You are in the coastal forests of North America, 20 million years ago.

The air in the early Miocene forest was thick, humid, and smelled intensely of wet earth and pine resin. You were hiking when a sudden silence befalls the woods. The chattering of arboreal rodents ceased. You froze when you scanned the trail ahead.

Emerging from the massive ferns about twenty paces away was an Amphicyon. It was huge, taller at the shoulder than a man, carrying the sheer bulk of a bear but walking with the terrifying, purposeful gait of a giant canine. Its fur was thick and brown, matted with mud. It didn't sneak. It knew it didn't have to.

Your eyes met. Its eyes were amber, intelligent, and entirely cold.

It stopped, raising its massive, blocky snout to scent the air. You saw the yellowed, jagged edge of its molars—teeth built for tearing through tough hide and shattering bone, not just eating fruit. It took a step toward you, its massive paws sinking into the soft mud, and you hear the low, rattling growl start in its chest…