Sphyrna sp.
Middle Miocene
Round Mountain Silt, Sharktooth Hill Bonebed
Ernst Ranch, Bakersfield, Kern County, CA, USA

Rare 6mm hammerhead shark tooth.

Sphyrna is the genus that includes extant and extinct hammerhead sharks.  It dates back to the Oligocene and perhaps the Late Eocene.  Hammerhead teeth tend to be uncommon wherever they occur (Oligocene of South Carolina, Miocene of California, Miocene-Pliocene of North Carolina, Miocene-Pleistocene of Florida, Early Miocene of Australia).

What should be understood is that the isolated fossil teeth of a few related sharks (e.g. sharpnose sharks) can be difficult-to-impossible to distinguish from hammerhead teeth.  This specimen does look like a hammerhead tooth but it also resembles a sharpnose shark tooth, which is also rare in the STH Bonebed. It’s an unusual form for the locality.