Shark Hunting in Kentucky

In a corner of rural Kentucky lies the world’s longest cave. What can the shark teeth embedded in its walls show us about the moral dilemma of the climate crisis? More importantly, can these fossils make us change? 

Words by AUSTYN GAFFNEY | Photos by JON CHERRY

Tight squeezes pose no problem for fossil hunter JP Hodnett, whose paleontological training serves him well as he searches for ancient shark teeth in the caverns of Mammoth Cave National Park.

“We’re in a world where we don’t have continents colliding, but we’re doing [environmental change] at a far faster rate than the world is capable of,” said Hodnett over the phone. “A place like Mammoth Cave is a little piece of evidence adding into a bigger data set to tell a bigger story, including modeling in the future.”

The extinct sharks share a subsurface world with another genus teetering toward eradication: bats. At Mammoth and surrounding cave systems, the Cumberland Piedmont Inventory & Monitoring Network has spent years tracking declining bat species while trying to predict their future in the state of Kentucky and noting changes in the region’s temperature. 

The juxtaposition created by the two groups — sharks buried in a landlocked cave and the bats plummeting closer to vanishment overhead — is a reimagining of what my landlocked home state looked like hundreds of millions of years ago, and an inverse of what occupies so much of my mind today: trying to picture how climate change will alter this place, its people, and our more-than-human kin.

Human life has been intertwined with the passageways of Mammoth Cave for thousands of years. Indigenous explorers once mined the cave for gypsum and mirabilite, according to The Longest Cave, a book by Roger Brucker and Richard Watson. They carried river cane torches and left behind broken sandals, ashen cane, and traces of food like sunflower and sumpweed. Today, the cave lies within seven nations: the Eastern Band of Cherokee Indians, Cherokee Nation, United Keetoowah Band of Cherokee Indians, Shawnee Tribe, Eastern Shawnee Tribe of Oklahoma, Absentee Shawnee Tribe, and the Chickasaw Nation. While European wars and illness decimated native populations, the caves were overtaken by saltpeter mining in the 18th century. In the dark, enslaved Kentuckians dug out the essential gunpowder ingredient needed to fuel the War of 1812. 

While Indigenous groups were forced onto Oklahoma reservations in the 1830s, tourist traps took root at the limestone entrances across south-central Kentucky. Visitors came up the Green River on steamboats or by train and stagecoach to enter privately owned parks. In 1853, Louisville businessmen purchased a piece of land to create a resort town near the nascent industry and called it Cave City. By 1941, many of the private caves had closed or been consolidated into what became the state’s singular national park. 

A shark tooth found embedded in a ceiling of fossil hash, the remnants of a seabed hundreds of millions of years old. In the prehistoric past, sharks of impressive size moved through a shallow, crystalline tropical sea that eons later would be the porous, miles-long system of caverns.

The morning of the shark teeth scouting, I drove south on I-65, leaving downtown Louisville for the greener outskirts, passing tobacco fields, Lincoln’s boyhood home, and billboards for Kentucky Down Under, an incongruous zoo of kangaroos and emus in the state’s heartland. Here, the landscape starts to smooth out to the pastures and barns of my childhood, rolling hills growing long like stretched-out arms. Off the interstate, I continued past other familiar landmarks: Guntown Mountain, across the highway from Dinosaur World, with its Tyrannosaurus rex lifting his head above the oaks. The gemstone store, Yogi Bear mini-golf, defunct bumper boats. Behind tapestries of sycamores and sassafras, old cemeteries. Beneath the car, cave passageways intersect, overlap, and run above and below one another like a tangled ball of yarn. 

A few miles later, I pulled up into the parking lot of Mammoth Cave’s science and resource management office, where Toomey greeted me in fatigues and brown boots. Toomey is lanky and tall — suited for fitting through cramped passageways. Leading me inside, he relayed the origin of the search for ancient sharks: In the 1990s, a group of guides on an after-hours trip found Meckel’s Cartilage — a Saivodus jaw and teeth. 

