Photographed at the edge of a wild marine estuary. A neat looking fly...even though it was perched on the (brace yourself) putrid carcass of a large sea lion. See this post for a trio of what I think may be the same species at the same spot 50 days later.

I'm assuming this is an acalyptrate (due to lack of a complete tranverse suture on scutum among other indicators). The aristae are barely visible...dorsally attached to the plump yellowish terminal antennomeres, and about twice as long. (The left one is pointing upward at ~90 degrees, the right one bending toward the viewer.) I believe I see one oral vibrissa just below the right antennomere, at the "middle angle" on the pale straw-yellow front of the face bordering the eye (that border almost appears to merge with the background). I wish the chaetotaxy were more discernible in the photo, but I think I see two flat longitudinal bristles on the frons, a few sticking out the back of the head (verticals or post-ocellars?) and a few above the point of attachment for the left wing (notopleural?).

Anyway, my best guess is something in the family Clusiidae. I'm hoping a knowledgeable BugGuide viewer will let me know if I haven't got a Clusiidae :-)