Artwork showing the relative scale of humans and Triceratops. Meaning 'three-horned face', Triceratops gives is name to an entire family of dinosaurs called ceratopsians, which includes Styracosaurus, Pentaceratops and Torosaurus. Triceratops lived at the same time and in the same place - North America during the Late Cretaceous period - as Tyrannosaurus rex, and the two likely had a predator-prey relationship. Triceratops is estimated to have grown to lengths of 9 m (30 ft).