I am a firm believer that we try too hard to blame just one variable with these things when it could actually be many different factors and variables that in total combination caused the end effect. I try not too, but I sometimes get pulled back into the box.
I had never put much thought into this event to realize all the different factor variables that may have come together in the total as a combination, such as species that were already adapted to low oxygen environments.
You just did that very well, thank you, it pulled me back out of the box and raised a lot of curiosities for me to look into further. :)
He couldn't quite make the step to part of the atmosphere being blown into space. The only referent he had was hydrogen bomb tests where the fireball would be larger than the depth of the atmosphere, and the fireball would be described as if it hit the stratosphere and was forced to "squat" on the surface of the Earth, (apparently the concept of the firmament being a solid was strong!).
Since Analog is mostly a science fiction magazine, Enever's work was largely ignored as a flight of fantasy. Even when Luis and Walter Alvarez and Jan Smit demonstrated that a major impact event coincided with the death of the dinosaurs.
I came across a mention, which I can't recall clearly enough to track down that the dinosaurs with their long, relatively narrow trachea were effectively turbocharged by the higher oxygen content of the atmosphere, but conflicting information that a higher percentage of oxygen in the air would lead to massive forest fires.
AFAIK, I'm the first to recognize that the only way to have more oxygen in every lung full of air without having such a high percentage that a single lightning bolt set everything ablaze was to have a denser atmosphere. That a goodly fraction of the Earth's atmosphere is just plain gone seems to be a blind spot. And why not? It's a very terrifying concept!
An animation on a recent NatGeo special on the Chicxulube impact showed the sea water gently flowing back into the crater without so much a a whisper of steam! Hello???
World wide any fault that is near its critical strain is apt to let loose, as is any volcano near its eruption threshold (think Mt. St. Helens, an eruption triggered by a landslide).
Worse, doctors and coroners have a term, 'coup contercoup', that means damage to the opposite side of the brain from where the skull was struck.
Imagine you are standing on the spot exactly on the opposite side from the strike. The shock waves race around the globe and come together (focus, if you will) right under your feet!
On a lower gravity bodies such as the moon, big impacts have delivered sufficient coup countercoup force to jet material off into space.
I don’t doubt that nearby magma would be squirted up through the resulting shattered bedrock. I think this is how the Deccan Traps formed. They weren't quite geographically exactly opposite Chicxulub, but exact opposite assumes perfectly uniform density and a straight-on strike.
All in all a BAD day...