You are in the forests of South America, 199 million years ago.

The air in the Patagonia region was already thick and heavy, smelling of ozone and crushed ferns. Lightning tore across the sky, bright enough to turn the stormy afternoon into momentary daylight. You huddled under a sandstone overhang, trying to keep your field journal dry, when the first flash of lightning tore through the, early Jurassic gloom, illuminating the floodplain.

Just then, you saw them.

Barely twenty meters away, huddled in a small, sandy trench, was a group of seven or eight creatures. They were tiny, maybe no larger than a housecat, with large eyes that caught the lightning’s glow—Mussaurus hatchlings. They were struggling, trying to stay close together, but the pounding rain was already turning their nursery into a muddy, dangerous mess. As infants, they were walking on all four legs, moving clumsily in the onslaught.

A deafening crack of thunder shook the ground, right above you.

The babies shrieked—a high, chirping sound—and huddled tighter against each other, looking absolutely terrified and completely exposed…