The Bramble Shark, Echinorhinus blakei, is yet another of the scarce species known from Bakersfield, CA, although they appear to be slightly more common than their East-Coast contemporaries. As with all Echinorhinus teeth they are only rarely found complete. Teeth are small, usually have cusps facing at odd angles on either side of the primary cone, and have a paper-thin root.

Echinorhinus blakei height 10 mm, width 15 mm

Also see:
Lee Creek Bramble Sharks by Bill Heim
The Genus Echinorhinus