You are in the forests of Europe, 136 million years ago.

The air in the Early Cretaceous forest was thick, damp, and smelled of decaying ferns and pine resin. You stood perfectly still, shielded behind a massive conifer, watching a scene that would not be described by science for another 140 million years.

Breaking through the thicket was a Hylaeosaurus, a stunning "forest lizard" about 16 feet long. It was a walking fortress, its back covered in dense, bony plates that shifted as it moved. You caught your breath when it turned, revealing three large, sharp spines jutting from its shoulder—natural, formidable armor that glinted in the sunlight filtering through the canopy.