You are in the swamplands of North America, 76 million years ago.

The mist hung heavy in the Cretaceous swamp, obscuring the base of the towering conifers. You froze, listening. It wasn't the roar of a predator, but something far more alien—a resonating, booming sound, like a tuba mixed with a dolphin's call.

Suddenly, a tall, crest-headed figure emerged from the foliage, pushing aside palm leaves with a distinctive, Corinthian-helmet-shaped crest. It was a Corythosaurus. Its skin was a mosaic of tan and brown polygonal scales. It looked right at you, its cheek filled with freshly clipped vegetation. The sheer size—nearly 30 feet of solid herbivore—was breathtaking, yet it seemed more curious than aggressive. Then, it turned its head, and the entire herd behind it called out in harmony, vibrating the very air around you…