Monoclonius one of the larger horned dinosaurs.  This centrosaur may have been very aggressive, based on a Pachyrhinosaurus skull with a severe head injury, evidence for which was apparent in that an extensive defect had scarred the right side of the face. It was determined that the animal most likely to have caused such a wound was a specimen of Monoclonius.
 
Named after the snake-like spikes on the frill, Medusaceratops is similar to the centrosaurine Albertaceratops and they may even be intermingled in the bone bed. It is the earliest known chasmosaurine.

Mercuriceratops was a chasmosaur found in Alberta and Montana.