Arthropleura

The Carboniferous Period was the era of giant invertebrates. This includes massive flying insects like the griffin flies and the millipede-like Arthropleura. Arthropleura is an extinct arthropod genus that looked much like modern-day millipedes and centipedes but was significantly bigger. It lived during the Carboniferous (about 345 to 280 million years ago). During this period, vertebrates were yet to gain dominance. Instead, creepy crawlies like the Arthropluera were the most dominant lives on the planet. This giant organism’s fossil has been found in North America and Europe. It holds the title for the largest land invertebrates that have ever lived. 

Description and Size

Arthropleura is a genus of millipede-like arthropods that lived on earth about 345 to 280 million years ago during the Carboniferous Period. The name of this giant invertebrate means “jointed ribs” in Greek. The name refers to the numerous jointed segments and hard plates covering this invertebrate’s narrow body. 

Since no complete fossils of these large fossils have been found to date, interpretations of how they might have looked have been controversial. However, experts mostly agree that Arthropleura looked a lot like modern-day millipedes. However, instead of a single continuous narrow body, the body of this giant arthropod was divided into three segments, including one center plate and two side plates. 

Thanks to the oxygen-rich environment of the Carboniferous and the lack of vertebrate predators, arthropods like the Arthropleura could grow to a considerable size. In fact, it is considered the largest land-dwelling invertebrate, measuring between 0.3–2.6 m (1–8.5 ft)—almost the size of a small car—and with a width of about 22 inches (55 cm). The millipede arthropod had up to 30 segments. Estimates of this arthropod’s size suggest that its body mass might have been up to 110 lbs (50 kg)—about the weight of a large dog. 

The underside of their body had several pairs of legs with a ratio of eight pairs of legs to six body segments. Initially, scientists thought the first segment of this arthropod was its head. However, later studies showed that the actual head was tucked underneath this armor plate. This first plate, the collum, also had non-filamentous antennae or trumpet-like organs.

Diet — What Did Arthropleura Eat?

Initial interpretations suggested that Arthropleura was a carnivore. Later studies showed that this is unlikely. An organism with strong mouthparts for chewing or crushing prey would have preserved some or all of those parts in fossilized remains. This and other factors led to the conclusion that this giant arthropod was most likely herbivorous. 

In a fossil recovered by scientists in Scotland in the 20th century, a giant clubmoss plant’s remains were found in this animal’s gut. Experts are not sure if the preservation occurred accidentally after the organism’s death or if it is evidence of what it ate when it was alive. 

If we interpret the Arthropleura’s diet to be similar to that of the present-day millipede, it would have lived on foliage, spores, and seeds. 

Habitat — When and Where It Lived

Arthropleura lived during the Carboniferous between 345 to 280 million years ago. Fossils of this invertebrate have been found in various locations in North America and Europe around the equator. 

Since paleontologists often found the fossils associated with roof shales, earlier interpretations suggested that Arthropleura lived in humid swamps. However, later evidence depicted that this organism probably lived in a wide range of other environments and landscapes but would have preferred locations with good vegetation cover. 

Threats and Predators

Considering the size of this arthropod and when it lived, it probably didn’t have a lot of natural enemies (if at all there were any). It was the largest known land invertebrate and lived along with other giant insects like giant dragonflies and prehistoric cockroaches. 

Discoveries and Fossils — Where Arthropleura was Found

Paleontologists have not found any complete fossil of the Arthorpleura’s carcass. Instead, molting shells (exuviae) are more common. Paleontologists have found these fossilized shells in various locations across North America, Germany, Belgium, the Czech Republic, and France. 

Another common way fossils of Arthorpleura are preserved is as fossilized footprints. These typically appear as long, parallel rows of prints that show how the animal moved along the forest floor. We can use these tracks to estimate the animal’s size and other habits, like how it moved in life. 

Extinction — When Did Arthropleura Die Out?

Arthropleura rose and went extinct during the Carboniferous about 280 million years ago. Previously, scientists attributed the disappearance of Arthropleura to the collapse of coal forests that were quite common during the Carboniferous. However, paleontologists have found many fossils of this arthropod even after the collapse of the forest. This suggests that they probably outlived it.

Based on more recent findings, the extinction of Arthropleura is typically linked to significant climatic changes that occurred during the Permian. The area around the equator where this animal lived became drier and was no longer favorable for them. The rise of the tetrapods may have contributed to their extinction as well. 

Similar Animals to the Arthropleura 

Similar animals to the Arthropleura include: 

• Meganeura: This is a genus of giant insects that lived during the Late Carboniferous Period. They’re related to present-day dragonflies but were significantly larger. Meganeura and other griffin flies ruled the skies of the Carboniferous. 
• Trilobites: Trilobites were one of the earliest-known arthropods. They lived in the marine environment about 520 million years ago (during the Cambrian). 
• Maiocercus: This is a species of prehistoric spider that lived during the Carboniferous. They looked significantly different from present-day spiders because their bodies were divided into segments. 

Related Animals 

• Giant African Black Millipede
• Anomalocaris
• Eurypterids 

1. Wales Museum, Available here: https://museum.wales/articles/2384/Arthur-the-Arthropleura/
2. Wikipedia, Available here: https://en.wikipedia.org/wiki/Arthropleura
3. Fandom, Available here: https://fossil.fandom.com/wiki/Arthropleura
4. National Geographic, Available here: https://blog.nationalgeographic.org/2011/01/15/largest-land-dwelling-bug-of-all-time/