Dragons, Dogs & Amadillos?

[asteckley]

Fortunately we can exclude the armadillo because of the C14 date. (Unless one assumes a modern forgery, which I don't).  

Well, one need not assume a forgery nor a modern one. It would only require that the drawing was made later than assumed -- sometime in the mid-16th century or later (barring any doubly extreme scenarios like earlier explorers reaching the Americas, etc.).