That seems to be a pretty good article. I'm not sure what your Luis Alvarez reference means. Of course, he's the one who provided the first scientific evidence of a large impact event in the form of a concentration of iridium many times greater than normal found in sedimentary layers found all over the world at the Cretaceous–Tertiary boundary.
Originally Posted by grapes
I guess there is still some controversy whether the impact was the sole cause. But, as wiki reports:
In March 2010 an international panel of scientists endorsed the asteroid hypothesis, specifically the Chicxulub impact, as being the cause of the extinction. A team of 41 scientists reviewed 20 years of scientific literature and in so doing also ruled out other theories such as massive volcanism. They had determined that a 10–15 km (6–9 mi) space rock hurtled into earth at Chicxulub on Mexico's Yucatan Peninsula. The collision would have released the same energy as 100 teratonnes of TNT (420 ZJ).
The megatsunamis would have killed off quite a few lifeforms. And all that dust and sulfuric acid aerosols thrown up in the atmosphere... Many immediate effects and then lasting effects would have wreaked havoc on our dear little Earth for at least a decade. [ETA: As I said, that wiki article spells it all out.] It's a good thing our mammalian forebears at the time were not picky about a fresh meat and vegetable diet.