One of the main names in the debate is Gerta Keller. The short article below talks about her research:
Report Says Asteroid Did Not Kill Dinosaurs
Obviously, as you can read, other's don't agree. Regarding the Deccan Traps volcanism, this is even more recent:
India's Smoking Gun: Dino-Killing Eruptions
Here's a quote: ""In only one case is there evidence for both volcanism and impact," she said. And that is the K-T mass extinction that ended the reign of the dinosaurs. "Our view is that impact added to the stress already generated by an ongoing massive eruption, enhancing significantly the extent of the extinction, which would however have taken place even if the impact had not occurred."
This is also an interesting summary page:
The Great Chicxulub Debate concludes - where next?
The summary from Smit does a good job of covering why the Chicxulub impact theory is still very strong regarding the demise of the dinosaurs.
This is a short overview of the diversity and extinction aspect (Lectures 36-39):
The Cretaceous-Tertiary Extinction I: Definitions and Dramatis Personae
Wrong. The Chixculub impact killed off all the dinosaurs within a fortnight in all probability. At least that is what all the evidence indicates. Most people have no idea of the devastating impact on life that an asteroid the size of Manhattan Island hitting the earth would cause. The surface of the entire North American continent was literally incinerated within an hour due to the angle of the asteroid's impact and the subsequent direction of the ejecta from the impact point.
While it feels very strange to debate this -- because I'm fascinated by the Chicxulub impact and the entire discovery of the K/T boundary and subsequent evidence leading to the crater structure -- it should be pointed out that a lot of organism groups survived it. Any analysis of the extinctions also has to also take into account what survived. If one surmises that the extinction and subsequent effects preferentially affected larger organisms, then what happened to the small dinosaurs? Why did some reptile groups survive? Etc.
I don't think you and I can resolve this. Note then that I should be clear in stating that the Chicxulub impact played the major role in the extinction of the dinosaurs, at least according to what I know. But there was climate stress at the time, and I think the evidence indicates that was a contributing factor.
I was talking about measured temperature variations, not CO2 levels. Those variations have continued throughout earth's history right up to the present day and in fact, looking at that data, we have still not 'warmed up' fully since the last Ice Age. For man to think that he can have a large impact on same is the ultimate in hubris.
Well, the Cretaceous was cooler than the Triassic and Jurassic, but both climate regimes were warmer than present, which is consistent with the much higher atmospheric CO2 concentrations.
No offense intended. Sometimes the 'political' voice in me doesn't sound nice in other areas (like science - you should see some of my posts to 'Young-Earth Creationists'.....but then, that's not science, is it)
You're right that there is an awful lot we don't know and some things we'll never know re: the where's and why's of the dinosaur extinction....and open debate is to be encouraged, I agree....though my own views on the matter are quite strong (see, as a kid who loved dinosaurs, I knew - I mean I KNEW that silly stuff like climate change and mammals eating dinosaur eggs just couldn't be the reason for the K-T die-off. Then Mr. Alvarez came along, and it all made sense. And still does. I guess I have a knee-jerk reaction when I encounter people who seem to want to resurrect the 'bad old days' of dinosaur theorizing.......)