Look close at the carnage...

Don't think this was a rod failure. This problem started in the wrist pin area of the piston. The pin may have just broke. This happens from weak pin or hydrolocking or severe detonation. The pin boss in the piston may have failed. But, I kinda tend to agree with Mike as I was thinking along the same idea. The pin boss is simply broken out of the piston. Looks like the pin may have dug into the cylinder wall and ripped the piston apart.

Post some pics of the cylinder wall. What kind of damage happened to the cylinder head on that cylinder?

Leon