340-million-year-old shark tooth found in world's longest cave
A 340-million-year-old fossilised shark tooth, measuring half an inch, was discovered in Kentucky's Mammoth Cave, world's longest cave system. The species, which has been named Macadens olsoni, is notable for its curved tooth whorl adapted to crush small sea creatures. Findings suggest the ancient shark likely grew to less than a foot in length and probably ate molluscs and worms.