Extinction of the dinosaurs?

Question

I've been looking for some evidence supporting the K-T extinction theory. Does anyone know how they dated the asteroid back to the time when the dinosaurs became extinct? Could you please give sources. Thanks.

Answer 1

Well, they didn't find the actual asteroid.  But they dated zircon grains found at the K-T boundary (which was identified via an overabundance of iridium)

http://adsabs.harvard.edu/abs/1992Metic....

Answer 2

I suggest that you read "T. rex and the Crater of Doom" written by Walter Alvarez, the former head of the geology department at UC Berkeley.  He and his father, Luis Alvarez (a Nobel Prize winner in Physics), wrote the original paper suggesting that the K-T extinction was caused by a meteorite.  The book is written for popular consumption, but it has an extensive bibliography.