“I had an expletive when I saw it,” said Hodnett of the jaw. Inside the office, Hodnett, wearing khaki pants and a T-shirt featuring a cartoonish geologic time scale, arranged dozens of clear plastic cases no bigger than jewelry boxes on a conference table. Most held shark fossils. Hodnett has collected roughly 1,000 fossils that he will clean, categorize, and return to the park system. While ancient sharks have been found throughout the Illinois Basin since the 1860s, Mammoth Cave is a new hotspot. So far, more than 70 species of shark and fish have been found. 

Beyond collection and preservation, Hodnett has even begun to speculate on the cause of death, like the opening of a cold case file millions of years later. In the Saivodus jaw, he found a smaller shark spine embedded in the cartilage. Hodnett wondered if the Saivodus caught an infection that led to its death, or if the spine was afixed later, when smaller sharks scavenged its corpse, shedding teeth like poppy-seed-sized clues. 

That morning, our mission was to find one of these larger teeth — the tooth of a Saivodus — deposited in the cave roughly 340 to 345 million years earlier. 

We piled into a white pickup truck with our caving helmets and packs thrown in the bed, and headed toward the Carmichael Entrance, established in 1931 as an alternative to the tourist-ridden Historic Entrance. On the surface, Kentucky was showing off — 73 degrees and a quixotic blue sky — but underground, the cave system was a cool and dependable 54 degrees. As we descended the limestone stairs, Toomey provided a basic geology lesson: If one looks at a crosscut of the earth’s interior, whatever rests on the bottom is oldest. 

Down a beaten dirt path, Toomey flicked lights on and off as we moved between sections of trail. If we’d existed roughly 330 million years ago, he reflected, we’d be swimming next to sharks, our shadows drifting across a tropical sea floor covered with crinoids, a starfish relative that looks like a miniature mop, and brachiopods, ancient shellfish mirroring clams, along with coral and sponges. Sediment on the sea floors began forming the limestone in which these teeth were preserved, and the sandstone that caps it. 

During this geologic era, cartilage, bones, and bright green plants pressed into layers in ancient swamps, forming Kentucky’s carbon beds. The peaks of the Appalachian Mountains, once perhaps as tall as the Andes, and decapitated during my lifetime for coal, would have risen sharply to the east. While Americans named this pocket of time the Mississippian Period, the international community knows it as the Carboniferous: the laying of our fossil fuel foundation. Among these rock layers, the hardest bits of shark were pressed down like dried flowers and preserved. 

Rick Toomey at one of the human-contrived cave entrances. If Mammoth Cave’s steady coolness becomes compromised by a warmer climate, it is likely its bat populations will suffer.

Two million years ago, a stream flowed through the rock, dissolving the limestone and forming the cave. In 1841, Stephen Bishop, an enslaved cave guide, began leading tours down the earthen path, naming it Cleaveland Avenue after a chemist who once collected minerals here. Almost a century later, teams from the Civilian Conservation Corps would build this trail, a two-mile route through a tubular section shaped like a giant subway terminal. 

An hour into our expedition, we veered off the main path to walls of fossil hash. While Toomey paused for a snack, peeling oranges, Hodnett used a small tape measure to size a tooth in the wall, then, with retooled dentist utensils, he carefully pried the fossil from the surrounding hash and dropped it into a pill bottle lined with cotton balls. 

“Do you ever feel like you’re time traveling when you touch a tooth?” I asked, hunched over next to Hodnett, my headlamp trained onto his graphic T-shirt illuminating the timeline of geologic history. As he nodded, I read the yellow box that came just after the Mississippian Period ended, announcing “GIGANTIC EXTINCTION.”

When the Great Dying occurred, some 250 million years ago, 96 percent of marine life perished. The ancient event had a different cause than our current era of climate change: A massive set of volcanoes in Siberia pumped carbon dioxide and ash into the atmosphere, changing the nature of the world where sharks once reigned, heating the oceans, acidifying the water, thinning oxygen, and suffocating life within.

