DryadLab Package: Extinction Risk  From The Dryad data
repository wiki Jump to: navigation, search    This dataset is a
version of that deposited in Dryad but with log10 values already
calculated.  Text version of the file  Excel version of the file
Teacher Background  Background extinction and mass extinction
Extinctions of species have occurred gradually and continuously
throughout the history of life, creating a turnover of species
through time. This is background extinction. However, there are
particular points in time when a very large number of species go
extinct, this is a mass extinction. Historically we recognize 5
big events including the most recent event, which occurred
approximately 65 million years ago at the K-T boundary when the
non-avian dinosaurs went extinct. The causes of these past
events are varied and still debated but include climate-change,
volcanic activity and asteroid impacts.  Insert image about
background vs mass extinctions from Understanding Evolution
website -> evolution.berk