Dinosaurs went extinct about 66 million years ago, at the end of the Cretaceous Period. This extinction event is widely believed to have been caused primarily by the impact of a large asteroid near what is now the Yucatán Peninsula in Mexico, forming the Chicxulub crater. The impact caused immediate devastation, followed by global environmental changes including massive wildfires, a "nuclear winter" effect from dust blocking sunlight, cooling, and then a period of warming. These changes led to the collapse of ecosystems and the extinction of about 75% of all species at the time, including all non-avian dinosaurs. Birds, which evolved from theropod dinosaurs, are the only dinosaur lineage that survived this event. Additionally, volcanic activity in the Deccan Traps of India and other gradual climate changes may have also contributed to their decline before and during this extinction event.