You are in the coal swamp forests of Europe, 310 million years ago.

The air in the Carboniferous swamp was thick, hot, and smelled intensely of sulfur and rotting vegetation. You were crouched behind the sprawling roots of a giant tree, observing a small tetrapod feeding in the shallows of a murky, slow-moving river. The canopy above was a dense mesh of ferns, blocking out most of the sky.

Suddenly, the small tetrapod vanished. A massive ripple disturbed the water, and the surface became still again.

Slowly, the predator emerged from the depths. It was an Anthracosaurus, measuring nearly 3 meters in length. Its elongated, crocodilian-like body was dark, dripping mud and water, and its 40-centimeter skull was aimed directly in your direction. You held your breath as its tiny, intelligent eyes locked onto yours.

It opened its massive jaws, revealing rows of sharp, conical teeth—the apex predator of this swampy world. It didn't look like a lizard, but rather a bizarre, dangerous hybrid of salamander and crocodile. It breathed out with a low hiss, fogging the humid air with its wet breath.