It's the little details that are hard to explain, like the missing tongue or the brain damage.
The brain damage is not out of the question if they were victims to a close range weapons test.
A halfway decent examination should show if it was torn on bitten through... Writing this I realise it must have been bitten through by either external means (animal) or localized (bit off own tongue) or it would have been mentioned as another mystery.
But for me, one thing that is harder to explain is the skull fragment. For that, there would have definitely been tooth or tool marks. Unless of course, she fell....
The bigger mystery IMO, is the absence of reported blast marks or damage to the terrain one would expect from testing explosives.
Mid air?