Hmm- would the markings have to be mostly taken from realistic animals or mythical ones? Maybe both?
This may seem a bit odd, but a lot of birds, fish, rodents, and of course regular FH-related felines and canines have inspirational patterns that you could use for making your marking pack.
Especially birds... There's so many various breeds, and I always found them so vibrant and mysterious, they can actually be good 'models' for marking ideas. x'DD
Had used some of them myself, personally, for my own designs.