Before I met Hodnett and Toomey at their office, I passed time walking through the park’s visitor center, where I found a map of an ever-evolving Earth. As I clicked through a video screen, the planet’s edges and mass undulated like the waxy globs of a lava lamp. 

I raced backward through epochs, before Mammoth Cave’s formation to the earliest known bats, to the rule of mammals and the doom of the dinosaurs, through the world’s greatest extinction event, past the Mississippian Period, when the digitized image of an underwater Kentucky is so blue it is almost white, and eventually reaching Pangea, or “all the earth,” when we were one big island of land surrounded by one big planetary sea. I hit the arrow back and forth, spun between our past and present planet. I suddenly became frustrated, calling out to an empty display, “Now show us the future!”

If you think of geologic history as a calendar year running from January through December, the dinosaurs arrive in the final month of the year, the last Ice Age ends two minutes before midnight on December 31, and all of recorded human history is the last 41 seconds of the year. Today, a scientific working group has proposed that we have reached a new geologic epoch: the Anthropocene, beginning around 1950, when human influence began to tip the climate scale beyond repair.

In the 1970s, a research arm of the U.S. government published the first report warning that burning coal could lead to a global rise in temperature. Nearly a decade later, NASA scientist James Hansen testified to Congress that climate change was decidedly human-induced and occurring so fast that cycles from the past were incomparable. The same year, the International Panel on Climate Change (IPCC) was established. 

“It is time to stop waffling so much,” Hansen told The New York Times, “and say that the evidence is pretty strong that the greenhouse effect is here.” 

But by the time I visited Mammoth Cave more than 30 years later, the span of my lifetime, so little had been done to prevent the worst impacts of global warming that in February 2022, an IPCC scientist had warned: “Any further delay in concerted global action will miss a brief and rapidly closing window to secure a liveable future.” 

In Kentucky, a state long wedded to the coal industry, climate science is either denied outright by our lawmakers or largely ignored. While Kentucky can feel immune from the worst impacts of climate change, between 2003 and 2022, 54 large disasters cost the state as much as $20 billion, doubling both the number of hazards and the recovery costs from the previous two decades. After the publication of that study in 2021, tornadoes took 81 lives west of Mammoth Cave, and a massive flood claimed the lives of 45 Kentuckians to the east, burying much of the region in a muddy sea. 

But even after such devastation, our legislative leaders have ignored or denied our human role in climate change and our ability and imperative to create laws and systems that prevent the worst effects of these largely predictable bouts of extreme weather.

Back in the spring, none of the leading candidates for governor, nor incumbent Democratic Governor Andy Beshear, had climate change listed among their priorities on their campaign websites. Joshua Basseches, assistant professor of public policy and environmental studies at Tulane University, told Louisville public radio reporter Ryan Van Velzer that, compared with other conservative states, “Kentucky has done among the least of any state in the country at tackling climate change.”

Daniel Cameron, Kentucky’s attorney general and the Republican candidate for governor, denies proven climate science, according to Van Velzer. While in office, his actions have included siding with conservative justices in a U.S. Supreme Court decision to limit federal regulation of greenhouse gas emissions and opposing federal proposals to curb transportation emissions.  At the state level, he’s discouraged utility regulators from reaching carbon neutrality goals by 2050 and backed a new law that keeps coal-generating power plants — the biggest polluters and contributors to climate change — from transitioning to cheaper, cleaner, and more reliable power supplies. 

In a tweet this spring, Cameron wrote: “I’ll never stop fighting back against climate alarmists who threaten our coal and natural gas industries!” 

Rick Toomey, Mammoth Cave’s resource management specialist and research coordinator, is more than glancingly familiar with the sometimes subtle signs of where shark fossils can be found deep underground, where the landscape — make that seascape — was once much different.

