[Freakazoid]

My guess? A large methane bubble erupted from their watering hole and suffocated them.

[blam]

"My guess? A large methane bubble erupted from their watering hole and suffocated them."

You mean like Lake Nyos?

" Some 1,700 people living in the valley below Lake Nyos in northwestern Cameroon mysteriously died on the evening of August 26, 1986. Word of the disaster spread, and scientists arrived from around the world. What they discovered was that the crater lake, perched inside a dormant volcano, had become laden with carbon dioxide gas. This gas had suddenly bubbled out of the lake and asphyxiated nearly every living being in the surrounding valley community."

[Cyber Liberty]

Scientifically speaking, I'd say you're on the money.

I hope I don't die that way. I'd hate to be remembered for dying from a big fart.