Part of Hall of Ornithischian Dinosaurs.

Triceratops dinosaur mount in the Museum's fourth floor fossil halls. R. Mickens/© AMNH

This 65-million-year-old Triceratops has a large frill on the back of its skull, two large horns over its eyes, and a smaller horn on its nose. On the side of the skull on display is a partially healed injury, perhaps caused by a conflict with another Triceratops.

The Triceratops horn was covered in material similar to that in our fingernails. The term "horn" refers to the hard, thick covering around the bone. The horn was about 40 percent larger than the bone.