North Dakota Fossil Site Reveals When Asteroid Killed Dinosaurs

Spring is a time for budding flowers, tender green leaves and baby animals. But 66 million years ago, that gentle season instead brought mass death and carnage from Earth's catastrophic impact with a massive space rock. Scientists pinpointed the season of the disaster and linked it to springtime in the Northern Hemisphere, after analyzing fossilized animals that died minutes after the impact at a site called Tanis, where a river once flowed through what is now North Dakota.