Dinosaur Farts, Prehistoric Climate Change Linked In New Methane Gas Study

By: Jennifer Welsh, LiveScience Staff Writer
Published: 05/07/2012 12:02 PM EDT on LiveScience

We might want to rename the Brachiosaurus with the moniker Gassiosaurus, new research indicates. The gassy emissions from these giant dinosaurs may have been enough to warm the Earth, the researchers say.

Sauropods are large plant-eating dinosaurs typified by such titans as Apatosaurus (once known as Brontosaurus) and Brachiosaurus. When they lived, during the Mesozoic era — from about 250 million years ago until the dinosaurs died out 65 million years ago — the climate was warm and wet. Nothing on Earth today compares with these giants.

The researchers found that the greenhouse gas methane produced by all sauropods across the globe would have been about 520 million tons per year, a number on par with the total amount of methane currently produced by both natural and man-made sources. [Album: World's Biggest Beasts]

Questionable numbers

The researchers, led by David Wilkinson of Liverpool John Moores University in the United Kingdom, did their best to get an accurate estimate of how much gas these big dinosaurs would have created, but their answers are still just estimates based on multiple assumptions, they warn.

The greenhouse gas methane is a natural byproduct of the digestive process of plant eaters, especially in herbivores called ruminants (like cows and camels). The researchers suspect that like ruminants, sauropods would have harbored methane-producing bacteria in their intestines to help digest these fibrous foods.

There is currently no way to tell what kind of bacteria lived in the digestive systems of dinosaurs, what gasses they produced, or what those digestive systems would have looked like, but Wilkinson thinks they would have produced methane like today's animals.

"To process that amount of vegetation they have to be relying on microbes in their digestive system," Wilkinson told LiveScience. "But without a time machine you can't be sure."

Crunching gassy numbers

They used a mathematical model to determine how much gas these plant-eating giants would have eaten. They extended data on methane production by modern mammals, based on size, up into the reaches of the sauropods.

In their calculations the researchers used middle-of-the-road numbers: 10 sauropods, each weighing 20,000 pounds (9,071 kilograms), could have roamed 1 square kilometer of lush Mesozoic habitats. "We've taken a middle-ground value," Wilkinson said. "We tried to be reasonably conservative."

They found that these 10 sauropods would have contributed 7.6 tons (6.9 tonnes) of methane every year. Expanding this number to cover the amount of land estimated to be hospitable habitat for these animals (about half the land on Earth at the time), the researchers end up with more than 550 million tons (500 million tonnes) of methane produced every year.

"I was expecting a number like that produced by cows, so the size of the number really surprised me," Wilkinson said. "It's way, way, way ahead of the estimated methane production by modern livestock." (Cows produce 55 to 110 million tons (50 to 100 million tonnes) of methane each year, he estimated.)

Big eaters

It makes sense, based on the animal's huge size, that they would make much more methane per individual than a cow. But, there are several other reasons why these large dinosaurs could have produced so much more gas than modern herbivores.

The animals would have had plenty of plants to eat, because they could reach high and low, and because of the warm climate, there was plenty of vegetation; in addition, these animals had much vaster areas in which to graze.

The real question is, did these dinosaur's gassy emissions warm the planet?

"The thing about methane is it is an extremely potent greenhouse gas," Wilkinson said. If the levels were anywhere near where their calculations indicate, he said, it very well could have been one of many factors that made that era warmer and wetter than modern times.

The study is detailed in today's (May 7) issue of the journal Current Biology.

You can follow LiveScience staff writer Jennifer Welsh on Twitter, on Google+ or on Facebook. Follow LiveScience for the latest in science news and discoveries on Twitter and on Facebook.

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• Avian Ancestors: Dinosaurs That Learned to Fly

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Comments

[Cayce58]

10:09 PM on 06/05/2012

Unmentioned variable. The big dinos could have been less than warm blooded but not cold blooded. They would have required less food in that case.

[charlesrfd2003]

01:48 PM on 06/01/2012

If one wants to quote statistics please quote the margin of error. I suspect that is very large. This information is not very useful except to deniers. Painting roofs white and lightening the surface of roads would be better use of science funds.

Yes there are things that compare to these giants. They are the machines on the highways that burn the remains of the dinosaurs and the plants that existed then.

[Tim Kunk]

07:59 AM on 05/19/2012

At one time the greeny meanies claimed that the cause of global warming was, cow farts. and that we all would have to give up beef.

