You are in the forested plains of South America, 70 million years ago.

The air in the Late Cretaceous was warm and semi-arid, vibrating with the drone of insects. You pressed yourself against the trunk of a large Araucaria tree, watching a herd of Saltasaurus graze in the distance. They were remarkably small for sauropods, maybe only 10 meters long, with barrel-shaped bodies and stubby, thick necks.

They looked almost defenseless at first glance, but as one turned, you saw the sunlight glinting off the armored nodules—osteoderms—embedded in its skin. The bumpy, crocodile-like scutes ran along its back and sides, a heavy coat of armor for a plant-eater.