but I'm leaning towards one of the Anatis sp. because the odd protrusions on the front of the elytra and the dark spots have a pale ring around them.

I concur with Anatis, and probably A. rathvoni. This individual is pretty 'young,' as they get progressively darker with age....Donner Pass, eh? Was it eating a conspecific? :-)

using Gordon's ref., this one keys to A. rathvoni. The "hips" on the lateral elytra margins and stronger angles on the shoulders are unique to A. rathvoni and A. lecontei, but A. lecontei has black pronotum lateral margins (and no spots). That said, a slight caution that this local is a bit further east than Gordon's distro shows. But if local were the only criteria, of the genus, only A. lecontei is shown from the Rockies in CO.

Tim, thanks again for another species identification. Donner Pass is in the northern Sierras in central/east California. It shows up in a field guide for the Sierra Nevadas (1), so range would seem to be ok.

looks like I'm helping to confirm those statistics of what little people know about our own geography/history. How embarrassing! Well, at least the beetle actually does fits within the expected range. Thanks for the correction :)