Published on June 15, 2025
Two ancient shark species have been discovered deep within Mammoth Cave, Kentucky - the longest cave system on Earth. These fossils are over 325 million years old and offer rare insight into early marine life that once thrived in what was then a shallow coastal sea.
The new species, named Troglocladodus trimblei and Glikmanius careforum, were identified by shark paleontology expert JP Hodnett in collaboration with the National Park Service Paleontology Program. These sharks belonged to an extinct group called ctenacanths and were each roughly 10 to 12 feet (3 to 3.6 meters) long - about the size of today’s oceanic whitetip shark.
A Rare Glimpse Into an Ancient Sea
The fossils were found in limestone formations dating to the Middle to Late Mississippian Period. During that era, large parts of eastern North America were covered by a warm, shallow sea rich in marine life. Over 70 ancient fish species have now been documented from Mammoth Cave alone, highlighting the area’s importance to paleontology.
“Finding baby shark cartilage in such good condition is incredibly rare,” said Hodnett. “These discoveries help fill key gaps in the fossil record during the formation of the supercontinent Pangea.”
The team recovered teeth and jaw fragments, including a well-preserved partial jaw from a juvenile G. careforum. Cartilage fossils are especially valuable, since cartilage decays easily and is rarely preserved.
Collaboration Below Ground
This success comes from careful planning and partnerships. “Every discovery here is thanks to deep collaboration,” said Barclay Trimble, superintendent of Mammoth Cave National Park. Volunteers, researchers, and the Cave Research Foundation helped explore hidden tunnels, riverbeds, and narrow crawlways.
In fact, G. careforum was named in honor of the Cave Research Foundation’s support in the field. A single T. trimblei tooth, spotted by Superintendent Trimble in 2019, kicked off the current wave of discoveries.
What These Sharks Tell Us
T. trimblei stood out with its branching tooth structure, likely used to grip prey in Mississippian-era waters. Meanwhile, G. careforum had a shorter head and a powerful bite - ideal for hunting smaller fish and squid-like orthocones.
These sharks likely lived in coastal habitats full of bony fish, shelled organisms, and other marine species. The fossilized remains offer a record of environmental changes during the slow merging of continents.
Preserving Fossils for the Future
Retrieving delicate fossils from tight cave spaces takes precision. Field crews used sediment screening and microscopic analysis to ensure nothing was missed. With stable underground temperatures, Mammoth Cave offers ideal conditions for preserving fragile fossils for decades to come.
Guidelines are now in place to protect and guide future digs, helping researchers continue uncovering the secrets buried in the world’s longest cave system.
Why This Matters
These fossils allow scientists to compare shark evolution across time and geography. The body sizes, teeth, and skeletal structures offer clues to how species adapted - or disappeared - as Earth’s oceans and landmasses evolved.
With similar fossils being found in Europe and northern Africa, the discoveries from Mammoth Cave help connect the ancient geological puzzle pieces of our planet’s past.
Exploration Is Far From Over
The recent findings of T. trimblei and G. careforum prove that even well-known locations like Mammoth Cave still have stories to tell. More fossils likely remain hidden in deeper chambers, waiting to shed light on Earth’s distant past.
As researchers turn to advanced scanning and mapping techniques, the next chapter in prehistoric discovery may be just around the bend — or deep below the surface.
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