Germanna Community College
The K-Pg extinction (or K-T extinction), more commonly referred to as the extinction of the dinosaurs, is the most recent mass extinction event in Earth’s history. The causes of the event have been widely debated, with the two main theories being a large asteroid impact or volcanism. While some scientists disagree, the most popular and agreed upon theory is that a large asteroid impacted Earth 65 million years ago, creating a toxic dust cloud that filled the atmosphere, and resulted in the eventual extinction of most of the dinosaurs. This theory was first brought to life by Luis Alvarez, his son Walter, and their team based on their findings of large spikes of the rare element iridium in different locations around the world at the K-Pg boundary (formerly known as the K-T boundary). Volcanism, specifically Deccan volcanism, was formerly the most popular theory for what caused the mass extinction event before Alvarez published his findings on the impact theory in 1980. It has since been surpassed because of recent discoveries such as, the Chicxulub crater, the evidence found within the layers of sediment at the K-Pg boundary, and the re-analysis of evidence conducted by a group of experts in 2010.
Johnson, Dimitrik, "Conflicting Theories: Impact and Volcanism" (2018). Student Writing. 24.