Extinction is the fate of all species, but sometimes species become extinct in near simultaneous geologic time. This class will survey five prehistoric mass extinctions and the ongoing Holocene extinction. We will discuss what constitutes a species, how a species develops through time and space, and what causes different species to go extinct. We also will explore what we know about mass extinctions, what led up to those events, what followed, and how extinctions change the face of the planet.