The largest scorpion ever to walk the Earth once roamed an unlikely place.
Measuring at one metre in length, the Praearcturus gigas was equipped with pincers more than 16cm long and roamed Britain 415million years ago.
Yes, that’s right.You could’ve once come face-to-face with the beast here in the UK.
The findings by the Natural History Museum and The University of Manchester, published in the journal Palaeontology, were made possible by studying fossils that have been housed in the museum’s collections for more than 150 years.
Researchers used modern analytical techniques and comparisons with newly described fossil species to conclude that Praearcturus was a distinct species of scorpion.
Dr Richard J. Howard, Curator of Fossil Arthropods at the Natural History Museum in London and lead author of the study, said: ‘When we think of giant arthropods, people often picture Carboniferous rainforests with giant millipedes or dragonfly-like insects from later in Earth’s history. But Praearcturus lived at least 50 million years earlier, well before the evolution of trees, when life on land was only just getting started.
‘Confirming that this animal is a scorpion fundamentally changes our understanding of how and when these creatures evolved to such extraordinary sizes.’
The animal lived during the Early Devonian period, when small plants and fungi had only recently begun to spread across the landscape. Forests and other complex terrestrial ecosystems had yet to emerge.
Unlike later giant arthropods, Praearcturus did not benefit from the high atmospheric oxygen levels associated with the rise of forests.
Instead, scientists believe its enormous size may have been linked to a lack of competition from other large predators.
Dr Russell Garwood, a palaeontologist at the University of Manchester and co-author of the study, said: ‘Praearcturus has puzzled us palaeontologists for more than a century. By bringing together material from several collections and using cutting edge imaging techniques, we’ve been able to build a clearer picture of the animal than was previously possible, which is really exciting.
‘What makes Praearcturus so interesting is that it became enormous at a time when life on land was otherwise very small. But it was a world that could somehow support a giant predator. To try and better understand this ancient world we compared the size of fossil scorpions with other animals alive at the time. To reach such extraordinary sizes, and conclude that perhaps it lived in water, where life was bigger.”
Evidence from the fossils also suggests the giant scorpion may have spent part of its life in water.
Some specimens show flap-like structures on the abdomen similar to those found in modern crustaceans such as lobsters, raising the possibility that the animal could move between aquatic and terrestrial environments.
Researchers also found that scorpion fossils are unusually abundant in rocks from this period compared with other arachnids. This supports the idea that some early scorpions may have lived in freshwater habitats, where they were more likely to be preserved as fossils.
The findings place Praearcturus at a crucial stage in Earth’s history, when animals were first beginning to adapt to life beyond the oceans.
Dr Greg Edgecombe, Merit Researcher at the Natural History Museum and co-author of the study, said: “The boundary between land and sea was much less defined at this time. Praearcturus gives us a fascinating glimpse into how early animals adapted to these changing environments.
“It may even represent a lineage that returned to the water after earlier ancestors had already begun living on land.”
First described in 1871, Praearcturus gigas was originally thought to be a giant crustacean resembling a woodlouse.
However, the fragmentary nature of the fossils, which lacked key anatomical features such as a tail, made it difficult for scientists to classify the animal with certainty for more than a century.