Dinosaurs may have warmed the prehistoric Earth's climate thanks to enormous amounts of methane-producing flatulence, researchers say.

Sauropods — the long-necked, long-tailed dinosaurs that included some of the largest ever land animals — could have produced enough methane to have "an important effect" on climate change, according to a report to be published in Tuesday's edition of Current Biology.

"Indeed, our calculations suggest that these dinosaurs could have produced more methane than all modern sources — both natural and man-made — put together," Dave Wilkinson of Liverpool John Moores University said in a statement.

Sauropods were plant-eaters. As happens in cows, microbes in the dinosaurs' digestive tract that aided digestion also produced methane, which is a greenhouse gas.

Co-authors Wilkinson and Graeme Ruxton from the University of St Andrews in Scotland made the calculations along with Euan Nisbet, a methane expert at the University of London.

Wilkinson said the group made an educated guess based on the large size of the animals (20,000 kilograms for a medium-sized sauropod) and their population density.

Their calculations suggest sauropod flatulence about 150 million years ago, when the world was warm and wet, is comparable to the amount of methane produced today by both animals and society — and more than double what was produced before the dawn of modern industry.