Lawyers used sheepskin as anti-fraud device for hundreds of years
As a related aside, split pieces of wood--so the holder could check and see the pieces matched up--were also used as an anti-fraud device (https://en.wikipedia.org/wiki/Tally_stick).  Apparently, these pieces of wood are were we get the term "stock."In case you ever wondered why the word for an ownership share is the same word as "stick, trunk, block of wood, or post" (Germanic / Dutch / Old English), this is apparently it.Second aside, 100s of years of such wooden stocks were stored in the British Houses of Parliament.  They were ordered cleaned out, but, apparently the cleaners got over zealous, and the stocks caught on fire with disastrous results.