Dinosaur Flatulence May Have Warmed Prehistoric Earth
Posted on May 7, 2012
Scientists say gaseous emissions from dinosaurs may have warmed prehistoric Earth. The researchers say sauropod dinosaurs could have produced enough of the greenhouse gas methane to warm the climate many millions of years ago. The calculations were reported in a paper published in the May 8th issue of Current Biology, a Cell Press publication.
Sauropods, which were widespread about 150 million years ago, are distinctive for their enormous size and unusually long necks. They also released a large amount of methane in the environment. As in cows, methane-producing microbes aided the sauropods' digestion by fermenting their plant food.
Dave Wilkinson of Liverpool John Moores University, says, "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. Indeed, our calculations suggest that these dinosaurs could have produced more methane than all modern sources—both natural and man-made—put together."
Wilkinson and study coauthor Graeme Ruxton from the University of St Andrews were studying sauropod ecology when a question dawned on them: "If modern cows produce enough methane gas to be of interest to climate scientists, what about sauropods?"
They teamed up with methane expert Euan Nisbet at the University of London to work out the numbers.
Wilkson said, "Clearly, trying to estimate this for animals that are unlike anything living has to be a bit of an educated guess."
Animal physiologists have studied methane production from a range of modern animals to derive equations that predict methane production from animals of different sizes. It turns out that those calculations depend only on the total mass of the animals in question. A medium-sized sauropod weighed something like 20,000 kilograms, and sauropods lived in densities ranging from a few large adults to a few tens of individuals per square kilometer.
Wilkinson, Ruxton, and Nisbet therefore calculate global methane emissions from sauropods to have been 520 million tons (520 Tg) per year, comparable to total modern methane emissions. Before industry took off on modern Earth about 150 years ago, methane emissions were roughly 200 Tg per year. By comparison, modern ruminant animals, including cows, goats, giraffes, and others, produce methane emission of 50 to 100 Tg per year.
The researchers say their study's conclusions show not only "just how strange and wonderful the workings of the planet are," but also serve as a useful reminder for the importance of microbes and methane for global climate.