Astronomy and the Extinction of the Dinosaurs
Marshall L. McCallLevel
Fossils show us that millions of years ago giant reptiles roamed the Earth. Yet, where are they now? In recent years, scientists have concluded that past collisions of the Earth with large extraterrestrial bodies caused widespread death of existing life forms. The speaker reviews the history of mass extinctions and ideas about the nature and origin of the intruders and summarizes implications for the future.