While farming HQ lion skins in North Karana , I killed everything that I came across. I looted a few of these off of,
a highland lion
a griffawn
a griffon
I was not keeping an eye out for them to begin with, should have!! They may also drop from the - a griffenne - But cannot say for sure?
They are about as rare here as the HQ lion skins though!! Because when I was done farming here I had almost the same number of each. LOL