You are in the forested lakesides of Europe, 125 million years ago.

The air was thick with the scent of wet pine and ferns. You were moving slowly, trying to stay downwind, when the snapping of branches stopped you in your tracks. Through the mist, a massive shape emerged. It wasn't a predator, not like the sharp-toothed terrors in the deeper forests, but it was enormous nonetheless.

It was an Iguanodon.

It stood on four legs, grazing on a thick bed of horsetails, its bulky body nearly ten meters in length. It was a mottled brown and green, blending perfectly with the foliage. Suddenly, it froze. It raised its head, its long, rigid tail counterbalancing its front half as it rose onto its hind legs to reach the top of a giant conifer.

It used its fifth digit on each of its hands—a flexible, prehensile pinky finger—to drag down a branch, while the rest of its hand acted as a sturdy hoof. But the most striking feature was the thumb. It wasn't a finger; it was a hardened, foot-long conical spike. It stood out against the green, a formidable weapon that reminded you that even herbivores in this era were not defenseless.

It looked directly towards you, its eyes wary but not immediately aggressive, perhaps just assessing whether you were a threat to its herd—which you could now hear grazing further down the valley.