You are in the coastal plains of North America, 90 million years ago.

The morning mist was still clinging to the ferns when you stepped out of the tree line into the river delta. It was supposed to be a quiet survey of the Early Cretaceous shoreline, a routine check for petrified wood. It was anything but quiet.

A low, guttural rasping sound, like grinding stones, broke the silence. You froze, your breath catching in your throat.

Twenty yards away, partially submerged in a boggy patch of mud, was a creature that looked more like a piece of the landscape than an animal. It was a Nodosaurus.

It was roughly fifteen to twenty feet long, a low-slung, heavily armored tank. You watched, hidden behind a conifer, as it adjusted its position, its dark, greenish-brown hide shimmering with moisture. The armor wasn't just skin; it was a complex mosaic of rounded bony knobs—osteoderms—that formed a protective shield across its back. As it turned to graze on a patch of low-hanging ferns, you saw the thick, dagger-like spikes projected outwards along its side, arranged in rows to deflect predators—a masterpiece of biological defense.

For a moment, it stopped eating and turned its head directly toward your hiding spot. Its eyes were dark and cautious.