Description

Arthropleura, derived from Greek meaning 'jointed ribs,' represents a genus of ancient millipede arthropods that inhabited regions which now constitute North America and Europe approximately 345 to 290 million years ago. Their existence spanned from the Viséan stage in the lower Carboniferous Period to the Sakmarian stage in the lower Permian Period. Within this genus, the species hold the distinction of being the largest terrestrial invertebrates ever recorded, likely existing with minimal or no natural predators.

As complete fossils of these massive creatures have yet to be discovered, there has been ongoing debate regarding their likely appearance. Nonetheless, the consensus among experts is that Arthropleura bore a striking resemblance to present-day millipedes. However, a notable distinction lies in the configuration of its body, which was divided into three segments – a central plate flanked by two side plates. Beneath their body, numerous pairs of legs were present, with a proportion of eight pairs of legs for every six body segments. Initially, researchers believed that the initial segment of this arthropod constituted its head. Yet, subsequent investigations revealed that the true head was positioned beneath this protective armor plate. This leading plate, known as the collum, was also adorned with non-filamentous antennae or trumpet-shaped organs.

Gigantism

As with other Carboniferous arthropods, its remarkable size is often linked to the elevated oxygen levels prevailing in that era's atmosphere. Numerous fossilized trackways have been conserved, revealing Arthropleura's movement through the Carboniferous forests, with some tracks indicating its traversal around trees.

Arthtropleura attained a length of 2.5 meters (8 feet 2 inches). Tracks measuring up to 50 centimeters (20 inches) in width, attributed to Arthropleura, have been discovered in Joggins, Nova Scotia. In 2021, a fossil, likely a discarded exoskeleton of an Arthropleura, was documented, estimating a width of 55 centimeters (22 inches), a length ranging from 1.9 meters (6 feet 3 inches) to 2.63 meters (8 feet 8 inches), and a body weight of 50 kilograms (110 pounds).

Diet and feeding habit

Due to the absence of a recovered mouth structure in Arthropleura, definitively determining whether it was an herbivore or carnivore has proven challenging. Researchers have thus turned their attention to the examination of the creature's digestive tract and fossilized feces, which have revealed the presence of plant spores such as those from ferns. This plant-based evidence, not typically found in carnivorous animals, strongly suggests that Arthropleura was indeed an herbivore.