La Brea Tar Pit Beetle?

[Mochaccino]

Hello,

 

Could anyone identify the species of these two beetles from the La Brea Tar Pits of Los Angeles, California, USA? The large one is 3 cm and the small one is 1 cm. I've heard the terms "water beetle" and "carrion beetle" get thrown around but it's confusing. I think the larger might be Cybister explanatus? Thanks.

 

Edited August 28, 2022 by Mochaccino