps placed throughout the area. To attract small animals, they’re baited with a combination of peanut butter, bacon grease from breakfasts, oats and vanilla. Shipley is studying the interactions between biology and geography — basically, where species live — both in the past and in the present.

Realizing the changes in abundance of the current microfauna in the area is an important part of the team’s research, he said. “By trapping these species we can get an idea of how climate change is affecting the environment. Of course, that’s what all of our projects are looking at through time — to give us clues for the future.”

John Jacisin, a doctoral candidate from Texas A&M, hikes to areas likely to have reptiles each night after the group’s modest dinners. Poking around in every crack and crevice in the canyons and on the desert floor, he collected species like prairie rattlesnakes and greater short-horned lizards — commonly known as horny toads.

“Lizards and snakes are poikilotherms, which means that they’re dependent on the environment to maintain their body temperature. The environment changes their behavior and locations,” Jacisin explained. “We’re comparing evidence from the ice age to what’s here now and trying to get a long-term picture of how they react to changes in the environment.”

He spoke of how few deaths are attributed to rattlesnakes while crawling into dark corners of the canyons, hoping to run into one of five types of snakes in the region. Jacisin was more concerned for the health of the species he sought than for his own, using special tools to protect the creatures during capture.

“Most of the strikes are dry bites,” he said, referring to adult rattlesnakes’ ability to strike without injecting venom. “They won’t use their venom unless they feel really threatened.”


Continuing work

While teams collect tons of material from the cave, others have to painstakingly sift through hundreds of bags of rocks and dirt looking for missed fossils and evidence of life and death in the cave. McGuire brought six students from Georgia Tech to assist in the process. Even the smallest fossils are important to scientists like Cory Redman. He has been with the trap cave study team since 2014 and returns every chance he gets. 

Originally from Powell, Redman is currently the science curator at the Grand Rapids Public Museum in Michigan and an expert in taphonomy — the study of how animals die and then decompose.

He’s pragmatic about the work and the importance of the scientific communion at the cave site. For the scientists working years to collect, catalog and research the evidence at the bottom of the cave and the environment surrounding the site, this is a labor of love.

“You don’t do anything in the natural sciences to make money. We do it because we love it, despite jobs being few and far between, requiring a ton of education and working in less than ideal environments,” Redman said.

The cave is closed to all but scientific researchers, with a large grate covering the important site. After the long permitting process is complete, funding is secured, the team is selected and they finally descend into the cave, the first thing the researchers do is clean up garbage dumped down the hole by some who visit the area.

“Unfortunately, every year we have to pick up all the garbage that people have thrown in. We find broken glass, packaging like cans — even the glow sticks people use to get a look at the cave,” Meachen said.

The study began nearly a decade ago. Due to permitting complications and the COVID-19 pandemic, the last time scientists were able to work at the site was 2017, but that didn’t stop their work. Team members have been analyzing data on everything from the fossils previously unearthed to pollen samples — and soon much of the research will be available to the public in a huge volume of papers about the site. The results are set to be published next year in the scientific journal, Quaternary International.

Possibly more important than the work currently is the future interpretation of the evidence, said Greg McDonald, senior curator of natural history at the National Park Service and regional paleontologist for the Bureau of Land Management.

“When this cave was first excavated back in the ’70s, those were the times of more traditional paleontology where we were interested in the bones we found,” McDonald said. “Now, with all the new technology, we can look at things like the DNA and stable isotopes unknowingly collected 50 years ago. All of that would have been science fiction at the time they were collected.

“Ultimately,” he said, “the value of the work today will become more clear with new techniques in the future.”