Not only is it a giant snake, but based just on the picture, that man must be a giant. His head is bigger than the building he is standing next to!!! Oh wait, the perspective is making him look gigantic. Hmm, wonder if the same is true for the snake? LOL. This is he old fisherman's trick, take a picture with your arms extended holding the fish towards the camera.
Based on the mass of that snake, I think it is might be around 5 and 1/2 feet, if that. Still a brute, but not that unusual a snake for south Texas atrox.
That photo has been around for a while. It is a Western Diamondback and it looks like it was shot in south Texas where big diamondbacks still occur with some frequency. I actually think I know where those abandoned buildings are. I have flipped trash around the back there (didn't find and 9 foot atrox, however).
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Chris Harrison
San Antonio, Texas