Among the earliest large inhabitants of the seas and shallow waters were giant relatives of the scorpions and spiders. Some of these creatures were around 10 cm in length, but others were enormous — up to 2 m long. These fearsome creatures had a flattened armoured body, and claws tipped with sharp spines for catching their prey. As well as ordinary jointed walking legs, they had large paddle-shaped limbs with which they rowed themselves along. They could swim by beating their tails up and down. These creatures were the largest predators living in the seas 450 million years ago.
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