Ooops… I never even thought of that image as possibly 'breaking the rules'.. mea culpa.
I guess that, in a purely technical sense, it is a portrayal of bestiality… Can it, however, be excused/excepted from the general rule on the grounds of its antiquity and artistic merit?
I suppose it raises the much debated issue of 'is it porn, or is it art?' I'd have to say that I think there are hundreds of images posted on certain other threads in this forum that, whilst they may not depict bestiality, could be considered much more graphically offensive than this one, depending on one's sensibilities… However, probably this thread is not the place to start a discussion of that sort.
I apologise, in any case, for any inadvertent transgression on my part! 