How long did it take to wipe out the dinosaurs?

Dr. Victoria Arbour from the University of Toronto answers this week's Quirks Question.
Mass extinction began immediately after the asteroid hit the Earth 66 million years ago. (Donald E. Davis/NASA)

This week's question comes to us from Alan Clapp in Ottawa, who asked the following, "We believe that the dinosaurs were wiped out by a giant asteroid impact near the Yucatan peninsula. How long did it take to completely wipe out the dinosaurs (and other life too). I know in geological time, this was pretty quick, but in  people time, how quick was it? Did it happen in hours, days weeks, years or longer?"

Dr. Victoria Arbour, a paleontologist and post-doctoral fellow at the Royal Ontario Museum and the University of Toronto explains that the extinction 66 million years ago began in the hours immediately following the impact. Anything living close to the site of impact — the Yucatan — would have been vaporized. There would have also been destruction caused by earthquakes, tsunamis and the shock wave — all the result of the impact. In the hours after impact, a heat pulse threw dust into the air, which heated the atmosphere to the point were animals would not have been able to breathe. Finer dust particles would have taken longer to settle and would create a nuclear winter, which would cool the environment to sub-zero temperatures, for a considerable time after the impact. This could have lasted for 30 to 50 years and killed off many species of plants and animals.