Charlie, there's a whole book on the origins and history of bunyip lore. Incidentally it didn't mention Masola's contribution, which described the outline, carved in the bank of a very inland river (dim memory says "the Murray, somewhere near Mildura) of what may have been a seal, as judged by Masola from its rather large size and shape. Associating it with bunyips was pure Masola, who was a curator at the National Museum of Victoria at the time.

Cheers, Rowan