You are in the forested plains of North America, 66 million years ago.

The ground trembled, a rhythmic, deep thudding that vibrationally announced the herd long before you saw them. Stepping through the humid Cretaceous ferns, you stopped instantly. A sea of dusty-brown, scaly hide shifted through the floodplain—an immense herd of Edmontosaurus migrating. They were massive, easily 40 feet long, moving mostly on four legs with surprising grace for their size, their horselike beaks tearing at vegetation while others stood bipedally to browse higher.

The noise was overwhelming—a cacophony of low, resonant honks, deep grunts, and the rhythmic sound of powerful jaws grinding plant matter. You were close enough to see the intricate, small scales covering their skin and the fleshy, segmented frill running down the back of a particularly large, scarred male.

A few individuals paused, turning their long, narrow heads toward you, their dark eyes cautious but not immediately panicked, likely used to dealing with predators. The sheer size of them—larger than a T. rex—was humbling. A juvenile, protected by the dense, tight-knit group, made a high-pitched chirping sound. You stood perfectly still, dwarfed and silent, as a living, breathing mountain of prehistoric life slowly moved past you, shaking the earth with every step.