Scientists at the UK's Liverpool John Moores University believe that methane gas emitted by sauropod dinosaurs may have had a major effect on the Mesozoic climate. Yes, this is basically a study on dinosaur farts.
Sauropods like Diplodocus, which lived 150 million years ago, probably generated methane in the same way modern cows do. The biggest difference, of course, is that a cow doesn't weigh 45 tons.
"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 Dave Wilkinson, the lead author of the study, published in Current Biology.
The study estimates that dinosaur-produced accounted for 472 million tons of methane emissions per year, which is about the same as the total of natural and man-made emissions today. Modern ruminant animals, including cows and giraffes, only account for 45 to 90 tons of that methane.
Those emissions, combined with forest fires and naturally-occurring gasfields, could have contributed to sustained warm climates throughout the Mesozoic.