World’s biggest scorpions were the size of baseball bats
Popular Science...
Giant scorpions the size of a baseball bat with pincers the size of a pencil once stalked what is now England and Wales. Praearcturus gigas is believed to be the largest scorpion to ever roam the Earth, and was discovered from fossils that have been tucked away in London’s Natural History Museum for more than 150 years. The findings are detailed in a study published in the journal Palaeontology.
Praearcturus gigas stalked the region’s floodplains about 415 million years ago, during the Early Devonian. Small plants and fungi had only recently begun to spread, and more complex land ecosystems like forests did not exist yet.
“When we think of giant arthropods, people often picture Carboniferous rainforests with giant millipedes or dragonfly-like insects from later in Earth’s history,” Dr. Richard J. Howard, a study co-author and the Curator of Fossil Arthropods at the Natural History Museum, said in a statement. “But Praearcturus lived at least 50 million years earlier, well before the evolution of trees, when life on land was only just getting started.”
Howard and the team believe that Praearcturus’ enormous size indicates that they had very little competition from other large predators roaming around. Praearcturus might have grown to three-feet-long with six-inch pincers simply because there weren’t any other large animals nearby, so it could dominate its environment in a way that wouldn’t be possible years down the road.
Praearcturus gigas was first scientifically decided in 1871. Scientists originally thought it was some kind of giant crustacean, similar to a woodlouse. The fossils were very fragmented, and lacked key features (such as a tail) that help classify it. To get a better picture, the team compared their fossils with some more well-preserved specimens found in 1972 and 2010.
“Praearcturus has puzzled us palaeontologists for more than a century,” added Dr. Russell Garwood, a study co-author and palaeontologist at The University of Manchester. “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.”
The fossils hint that this giant scorpion may have lived in the water some of the time. Some specimens have flap-like structures on the abdomen that are similar to those found in modern crustaceans like lobsters. These flaps suggest Praearcturus may have been capable of moving between water and land. Their place in the wider arachnid fossil record shows that most scorpions are unusually abundant in rocks dating back to this time period, compared with other arachnid species. This supports the idea that Praearcturus may have lived in freshwater environments, where they are more likely to survive as fossils. Excitingly, it shows that Praearcturus lived at a pivotal moment in our planet’s history, when animals were first experimenting with living life outside the oceans.
“The boundary between land and sea was much less defined at this time,” said Dr. Greg Edgecombe, a study co-author and Natural History Museum researcher. “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.”
According to the team, a breakthrough like this shows how important discoveries are still being made from museum collections. It also challenges assumptions about why prehistoric arthropods reached such enormous sizes. Instead of being driven solely by environmental factors like oxygen levels, a lack of competition, and other ecological opportunities may have played a crucial role.
“Confirming that this animal is a scorpion fundamentally changes our understanding of how and when these creatures evolved to such extraordinary sizes,” said Howard.
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