It is warm morning during the Late Cretaceous of what is now Dinosaur Provincial Park, in southern Alberta, Canada. It is spring, and numerous species of angiosperms, or flowering plants, are beginning to bloom, and the sun is shining across the vast coastal floodplain on the western shore of the Western Interior Seaway.

It is also mating season for the vast herds of large plant eating dinosaurs that inhabit the area. A lone male Chasmosaurus struts about on the coastal floodplain, meandering among his herd, looking for a mate. In the distance he spots a female Chasmosaurus, and he advances towards her.

He calls to her with a low bellow and lowers his head, exposing his large rectangular frill. The thin sheet of skin across his frill is packed with blood vessels, which when flushed with blood, could have created a striking and vivid display to attract females.

After several minutes of displaying, he hears an unusual call. A small subadult male Styracosaurus rushes past him in a hurry, nearly missing him. Disturbed by the commotion, he turns around to investigate. He sees a second, larger adult male Styracosaurus, rushing at full speed towards him. This Styracosaurus is full of adrenaline and is ready to fight any animal in his way for access to females.