The
temperature of the earth has had its ups and downs in its history. At the
moment it is beginning a rapid rise, which we blame emissions from cars, but
also emissions from cows that is due in large part to our love of hamburgers.
Cows
in our idyllic picture wander at large munching grass and putting to work
hordes of bacteria in their multiple fermentation vats converting the cellulose
into useful sugars. A by-product of the fermentation process is methane, which
is a more potent greenhouse gas than carbon dioxide. Now we can’t eat grass but
we can eat cows so I don’t anticipate the problem disappearing any time soon.
Herbivores
have been around for quite awhile and back in the Mesozoic huge sauropods
wandered about doing what their parents taught them and munching on their
greens. Wilkinson et al started to wonder about whether they suffered from
greenhouse gas as a result and sat down, exercised their computer and wrote a
letter to Current Biology (1,2).
The
fun started with estimating the weight of dinosaur per square kilometer. Their
estimates came out at a weight of 0.2 to 0.7 million kg/km2. This is a pretty high stocking rate if we compare
it to today’s mammalian species in the wild.
But we move on to the next
assumption, which is the bacterial fermentation is pretty much the same whether
it takes place in the stomach of a Hereford or a Brontosaurus. The greenhouse
gas output from either end gives (liters/day of methane) ~ 0.18 x (body weight
in kg). So our Brontosaurus would have burped and farted approximately 2.7 kL
each day.
The even bigger news is
that when all this flatulence is added up, the annual output of methane is
pretty close to what we produce today, which might have accounted for the 10°C
higher temperature in those days.
That just leaves my big question that has been worrying me for
years and that is what did they taste like? Did they taste like chicken? After
all chickens are rumored to be relatives.
- http://www.cell.com/current-biology/fulltext/S0960-9822(12)00329-6
- http://www.bbc.co.uk/nature/17953792
