High Noon

Actually, it's a bit after, but it works.
Snagged from Julia Segal, who posted it with the tile, "Damn you, little T. Rex Arms!" So now you know: the way to survive a T. rex encounter is to challenge the dino to a gunfight. (And technically, the genus name should be capitalized; the species name shouldn't.) Also, I think the following panel at the very bottom, below the first eye close-up, and beside the holstered gun, would be very funny.