Millions of years before the emergence of dinosaurs, there was a creature running around that some people might find much scarier than any tyrannosaur. Imagine a millipede, but it weighs more than 100 pounds and its body is the length of a car.
These Lovecraftian nightmares were called Arthropleuraand are the largest known species of arthropods that have ever existed. Fortunately for those who get goosebumps from writhing animals, the 8-foot-long creatures, which first appeared 346 million years ago, disappeared about 50 million years after that.
The creatures left behind a mystery for modern paleobiologists to ponder: How closely related were they to their much smaller modern counterparts? Although the ancient giants are commonly classified as myriapods, a group of animals that is dominated in the modern day by millipedes and centipedes, it was unclear where, exactly, they lived. Arthropleura belonged to the family tree. Scientists from several French universities may have found the answer by looking directly at the bizarre creatures.
This was actually quite a difficult thing to do. Although Arthropleura was first discovered in 1854, most of the fossils found were fragmentary – and none included a complete head. The record was so incomplete and the creatures so strange that some paleobiologists mistook a neck-like part called the collum for the head. There was no evidence of what Arthropleurathe animal's eyes, antennae, and mouth may actually look the same, so it's been difficult for scientists to tell whether there's a family resemblance to the multi-legged organisms you can find in most gardens.
To solve this problem, paleobiologists, led by Mickaël Lhéritier of the Universite Clauder Bernard, digitized the remains of several particularly well-preserved juveniles and used tomographic imaging techniques to recreate their mugs. As Lhéritier and his colleagues described in the diary Science AdvancesAncient arthropods passed on some of their facial features to their distant modern-day relatives.
Like millipedes, scans showed Arthropleura they had seven-segmented antennae and a modified spine behind their heads. Arthropleura it also had some features in common with centipedes, such as fully encapsulated jaws and a pair of leg-like jaw structures called maxillae. Although centipedes and millipedes are both myriapods, their exact relationship to each other has been the subject of some controversy among myriapod enthusiasts. The new findings suggest that the two species should be grouped together, due to a common heritage that makes them more closely related to each other than to other myriapods, such as pauropods.
With a more complete idea of what Arthropleura it seemed, paleobiologists said there were some inferences that could be made about how they behaved. Their diet, the scientists wrote, likely consisted of already dead animals that they could eliminate.
Although the study offers the most complete look at extinct arthropods to date, James Lamsdell, associate professor of paleobiology at West Virginia University, wrote a follow-up article stating that there is still much we don't know.
“Without direct evidence from the digestive tract, it is still unclear exactly what Arthropleura I ate it,” he wrote. “The respiratory organs also remain unknown, leaving the possibility that Arthropleura it was aquatic.”
Lamsdell said it also cannot be ruled out that Arthropleura He spent different phases of his life in different environments. So there you have it: millions of years ago, creepy crawlies that were almost as long as an alligator roamed the land, and possibly the water, snatching bites from dead animals. The next time you see a millipede scurrying across the ground, take a second to be thankful for its diminutive size before deciding to squish it.
