Let's rate some bulls

[Koen G]

Medieval artists didn't necessarily have the modern reflex to "correct" back to nature what was in their example. Quite often, they copied what was in their example and made it worse. The living animal as it is projected on the retina is a separate thing from the way a culture depicts it. 

When I was little, me and my classmates all drew houses with pointed roofs and rounded shingles. But shingles in this area are mostly straight-edged, like rectangles. But this was how we saw others draw a house, so we just adopted the technique. There was no possible sequence of events that would have made us go outside, observe shingles, and note that we were drawing them weird. Or that we had the orientation of the roof flipped compared to the usual position of the front door. Or that our layout of doors and windows didn't make sense, or that our chimney was in an impossible position. We just drew houses the way we saw others draw houses.

It is possible, maybe even likely, that when the VM artist copied this bull, the thought "what do actual bulls look like" did not cross their mind a single time. They were just copying the image, which was the only referent at that moment. If their example was already flawed or confusing, unclear, faded, degraded, they would have compounded these features rather than go out to the pastures, holding up a pencil to a bull while squinting one eye to take its proportions and shapes.