Giant millipedes as long as a car and weighing 50kg once hunted across northern England, experts have revealed, after the discovery of a fossil from 326 million years ago.
The largest fossil of a giant millipede was found by a “fluke” on a Northumberland beach at Howick, after a section of cliff fell on to the shore.
To grow so large, the creature, known as Arthropleura, must have found a nutrient-rich plant diet or may even have been predators, feasting on other invertebrates or small amphibians.
The specimen is made up of articulated exoskeleton segments, broadly similar in form to modern millipedes.
It is only the third such fossil found, and is also the oldest and largest.
Experts believe the fossil represents just a section of the creature’s exoskeleton that it shed near a river bed, which was then preserved by sand.
The segment is about 75 centimetres long, leading scientists to believe its entire body could have measured about 2.7 metres and weighed 50 kilograms.
The remains of the creature date from the Carboniferous Period, more than 100 million years before the Age of Dinosaurs.
At the time, Great Britain was near the equator and enjoyed warm temperatures.
A former PhD student who was walking along the coast in January 2018 noticed it in a large block of sandstone that had fallen from the cliff.
"It was a complete fluke of a discovery," said Dr Neil Davies, from Cambridge University’s department of earth sciences, who was lead author of a paper on the fossil.
“The way the boulder had fallen, it had cracked open and perfectly exposed the fossil, which one of our former PhD students happened to spot when walking by.”
The fossil was removed with permission of Natural England and the landowners, the Howick Estate, and was taken to Cambridge for analysis.
It was so big it required four people to carry it.
“While we can’t know for sure what they ate, there were plenty of nutritious nuts and seeds available in the leaf litter at the time," Dr Davies said.
"And they may even have been predators that fed off other invertebrates and even small vertebrates such as amphibians.”
The creatures crawled around the equatorial region for about 45 million years before becoming extinct, possibly due to global warming that made the climate too dry for them, or because the rise of reptiles, which could have out-competed them for food.
The fossil will go on public display at Cambridge’s Sedgwick Museum in the New Year.
The results are reported in the Journal of the Geological Society.