Teeth discovered in Mammoth Cave National Park in Kentucky, USA, have led to the identification of a new species of ancient shark. The park, home to the world's largest known cave system, Mammoth Cave, served as the backdrop for the find.
During a paleontological resources inventory conducted by Mammoth Cave and the National Park Service (NPS), palaeontologist unearthed spoon-like teeth embedded in a cave wall and ceiling. This inventory, ongoing since 2019, focuses on collecting and identifying fossils within the cave.
The extinct shark, named Strigilodus tollesonae or "Tolleson's Scraper Tooth," belongs to the petalodont family, characterised as "petal-toothed" sharks. According to the NPS, this shark is more closely related to a modern ratfish than to contemporary sharks and rays. An artistic representation suggests the shark might have possessed broad fins resembling those of a stingray.
The new species received its name in homage to Kelli Tolleson, a guide at Mammoth Cave National Park, recognised for her exceptional field support during the paleontological inventory. Tolleson's efforts involved discovering crucial fossil sites in challenging and remote cave sections, often requiring extensive crawling and collection using handheld tools.
The teeth found in the cave showcase all known tooth positions in both adult and juvenile specimens. Arranged in a fan-like structure with a large central tooth surrounded by progressively smaller ones, these teeth feature a single rounded curved cusp for clipping and grasping hard shell prey. The side facing the tongue or inside of the mouth is long with ridges designed for crushing. Scientists infer that the shark likely lived similar to a modern skate, feeding on snails, bivalves, soft-bodied worms, and smaller fish.
This newly identified species adds to the diversity of ancient fish found within Mammoth Cave, with the NPS noting the discovery of at least 70 species in the 350-million-year-old cave system. The consistent temperatures, slow erosion rates, and protection from external erosional forces contribute to the preservation of shark and fish fossils in the cave.
As we delve into the depths of Mammoth Cave, we unearth not only the remnants of a bygone era but also a testament to the remarkable diversity of life that once thrived in these subterranean realms. With each find, we are reminded that, even in the darkness below, the past continues to whisper its secrets, inviting us to unravel the mysteries of ancient life that echo through time.