Centrosaurus apertus

This was once going to be part of a bigger drawing, with just the head of Centrosaurus, compared to other ceratopsian heads (Triceratops, Torosaurus, Anchiceratops, etc), but I loved this guy's face so much I wanted to expand. Thus, you got a rearing centrosaur, probably in rear as part of a threat. Centrosaurus lived 76-75mya, was 20ft long, and prey for the tyrannosaurs of the area.

Greg Paul's Princeton Field Guide to Dinosaurs and Bakker's Dinosaur Heresies, a good book despite its age, used as references.