You are in the savannas of North America, 32 million years ago.

The air in the early Oligocene floodplain was humid and smelled of wet clay and rust. You were crouching behind a thick stand of ferns, watching a nightmarish creature in broad daylight.

It was an Archaeotherium—a “killer pig”—though it looked more like a fanged, six-foot-tall warthog-cow hybrid.

The beast was taking a drink, standing knee-deep in the shallow, mud-brown water of a wide river, its massive, bony-lumped head bowed down. It didn’t drink delicately. It took massive, snorting gulps, splashing water onto its shoulders. It had a high, hump-like shoulder structure that made its front end look incredibly powerful, almost unbalanced compared to its hindquarters.

Even from fifty feet away, the sound was terrifyingly loud—a rhythmic, guttural slopping noise that vibrationally shook the ground. Its snout was long and wet, coated in sludge from rooting.

Suddenly, it stopped, lifting its head. The massive skull, nearly three feet long, was adorned with grotesque bony protrusions under the eyes. Water dripped from its white, dagger-like canines. It didn't look smart, but it looked incredibly aggressive, its tiny eyes scanning the banks with a raw, primal alertness, eventually landing on your hiding spot. It grunted, a deep sound that felt more like a rumble of thunder than an animal noise.