You are in the floodplains of North America, 75 million years ago.

A low rumble shakes the ground, accompanied by a sound like crashing timber—the movement of hundreds, perhaps thousands, of Centrosaurus. The air is thick with the sounds of grunting, bellowing, and the constant ripping of vegetation as they move along the riverbanks. Young juveniles and mature adults move together in a collective unit. The high density of the herd suggests constant, close-contact interaction, perhaps communicating via social displays or vocalizations.