Triceratops

What it was like

Triceratops was a heavily built plant eater with three horns on its face and a wide bony frill behind its head. It grew up to about 9 meters (30 feet) long, making it one of the largest horned dinosaurs known.

Scientists disagree about what the horns and frill were mainly for. Some think they were weapons for defense against predators, while others argue they were used to identify rivals and attract mates.

Its world

Triceratops lived in the Late Cretaceous, from about 72 to 66 million years ago, across what is now the western United States and Canada. Its bones turn up in rock layers such as Hell Creek and Lance, alongside Tyrannosaurus, Edmontosaurus, Ankylosaurus, and Pachycephalosaurus.

Triceratops was likely prey for Tyrannosaurus, and it was one of the last dinosaurs alive before the extinction 66 million years ago, when an asteroid struck near Chicxulub in Yucatan, Mexico.

How it was found

Marsh named Triceratops in 1889. More than any other horned dinosaur, its fossils keep turning up: about 142 finds have been recorded so far, including skeletons from hatchlings to full-grown adults.