How Many Mass Extinctions Have There Been?

Want to learn more about the topic in this week's video? Here are some keywords/phrases to get your googling started:
- Mass Extinction Event: a significant, global decrease in the diversity of life
- "Big 5": The five biggest mass extinction events since the Cambrian explosion of Life 550 million years ago
- Biodiversity Crisis: Like a mass extinction, a biodiversity crisis is a marked depletion in diversity in the fossil record. Some scientists prefer to call the late-Devonian extinction a "biodiversity crisis" because a lack of speciation contributed to the loss in diversity just as much as extinction did.
- Diversity curve: A line chart that shows the diversity of life (usually by genera, but sometimes by species or family) over time
- Lagerstatte: a deposit of sedimentary rock that contains a profound number of fossils, often with excellent preservation
- Shareholder Quorum Subsampling: A statistical method that corrects for some of the biases in the fossil record, allowing scientists to generate more accurate diversity curves