I’ve beheaded Western Diamondbacks before, and the head will keep yawning for well over an hour.
When I was a kid, I used to hunt snakes with a pellet pistol. If you draw a line between the snake’s two eyes, and then aim just behind the middle of that line, that’s where you place your shot for an instant kill. If you miss, the snake will focus all its attention on striking you and move directly at you, with its head raised off the ground. Your second shot better be on the mark.
When I was a kid, my friend and I caught big snapping turtles in the canal and river. Biggest was 63 pounds! We’d butcher them and sell the meat to a Deli in Cleveland. When we cut off the heads, we’d throw them in the fire, cuz they’d snap at anything that got close! Up to 18 hours.