[TYRANNASAURUS]

10:46 AM on 05/17/2012

.............................................but their answers are still just estimates based on multiple assumptions, they warn.

Right...this is the catch.....and how many billions of sauropods would really be needed to accomplish this?

[darrtown]

12:29 AM on 05/17/2012

For all those who don
y believe in climate change: we have bee recording above average monthly temperatures for 326 straight months. The last below average month was in 1987.

[ceekreewd]

09:46 PM on 05/15/2012

Please don't let the radical 'greenies' see this -- we'll all be wearing charcoal-filter diapers..

[trailerguy]

10:18 AM on 05/15/2012

nobody light a match

[uniqumm]

11:29 PM on 05/14/2012

I'm guessing that grants for research are a bit difficult to come by. So, what's an enterprising biologist to do when publish he must?

And, all it requires is some paper and a pencil!

[DrTachyon]

05:04 PM on 05/16/2012

It's so easy! Why aren't you doing it?

[uniqumm]

08:09 PM on 05/16/2012

1.  I'm not a biologist.
2.  I have no compulsion to publish anything.
3.  I have few compulsions other than occasionally to go to bathroom quickly.  And a bit of a compulsion to hoard/keep things that may prove useful!
4.  I seem to hardly ever find either a pencil, a pen, or paper at the same time when I need it.

[roc-o-rama]

01:03 PM on 05/14/2012

I smell a new Hollywood remake coming..."Jurassic Fart" coming soon to an enclosed theater near you.

[Mercer2]

12:45 PM on 05/13/2012

Hahahahahaha

[thecastermaster]

05:40 PM on 05/12/2012

Quick, pull my claw..

[WILSPIN812]

11:24 AM on 05/12/2012

Should the time machine ever be invented I have a new candidate for worst job ever-dinosaur fart measurer!

[Boissiere Parker]

12:43 AM on 05/12/2012

Quite honestly that sounds like the pure BS! But, who knows we sure as hell won't.

[jimboy71]

12:48 PM on 05/23/2012

For what reasons?

Pick one aspect of the hypothesis, and critique it.

Can you do that?

[Boissiere Parker]

02:33 PM on 05/23/2012

Jim I am not exactly sure what story the above from. I do not have a way to see this....how long ago was the post? Quite interested now because I definitely do not like your tone!

[Sjoerd W]

05:38 PM on 05/11/2012

In my humble opinion, farts should be changed into burps.

Humans do the bulk of their digestion in their intestines, where we also get help from a selection of microbes. Since it is in the intestines where sideproducts like methane are formed, most of it comes out of our erhm.. lower business end.

If the dinosaurs in question really were ruminants, they would probably have four stomachs and do most of their digestion, aided by microbes, in their stomachs instead of in their intestines. Just like our modern day cows do. And just like our modern day cows, most methane would be expelled through belching, rather than farting (a common misconception).

PS: a quote from 'Alan4discussion' since he words it so much better than I do: "In estimating methane output, the mass of production of edible vegetation in a given area is probably more relevant than the size of the animals which were supported by eating it, as clearly, this vegetation will support more smaller animals. It is the volume of fermented vegetation digested by ruminant species which largely determines methane production."

[jimboy71]

12:51 PM on 05/23/2012

Dinos didn't have four stomachs. You're trying to reverse engineer a dinosaur from a mammal.

Lizards and birds only have one stomach. These are the living relatives and descendants of the dinos.

[zippy335]

11:31 AM on 05/11/2012

"Did these dinosaur's gassy emissions warm the planet?"

I don't think that this would all be additional methane in the atmosphere because had the vegetation not been eaten and digested, it still would have been broken down and methane would still be released.

[Sjoerd W]

05:21 PM on 05/11/2012

Depends, these bacteria process the cellulose in a way that results in nutrient, energy and methane. But different classes of bacteria could use different processes resulting in different compositions of the molecules.

A huge difference would be anaerobe bacteria versus aerobe bacteria. They employ completely different ways (without and with help of oxigen respectively) to break down their food. If I remember correctly those in a ruminants stomache(s) do use oxigen.

Fact check yourself, I'm bound to have stuff wrong.

[Sjoerd W]

05:24 PM on 05/11/2012

Woops, considering the climate was hot and swampy so to say, the most likely outcome of decaying plant matter would be methane too. Zippy, Ignore my previous post.