I’m not sure that counts. The platypus isn’t a myth, even though the first specimen of it brought to European scientists was (reasonably) thought to be a fake.
There’s a myth about a giant leopard-creature whose breath can wipe out entire villages. That myth existing doesn’t mean that leopards are mythical. Plenty of mythical creatures are inspired by real animals, but I don’t think that means that the real inspirations are myths, even if someone only knew about the myth for awhile before learning about the inspiration.