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A new illustration of Strigilodus tollesonae created specially by artist Benji Paysnoe. The new species is more closely related to modern ratfish than to other modern sharks and rays. Illustration by artist Benji Paysnoe

New Species of Ancient Shark Identified at Mammoth Cave

Mammoth Cave National Park will celebrate the new discovery and other types of fossils found within the cave on Monday, October 23.

A brand new species of petalodont (“petal-toothed) shark was discovered within the Ste. Genevieve Formation rock layer at Mammoth Cave National Park.

The new shark species, Strigilodus tollesonae, was discovered when several small spoon-like teeth were found in a cave wall and ceiling during an ongoing paleontological resources inventory (PRI) coordinated by Mammoth Cave and the National Park Service (NPS) Paleontology Program. The public announcement came on National Fossil Day (NFD), a day to celebrate and promote the scientific and educational values of fossils.

“We are excited to finally announce the discovery of our first new shark species at Mammoth Cave on NFD,” said Superintendent Barclay Trimble. “Teams of geologists, paleontologist, park staff, and volunteers have been hard at work deep inside the cave identifying and collecting fossils since the paleontological resources inventory began in 2019. Their important research allows us to better understand the scope, significance, distribution, and management issues associated with the fossil record found within Mammoth Cave.”

About the new shark, Strigilodus tollesonae

Strigilodus tollesonae was a type of extinct shark that is more closely related to modern ratfish than to other modern sharks and rays. The teeth uncovered at Mammoth Cave represent all known tooth positions in the mouth of both adult and juveniles of the new species. The teeth were arranged in a fan-like structure with a large tooth in the middle and three other teeth, decreasing size, next to it. Each tooth had a single rounded curved cusp for clipping and grasping hard shell prey, while the inner/tongue side of the tooth was long with ridges for crushing. Strigilodus tollesonae may have lived like a modern skate, feeding on snails, bivalves, soft bodied worms, and smaller fish.

The name Strigilodus tollesonae translates to “Tolleson’s Scraper Tooth.” It is named in honor of Mammoth Cave National Park Guide Kelli Tolleson who provided outstanding field support for the PRI. Tolleson discovered many important fossil localities through her work and led expeditions to the fossil sites which are limited in accessibility due to the remote and sometimes challenging sections of cave where the specimens are found. Many of the sites are in areas of low ceilings requiring crawling for long distances on hands and knees, and at times, belly crawling. The fossils are commonly located in the cave ceilings or walls which researchers and volunteers carefully collect using small handheld tools.

The PRI began in November 2019 when shark fossil specialist John-Paul (JP) Hodnett of the Maryland-National Capital Parks and Planning Commission began to work with the NPS Paleontology Program to identify the park’s shark fossils. At least 70 species of ancient fish have been identified at Mammoth Cave from the over 25 caves and cave passages that have been surveyed.

Upcoming fossil event!

National Fossil Day was officially celebrated on October 11, 2023, but Mammoth Cave National Park will celebrate the Strigilodus tollesonae discovery and other types of fossils found within the cave system on Monday, October 23. Paleontologists, educators and park guides will present fossil-related activities to highlight the scientific and educational value of paleontology and the importance of preserving fossils for future generations.

Learn more about the amazing fossils at Mammoth Cave and the 2023 National Fossil Day artwork at A 350-Million-Year-Old Time Capsule in the World’s Longest Cave System webpage.


About the Author

Michael Aldrich

Michael Aldrich is Nashville Parent's Managing Editor and a Middle Tennessee arts writer. He and his wife, Alison, are the proud parents of 4-year-old Ezra and baby Norah.