The oldest known horned dinosaur in North America iscalledZuniceratops. It lived 12 million years before Ryans find,andalso had large horns.

• 目前在北美地区发现的最为古老的有角恐龙是祖尼角龙。它生活的年代比上面所说的那个恐龙还要早上1200万年，其头上同样长着多只硕大的角。