Dinosaur extinction. Artwork of the death of the dinosaurs after the Earth was struck by a comet or asteroid 65 million years ago. A Triceratops dino- saur skull lies in a landscape which has been burnt by the blast of the impact. Dark clouds of smoke and dust fill the sky, blocking the light & warmth of the Sun and providing a source for acid rain. The comet or asteroid struck the Earth at Chicxulub on the Yucatan peninsula, Mexico. This event, which may have caused the extinction of the dinosaurs & 70% of all species on Earth, is known as the 'K/T impact' because debris from it forms a boundary in sediments between the Cretaceous (K) and Tertiary (T) geological periods.