Australasian Science: Australia's authority on science since 1938

Dinosaur Farts May Have Warmed the Earth

By Magdeline Lum

Scientists estimate that sauropods emitted substantially more methane than modern ruminants.

Giant leaf-eating dinosaurs roaming the Earth millions of years ago may have produced enough of the greenhouse gas methane to warm the climate, according to a study published in Current Biology. The Mesozoic era spanning from 250 million years ago to 65 million years ago is believed to have had a hotter climate than today.

Sauropod dinosaurs like Apatosaurus had large, bulky bodies with long necks that allowed them to graze on grasses as well as from the treetops. They were in large numbers 150 million years ago.

Researchers led by David Wilkinson of Liverpool John Moores University in the United Kingdom estimated how much methane these dinosaurs would have released. The estimates, they warn, are based on a number of assumptions.

Methane is a natural byproduct of the digestive process of plant-eaters, especially in ruminants like cows and camels. Researchers suspect that, like ruminants, sauropods may have had methane-producing bacteria in their intestines to help digest fibrous foods. However, there is currently no way to tell what kind of bacteria lived in the gut of dinosaurs or even what their digestive systems looked like.

A mathematical model was used to calculate how much gas the plant-eating giants would have released. This was based on data available today on methane production by modern mammals based scaled up to the size of sauropods. The team used average numbers to perform their calculations. They chose to work with 10 medium-sized sauropods weighing 20,000 kg that would have roamed together in a 1 km2 area.

These 10 sauropods, according to the calculations, would have released 7.6 tonnes of methane per year. When the number of sauropods was scaled up to include all the areas of land thought to be habitable, more than 520 million tonnes of methane would have been produced each year.

Before the Industrial Revolution, methane emissions on Earth were 200 million tonnes per year. By comparison, modern ruminant animals produce 50–100 million tonnes per year.

These values have attracted the interest of climate scientists today. Did the sauropod flatulence lead to a warming of the planet?

“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,” Wilkinson said. “Indeed, our calculations suggest that these dinosaurs could have produced more methane than all modern sources – both natural and man-made – put together.”

However, it is difficult to know for sure. “Clearly, trying to estimate this for animals that are unlike anything living has to be a bit of an educated guess.”

The study’s conclusions not only show “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 to global climate.

Walking with Coffee: Why Does It Spill?
The task of walking with a cup of coffee nearly always results in it spilling. It is something that we live with. A few drops of coffee lost on the way between places is not an issue as long as we still have the bulk of the contents. However, engineers Rouslan Krechetnikov and Hans Meyer from the University of California decided to explore this in a systematic manner.

It turns out that the problem of spilling coffee is complex, and involves biomechanics and the physics and behaviour of sloshing liquids. How liquids slosh is important. If this is out of control, the movement of the liquid can lead to the sinking of a ship, starve an engine of fuel, and even cause the failure of a rocket launch.

Krechetnikov and Meyer’s experiment filmed volunteers in different scenarios while walking with a cup of coffee filled with different volumes. The volunteers walked while looking at the cups, straight ahead or at the floor. Sensors were used to monitor the liquid in the mugs.

After watching the videos, Krechetnikov and Meyer concluded that the natural frequency of coffee matched the frequency of a person’s walk, causing coffee to oscillate or slosh. This oscillation would increase as a person walked, and spillage always occurred between the seventh and tenth steps. Coffee spillage is inevitable if the walking rhythm matches the oscillation of coffee in a cup.

Yet hope remains that we can still walk with coffee and not spill any of its contents. Krechetnikov and Meyer suggest that if the walls of the coffee cup are flexible, they can absorb the energy of the incoming wave and dampen the first slosh. Another modification to the coffee cup could be a series of concentric rings that would break down a large slosh of coffee to smaller manageable sloshes. These rings could even have holes to make them lighter but also enable further dampening of coffee sloshing.

Of course, we could try a low-tech approach to coffee sloshing and spilling by watching our steps, but where is the fun in that?