You are in the badlands of Mongolia, Asia, 90 million years ago.

The air in the landscape was freezing, a sharp contrast to the scorching day, and your headlamp beam was already flickering, cutting a weak path through the sparse scrubland. You were only trying to reach the base camp before the midnight dust storm, but the silence—deeper than any desert silence you had known—made you stop.

Then came the sound. Not a roar, but a low, rhythmic hiss, like a dying radiator, followed by the soft crunch of feathers against dry brush.

You froze. Fifty feet away, a shadow detached itself from the rocky outcrop. Even in the gloom, its massive 16-foot, stocky frame was unmistakable, covered in a mottled, grayish-brown plumage that made it look part of the landscape.

An Achillobator.

Its slit-pupil eyes caught the fading light of your headlamp, reflecting a predatory yellow. It didn’t charge immediately. Instead, it tilted its head—an eerily bird-like movement—communicating with a second member of its pack—which has been skulking in the shadows of another corner of the outcrops as you noticed at the corner of the eye—with a quiet, guttural bark.

You then knew that the raptors are hunting, and they have you cornered…