At the base of a pale hill in the badlands of northeastern Wyoming, Susie Maidment hits her hammer against stone. She breaks off a fist-size chunk, grabs a loose piece between her fingers, and places it on her tongue. “Silty,” she announces, as the sediment brushes the roof of her mouth.
Maidment’s graduate student, Joe Bonsor, takes note on his clipboard, then brings a piece of rock close to his face and squints at it through a hand lens. The layer below this one has slightly larger sand particles, Maidment says—suggesting that the two formed under different conditions. It’s one of many bits of data needed for the job the two paleontologists have come over from the United Kingdom to do: piece together, layer by layer, the history of the Late Jurassic, from details in the rocks that formed at that time.
The hills around us on this June day sprawl with dusty prickly pear cactus, juniper, and sagebrush. Scorpions and rattlesnakes pose the most immediate threats. But during the Late Jurassic, streams and ponds would have flushed through the landscape, and dinosaurs—the creatures that make this spot so compelling to Maidment and Bonsor—would have sent prey scurrying into the shadows.
Along our path, we stop to huddle over a two-inch fossil fragment that Bonsor picked up from the dry rubble—tangible remains of these long-departed animals. Maidment notes that every creature larger than one meter in size that lived on land during the Late Jurassic would have been a dinosaur—and any bone as thick as this one would have come from one. “If it’s big and it’s from the Jurassic,” she says, “it’s a dinosaur bone.”