THESE RELATIVES of modern scorpions and horseshoe crabs were found in freshwater and sea between 440 million and 250 million years ago. Sea scorpions used their paddlelike limbs to swim rapidly. The larger species grew up to 7 feet (2.1m) and caught fish with their huge pincers.
EURYPTERUS This sea scorpion, about 5 inches (12.5cm) long, became extinct about 250 million years ago.
