I meant you missed the dialog by not talking to the skull first. If Fergus was alive, after the skull's initial question, he would have made a comment that lead to a short conversation about Fergus and the quest to kill him.
Do you have a recent save before killing Fergus? I don't know if the Luck bonus (+12 IIRC) on the cap for the quest reward would be worth doing too much over for, though.
Oh BTW, welcome to the forum. <img src="/ubbthreads/images/graemlins/wave.gif" alt="" />