Kentucky, a state not commonly associated with marine discoveries, has become the focal point of a significant marine paleontological find. The fossilized teeth of a 300 million-year-old shark species, known as Strigilodus tollesonae, were recently unearthed in Mammoth Cave National Park, revealing a fascinating glimpse into the ancient seas that once covered the region. “We are [so] excited to finally announce the discovery of our first new shark species at Mammoth Cave,” said Barclay Trimble, the superintendent of Mammoth Cave.
“Strigilodus tollesonae was a type of extinct shark that is more closely related to modern ratfish than to other modern sharks and rays,” explains John-Paul Hodnett, a paleontologist with the National Park Service and Maryland-National Capitol Parks and Planning Commission, and his colleagues. Ratfish, which inhabit the deep sea, share similarities in their diet, cruising the seafloor for shrimp, clams, worms, seastars, and small fishes. Belonging to the now-extinct group of petalodonts, or “petal-toothed” sharks, Strigilodus tollesonae boasted spoon- or petal-shaped teeth, arranged in a fan-like structure; the teeth exhibited a prominent central tooth surrounded by three smaller teeth, progressively diminishing in size. The collected specimens represent the complete array of tooth positions found in both adult and juvenile individuals of the newly discovered species. Characterized by a singular rounded curved cusp, each tooth was adept at clipping and grasping hard-shelled prey, while the inner or tongue side of the tooth featured an elongated structure with ridges, designed for efficient crushing. This unique dental configuration suggests a diet that included snails, bivalves, soft-bodied worms, and smaller fish. The species was found in the Ste. Genevieve Formation rock layer at Mammoth Cave National Park and named in honor of Mammoth Cave guide Kelli Tolleson.
Although Kentucky now has no direct access to the ocean, during the time of Strigilodus tollesonae, the region was submerged beneath shallow tropical seas. This period, occurring approximately 340 to 320 million years ago, aligns with a chapter in Earth’s history when the continents were in constant motion. Pangea (the supercontinent that would later amalgamate North America, South America, Africa, Europe, and other landmasses) was still in the process of formation. Kentucky, then, found itself submerged within the ebb and flow of ancient seas that stretched across what would eventually become familiar continents. As the land underwent transformation through geological epochs, the remnants of this submerged history were preserved, waiting for scientists to unravel the secrets hidden within the layers of time.
The finding of 300 million-year-old extinct shark teeth from a previously unknown species marks a significant milestone in paleontological research. “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,” said Trimble. “Their important research allows us to better understand the scope, significance, distribution, and management issues associated with the fossil record found within Mammoth Cave.”
The groundbreaking findings were publicly announced on October 11, coinciding with National Fossil Day. The discovery is reported in a paper in the journal Historical Biology.
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