Everyone, even the normally open-minded Longrider, is poo-poohing this idea for why the climate changed but they haven't looked at the evidence. I've seen filums with dinosaurs and they are always growling as if their bellies hurt, which is only to be expected if you try to eat whole trees, other dinosaurs and ladies wearing fur bikinis.
It's all true and here's the film to prove it. Note they have actually photographed the gas. This explains megafaunal extinction.
Please can I have a PhD from UEA now for this valuable piece of conclusive research?