PLSC 213 Lecture Notes - Lecture 24: Background Extinction Rate, Ruderal Species, Keystone Species
Document Summary
Estimates of undiscovered species from rates of species accumulation with time. Over time life has been getting more complex and there is a wider diversity of organisms occurring. There is other patterns where there is dips in the graph, this occurs because there is evidence of periodic disturbances that have enormous and wide ranging e ects on life. When the dinosaurs died there is good evidence, there was a massive crater that made them disappear very quickly. There is unusual metals in the soils that occur in the same time and can be viewed as a massive or sudden fall of an asteroid putting crustal material into the atmosphere. The one before the dinosaurs is not as well known. Around 95% of the species disappeared, land plants, oceanic fauna, land animals. This was said to be massive volcanic eruptions, the volcanic eruption and the e ect on the atmosphere was the main cause of extinction.
