Evans & Hogue 2006 says there are only 10 species in CA! Imagine that, a beetle family with only 10 species anywhere. Sadly, they don't list them all. This list extracted from that book.

Escarabajos Carroñeros - Photo (c) Victor W Fazio III, algunos derechos reservados (CC BY-NC), subido por Victor W Fazio III Lista de comprobación para Escarabajos Carroñeros (Familia Silphidae)