The fossil is made up of the bones of a creature called Arthropleura, which lived 326 million years ago. This is more than 100 million years before the Age of Dinosaurs. It shows that Arthropleura was the biggest invertebrate animal ever found. It was bigger than the ancient sea scorpions that were the previous record-holders, which were small. During the winter of 2018, a large block of sandstone fell from a cliff and hit the beach at Howick Bay in Northumberland. The fossil was found in the sandstone in January 2018. It was because of the way the boulder fell that it cracked open and perfectly exposed the fossil, which one of our former PhD students happened to see as he walked by.
With permission from Natural England and the owners of the land, the Howick Estate, a fossil was taken from the ground in May 2018. ‘It was a very exciting find,’ said Davies. The fossil is so big that it took four of us to carry it up the cliff face. The fossil was brought back to Cambridge so that it could be looked at in more depth. Arthropleura was previously thought to live in coal swamps, but this specimen shows that it prefers open woodlands near the coast.
Few in the world
There are only two other fossils of Arthropleura, both of them from Germany, and both of them are much smaller than the new one, which is a new species. It doesn’t matter that this is the largest Arthropleura fossil skeleton ever found. There is still a lot we don’t know about them. Getting fossils of these giant millipedes is very rare because their bodies tend to disintegrate when they die, so it’s likely that the fossil is a moulted shell that the animal shed as it grew, said Davies. Before, it was thought that Arthropleura was big because there was more oxygen in the air during the late Carboniferous and Permian periods. Because the new fossil comes from rocks that were deposited before this, it shows that oxygen isn’t the only reason.
In order to grow so big, Arthropleura must have had a lot of food. A group of animals called arthropleura lived on Earth’s equator for about 45 million years before they died out in the Permian period. The fossil will be shown to the public at Cambridge’s Sedgwick Museum in the New Year, when the museum is open again.
