Here's my contribution for the evening... not very cool, perhaps... but it was taken by a monkey.
The website could not telegraph my request to view the picture.
I don't doubt the last photo's authenticity, but how much does it look like the bull's been sloppily photoshopped onto a crowd scene?
Oh, you better don't get started on bull vs people photos... It can get very nasty and unpleasant.
I'm going to say dirt, because it matches the wheels/tires, as well as the street and everything else in the picture.