I'd be more interested to see medieval depictions of elephants from the South of France, Spain or Italy to compare against.
Stuff from England or Northern France is going to be driven by descriptions given by priests and monks. So not only do you have secondhand accounts or reproductions of other pictures, but you're filtering it through a religious filter. Trumpets and ivory have religious significance, and depicting them incorrectly may have some significance.
Also, didn't mammoth tusks curve upward? There may have been some symbolic legacy taking place there as well.
The article notes that some scholars would ascribe religiously inspired characteristics to real animals, but it also says that readers were generally canny enough to realize this was going on and points out that there were well-known works that didn't do this.
Stuff from England or Northern France is going to be driven by descriptions given by priests and monks. So not only do you have secondhand accounts or reproductions of other pictures, but you're filtering it through a religious filter. Trumpets and ivory have religious significance, and depicting them incorrectly may have some significance.
Also, didn't mammoth tusks curve upward? There may have been some symbolic legacy taking place there as well.