Triceratops existed 68 million years ago in Maastrichtian stage, of the late Cretaceous period (what is now North America).
Did You Know? Traditionally, the frills on Triceratops’ head have been viewed as defensive weapons against predators. More recent theories suggest that these features were primarily used in identification, courtship and dominance displays just as reindeer, mountain goats and rhino beetles.
Fun Fact: Triceratops are called "tri" because of the three horns they possess.