1.36" Serrated Fossil Auriculatus Tooth - Sarysu River, Kazakhstan

Carcharocles (Otodus) auriculatus was a large, "mega-toothed" shark that lived during the Middle Eocene, about 38 to 48 million years ago. It had coarsely serrated teeth with distinctive serrated side-cusps. During the Oligocene, Auriculatus would evolve into Carcharocles angustidens, which in turn evolved into the much larger and better known Megalodon during the Miocene.

Fossil teeth of Auriculatus are fairly hard to obtain compared to other sharks in the Carcharocles genus. They are only found in a handful of locations: most come from North Carolina, South Carolina and Morocco. Teeth have also be found in Kazakhstan and the United Kingdom.

Auriculatus teeth have been found up to a maximum size of about 5 inches, compared to a maximum size of 7.5 inches for those of the Megalodon.

Researchers debate whether Auriculatus and other mega-toothed sharks belong in the Carcharocles genus or the Otodus genus. The Otodus designation is considered fairly controversial, so Carcharocles is much more widely used for this shark.