The ankylosaur (ANG-kuh-lo-sawr) lived about 80 million years ago. This tank-like dino had armor, or protective skin, and a powerful tail it could swing like a club.
For years, scientists thought it used its tail to fight other types of dinos. But after studying marks on fossils, experts wondered if it used its tail to fight other ankylosaurs!
To find answers, Arbour studied living animals like deer. Deer use their antlers against other deer to protect things like territory. That’s an area that an animal claims as its own. Arbour thinks ankylosaurs used their tails for similar reasons. The dinos swung them hard enough to break through other ankylosaurs’ armor. Ouch!