[mordant]

This is about the supervolcano hypothesis.

Note that this and the Alvarez asteroid hypothesis aren't mutually-exclusive; a significant impact event could in fact trigger vulcanism on a massive scale.

There's plenty of evidence that the K-T impactor was real and slammed into the Earth. It alone might've caused the massive die-offs, or it might've triggered vulcanism and/or venting of poisonous gas deposits from beneath the seabed.

[bryanlarsen]

According to the article, the vulcanism starts two hundred thousand years before the impact.

[EdwardDiego]

Sure, started, but...

http://science.sciencemag.org/content/350/6256/76

> The existing Deccan Traps magmatic system underwent a state shift approximately coincident with the Chicxulub impact and the terminal-Cretaceous mass extinctions, after which ~70% of the Traps' total volume was extruded in more massive and more episodic eruptions. Initiation of this new regime occurred within ~50,000 years of the impact, which is consistent with transient effects of impact-induced seismic energy.

Then there's the possibility of another impactor coincident in time to Chicxulub: https://en.wikipedia.org/wiki/Shiva_crater

[Jedd]

This was discussed in TFA.