Above is the front and back of a tooth of Carcharocles chubutensis, UF262182. This fossil was found in the Culebra Formation in Panama (Miocene). Although this shark was not as large as the famous C. megalodon, it could reach large sizes—at 12.2 m (40 feet), it was about the length of a city bus! The tooth featured above is about half the length of the largest C. chubutensis that has been found. A paper detailing this (and other fossil shark teeth found in Panama) can be accessed here.