Scientists think that about 65 million years ago, an asteroid struck Mexico and created a huge cloud of dust in the atmosphere. The dust contained iridium, an
element found in asteroids. The dust cloud blocked the sun, killing most of the
plants on Earth. Plant-eating dinosaurs starved. Without herbivores to eat, meat-
eating dinosaurs died, too. Scientists studied rock layers from the time of the
strike to confirm their theory. What evidence would support the theory that an
asteroid impact could have contributed to the extinction of the dinosaurs?