I think that if you had no problems in training, then the type of shoe is not really the cause.
It's just the extra distance, more miles of pounding your toes, your feet getting damper as you run (and sweat) for longer - especially if you went through the showers?
I lost a toenail after one marathon, but not the others, but all were done in the same kind of shoe (not the same pair, though!).