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Friday, November 1, 2013

A prehistoric blood meal

Dale Greenwalt from the National Museum of Natural History and his colleagues have found a 46 million year old fossil mosquito containing its last blood meal. What this does not mean: that we could get dino DNA out of mosquitoes after all. No it doesn’t. What it does mean: mosquitos were dining on blood 46 million years ago, something we suspected but had not been able to prove.


This image shows a 46-million-year-old blood-engorged female mosquito from northwestern Montana. Image credit: Dale E. Greenwalt et al.
A 46-million-year-old blood-engorged female mosquito from northwestern Montana.
Image credit: Dale E. Greenwalt et al.

You might think paleontologists find blood-engorged mosquitoes all the time.  Not so. Fossil mosquitoes are only rarely found, possibly because their fragile bodies do not readily fossilize and because they did not seem to frequent the resin-producing forests that preserved other insects in amber. This specimen was found in oil shale, not amber.

Only 36 mosquitoes were found in the area, and all but one of them were either males, which do not eat blood, or females that had not recently eaten. Thus, this is the first and only Middle Eocene mosquito ever found with its last blood meal still in its abdomen.

The female mosquito’s abdomen contained high levels of iron and porphyrin molecules, both hallmarks of hemoglobin. The scientists did not find DNA. And even if they had, there were no dinosaurs 46 million years ago, apart from birds. 

So, we know a little more about the history of blood-sucking insects. But still no Jurassic Park.

Dale Greenwalt, Yulia Goreva, Sandra Siljeström, Tim Rose, & Ralph E. Harbach (2013). Hemoglobin-derived porphyrins preserved in a Middle Eocene blood-engorged mosquito Proceedings of the National Academy of Sciences of the United States of America DOI: 10.1073/pnas.1310885110.