For decades, experts debated what had killed the dinosaurs. Evidence found in 1977 gave scientists a major clue. They discovered a metal called iridium in Earth’s crust, or outer layer. It dates back to when the dinosaurs went extinct. Iridium is rare on Earth, but it’s common in asteroids.
Experts later found the location of the asteroid strike—a giant crater deep underwater near the east coast of Mexico. But no fossils were ever found to link the asteroid to the dinosaurs.
Then, in 2013, a scientist found a fossil site in North Dakota—about 3,000 miles from the crater. It included the remains of plants, fish, and a Triceratops. The fossils had traces of iridium in them.
Burnham’s team released the first results of their find this year. They determined that the fossil site was once near the shore of a prehistoric sea. When the asteroid hit, waves from the sea sloshed violently. They grew into a 300-foot wall of water, rocks, and sand that buried nearby creatures alive.
“Everybody’s always said, ‘Where are the bodies?’” Burnham explains. “Well, we just found them. It’s a huge milestone.”