Pristiophorus sp.
Early Miocene (Saucesian)
Jewett Sand, Pyramid Hill Sand Member
Pyramid Hill, Kern County, California, USA

0.5 inch excellent rostral spine of a sawshark (not a sawfish).

Pristiophorus is a sawshark genus that appeared by the Late Cretaceous and still lives today.  Rostral spines and teeth are also known from the Eocene of Antarctica, the Middle Miocene of Peru, and the Early Pliocene of Chile.

Sawsharks are actual sharks (Order Pristiophoriformes) while sawfishes are technically classified among the rays. In sawsharks the rostral spines are enameloid-coated and are shed. In sawfishes the spines are not enameloid-coated and grow throughout life.

Sawshark remains are not found in many fossil localities because they have always frequented deepwater environments, and even today, many of those deposits remain in deepwater.