A few months later, in July 2022, Mika Potter was home when rainfall started in Eastern Kentucky. While Potter’s husband, Cody, was working in an underground coal mine, she and their 6-year-old daughter, Addilynn, watched the rising water with increasing alarm. In the loud black of a midnight thunderstorm, Potter put Addilynn in a life jacket, stuffed what she could in backpacks, and swam out the front door of their mobile home to their neighbor’s. When water began entering that house, too, they fled again, walking up a wooded hillside to a house on higher ground. 

I met Potter three weeks later outside Fleming Neon Middle School, where she was waiting with nearly 100 others for $100 gift cards donated by a local Rotary Club for flood-affected families. The Potters, like most people in Eastern Kentucky, didn’t have flood insurance because they didn’t live in a flood zone. Yet due to the increasing prevalence of extreme weather events, they’d lost their entire home, and all their possessions, along with four cars and a motorcycle. 

“She’s a little bit traumatized,” Potter said of Addilynn, as she waited in the hot morning sun for a small sum that might begin to help her family recover.

The winter before, a devastating wave of tornadoes hit the western half of the state. While the link between tornadoes and climate change is less scientifically settled than that between climate change and floods, global warming seems to be increasing the range and concentration of tornadoes. Stronger twisters are pushing east of Tornado Alley, a broad geographic area including portions of Texas, Oklahoma, Kansas, and Nebraska.

The day after the tornadoes, I spent hours walking around downtown Mayfield, where the roof of City Hall looked clawed off by a twister. I interviewed residents next to ripped-apart trees, taking one up on an invitation to attend a church service on Sunday morning. In the sanctuary, parishioners bent their heads and held hands in concentric circles. Cold air spilled through open windows sheathed in fluttering plastic. 

After only a couple of days, the devastation had begun to feel claustrophobic.

Back in the cave, Toomey would tell me how he managed claustrophobia. He gets uncomfortable if a passage is so tight he can’t turn his head from side to side, he said. His friend, meanwhile, reaches his limits when he must exhale all the air out of his chest to slide between rock walls. I asked how cavers in a previously unexplored passage know, when their necks are stuck and their lungs are emptied, that the passage will widen on the other side. You don’t, Toomey said. 

Once, during a similar conversation, the same friend told Toomey, “We’re all claustrophobic. The question is, how tight does it have to be before it starts freaking you out.”

While Hodnett inspected the most impressive tooth of the day, Toomey sent me down a crawlway, where I lay flat on my stomach, shimmying forward as the space between my back and the ceiling quickly shrank. We were in search of another shark tooth that an off-duty caver had flagged weeks earlier with a scrap of blue tape. Fresh air flowed from the wedge of the tunnel. It felt like the cave was breathing. 

“I can always come get you,” Toomey called as I elbowed my way toward the shock of blue no bigger than a twist-tie. I lay there in the damp, turning my neck to better see the spot with my headlamp. I considered the age of my own human ancestors. My evolutionary lineage has been around for about 2 million years, when the waterway now known as the Green River cut into Cleaveland Avenue. While I know this, and can now write it down, such a time scale still feels incomprehensible. 

During human history, while our brains have evolved to respond to more immediate threats — like weather-related disasters — long-term, complex menaces like climate change can still feel beyond our daily grasp. Instead, humans progress in a rush: We developed our modern bodies, our modern agriculture, our modern electric grid, and our modern planetary change all within 10,000 years. 

In The Longest Cave, Brucker and Watson reflect on the two-decade effort by the Cave Research Foundation, a group of spelunkers and explorers, to create the longest cave in the world by connecting Mammoth Cave to the Flint Ridge Cave System. After almost 12 hours exploring unknown passageways beyond Flint Ridge, holding their breath in tight spots, and submerging themselves in cold underground rivers, the group emerged from a tunnel, and their headlamps picked up the iron flash of a Mammoth Cave tourist handrail. They had linked both systems. The 1972 discovery heralded the world’s longest cave at 144 miles. Discoveries since have more than doubled the foundational survey to 426. Six hundred more miles of uncharted passageways are thought to exist. 

