Ah, the blast that ended the dinosaurs! So much controversy!
And to think it all dates back to the days when religion dominated science. When extinctions were explained by catastrophes ordered by God. Need to get rid of Pleistocene animals? Invoke a flood. Not just Noah's flood, either, the various churches decided there were plenty of catastrophes to go around. Catastrophism its known as.
Things started to change when Charles Lyell published his Principles of Geology. His theory was that you could observe geological processes at work in the world and make conclusions based on that. Erosion, sedimentation, etc. are slow, gradual processes. Lyell's book was reading material that Charles Darwin took with him on his Beagle voyage and the whole slow-and-steady change message really influenced his thought on evolution. It's known as Uniformitarianism.
But here's the thing--the geological community got hung up on this. It became verboten to attribute change to catastrophes. That was considered a reversion to the past, to the Church. Hence all the denial that a comet or asteroid impact could possibly be the reason for the Cretaceous extinction event.
At University of Calgary, we have a professor, Dr. Alan Hildebrand, who studies meteorites and impact sites. He has been a major contributor to the study of the Chicxulub Crater on the Yucatan Peninsula, the impact that is thought to have ended the Cretaceous period.
Just like Brusatte, I got my moment with the K/T boundary while in Cuba. Our tour guide took us to a place where that fateful layer was exposed. I got to put my hands on it, iridium, shocked quartz, and tektites included! After a bit of searching, I found my photo of it. Guys, its a seriously boring photo, but here it is:
Wish I had posed by it now, but what can you do?