The Carolina Butcher (not to be confused with the Carolina Reaper):
We really need to thank that asteroid. 
Yeah, that’s correct. Some may have been somewhat more upright than the thorax forward orientation of a theropod but it would have moved by digitigrade movement; think in terms of the morphophorm of an ostrich, but definitely up off the ground rather than the belly run or quadrupedal lurching of most modern alligators and crocodiles.
That layer includes a highly elevated concentration of elemental iridium, which is otherwise very rare in the Earth’s crust but is often found in much higher concentrations in meteorites. So we have high confidence that a cataclysmic-scale impact occurred at around the time of the K-Pg extinction event (within a few hundred thousand years). That is about as good as it gets in the geologic record going that far back.
Disruption of the photosynthetic-driven nutrient uptake cycles for even a few years could be massively disruptive, but it is also possible that acidification of the ocean due to a combination of a lack of carbon dioxide removal and the aforementioned vulcanism could have had an equal role in disrupting the nutrient uptake by microbiotic heterotrophs. Once whole segments of the nutrient ecology are substantially diminished, the entire food web can collapse resulting in mass extinction even if photosynthetic organisms recover.
Stranger
Beyond, even.
12% of the ejecta plume reaches escape velocity.
Cite
From a quick trawl of the recent palaeobotanical literature there is still argument about the nature of the impact on marine ecosystems at the K-T boundary. For vertebrates there was, like on land, massive extinction of diversity, but it is still not clear where in the food chain from top predators down to the tiniest mud algae the system collapse set in. A top predator like a mosasaur will die if its direct food source collapses, or the one below that, or the one below that.
The palaeontological evidence for the sea grasses, reefs, planktons etc that form the foundation of the food web is, surprisingly, still patchy and poorly synthesised according to recent papers. Some appear to have not been impacted on some diversity measures, while others have collapsed locally, but whether this was sufficiently extensive to cause disappearance of animals that relied on them is unclear. We need to know more, preferably in the form of a gripping Hollywood movie. Lift your game, scientists!
For those not wanting to watch:
Crocodiles/some other reptiles: they can go a looooooong time without eating, and being cold blooded didn’t require as much food to survive as warm blooded animals.
Birds: actually, as a group they were hit pretty hard. The ones that survived were small, were generalists/adaptable in feeding, and due to being able to fly could relocate to better areas as needed. Also, maybe smarts and the ability to problem solve and/or pass on foraging techniques to offspring.
Another reason why it’s not correct to say that the K-T event killed off all of the dinosaurs: Plenty were already extinct by that time. For some species, the reason why they didn’t survive the K-T event was that something else had already killed them off millions of years previous.
On another note, remember that while 99% of species went extinct, the number of individuals that died was far greater than that. Even for the species that survived, many of them saw almost all of their population die off, and the few that survived were able to struggle back. Which underscores that there was a significant element of luck, too.
Of course, the chemosynthetic ecosystems at the ocean vents probably never even noticed.
Pseudosuchian diversity:
Proto-Godzilla
That article might be… overstating the creature’s size.
It was much worse than just a big rock throwing up a bunch of debris and ash.
The Chixulub impact was so massive that debris from the impact rained down as far north as what is now Kentucky (maybe even further). We’re not talking about stuff that floated through the atmosphere and eventually fell out, we’re talking about direct debris from just the impact itself. The stuff that floated through the atmosphere rained down all over the entire world. There is a layer of carbon that has been found pretty much everywhere from the event, indicating that the entire world burned. Literally it was Hell on Earth.
And if all of that debris and ash that was kicked up wasn’t enough, the shock wave from the impact travelled outwards in all directions. Some people have likened it to ringing the Earth “like a bell”. The shock wave caused tsunamis and caused a huge uptick in volcanic activity, and since the Earth is a globe, all of those shock waves converged at the exact opposite point on the Earth (the antiopode) causing even more significant damage to the Earth’s crust at that point. The increase in volcanic activity threw up even more crap into the Earth’s atmosphere, blocking out the sun even further.
On land, anything bigger than about 3 feet long died. Crododilians survived because they could dive under the water and stay there long enough to avoid being burned to death. Plus they can go for a really long time without food. Most plants died. Most animals that ate those plants died from lack of food. Most animals that ate the other animals then also died from lack of food, so on and so forth up the food chain.
Life in the oceans didn’t burn, but the lack of sunlight killed off most of the phytoplankton, kelp, sea grasses, etc. that need light to survive. And then of course the sea animals that ate those didn’t have enough food, and once again it goes right up the food chain with everything starving. All of the ash and debris falling out of the sky also dramatically increased the water’s acidity, which certainly didn’t help.
It was not a happy time.
It kicked up a mountain taller than Everest, which then collapsed. All within 10 minutes.
I recall hearing a Radiolab podcast that detailed one theory—that all the ejecta re-entering the atmosphere would have, as it heated upon reentry, essentially turned the entire earth into an oven. That might only have lasted a few hours, but it would have been long enough to bake to death anything that wasn’t underwater or buried underground/inside dead trees/etc. (hence the little critters on land surviving). Afterwards you get the aforementioned darkness, reduced photosynthesis, and all the knock-on effects slapping around the big things in the ocean, too.
There was a theory going around a while back that conjectured that the extinction happened pretty instantaneously. It made the news for a while but, interestingly, I can’t find a link to it or mention of it online. Not that I believed it, but it was interesting.
Fuck that thing.
I’d prefer to engage in activities that do not involve close physical contact with it, thankyouverymuch.
snerk
Also a good idea with the Carolina Reaper.
What does that look like now? It’s the middle of the Indian Ocean I believe.
Some think the Deccan Traps volcano was triggered this way.
Here’s what your link says about that theory: