Need to heat your planet? Install some dinosaurs. The biggest plant-eating dinosaurs pumped out huge amounts of greenhouse gas, helping to keep Earth toasty warm, according to new calculations.
 |
| Swamp-bound 'Brontosaurus' (now Apatosaurus), painted in 1897 by Knight, with static terrestrial Diplodocus in background |
For much of the Mesozoic, the dinosaur era, the long-necked sauropods were one of the dominant groups. Like all herbivores, sauropods probably had gut bacteria to help them digest their food. "They were just containers for a lot of microbes," says David Wilkinson of Liverpool John Moores University in the UK. The bacteria in the foreguts of herbivores like cows produce methane, which the animals belch out, contributing to climate change. Sauropods probably kept bacteria in their hindguts, and released methane in their farts.
On the basis of data from modern plant-eaters, Wilkinson and his colleagues estimate that the global sauropod population pumped out 520 million tonnes of methane a year, about the same as the total current emissions of the greenhouse gas.
The estimate could be out by a factor of 2, says Wilkinson. "There are a lot of educated guesses."
Assuming the numbers stack up, sauropods warmed the planet by about 1 °C, says climate modeller David Beerling of the University of Sheffield, UK. We know from fossils that the climate in the dinosaur era was much warmer than today – for instance, there was no polar ice. Beerling's models suggest that high carbon dioxide and methane levels contributed to this.
Other dinosaurs may have been more important for the climate, says Paul Barrett of the Natural History Museum in London, UK. Sauropods were most common in the Jurassic period, but temperatures were highest in the Cretaceous, which followed it, he says. "These animals are just not around when we get the highest temperatures."
In the Cretaceous, other plant-eaters, such as the duck-billed hadrosaurs and beaked ceratopsians, could have pumped out methane, says Barrett.
Sources:
- Michael Marshall, Sauropod farts warmed the planet, New Scientist issue 2864, 7 May 2012
- David M. Wilkinson, Euan G. Nisbet, Graeme D. Ruxton, Could methane produced by sauropod dinosaurs have helped drive Mesozoic climate warmth?, Current Biology, Volume 22, Issue 9, R292-R293, 8 May 2012
- Gaseous Emissions from Dinosaurs May Have Warmed Prehistoric Earth, ScienceDaily, May 7, 2012
- Ella Davies, Dinosaur gases 'warmed the Earth', BBC Nature News, 7 May 2012
