Science column: Blood, sweat and shale
Published: Monday, October 28, 2013
Updated: Monday, October 28, 2013 22:10
Forty-six million years ago, in what we now call Montana, an unlucky mosquito bit the dust just after gorging itself on a meal of animal blood. Two weeks ago, a team of researchers published a paper detailing their one-of-a-kind find: a mosquito fossilized with a stomach full of blood.
This mosquito is the first of its kind, and while the 1993 film “Jurassic Park” is based on the idea that, having found insects with ancient blood in them, one could clone a dinosaur. That is inaccurate.
Of course, the movie was awesome but still incorrect: not only does DNA break down at a rate too fast for any of it to have survived to the present, no one has ever found a mosquito with a full meal of blood.
Statistically, it’s almost impossible. Insect fossils are hard to find (imagine searching through rocks that cover the entire Earth looking for bits of bug!), but a mosquito would have to have eaten a meal, immediately fallen into fossilizing conditions, and then been found by a researching team tens of millions of years later. As impossible as that sounds, it just happened.
Unlike the mosquitoes in “Jurassic Park,” this one was not preserved in tree sap (or amber), but was found in shale. Shale is a type of rock that forms from sediments as they’re deposited in the bottom of bodies of water, like lakes.
In a large still lake, the bottom layer of water can become devoid of oxygen (or anaerobic). These conditions are perfect for fossilization, and would keep a mosquito that fell into the lake from decomposing until it was buried and ultimately fossilized.
The mosquito was given to the National Museum of Natural History in Washington, D.C. two years ago as a gift, and researcher Dale Greenwalt immediately recognized it for what it was and began looking into the implications of such a rare find.
One thing this discovery shows is that blood-feeding insects were around much earlier than scientists originally thought.
One of the claims against “Jurassic Park” was that mosquitoes and dinosaurs never co-existed, so a mosquito full of dinosaur blood could never be found. However, this mosquito shows that blood-feeding insects and dinosaurs could have existed together after all.
Some scientists are asserting the find indicates the Montana shale, which was thought to be about 43 million years old, is actually much younger. Science writer Brian Thomas says there is no way blood could possibly survive 50 million years, and this find indicates that scientists need to revisit their geologic dating methods.
Geologists have ways to date prehistoric life forms, and once they do that, they tend to correlate other places including that life form with the same date. From there, the areas with dates are applied to other life forms in the area.
While this process works in theory, Thomas calls it out as “circular reasoning” and says it needs to be re-evaluated. If Thomas is correct, this mosquito could be the beginning of a big change in the world of paleontology.