What Caused the Dinosaurs to go Extinct?
All dinosaurs, except a few which would later go on to become modern birds, went extinct about 65.5 million years ago, during the Cretaceous-Tertiary extinction event. No land animal larger than a cat survived. The sky was largely blacked out for a period of years to decades, killing numerous plant and microbe species which rely on photosynthesis to survive. Species that depended on the consumption of plant matter, such as all vegetarian dinosaurs, went extinct when their food sources died off and decomposed. In North America alone, 57% of plant species went extinct. In paleontology, the layer of rock that corresponds to this extinction is known as the K-T boundary. Even today, we don’t know with 100% confidence what really caused this massive extinction. But the prevailing theory, by Nobel Prize-winning physicist Luis Alvarez, is that a 6-mile asteroid impacted the Earth, releasing the energy of 2 million atomic bombs and raining molten magma across the entire surface of the planet. A
