The End of the Dinosaurs
Non-avian dinosaurs went extinct about 66 million years ago at the close of the Cretaceous period. This event, known as the Cretaceous–Paleogene extinction, removed more than 75 percent of all species on Earth.
Asteroid Impact and Climate Effects
A large asteroid struck what is now the Yucatán Peninsula in Mexico, forming the Chicxulub crater. The impact triggered fires, tsunamis, and a haze of dust and aerosols that blocked sunlight, cooled the planet, and disrupted food chains.
Survival and Legacy
While most dinosaurs disappeared, some bird lineages survived and evolved into modern birds. The extinction opened ecological space for mammals, which later diversified into many of the large land animals we see today. Learn more about the evidence for this mass extinction at Britannica.
