I too, have seen differences of opinion on Fugger v. Kortbrath engraving.

In conversations with Winston Churchill he told me that he worked with Fugger at G&H, and that Fugger would let him watch while he worked, but Fugger never directly taught him anything.

Unfortunaely my copy of Prudhomme's book was lost on a loan several years ago so I can't look up earlier squirrels. These engraved squirrels by Robert Swartley on a Low Wall I completed many years ago and was shown at the Minneapolis Institute of Arts. (BTW, oakleaf is one of my least fav designs but requested by the client.)
From Custom Rifles In black & white