The 46 million year old skeeter

This is the story of a mosquito. Like many mosquitoes, it bit something and sucked its blood, filling its gut with hemoglobin. But then it died, perhaps on the algae film of a lake.

The algae covered its tiny body, coating it and protecting it from decay. Eventually it sank to the bottom, part of the detritus of the past, and stayed there — for 46 million years.

The lake was huge, stretching from Canada into the Bob Marshall Wilderness, and the climate back then was subtropical.

“The whole world was much warmer,” explained Dale Greenwalt, a paleobiologist at the Smithsonian Institution’s National Museum of Natural History.

Eventually the earth cooled. The lake disappeared, and the millions of years of accumulated sediment at the bottom turned to rock — the Kishenehn formation. The north and middle forks of the Flathead River gnaw at this formation every year, revealing its secrets.

Fast forward to the 1980s. A young geologist from Whitefish named Kurt Constenius was poking around the Middle Fork of the Flathead River, working on his master’s degree, when he found some interesting fish fossils.

Constenius grew up fossil hunting in Eastern Montana with his parents Norm and Leona. One day, they went looking themselves for fossils and found prehistoric grasshoppers, which intrigued their son. They began more searches and found more prehistoric bugs. They also found fossils from rhinoceros, hippopotamus, horses, tapirs and flying lemurs.

Constenius wrote up his work in his thesis, but not many people read it. But 30 years later, the study caught Greenwalt’s eye. He struck up a friendship with Constenius and his family and began making trips to Northwest Montana, gathering more than 6,000 shale samples that he examined later back in Washington, D.C.

While those samples contained plenty of prehistoric bugs, none of them contained the blood-filled mosquito. That was in a fossil sample Constenius’ parents had donated a few years earlier. It had been collected decades ago and was sitting on a shelf with thousands of other samples.

At first look, Greenwalt knew he had something special. A blood-engorged mosquito is a rare find indeed. But he needed to make sure it was, in fact, blood, so he contacted the mineral sciences division at the Smithsonian.

A non-destructive X-ray analysis revealed that the mosquito’s gut had a high concentration of iron — a key component in blood. Further analysis using mass spectrometry revealed the fingerprint of the heme molecule — another indication that the mosquito was, indeed, full of blood.

The find was not a “Jurassic Park” moment, Greenwalt concedes. In the story by Michael Crichton, scientists extract DNA from the blood of a mosquito caught in 95-million-year-old amber and clone a dinosaur community that goes horribly awry.

Greenwalt said he didn’t even look for DNA. His mosquito was not found in amber — it was a fossil, and the fossilization process destroys DNA. Also, dinosaurs went extinct about 66 million years ago. Montana 46 million years ago had plenty of interesting creatures, including a relative of the rhinoceros, but no dinosaurs.

The true joy was simply proving the mosquito was indeed full of blood. And the site itself, he said, has some of the best-preserved insect fossils of any place in the world.

Greenwalt said he plans on returning to do more research in the coming years.

“This site is very unique,” he said. “It’s one of a kind.”