[PatrickHenry]

Alternative extinction scenarios:
Is This What Killed The Dinosaurs? New Evidence Supports Volcanic Eruption Theory.
Hydrogen Sulfide, Not Carbon Dioxide, May Have Caused Largest Mass Extinction.

[jennyp]

Alternative extinction scenarios:

Is This What Killed The Dinosaurs? New Evidence Supports Volcanic Eruption Theory.

Didja notice that Prof. Keller is also the person they quote here?

Hydrogen Sulfide, Not Carbon Dioxide, May Have Caused Largest Mass Extinction.

This article is about the Permian extinction 251 mya.

Here are some more theories about the K-T extinction, from the CrEvo:TED archives (natch):

• 'Dinos were doomed before meteors struck' (global cooling)
• Dinosaurs experienced climate changes before K-T collision
• Report: Climate change didn't kill dinosaurs
• Mass-extinction controversy flares again (earlier claims by Keller's team of fossil plankton living in Chicxulub crater for 300,000 years post-impact)
• Dinosaur demise theory, version #451 (it's all a house-o-cards!)
• Earth Suffered Pulses of Misery in Global Wildfires of 65 Million Years Ago (continent-wide wildfires after Chicxulub impact)

And on a related note:

• Scientists hope to get more accurate Earth history ("...But geologists can't date the impact to within a million years, making it uncertain whether the collision preceded or followed the dinosaurs' extinction.")