You've heard that an asteroid killed the dinosaurs. 65 M years ago an
asteroid hit Mexico's Yucatan peninsula, covered the earth in a layer of dust, including rare iridium, destroyed the plant life, then herbivores, then carnivores.
You may not have heard that it was the volcanoes. Starting 70 M years ago, near Mumbai in India, a collection of volcanoes called the Deccan Traps spewed sulphur and ash, including iridium, acidifying the oceans and blocking out the sun...etc. But could you have sworn that it
mightn't be both?