The deadening sound of the skulls smashing against one another echoed across the Juarez bullring. The year was 1907, and an American bison and a Mexican bull had just collided head on. Promoters had brought the two animals together with dual purposes. They wanted to see which of the beasts was tougher, and they wanted to make money. Having sold 10,000 tickets to the event, the promoters had accomplished the latter goal. The only thing that remained, then, was to see whether the buffalo or the bull be the first to fall.