Somewhere near the Flathead River of Montana’s Glacier National Park, lies a fossil ground where researchers discovered a rare insect fossil of a female mosquito dated to about 46 million years. Their findings were published this week in the journal Proceedings of the National Academy of Sciences. The find is quite rare as only four other fossils like this one, with evidence of blood-feeding, have been found despite the existence of nearly 14,000 species of blood-feeding insects today.
Most of the blood-feeding insect fossils that have been discovered thus far belong to biting midges. In fact, there are some 200 known species of extinct midges and midge-like flies when compared to only 25 documented species of extinct mosquitos.
The oldest known insect fossil is, however, much older than this mere 46 million-year old newbie. In London’s Natural History Museum, one can find an insect fossil that has been dated back to 400 million years ago from a rock known as the Rhynie Chert. This rock hales from the Scottish village of Rhynie and is made of silica beds formed by hot spring deposits nearly 400 million years ago. However, this insect fossil more or less resembles a modern-day silverfish, not a mosquito.
While this female mosquito may not score max points for antiquity, she certainly makes a statement with her belly. Scientists report, “The preservation of (this) fossil female mosquito…was an extremely improbable event.” They state that the insect had to have recently fed, then get “blown to the water’s surface, and sink to the bottom of a pond or similar lacustrine structure to be quickly embedded in fine anaerobic sediment”, without causing damage to the distended belly full of blood.
In other words, this ancient mosquito has some “junk in her trunk.” Of three dozen other mosquito fossils discovered in the same area of Montana, this is the first one found to have an intact belly of blood.
However, the discovery of this prehistoric blood does not cash into DNA information. Studies on the half-life of DNA suggest that anything older than 1.5 million years cannot be coded for its genome. To date, the oldest DNA to have yielded a full genome comes from a horse leg bone that dates back to 700,000 years ago. The bone was found preserved in the permafrost of Canada’s Yukon Territory in 2003.
While this blood is not useful for DNA information, it does support other research claiming that biomolecules called porphyrin are found in fossilized hemoglobin just as they are today.
With the help of a secondary ion mass spectrometer, researchers were able to distinguish porphyrin biomolecules inside the blood contained in the fossil’s belly.
Prior to this discovery, blood had been found in fossilized mosquitoes preserved in Dominican amber dating back to between 45 – 15 million years. Bird malaria parasites were found in the blood of these ancient mosquitos.
While the film Jurassic Park, released in 1993, mistakenly portrays how fossilized mosquitos can be mined for DNA to clone dinosaurs, it did put the spotlight on how these ancient insects can become a portal to the past. As pesky back 40-some-odd millions of years ago as they are now, mosquitos continue to compel with their resiliency.
Written by: Fatema Biviji