You know those special effects that involve shooting insects up close and then layering them on a background to make them look awfully huge? It was not this.
They might have missed being the stars of 300 million year old horror movies, but centipedes of the Arthopleura genus were the most gigantic insects of all time. Now, this creature’s largest fossilized exoskeleton has emerged (at least a segment of it). It is believed to have literally been the size of an average sedan at almost eight feet long and must have weighed around a hundred pounds. This easily makes this specimen the largest arthropod ever found – no special effects needed.
Discovered by Cambridge University researcher Neil Davies, who led a study recently published in the Journal of the Geological Society, it is a rare portal to the past. Insect exoskeletons rarely fossilize without collapsing. Creepy critters that are quite small are usually best kept in amber balls, but nothing like that. It turned out that one beam in Northumberland had fallen on another and opened it, exposing this nightmare fuel.
“The best-known fossils were from ancient coal mines, so people associated them with coal forests, but in fact the traces and this fossil suggest they lived in open woods,” Davies told SYFY WIRE .
Arthopleura used to thrive in what is now Northumberland, as it was a lush tropical refuge during the Carboniferous Period, when these many-legged monsters crept into the woods near the edges of rivers. The segment of the exoskeleton found had been molten. It could mean that this particular bug has gotten even bigger, although no one will ever really know how many times it has lost its outer shell in their lifetime. Most centipedes live around two years, but some could reach five and even ten years. By then, it might have grown to the size of a minibus. Davies agrees.
“It is likely that this individual has grown in size as it has moulted,” he said.
How did this bug become a monster? During the Carboniferous period, there was 10 to 15% more oxygen in the air. The bigger the body, the more oxygen it needed, and Arthropleura was taking massive amounts of it. Insects do not have lungs, but “breathe” through tiny openings, or stigmas, all over their body, which is why they are highly dependent on oxygen. Spiracles are directly connected to tissues that need oxygen. So many prehistoric life forms reached incredible sizes hundreds of millions of years ago because there was more oxygen available to them.
Obviously, Athropleura needed immense amounts of food, and while we couldn’t be sure what it was eating, the extant centipedes are decomposers looking for fungi, rotten leaves, and the like. detritus. Maybe he chewed on a few small vertebrates or invertebrates along the way. The worst thing that it would have ever done to modern humans is to panic us. In order to survive on our side, however, they would have had to somehow have developed an adaptation to maximize the oxygen supply to the atmosphere. The absence of birds and reptiles at the time would also have helped. The size of the insects began to decrease when predatory birds appeared on the scene with insect-hungry reptiles in the late Jurassic and began to capture them. There was also deadly climate change.
“Most likely, the assemblage of the Pangea supercontinent led to increased aridity, which means that previous forests have been replaced by conifers,” Davies said. “At the same time, reptiles have become dominant, so a double hit from less food and more competition.”
What’s mysterious about this new specimen is that it was preserved before atmospheric oxygen reached its peak, so species in this genus may have really turned into SUVs with legs. The only other known Arthropleura fossils that have surfaced, both in Germany, were considerably smaller than this specimen. Whether it is a different species of Arthropleura, juveniles or smaller individuals of the same species remains unknown. Perhaps finding a fossilized head of at least one of these creepers would reveal more about them.
“We want to know more about his affinities, because he is directly related to modern centipedes, as well as to have a better idea of what he was equipped to eat,” Davies said.
Don’t let a car-sized centipede slip into your dreams.