The Triceratops had the unfortunate honor of being one of Tyrannosaurus Rex's favorite meals, and when there are Rexes hunting you, you'd be wise to evolve some pretty spectacular defenses (just a Triceratops pro tip). This herbivore could inflict serious damage on marauding predators with its sharp facial horns and frill. In fact, they were such insane fighters that some paleontologists think Tyrannosaurs had to literally behead them to get them to quit! Artwork by Cheung Chung Tat.