You are in the floodplains of North America, 150 million years ago.

The air in the Morrison valley was thick, humid, and smelled of wet earth and resinous conifer needles. It was mid-morning, and you were navigating a dense thicket of ferns, keeping close to the treeline.

Then, the ground began to tremble. It wasn't a sharp seismic shock, but a rhythmic, deep vibration that resonated in your chest.

You moved behind a massive, rotting log and waited. Emerging from the ferns were the owners of the valley. A herd of Camarasaurus was moving toward the river. There were at least a dozen of them, a mixture of sub-adults and massive, fully-grown individuals. Their bodies were robust and barrel-like, sturdy, and built for strength. The most striking feature was their heads; they were high-held, blunt, and boxy, with large nostrils located in front of their eyes.

The herd stopped to feed, and the sheer volume of foliage they consumed was breathtaking. They didn't strip leaves gently like some sauropods; they used their spoon-shaped teeth to bite through thick branches, chomping up ferns and conifer cones with efficient, powerful bites.

They were remarkably communicative. A low-frequency rumble, too deep for you to fully hear but felt in the jawline, seemed to maintain the herd's coordination.