Tikalon Blog by Dev Gualtieri

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Dino Farts and Fleas

May 16, 2012

As if to balance all the publications about the futuristic gadgets of our information age , there have been two recent articles about dinosaurs . No, these articles aren't about Kodak , or the music industry (at least Kodak is trying to modernize its business model ), it's about those hefty creatures that dominated Earth's ecosystem many millions of years before man arrived to take over the planet.

Children of my generation were fascinated by dinosaurs, and there were many dinosaur books published for children. My friends and I used to make drawings of dinosaurs based on the many images in those books. In those days of monochrome television with just a few channels , there wasn't much else to keep

Tyrannosaurus Rex fossil head

ourselves entertained. We read a lot of books, since there wasn't anything to distract us from reading.

The first article, in the April 24, 2012, issue of Current Biology ,[1] doesn't address dinosaurs directly, but rather some giant fleas that appear to have lived by sucking dinosaur blood .[1-5] One thing about nature , if there's an ecological niche , there will be a species to fill it. Fleas are associated with birds , which are the genetic relics of the dinosaurs. There had been no evidence of flea parasitism of dinosaurs, although many fossils of fleas from ages closer to the present, the Eocene (34-56 million years ago) and Oligocene (23-34 million year ago), have been discovered.[1]

Fossil evidence for fleas has been sparse in the Mesozoic (65-250 million years ago), which is the time when dinosaurs dominated both the land and seas .[1] One preoccupation of entomologists is the mouth parts of the insects that they study, since these tell a lot about the insect's feeding adaptation. Unfortunately, no clear fossil images of mouth parts had been found for fleas in the Mesozoic.[1]

The paper in Current Biology, by authors from the Capital Normal University (Beijing , China ) and the Chinese Academy of Sciences , presents fossils of two primitive flea species from the Jurassic (145.5-199.6 million years ago) and the Cretaceous (65.5-145.5 million years ago) in Inner Mongolia .[1] These fleas had large bodies, and, more interestingly, they had long serrated stylets that seem to be adapted for piercing tough and thick skin . This demonstrates the likelihood that such fleas were adapted to feed on their contemporaneous feathered dinosaurs , and the flying dinosaurs, the pterosaurs .[1]

Figure caption

This ancient flea, Pseudopulex jurassicus, lived about 165 million years ago.

It was a about an inch long, which is ten times larger than the dog fleas of today.

(Illustration by Wang Cheng, Oregon State University).

George Poinar, Jr., an emeritus professor of zoology at Oregon State University and an international expert in ancient and extinct insects, thinks that these fleas are a distinct flea lineage ; that is, modern fleas did not evolve through such a form. Poinar, who studied fleas in amber from 40-50 million years, wrote a commentary on the Chinese paper in the same issue of the journal.[2] The species, which have been named Pseudopulex jurassicus and Pseudopulex magnus, had long claws that allowed them to effectively grasp their host while feeding.[Oregon]

In a previous article (Cow Farts and Beefy Burps, March 16, 2011), I wrote how methane is about twenty times more potent a greenhouse gas than carbon dioxide ; and that cattle farming is responsible for 18% of greenhouse gases .[6]

The culprits here are cattle , since the methanogenic bacteria in their digestive systems produce large quantities of methane. Cattle expel 95% of this gas through burping , and 5% through flatulence . We have a lot of cattle on the Earth, today, but there were a lot of dinosaurs,much larger, around in the Mesozoic.

Another paper in Current Biology,[7] this one in the May 8, 2012 issue, examines the idea that dinosaur flatulence may have had a major affect on Earth's climate of their time.[7-11] Sauropods , such as the Apatosaurus (a.k.a., Brontosaurus), the long-necked, long-tailed herbivores of the Mesozoic, were likely to have hosted microbial methanogenic symbionts , since these are an efficient means for digestion of vegetation via fermentation .[7, 9]

Sauropods weighed about twenty tons, and they lived together in herds of a few tens per square kilometer.[10] Unlike cows, Sauropods bacteria likely populated the hindguts, and methane was released through flatulence, not burping.[11] As David Wilkinson of John Moores University (Liverpool, UK), one of the authors of the study, told the BBC ,

"Cows today produce something like 50-100 [million metric tons ] per year. Our best estimate for Sauropods is around 520 [million metric tons]"[9]

Wilkerson admits, however, that this estimate may be off by a factor of 2. "There are a lot of educated guesses."[11]

Present day methane production is about 500 million netric tons per year. This is from natural sources and human activity, such as cattle farming for meat and milk .[9] Before the Industrial Revolution , global methane production was only 181 million tons per year.[10]

The Mesozoic was much warmer than today, about 10°C (18°F ) warmer, but the Sauropods contributed only about 1°C of this.[9, 11] Other dinosaur species would have added to this total, as would sources such as rotting vegetation.[9] Climate modeling indicates that methane existed in 4-5 times higher concentrations in the Mesozoic than now.[8]

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