Scientists in Germany have discovered a giant sea scorpion a massive 2.
5 metres in length; but don't panic it's been extinct for several million years.
Researchers at the University of Bristol discovered the fossilised 45 cm long chelicerae " pointed mouthparts used to grab food- in Prm, Germany in what is thought to be the remains of either a brackish lagoon or a flood plain lake.
The chelicerae come from Jaekelopterus rhenaniae an extinct euryptid thought to have been alive 390-428 million years ago, and now thought to be the largest arthropod ever to have evolved.
Using techniques used on other arthropods, the researchers extrapolated the size of the arthropod s body from it s claw size.
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They calculated that it must have measured somewhere between 233-259cm long with the extended chelicerae adding an extra metre to its total body length.
Previously, a number of terrestrial arthropods have been discovered such as 2 metre long millipedes and dragonflies with 75cm wingspans. This is thought to have been due to the elevated oxygen levels at the time.
However, J. rhenaniae and other related pterygotid euryptids were entirely aquatic so some other mechanism must have been operating.
This group were at the top of the food chain for their habitats and their chelicerae had developed into a pair of large, raptorial prey-catching organs.
Simon Braddy one of the team involved in the discovery of this fossil is reported as saying in Nature News:
This huge monster lived alongside other sea scorpions and fish, they would probably lie in wait. When another animal went in front of it, it would lurch forward and capture it. ... These things would tear their prey to shreds and then eat the little pieces."
Braddy speculates that they grew so big due to a lack of competition and predation from vertebrates.
The arrival of vertebrates that could out compete these sea scorpions in terms of locomotion, respiration and capturing prey meant that this species could no longer survive "It s a case of the vertebrates coming along and spoiling the arthropod party," he says.
For more information see: Braddy SJ, Poschmann M and OE Tetlie (2007) " Giant claws reveal the largest ever arthropod. Biology Letters. doi:10.1098/rsbl.2007.0491.