Dinosaur Powered Global Warming?
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.
…
To estimate methane production we follow the relationship … for modern non-ruminant herbivores, where Methane (litres per day) = 0.18 (body mass in kg)0.97. … [Using] a conservative estimate of the adult mass of the medium sized sauropod Apatosaurus louise, colloquially known as ‘Brontosaurus’ [as 20,000 kg] … gives methane emission of 2675 litres per day for one animal, equivalent to about 1.9 kg per day[.] … Scaling up, assuming a global vegetated area of 75 x 106 km2 (equivalent to half the total land area), gives global methane production from sauropods of 520 Tg (520 million tonnes). This is comparable to the total modern-day methane emission (Figure 1).
…
[O]ur calculations suggest that sauropod dinosaurs could potentially have played a significant role in influencing climate through their methane emissions. Even if our 520 Tg estimate is overstated by a factor of 2, it suggests that global methane emission from Mesozoic sauropods alone was capable of sustaining an atmospheric methane mixing ratio of 1 to 2 ppm.
Source: David M. Wilkinson et al., Could Methane Produced by Sauropod Dinosaurs Have Helped Drive Mesozoic Climate Warmth?, 22(9) Current Biology 292-93 (May 8, 2012) (citations omitted, emphasis added) [PDF]; see also Michael Marshall, Sauropod Farts Warmed the Planet, New Scientist (May 7, 2012); John Timmer, Belching Dinosaurs May Have Helped Keep Their World a Hot One, Ars Technica (May 8, 2012).