May 9, 2012
It sounds like perfect journalist bait: Earlier this week, a new Current Biology paper proposed that the accumulated output of dinosaur farts could have changed the global climate. You could hardly ask for a better story. Dinosaurs are ever-popular media darlings, and the science of sauropod farts is just silly enough to grab the public’s attention. Too bad sources like FOX News, Gawker and the Daily Mail issued some rather noxious stories about the research.
The paper itself, written by researchers David Wilkinson, Euan Nisbet and Graeme Ruxton, is an exercise in short but serious speculation. For a long time, the digestive biology of sauropods has confounded paleontologists. Sauropods had small teeth good for gripping, nipping and plucking plants, but not for chewing or otherwise mashing up their food. How they broke down the masses of plant food they must have required is a mystery. For a time, swallowed stones called gastroliths were thought to be the answer, but recent reviews of the evidence have failed to turn up any indication that stones ground up food in sauropods’ guts. Instead, some paleontologists have gravitated toward the idea that sauropods had vast communities of microscopic organisms in their stomachs that broke down the incoming plants. This microorganism-assisted fermentation could have produced methane, and as Wilkinson and co-authors point out, sauropod farts would have been the end result.
Since emissions from cows and other livestock contribute greenhouse gases to our warming atmosphere, Wilkinson and collaborators wondered if sauropods might have had a similar effect on the Mesozoic world. To find out, they paired estimates of sauropod population size derived from the fossil record of the roughly 150-million-year-old Morrison Formation—the geological slice in which Apatosaurus, Diplodocus, Barosaurus and other Jurassic giants are found—with an estimate of how much methane each dinosaur would produce based on observations of modern rabbit and guinea pig emissions. Assuming that ten Apatosaurus-size sauropods lived per square kilometer, and that half the world’s land area was inhabited by dinosaurs, Wilkinson and colleagues found that the giant, long-necked dinosaurs would have produced 520 million metric tons of methane annually. In their estimation, this is comparable to the amount of methane that we’re currently pumping into the atmosphere each year. The researchers conclude that so much dinosaur flatulence—in addition to greenhouse gases from fires and other sources—might have created and sustained the relatively warm world of the dinosaurs.
But we don’t know for sure. The new research relies on a stack of assumptions and is, at best, a rough model. We don’t know what the gut flora of sauropods was like; therefore, we don’t know whether they farted at all. And small, mammalian herbivores such as rabbits and guinea pigs are unlikely to be the best models for sauropod emissions. Living dinosaurs and their cousins aren’t much help here. Modern avian dinosaurs don’t fart, and I haven’t seen any research on whether crocodylians—the closest living cousins of dinosaurs as a whole—produce methane-rich eruptions. (If you know about croc fart research, please chime in.)
It’s not unreasonable to wonder about dinosaur digestive products. Paleontologist Tony Fiorillo speculated about hadrosaur gas at a 2010 American Geophysical Union meeting. Perhaps fortunately, our ability to investigate dinosaur farts is severely limited. Furthermore, paleo-blogger Jon Tennant names a number of other problems with the back-of-the-envelope calculations at the heart of the paper—including the estimates of sauropod abundance worldwide—and rightly concludes that the paper is a “crude analysis.”
The media coverage has been even cruder. 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.
Gawker simply recycled Fox’s bad air. “A new study from British scientists published in Current Biology suggests the dinosaur infraorder known as sauropods may have actively contributed to its own extinction through excessive flatulence,” wrote site contributor Neetzan Zimmerman, who linked backed to the Fox News item. News aggregation and snarky commentary are popular right now, and in cases like this, lazy and sensationalist reporting can rapidly be echoed across the web. Although I’m not going to give the typically awful Daily Mail credit for independently misconstruing the paper’s results.
The Daily Beast’s Daniel Stone and PZ Myers of Pharyngula tore into the media coverage earlier this week. There’s sadly no shortage of facepalm-inducing reporting, but it’s even worse when news sources are so enamored with a punchline that they simply make up conclusions. Not that I expect Fox News, the Daily Mail, or Gawker to stop blowing hot air whenever the opportunity arises.
Wilkinson, D., Nisbet, E., & Ruxton, G. (2012). Could methane produced by sauropod dinosaurs have helped drive Mesozoic climate warmth? Current Biology, 22 (9) DOI: 10.1016/j.cub.2012.03.042