Researchers in Britain say that huge plant-eating dinosaurs may have produced enough greenhouse gas with their flatulence to alter the Earth's climate.
Scientists believe that, just as in cows, methane-producing bacteria aided the digestion of sauropods by fermenting their plant food and they would have generated enormous quantities of methane.
Sauropods were super-sized land animals that grazed on vegetation during the Mesozoic Era around 150 million years ago. They grew to be longer than 150 feet and weigh up to 90 tons.
The research was published in the Current Biology journal by Dr David Wilkinson from Liverpool John Moore's University and colleagues from the University of London and the University of Glasgow.
Previous studies have suggested that the Earth was up to 10C degrres warmer in the Mesozoic Era.
By scaling up the digestive wind of cows, the researchers estimate that the population of dinosaurs - as a whole - produced 520 million tonnes of gas annually.
''Cows today produce something like 50-100 (million tonnes) per year. Our best estimate for Sauropods is around 520 (million tonnes),'' Dr Wilkinson told the BBC.
He added that dinosaurs were not the sole producers of methane at the time.
''There were other sources of methane in the Mesozoic so total methane level would probably have been much higher than now,'' he said.