Fig. 1

Example of ceratopsians in which the similarities are greater than the differences. Two genera of long faced chasmosaurines Chasmosaurus belli (a) and Anchiceratops (b) versus two genera of short faced centrosaurines Styracosaurus ovatus (c) and Centrosaurus apertus (d). Compare with the two species of Centrosaurus: Centrosaurus apertus (d) and Centrosaurus nasicornis (e). The two Centrosaurus species are linked by the hook-like process over the frill fenestra, and are separated in part by the nasal horn. Courtesy of Gregory S. Paul. Scale bar 1 m