A remarkable fossil discovery in Northumberland, United Kingdom, has astonished scientists by confirming that a millipede species once grew to the size of a small car. Unearthed along the northeastern coast, the find reveals a colossal creature that lived 326 million years ago during the Carboniferous period, long before the age of dinosaurs.
The species, known as Arthropleura is an extinct genus of millipedes believed to be the largest invertebrate ever to walk on land. While the fossil segment found in 2018 measured just under 30 inches, researchers estimate that the animal it belonged to likely stretched nearly 9 feet in length and weighed around 110 pounds. The fossil was preserved in sandstone, and scientists say it is one of the most complete remains ever found of this ancient giant.
Earth scientist Neil Davies of the University of Cambridge described the find as a “complete fluke,” noting that the boulder containing the fossil split open naturally and exposed the segments. The preserved structure has allowed researchers to study the physical features of this long-extinct arthropod in greater detail.
Arthropleura thrived in dense forests during a period when Earth’s atmosphere contained higher oxygen levels, a factor long thought to contribute to the giant sizes of ancient arthropods. However, scientists point out that oxygen levels at the time were still lower than previously believed necessary for such growth, suggesting that other environmental advantages including nutrient-rich vegetation and limited predators likely played a key role in allowing these creatures to reach extraordinary proportions.
Further clues about the Arthropleura have emerged from separate fossil findings, including skull fragments discovered decades ago and recently analyzed through CT scanning. While earlier research focused on body segments and exoskeletons, these scans revealed unexpected details about the creature’s head. According to a study co-author, Mickael Lheritier, the head structure appeared more similar to that of a centipede, with short antennae and protruding eyes, distinguishing it from modern millipedes. The head also featured an opening used to shed its exoskeleton, an adaptation that offers insight into the animal’s growth and behavior.
Scientists believe that Arthropleura roamed humid, forested regions near the equator, feeding on vegetation and possibly hunting smaller animals. The discovery suggests that these prehistoric environments were far more complex than previously assumed and may not have been limited to coal swamp ecosystems traditionally associated with large arthropods.
Even with this major discovery, the fossil record for Arthropleura remains incomplete. Researchers have yet to find an intact specimen with both body segments and a preserved head, leaving questions unanswered regarding its full anatomy and life cycle. For now, the Northumberland fossil adds a crucial piece to the puzzle of one of Earth’s most extraordinary ancient inhabitants, offering a rare glimpse into life hundreds of millions of years before humans appeared.