I've been doing a fair bit of training/exploring in the ancient cavern and I've accumulated some mangled bones. Are they useful?

 

 

 

"You must first find the bones of barbarian heroes. These can be found as drops in the Ancient Cavern. Be warned that you must find 'chewed bones' rather than 'mangled bones'. Mangled bones are the remains of barbarians whose spirits are maddened by their imprisonment within the caves. Burning Mangled bones will reward you with a spectral assault! "

 

 

 

Is what the guide says... but do those barbs that spawn have better than normal drops?

I've used every Mangled Bone I had, always a drop. I think the best was a ranarr seed though. The drops as compared to the ones in the cavern that you normally fight are superior.