In the first overview of horned dinosaurs, R. S. Lull hypothesized two lineages, one of "Monoclonius" and "Centrosaurus" leading to "Triceratops", the other with "Ceratops" and "Torosaurus", making "Triceratops" a centrosaurine as the group is understood today.
To se lahko vidi na slikah, ki sta jih izdelala Charles Knight in Rudolph Zallinger.