Imagine walking through a peaceful forest and running into huge prehistoric creatures, like a dragonfly with a two-foot wingspan. Then imagine seeing the world's largest land invertebrate: an enormous, six-foot-long millipede. During the Pennsylvanian period, massive bugs roamed North America, and the largest was Arthropleura, the millipede king of the forest. Arthropleura was a stunning one-and-a-half feet wide, and it could grow to nearly seven feet in length. The largest millipede fossils ever found, including tracks from the creature, prove that Arthropleura dominated the swampy forests of North America 300 million years ago.
Just like the giant Megalodon, a 60-foot prehistoric shark, Arthropleura was much more giant than its descendants, today's millipedes. And Arthropleura dominated the Earth long before the dinosaurs, along with many other prehistoric creatures.
The massive Arthropleura flourished from around 320 to 290 million years ago, during the same period when coal deposits laid down rich resources in North America and Europe. While other aquatic arthropods beat Arthropleura in size, no one could match it on land.
But just how big was Arthropleura? Scientists believe it grew to over six feet in length and may have been as much as one-and-a-half feet wide. It was the creepy, crawly king of the forest.
It's hard to imagine a millipede at the top of the food chain, but Arthropleura had no known predators. Scientists established that fact by looking at the creature's body armor. Researchers Otto Kraus, a millipede expert, and Carsten Brauckmann, a prehistoric arthropod specialist, uncovered the surprising fact that the armor itself was quite thin.
The plating was just a few millimeters thick, and unlike the exoskeletons of modern crustaceans, it did not contain the hard calcium carbonate. This evidence indicates that Arthropleura had few, if any, enemies that tried to catch and eat it.
Just how big was Arthropleura, anyway? If an average-height man lay down in the swamps of the Carboniferous Period, an adult Arthropleura could completely cover his body. Scholars believe Arthropleura grew at least two meters in length or the equivalent of over six-and-a-half feet.
They still haven't recovered a complete fossil from the creature, however, so it's possible the prehistoric millipede grew even larger.
Where did the prehistoric millipede Arthropleura live? About 300 million years ago, many called the current United States home. That's the story scientists uncovered in fossil records. Fossilized Arthropleura remains have been found in Kentucky and New Mexico.
One researcher described the New Mexico tracks left by the massive millipede as similar to tire tracks from a vehicle.