Triceratops
was one of the last of the highly successful horned dinosaurs
(suborder Ceratopsia, order Ornithischia). It is known from
perhaps hundreds of partial to complete fossil skeletons
collected in western North America from Late Cretaceous
rocks about 70 million years old. The name Triceratops means
"three horn face" and derives from the prominent
horns on the skull: one on the snout and one above each
eye. There can be little doubt that these horns were used
in aggressive behavior, whether for defense against contemporaneous
predators, such as Tyrannosaurus and Gorgosaurus, or in
sparring matches with others of its own kind.