Be aware that everything else at the undead tower will agro on the putrid skellies and KS you if you are not careful.
Yes the Putrid Rib Bones drop.
Highly resistant to cold, disease and poison. (Using an 21 shammy, here). EDIT: Poison and disease dots never got past resist and cold only did about 1/3 normal damage.
Only seem to spawn at night.
Edited, Aug 22nd 2016 5:10am by Bijou