October 10 – Bug Out

Today’s factismal: The largest insect known to have ever lived was the Meganeuropsis americana which had a 28 inch wingspan and weighed more than a pound.

Imagine that you are in Oklahoma a mere 265 million years ago. Instead of the rolling prairies that cover Oklahoma today, you are surrounded by a swamp that is filled with amphibians and reptiles. And instead of today’s rather oxygen-deprived atmosphere (a mere 21%), you are in air with 30% oxygen content. That higher oxygen content makes wildfires more common; it also allows many creatures to get much larger than they could today.

And no group of critters does better than the insects; high oxygen levels allow them to grow much larger than is possible today. Of course, there are some paleontologists who believe that the oxygen levels are at best a secondary cause for the bigger insects back then; they argue that there were fewer large predators of insects which allowed for bigger insects to survive. In either case, one thing is sure: insects back then were big. Mosquitoes the size of your hand. Roaches the size of your foot. And primitive dragonflies the size of your desk.

A M. americana wing and a couple of modern dragonflies for scale. (Image courtesy Harvard Museum of Natural History)

A M. americana wing and a couple of modern dragonflies for scale.
(Image courtesy Harvard Museum of Natural History)

First found in Oklahoma by a Harvard paleontologist in 1947, their fossils are impressive. The best known is a single forewing which stretches 14 inches in length. The limestone that it was found in was known to come from a lake-type environment, which tells us that dragonflies haven’t changed much in their habits in 265 million years. And other evidence tells us that they fed on small reptiles, frogs, newts, and anything else foolish enough to get in their way, just as today’s dragonflies feed on small fish, tadpoles, and other insects.

Though you are unlikely to run into a Meganeuropsis americana today (unless you happen to be in a bad B-movie), you may still see one of its distant great-great-great-grandkids flitting by. If you are that lucky, then why not report it to your local entymologist? Many states have set up portals like the Arizona Odonta site, hoping to get more information on these fascinating fliers.
http://www.azodes.com/Report.aspx

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