“For brief moments we have possessed — or been possessed by — the longest cave,” the authors wrote. “And when in time we become another part of mother earth, know that she has already been a part of us.” 

We humans are soft-bodied. We will not make good fossils. We lack exoskeletons and excessive cartilage. Like sharks, our teeth are often what remain, Homo sapiens canines meant to tear, cut, and grind meat. We have funerary practices, leaving our dead not where they lie, but entombing them in long boxes of oak, iron, and marble. We put all these dead together in a field, and after enough time passes, many of those fields are forgotten, paved over or overgrown. What may remain long after we perish is not the hand on the railing, but the railing itself. The environment we have created to house our human bodies is likely to outlast us.

The evening after witnessing the remains of the cave’s fossilized species, we counted the numbers of a declining one in neighboring Long Cave, about three miles to the south. A group of interns set up infrared equipment and camp chairs to tick off the number of bats flying out of the cave’s entrance. In this mock count — media aren’t allowed at official counts, to minimize bat disturbance — more than 5,000 bats spiraled out of a bat-shaped sinkhole. 

The September count came as Mammoth Cave began monitoring cave temperature — which bats depend on to hibernate and reproduce — to determine whether the subterranean climate is changing. 

“If you have a warming climate, where the surface is warming, that means less cold air is getting in the cave, so the cave itself will not be as cold,” said Steve Thomas, manager of the Cumberland Piedmont Network, a group of 14 national parks across the Southeast focused on monitoring aquatic, cave, and terrestrial ecosystems. In Kentucky, this mission extends to include the conservation of cave bats. 

When you go deep into a Kentucky cave, the stable air temperature is equivalent to the mean annual surface temperature of the vicinity. In Mammoth Cave, that’s roughly 54 degrees Fahrenheit. If the mean temperature gradually warmed, Thomas assumed the cave would warm at a similar rate. That could be a problem for the 13 bat species found in the park, at least four of which are federally endangered or proposed for the endangered species list. Like climate change, their endangerment is attributed to human causes, like habitat loss, along with more natural causes, especially white-nose syndrome, a deadly fungus that infects the ears, muzzle, and wings of hibernating bats.

“It’s incredibly depressing watching our bat populations get decimated,” Toomey said. He’s followed the Indiana bat for decades. The bat was on the first list of endangered species in 1967, even before the Endangered Species Act was passed in 1973. Over 15 years later, Toomey remembered a group of scientists at a conference talking about Indiana bats possibly going extinct within their lifetimes. But over the next decade, the population stabilized, and there were signs it might even be increasing. Then came white-nose. 

“When they go, they don’t come back,” said Toomey. In the dark, bats circled in ever-expanding helixes from the mouth of the cave. I watched them through an infrared camera, where they appeared like erratically darting bright yellow tennis balls. They flew too fast to identify the species, just the whoosh of soft parchment wings whipping past. 

When I was nearing claustrophobia in the tunnel, I heard Toomey call to me, his voice a quiet echo though he was just a few dozen feet away, instructing me to flip my legs around like a roly-poly and wiggle my way back toward the wider gap of underground air. Right before he spoke, I felt stuck. But when I acted on his expertise and forethought, when I twisted my body around, I found a new direction. 

In The Longest Cave, Brucker and Watson write that their exploration as cavers never ends. Our endings never end. We go on in new, evolved, and invented forms. We look for passageways we hope to hold our breath through, to find another side, and hope that side has a bit more breathing room. 

The difference between us and the sharks is that we have the intellectual forethought to make changes. We can make a choice favoring an expansion, rather than a contraction, of life. We have enough computer modeling to predict the worst effects of climate change, and we can work to scale that planetary disaster back. We have enough respect for our ecological interconnection with bats to protect their vital, singular, and ever-overlapping place in our universe. 

The passageway ends only when it ends, when the cave tapers to a point insufficient for a person to push through. 

“The only sign that you have reached the end is that you cannot go on,” Brucker and Watson write. “And there is no view.”

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