The humongous herbivores — who count the dino-formerly-known-as-Brontosaurus among their ranks — produced over 500 million tons of methane a year through farts, according to the study.
"A simple mathematical model suggests that the microbes living in sauropod dinosaurs may have produced enough methane to have an important effect on the Mesozoic climate," said co-author David Wilkinson of Liverpool John Moore's University. "In fact, our calculations suggest these dinosaurs may have produced more methane than all the modern sources, natural and human, put together."
It is believed the Mesozoic Era was up to 18 degrees Fahrenheit warmer than average.
Cows, which were used by Wilkinson and his colleagues to estimate the total methane output of sauropods, produce some 50-100 metric tons of the greenhouse gas annually. "There were other sources of methane in the Mesozoic so total methane level would probably have been much higher than now," said Dr. Wilkinson.
UPDATE: Noted biologist PZ Myers challenges the claim that dino farts in any way contributed to their extinction. "[T]he gassy beasts made the world pretty warm and not so pleasant to live in," he says, "but none of them died because of it."