Researchers collecting fossils deep inside Kentucky's Mammoth Cave have uncovered the remains of a never-before-seen species — an absolutely tiny ancient shark with nail-like teeth.
The newfound species is called Clavusodens mcginnisi, or McGinnis' nail tooth. The animal lived 340 million years ago and belonged to a group of sharks known as obruchevodid petalodonts, or "chipmunk sharks" because of their tiny size and unusual teeth.
