Fossil of a giant millipede reveals “the biggest insect that ever lived”

One fossil of giant millipede, found on a beach in the north of the England, revealed the “largest insect that ever lived”, say paleontologists.

The fossil was discovered in January 2018 in a piece of sandstone that had fallen off a cliff on Howick Bay Beach in Northumberland. The rock split open, revealing the fossil.

“It was a complete accidental discovery,” said Neil Davies, professor of sedimentary geology in the Department of Earth Sciences at Cambridge University, who said the fossil was located by a former doctoral student.

“It was an incredibly exciting discovery, but the fossil is so big that it took four of us to carry it to the cliff face,” continued Davies.

The fossilized remains of the creature, called Arthropleura, dated back to the Carboniferous period about 326 million years ago. This was over 100 million years before the rise of the dinosaurs.

When alive, the creature was estimated to be 55 centimeters (22 inches) wide and up to 2.63 meters (8.6 feet) long, weighing 50 kilograms (110 pounds). That would make it the largest known invertebrate of all time — larger than the ancient marine scorpions that once held that title, the statement said. Invertebrates are animals without a backbone.

“This is definitely the biggest bug that has ever existed,” Davies confirmed via email.

It is only the third fossil of Arthropleura discovered. The other two were found in Germany and were much smaller than the new specimen.

To reach that size, they must have eaten a nutritious diet. At that time, Britain’s territory was on the equator, and invertebrates and early amphibians probably lived on vegetation that grew in a series of streams and rivers.

The researchers think the fossilized skeleton was likely a changed exoskeleton segment that filled with sand, preserving it.

“Finding these giant millipede fossils is rare, because once they die, their bodies tend to disarticulate (separate at the joints), so it’s likely that the fossil is a mute shell that the animal expelled while growing,” added Davies. “We haven’t found a fossilized head yet, so it’s hard to know everything about them.”

Arthropleura animals crawled for about 45 million years before becoming extinct. It is not known exactly why they disappeared, but it could be due to a change in climate that did not suit them. Or it could have happened during the rise of reptiles, which came to dominate the same type of habitat.

The fossil will be exhibited to the public at the Sedgwick Museum in Cambridge in 2022. The research was published in the Journal of the Geological Society.

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