You are in the floodplains of South America, 80 million years ago.

The air in the Cretaceous marshland was heavy, smelling of sulfur and wet ferns. You froze.

Twenty yards away, a streak of textured, reddish-orange hide moved against the dry mud—an Aucasaurus. It wasn’t massive like a T. rex, but its narrow skull and piercing, intelligent eyes made it terrifying. It spotted you. With a low, rattling hiss that vibrated in your chest, it didn’t roar; it just leaned forward, those absurdly tiny, useless arms tucked against its chest. And it starts to approach you, crouching low in a stalking position…