Flatulosaurus Heats Up the Mesozoic
A new Current Biology paper proposes that the accumulated output of dinosaur flatulence could have changed the global climate during the age of the dinosaurs. Insert dinosaur fart joke here. No, seriously, this is a real report in an actual scientific journal. It just happens to be on a subject that the news media could not resist blowing out of proportion on their best day. Given that much of the CO2 in Earth's atmosphere was emitted by some form of living creature this is a serious area for study by environmental scientists. So after giving the chattering media magpies some time to calm down, here is a more serious take on this heady topic.
Forget T-Rex, fear the Flatulosaurus—particularly if you are afraid of global warming. You may have already heard this story, scientists say that dinosaur farts had a part in warming the ancient Earth. Published online on the Cell web site, the story quickly broke in The Telegraph. A story too perfect and too funny to be ignored, the news flashed across the internet, appearing everywhere from Slash Dot to The Huffington Post.
While gushing erroneous reports that the dinosaurs farted and belched themselves into extinction, the world's entire news gathering community turned into a bunch of snickering school boys. Right-wing talk radio personality, Rush Limbaugh said it was just another attempt to bolster the argument of global warming, no matter how absurd it may seem. Some in the scientific community looked askance at the mirthful media reports. On the Smithsonian's web site, in an article entitled “Media Blows Hot Air About Dinosaur Flatulence,” the low mindedness of the news media was described this way:
In the past month we’ve had vapid reports of aquatic dinosaurs and alien dinosaurs, but at least three news sources decided to up the ante with additional bad reporting. Fox News led off with “Dinosaurs may have farted themselves to extinction, according to a new study from British scientists.” Wrong right out of the gate. Wilkinson and co-authors didn’t say a thing about dinosaur extinction in their paper. Not to mention that the idea doesn’t make any sense. Titanic sauropods were around for about 130 million years. If their gases were so deadly, why did it take so long for the world to be overwhelmed? The Fox News gloss isn’t even a misrepresentation of what the researcher said. The story’s headline and lead are outright fabrications. And the same fiction was repeated on the network’s late-night roundtable of chattering commentators, Red Eye.
Hey, I like Red Eye, and this is precisely the kind of humor that would appeal to host Greg Gutfeld. Just what did they expect? To be fair, the sophomoric guffawing was not limited to Fox: Gawker and the Daily Mail also received a fair dollop of opprobrium. No matter, there is serious science to be examined here.
Was that you, mate?.
The Smithsonian article went on to explain that, for a long time, the digestive biology of sauropods has confounded paleontologists. From their fossilized remains it is known that Sauropods had small teeth good for cropping and harvesting plants. Unfortunately, their dino dentition was not well suited for chewing or mashing up their food. How they broke down the masses of plant food they must have ingested (estimated at 520 million tons per year) remains a mystery.
Large swallowed stones called gastroliths, often found within the skeletons of herbivorous dinosaur fossils, were thought to be used to grind up the creatures food post ingestion. They would be similar to gizzard stones used by some modern birds. This would be a natural assumption since scientists think birds descended from the dinosaurs. Unfortunately, recent reviews of the evidence have failed to turn up any indication that sauropod's stones were used to grind up food.
Instead, some paleontologists have put forth the idea that sauropods were hosts to vast communities of microscopic organisms in their stomachs. In effect, the herbivorous dinosaurs were walking, microorganism-assisted fermentation vats that broke down the ingested vegetation. Such fermentation could have produced large quantities of methane, and as Wilkinson et al. point out, the end result would have been copious sauropod farts. As David M. Wilkinson, Euan G. Nisbet and Graeme D. Ruxton reported in their paper:
Mesozoic sauropods, like many modern herbivores, are likely to have hosted microbial methanogenic symbionts for the fermentative digestion of their plant food. Today methane from livestock is a significant component of the global methane budget. Sauropod methane emission would probably also have been considerable. Here, we use a simple quantitative approach to estimate the magnitude of such methane production and show that the production of the ‘greenhouse’ gas methane by sauropods could have been an important factor in warm Mesozoic climates.
The paper goes on to outline the authors' assumptions and resulting calculations. Citing recent estimates of the biomass density of herbivorous dinosaurs of 80,000–90,000 kg/km2, some 7–24 times the biomass of extant large-bodied herbivorous mammals (~28,000 kg/km2), they calculate methane emission of 2675 liters per day for one animal under the standard temperature and pressure conditions. A world full of sauropods would emit as much as 520 million metric tons, far more than the frequently maligned modern cow population.
Comparison of estimated sauropod methane emissions.
“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,” said co-author David Wilkinson of Liverpool John Moore's University. “In fact, our calculations suggest these dinosaurs may have produced more methane than all the modern sources, natural and human, put together.”
This level of methane production—methane being a much more potent greenhouse gas than carbon dioxide—could have be enough to cause a 10°C rise in global temperatures during the Jurassic. “Even reducing our estimate by half still predicts a major role for sauropod methane in the Mesozoic,” the authors' conclude. In fact, they think we might take some solace from knowing we are not the only species accused of causing global warming. Contrary to what some misanthropes say about adverse human impacts on the ecosystem, humanity might find cover in this new work.
“Although dinosaurs are unique in the large body sizes they achieved, there may have been other occasions in the past where animal produced methane contributed substantially to global environmental gas composition: for example, it has been speculated that the extinction of megafauna coincident with human colonization of the Americas may be related to a reduction of atmospheric methane levels,” the paper explains. So our Paleo-Indian ancestors could claim that they were not just slaughtering native North American megafauna for food, they were fighting global warming.
Be safe, enjoy the interglacial and stay skeptical.