Triceratops. Computer enhanced image of the fossilised skeleton of a Triceratops dinosaur. Triceratops (threehorned face) was a herbivore that grew up to 9 metres (m) long and weighed up to 6 tonnes; their skulls were up to 2m long. This powerful and heavilybuilt dinosaur was a formidable opponent for any predator. They defended themselves with horns, whilst a bony frill protected their neck. The frill had slots where large muscles for powering the creatures beaklike jaw were attached. Triceratops evolved only a few million years before dinosaurs became extinct at the end of the Cretaceous period (about 65 million years ago).