If you're like me, you probably skipped killing the crocs along the way due to the awesomeness of the story line or was distracted by something else and chose not to fight them. This, however is a mistake. If you finish the storyline quest progression for Silverpine Forest w/o getting this item AND turning it in w/ the finished quest it gives, you'll be out of luck for the 60/60 quests completed achievement and locked out of getting the Loremaster as well.
I currently have a ticket in for this and will report back on it.
Update: My darling wife just finished Silverpine with 3 quests to spare and got the achievement. Going to compare her list to mine and see what I missed.