You are in the swamplands of North America, 280 million years ago.

The air in the early Permian swamp was thick and carried the smell of rot and sulfur. You moved slowly along the muddy bank, navigating around giant horsetails and towering conifers. The area was alive with the sound of insects and the distant splash of something moving in the shallow, tannin-stained water.

You paused, feeling the air growing still. From the shadows of the dense fern forest, a massive, sluggish shape emerged. It was an Ophiacodon, nearly ten feet long from its narrow snout to its trailing tail. Its skin was mottled with dull shades of brown and green, blending perfectly with the wet bank. It moved heavily, its short legs struggling to lift its broad belly off the ground, yet it moved with the confidence of a top predator.

The creature stopped, turning its long, towering skull toward the bank. Its jaws, packed with dozens of sharp, needle-like "snake teeth," hung slightly open, displaying a ferocious grin. It didn't roar; early synapsids rarely did. It only breathed—a raspy, rhythmic sound.

For a moment, the Ophiacodon looked directly at you, its large dark eyes narrowing and locking onto you…