Giant dinosaurs could have warmed the planet with their flatulence, say British scientists.
By scaling up the digestive wind of cows, they estimate that dinosaurs produced 520 million tonnes of methane annually.
They suggest the gas could have been a key factor in the warm climate 150 million years ago, reports the Media.
David Wilkinson from Liverpool John Moore's University, and colleagues from the University of London and the University of Glasgow published their results in the journal Current Biology.
They calculated the methane output of sauropods, such as the Brontosaurus, super-sized land animals that grazed on vegetation during the Mesozoic Era.
For Dr Wilkinson, it was not the giants that were of interest but the microscopic organisms living inside them.
"Although it's the dinosaur element that captures the popular imagination with this work, actually it is the microbes living in the dinosaurs guts that are making the methane," he said.
Methane is known as a "greenhouse gas" that absorbs infrared radiation from the sun, trapping it in the Earth's atmosphere and leading to increased temperatures.
Previous studies have suggested that the Earth was up to 10C (18F) warmer in the Mesozoic Era.